Symposium Organizers
Antigoni Alexandrou Ecole Polytechnique
Jinwoo Cheon Yonsei University
Hedi Mattoussi Florida State University
Vince Rotello University of Massachusetts
XX1: Design of Luminescent QDs and QD-assemblies for Targeted Use in Biology
Session Chairs
Moungi Bawendi
Paul Mulvaney
Monday PM, November 30, 2009
Room 309 (Hynes)
9:30 AM - **XX1.1
Nanocomposite Engineering of Nanocrystalline Materials.
Jackie Ying 1
1 , Institute of Bioengineering and Nanotechnology, Singapore Singapore
Show AbstractNanocrystalline materials are of interest for a variety of applications. This talk describes the design and functionalization of nanocomposite materials for biological and chemical applications. Specifically, we have synthesized metallic, metal oxide and semiconducting nanocrystals for bioimaging, biolabeling, bioseparation, biosensing and catalytic applications. These nanocrystals are ≤ 10 nm in size, and are surface modified to provide for high dispersion, biocompatibility, and water solubility. They are used as building blocks to create multifunctional nanocomposite particles with unique properties.
10:00 AM - XX1.2
InAs(ZnCdS) Quantum Dots Optimized for Biological Imaging in the Near-infrared.
Peter Allen 1 , Wenhao Liu 1 , Moungi Bawendi 1
1 Chemistry, MIT, Cambridge, Massachusetts, United States
Show AbstractWe present a series of InAs(CdZnS) semiconductor nanocrystals, aka quantum dots, that are optimized for bright and stable emission in the near-infrared region (700-900nm). The synthesis and characterization of the core/shell InAs(CdZnS) quantum dots is presented. The quantum dots are then functionalized, via ligand exchange, with a variety of biocompatible ligands to enable water solubilization. Preliminary in vivo and in vitro biological imaging experiments are discussed.
10:15 AM - XX1.3
Bioactivated PEGylated Quantum Dots and Magnetic Nanoparticles: Functionalization and Interaction with Biological Systems.
Valerie Marchi-Artzner 1
1 chemistry , university rennes 1, Rennes France
Show AbstractThe inorganic core-shell semiconductor nanocrystals (QD), for example CdSe/ZnS, possess a range of tunable optical fluorescence properties whereas the surface ligand can be optimized to tailor interactions with the surroundings and control the final size of the nanocrystals. Whatever the application involving nanocrystals is, the chemical grafting of their surface has to be very well controlled. Therefore we developed two strategies to chemically functionalize the surface of the nanocrystals. The first one is based on the use of the self-assembling properties of synthetic gallate amphiphiles (Boulmedais, F. Langmuir, 2006, 22 (23), 9797) or polymer (Luccardini et al, Langmuir, 2006, 22(5), 2304). Its simple dilution into water induced the formation of well dispersed QD micelles. The second one consists in remplacing the initial ligands with short peptides having a higher affinity for the QD surface (Dif A. et al, J.A.C.S.2008, 130, (26), 8289). The use of the QD as biolabel for individual protein tracking requires the developments of simple methods to target an individual protein in a controlled manner in living cells or cellular extract. In particular the controlled stoechiometry of a stable protein-QD complex together with the preservation of the biological functionality after labelling remains unsolved. In this view, we describe here a specific targeting of proteins bearing a histamine-rich sequence with either QD micelles (Roullier, V. et al, Nanolett. 2009, 9(3), 1228-1234) or small PEGylated peptidic quantum dots (Dif, A. et al, submitted). The quantum dots possess a metal ion-chelating (multi-dentate) ligand at the surface that can bind selectively the histag proteins in vitro and in living cells (HeLa cells transfected with a histag membranar protein). The cytotoxicity of these QD micelles and Pegylated peptidic QD was studied on living cells.We describe here the properties of bioactivated nanoparticles combined magnetic and fluorescent properties within one single nanometer-sized nanoparticle used as an active label of a biological receptor. Bioactivated fluorescent magnetic micelles with a hydrodynamic diameter of around 30 nm containing both hydrophobic CdSe/ZnS quantum dots (QD) and γ-Fe2O3 nanocrystals are obtained and can be manipulated to induce a non-diffusive spatiotemporal distribution in the presence of a magnetic gradient field (Roullier, V. et al, Chem. Mat., 2008, 20, (21), 6657). Their magnetic and fluorescent properties were evaluated as dual probes for MRI and fluorescence imaging as well as their cytotoxicity in living cells.
10:30 AM - **XX1.4
The Preparation of Colloidally Stable, Water-Soluble,Biocompatible, Semiconductor Nanocrystals with a Small Hydrodynamic Diameter.
Paul Mulvaney 1
1 School of Chemistry & Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
Show AbstractWe report a simple, economical method for generating water soluble, biocompatible nanocrystals that are colloidally robust and have a small hydrodynamic diameter. The nanocrystal phase transfer technique utilizes a low molecular weight amphiphilic polymer that is formed via maleic anhydride coupling of poly(styrene-co-maleic anhydride) with either ethanolamine or Jeffamine M-1000 polyetheramine. The polymer encapsulated water soluble nanocrystals exhibit the same optical spectra as those formed initially in organic solvents, preserve photoluminescence intensities, are colloidally stable over a wide pH range (pH 3--13), have a small hydrodynamic diameter and exhibit low levels of non-specific binding to cells [1].[1] Emma E. Lees, Tich-Lam Nguyen, Andrew H. A. Clayton, and Paul Mulvaney, "The Preparation of Colloidally Stable, Water-Soluble,Biocompatible, Semiconductor Nanocrystals with a Small Hydrodynamic Diameter", ACS Nano, 3, 1121-28 (2009).
11:30 AM - **XX1.5
Designing Nanocrystal Quantum Dots for Biological Imaging.
Moungi Bawendi 1
1 Department of Chemistry, MIT, Cambridge, Massachusetts, United States
Show AbstractThis talk will focus on the application of nanocrystal quantum dots in biological and biomedical imaging. We will discuss control of the hydrodynamic size, valency, and non-specific binding. We will also discuss the development of quantum dots and their ligand families that aim for minimized hydrodynamic diameter and that emit in the visible and the near IR. We will also discuss the development of “smart” quantum dot systems that are more than passive reporters of their location, but that also act as biochemical sensors of their microenvironment. For this we will focus on quantum dot pH sensing of the tumor microenvironment.
12:00 PM - XX1.6
Synthesis of Visible and Near Infrared-emitting CuInS2/ZnS QDs and Their Application for in vivo Imaging.
Thomas Pons 1 , Emilie Pic 2 , Nicolas Lequeux 3 , Elsa Cassette 1 , Lina Bezdetnaya 2 , Frederic Marchal 2 , Francois Guillemin 2 , Benoit Dubertret 1
1 LPEM - UPR0005, CNRS, Paris France, 2 Centre de Recherche en Automatique de Nancy, Centre Alexis Vautrin, CNRS, Nancy France, 3 PPMD - UMR7615, CNRS-ESPCI, Nancy France
Show AbstractSemiconductor nanocrystals, or quantum dots (QDs), have attracted much attention over the last years due to their exceptional electronic and optical properties. They present high extinction coefficients, photoluminescence (PL) quantum yields (QY) and photostability, and their narrow emission spectra can be tuned by size and composition. They have therefore become promising alternatives to organic chromophores in many applications as light absorbers or emitters, from photovoltaics and light emitting diodes to fluorescent probes for biological imaging. In particular, QDs have the potential to significantly impact the performance of near infrared fluorescence imaging for biomedical research, diagnostics and optically assisted surgery. For example, QDs could be applied to detection of the sentinel lymph node, the status of which is a key prognostic factor for treatment of many types of cancer. Unfortunately, QD emitting in the near infrared have been so far composed of toxic compounds (Cd, Pb, Hg, Te, As…). The potential long term release of these toxic elements in the body has thus been a major obstacle to the QD clinical use, but would also represent an important hurdle for large scale optoelectronic applications.CuInS2 is an I-III-VI2 semiconductor with a direct band gap of 1.45 eV, corresponding to an 855 nm emission wavelength, and does not contain any toxic heavy metals. This material could therefore offer the opportunity to fulfil the potential of semiconductor QDs without the toxicity limitations encountered by II-VI QDs, and provide PL emission ranging from the visible to the near infrared. Here we present the synthesis of bright and photo-stable core/shell CuInS2/ZnS QDs with emission ranging from the visible to near infrared range using air-stable compounds and discuss their optical properties. We show that these QDs could be easily transferred in water using two standard solubilization techniques, ligand exchange and micelle encapsulation. We demonstrate their use for in vivo imaging and detection of regional lymph nodes in mice, and present a preliminary comparison of toxicity with Cd-based QDs. Careful toxicity studies will be required before any clinical applications, but we expect that these QDs will find many applications for in vivo biomedical imaging where toxic heavy metals cannot be tolerated.
12:15 PM - XX1.7
Quantitative Quantum Qot (QD) Methods for Tracking Stem Cells Noninvasively in vivo.
Rowena Mittal 1 2 , Marcel Bruchez 3 2 1
1 Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 2 Molecular Biosensor & Imaging Center, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 3 Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
Show AbstractOne of the most promising advances in the field of regenerative medicine has been the isolation of pluripotent stem cells, embryonic and adult, capable of differentiating into multiple tissue types. Yet a critical question remains: what is the fate of transplanted stem cells in vivo over the time of an experimental study? Presently, there are no effective noninvasive toolsets available to monitor stem cells in vivo. Due to their tunable physiochemical and fluorescent characteristics, brightness, and stability, quantum dots (QDs) have great potential for noninvasive cell tracking in regenerative medicine. However, observations of QD labeled cells have been mainly qualitative in nature, limiting our ability to determine ideal loading conditions for long-term imaging in vivo. Currently, there is no standard method for determining the number of particles taken per cell to make comparisons between experiments and literature. Without this value, optimizing a QD toolset for tracing stem cell fate will be challenging.Therefore, we developed methods utilizing commercially available materials and accessible tools to quantify QD characteristics and internalization by cells. First, we present a method using flow cytometry and calibration standards to assess the number of QDs internalized per cell. This method accounts for batch dependent differences in relative brightness of QDs. Second, we describe a biotin-4-fluorescein fluorescence plate reader assay to quantify the number of biotin binding sites per QD available per batch of streptavidin (SAv) QDs. Applying these straightforward techniques in vitro demonstrated unique uptake behavior by mouse fetal skin-derived dendritic cells (FSDCs), mouse myoblast stem cells (C2C12s), and mouse fibroblast cells (NIH3T3s) exposed to 0, 1, 4, and 8 nM loading concentrations of 705 nm polyarginine (polyarg) conjugated SAv QDs. The retention of polyarg QDs loaded at 8 nM was quantified over 5 days in all cell types. Moreover, the internalization of polyarg QDs by cells was dependent on the number of biotin binding sites available per SAv QD and conjugation reaction conditions. Lastly, initial limits of detecting QD tagged cells in our in vivo imaging system were benchmarked to establish in vivo QD loading criteria. These novel methods and quantitative results have allowed us to make comparisons of QD uptake and retention by cells with respect to cell type, QD conjugate type, QD bioactivity, and experimental conditions. This information will be invaluable for improving commercial and novel QD toolsets for cell tracking and for determining the effect of QD uptake on stem cell function and cytotoxicity – an area still under investigation. In the long term, the application of quantified methods developed here will help move cell-based therapies from the bench to the clinic.
12:30 PM - XX1.8
Tailored Quantum Dot Surface Modification for Biomedical Applications.
Joonhyuck Park 1 , Jutaek Nam 2 , Jin Ho 2 , Sungho Jung 2 , Nayoun Won 2 , Sungwook Jung 1 , Sungjee Kim 1 2
1 School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang Korea (the Republic of), 2 Department of Chemistry, Pohang University of Science and Technology, Pohang Korea (the Republic of)
Show AbstractBio-compatible quantum dots (QDs) can be used for a platform technology to track various biomolecules or target specific cells by their unique and advantageous optical properties. We synthesize a family of modified Dihydrolipoic acids to meet the diverse demands of QD surfaces for biological applications. The QD surfaces can be decorated by, but not limited to, carboxylic acids, various amines, sulfates, and zwitterion groups. We can provide QDs with excellent colloidal stabilities over a broad pH range in complex biological media. We can also make QD surfaces anti-fouling as minimizing the non-specific bindings. The surface engineered QDs can be used for cell trafficking, tissue imaging, and single molecule imaging of a protein on an extracellular matrix. We have investigated the endocytosis mechanisms of QDs depending on their surface properties. HeLa cells were cultured with QDs with the surfaces of carboxylic acids, tertiary amines and zwitterions. Systematic endocytosis inhibition studies were performed along with flow cytometry and confocal laser scanning microscopy. The nature of QD surface critically determines the mechanism and rate of cellular uptakes. It was revealed that carboxylic acid coated QDs internalize into HeLa cells mostly by ATP-dependent endocytosis whereas tertiary amine coated ones prefer lipid-raft-dependent macropinocytosis. We will also discuss the internalization of QDs into cytosols of prokaryotic cells by electroporation.
12:45 PM - XX1.9
Bio-imaging of Hyaluronic Acid Derivatives Using Quantum Dots.
Sei Kwang Hahn 1 , Ki Su Kim 1 , Sang Joon Park 1 , Jiseok Kim 1
1 Advanced Materials Sciences and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk, Korea (the Republic of)
Show AbstractHyaluronic acid (HA), is a biodegradable, biocompatible, non-immunogenic and non-inflammatory linear polysaccharide, which has been used for various medical applications such as arthritis treatment, ocular surgery, tissue augmentation, and so on. In this work, the effect of chemical modification of HA on its distribution throughout the body was investigated using quantum dots (QDot) for target specific and long acting drug delivery applications. According to the real time bio-imaging of HA derivatives, HA-QDot conjugates with 35 mol% HA modification maintaining enough binding sites for HA receptors were mainly accumulated in the liver, while those with 68 mol% HA modification losing much of HA characteristics were evenly distributed to the tissues in the body. The results are well matched with the fact that HA receptors are abundantly present in the liver with a high specificity to HA molecules. Based on these findings, slightly modified HA derivatives were used for target-specific intracellular delivery of siRNA and highly modified HA derivatives were used for long acting conjugation of peptide and protein therapeutics. This presentation will give you a brief overview on novel HA derivatives for various drug delivery applications.
XX2: Nanocrystal Functionalization to Promote Hydrophilicity and Biocompatibility
Session Chairs
Charles Cao
Francisco Raymo
Monday PM, November 30, 2009
Room 309 (Hynes)
2:30 PM - **XX2.1
Nanocrystals for Biomedical Diagnosis.
Charles Cao 1
1 Chemistry, University of Florida, Gainesville, Florida, United States
Show AbstractBecause of their unique size-dependent optical, electronic, magnetic, and chemical properties, inorganic nanocrystals are becoming a new class of powerful tools in biological and medical applications for sensing, labeling, optical imaging, magnetic resonance imaging (MRI), cell separation, and treatment of disease. These applications, however, require nanocrystals that are soluble and stable in aqueous solutions, and thus creating a need to further engineer nanocrystal coatings, because those high-quality nanocrystals are often synthesized in organic phase and stabilized with hydrophobic ligands. To date, two major approaches have been developed to modify the coatings of hydrophobic nanocrystals using organic ligands. The first approach is based on coordinate bonding. Functional groups (such as thiol, dithiol, phosphine and dopamine) are used to directly link hydrophilic groups onto the surface of hydrophobic nanocrystals by replacing their original hydrophobic ligands. The second approach uses hydrophobic van der Waals interactions, through which the hydrophobic tails of amphiphilic ligands interact with (but do not replace) the hydrophobic ligands on nanocrystals, and it leads to the formation of nanocrystal-micelles. Many types of water-soluble nanocrystals made by these two approaches suffer low stability and/or high non-specific binding with non-target biomolecules. Water-soluble nanocrystals coated with PEGylated amphiphilic polymers are proven to have very high stability and low nonspecific-absorption levels, but PEGylated polymer shells often produce large hydrodynamic diameters (HDs) on the order of 30-40 nm, which could limit the use of these nanocrystals in applications such as in vivo cell imaging. Herein, we report an alternative nanocrystal-surface-engineering approach that uses a new class of ligands (here called dual-interaction ligands) to produce water-soluble nanocrystals of gold, Fe3O4, CdSe/ZnS quantum dots (QDs) and Mn-Doped QDs. These dual-interaction ligands can bind onto the surface of hydrophobic nanocrystals through both coordinate bonding and hydrophobic van der Waals interactions. The resulting water-soluble nanocrystals have relatively small HDs (e.g., less than 20 nm), and exhibit extraordinary stability in a wide range of pH (e.g., 1-14), salt concentrations, and thermal treatment (at 100 oC). We have demonstrated the use of these nanocrystals for monitoring virus expression in cells as well as for detecting protein of interest in blood samples.
3:00 PM - XX2.2
Dual-Water-Phase Reverse Micelle Method to Prepare Silica Beads with Separately Impregnated Highly Photoluminescent and Magnetic Nanocrystals.
Norio Murase 1 , Ping Yang 1 , Masanori Ando 1
1 Photonics Research Institute, National Institute of Advanced Industrial Science & Technology, Ikeda, Osaka563-8577, Japan
Show AbstractSol-gel-derived silica beads encapsulating highly luminescent semiconductor nanocrystals (NCs) can additionally host other materials, such as magnetic NCs, in a specially prepared hollow sphere within the beads, resulting in dual functionality. Several sol-gel approaches have been used to synthesize magnetic-luminescent silica beads. However, the direct attachment of magnetic nanocrystals (MNCs) and luminescent nanocrystals (LNCs) reduces photoluminescence (PL) efficiency. We have prepared luminescent silica beads by using a reverse micelle method, in which water droplets formed in a continuous oil phase. Water-soluble CdTe NCs disperse in the water droplets. Alkoxide molecules, such as tetraethoxysilane (TEOS), initially disperse in the oil phase gradually enter the water phase as they becomes more and more hydrophilic accompanied by hydrolysis. After the hydrolyzed TEOS condenses in the water droplets, silica beads with impregrated LNCs are synthesized. A newly developed modified version of this reverse micelle method presents silica beads with impregnated LNCs with high PL efficiency and MNCs. In this version, two water phases are used. The first is the same as described above: aqueous solution of LNCs and hydrolyzed TEOS. The second phase is dispersion of MNCs under high pH (~10) conditions. Following the formation of droplets by the first water phase and subsequent hydrolysis of TEOS in the droplet, the second water phase goes in to the water droplets. This creates a hollow space inside of each droplet because the interface in a droplet quickly forms a wall of silica by condensation of alkoxide due to the high pH of the second water phase. This creates silica beads (100–200 nm in diameter) with dispersed LNCs in the continuous silica phase and MNCs in the hollow part of each bead. Since the two types of NCs are separated, their specific properties are not degraded by the preparation. The result is highly photoluminescent and magnetic beads. The initial PL efficiency (68%) of the LNCs was maintained with saturated magnetization of 3 emu/g; the decrease from the initial value (45 emu/g) is explained by the reduced weight ratio in the silica beads. The brightness of these beads makes them well suited for biological tagging and collection. The characteristics of the prepared beads were clarified by TEM, ADF, and chemical analysis together with XRD.
3:15 PM - XX2.3
Mediating Cellular Uptake and Endosomal Escape of Quantum Dots using Modular Designer Peptides.
Kelly Boeneman 1 , James Delehanty 1 , Bing Mei 2 , Juan Blanco-Canosa 3 , Phillip Dawson 3 , Hedi Mattoussi 2 , Igor Medintz 1
1 Center for Biomolecular Science and Engineering, Naval Research Laboratory, Washington, District of Columbia, United States, 2 Division of Optical Sciences, Naval Research Laboratory, Washington DC, District of Columbia, United States, 3 Departments of Cell Biology and Chemistry, Scripps Research Institute, La Jolla, California, United States
Show AbstractTo realize the full potential of luminescent semiconductor quantum dots (QDs) as intracellular labeling reagents and sensors, robust methods for their targeted intracellular delivery must be developed. We have previously shown that QDs self-assembled with a histidine-appended polyarginine ‘Tat’ cell-penetrating peptide (CPP) could be specifically delivered in a non-toxic manner to HEK293T/17 and COS-1 cells via endocytic uptake [1]. We have further assessed the long-term intracellular stability and fate of these QD-peptide conjugates and found that they remained sequestered within the acidic endolysosomes for at least three days after initial uptake; the CPP remained stably associated with the QD throughout this time. This appears to corroborate other findings that, regardless of the size or nature of the ligand used to facilitate endocytic uptake, almost all QD-conjugates subsequently remain in this vesicular system and do not access the cytosol [2]. To address this limitation, we explored a variety of techniques to either actively deliver QDs directly to the cytosol or facilitate their endosomal escape into the cytosol. Active methods such as electroporation and nucleofection delivered only modest amounts of QDs to the cytosol that appeared to be aggregated. Delivery using polymeric transfection reagents resulted in primarily endosomal sequestration of QDs, although in one case a commercial reagent did facilitate a modest cytosolic dispersal of the nanocrystals, but only after several days of culture and with a significant amount of polymer-induced cytotoxicity. In comparison, a modular, amphiphilic peptide expressing a variety of overlapping functionalities and designed for cell penetration and vesicular membrane interactions was found to mediate rapid QD uptake followed by a slower endosomal release of the QD-conjugates which peaked at 48 hours after initial delivery. Importantly, this QD-peptide bioconjugate elicited minimal cytotoxicity in the cell lines tested. We have also utilized various modifications of this peptide sequence expressing specifically deleted residues to identify the critical functional attributes which provide it with both cellular uptake and endosomal escape capabilities. We will present these results and discuss how a better understanding of these processes can allow cellular delivery of QD-conjugates capable of targeted in vivo sensing applications. 1.Delehanty, J.B., et al., Self-assembled quantum dot-peptide bioconjugates for selective intracellular delivery. Bioconj. Chem., 2006, 17:920-927.2.Delehanty, J.B., et al., Delivering quantum dots into cells: strategies, progress and remaining issues. Anal. Bioanal. Chem., 2009, 39:1091-1105.
3:30 PM - XX2.4
Synthesis and Cytotoxicity Evaluation of Highly Luminescent, Water-Soluble InP and ZnS-Coated InP Quantum Dots.
Yuxuan Wang 1 , Chai Hoon Quek 2 , Kam Leong 3 , Jiye Fang 4 1
1 Materials Sci. & Eng., State University of New York at Binghamton, Binghamton, New York, United States, 2 Mechanical Eng. & Materials Sci., Duke University, Durham, North Carolina, United States, 3 Biomedical Eng., Duke University, Durham, North Carolina, United States, 4 Chemistry, State University of New York at Binghamton, Binghamton, New York, United States
Show AbstractSemiconductor quantum dots (QDs) are gaining much attention as a new class of luminescence probes for biological detection and labeling. For in vivo imaging, the QD should ideally emit at the near IR range to minimize background interference. However, the frequently used CdSe-based QDs often exhibit properties too close to the optimal biological window of transmission. Hypothesizing that InP-based QDs would overcome this disadvantage, we synthesized InP and ZnS-coated InP QDs using a high-temperature organic solvent approach, and subsequently transfer them into aqueous phase through a ligand-exchange process using various functional surfactants including Trichloro-s-triazine modified mPEG. Structural characterizations and luminescence examination of these water-soluble QDs revealed an average size of ~3-4 nm and a high quantum yield. The cytotoxicity of the as-synthesized QDs against phaeochromocytoma PC12 cells and primary hepatocytes as evaluated by the MTS cell viability assay was low relative to other inorganic QDs. This study suggests a bright potential for this new type of InP/ZnS-coated InP QDs in bioimaging.
3:45 PM - XX2.5
Toward Development of High-quality Water-soluble PbS Quantum Dots.
Haiguang Zhao 1 , Mohamed Chaker 1 , Dongling Ma 1
1 , INRS, Varennes, Quebec, Canada
Show AbstractNear infrared (NIR) quantum dots (QDs) have attracted much attention due to their unique size-tunable optical properties. They are currently exploited for various applications, such as optoelectronics and biological markers. Among them, the use of NIR QDs for in vivo deep-tissue imaging is particularly attractive in view of the improved tissue penetration of lights and decreased tissue autofluorescence. However, it is still a challenge to synthesize bright, highly stable and biocompatible NIR emitting QDs. Recently, we have synthesized high-quality PbS QDs via a simple, solventless, greener approach which can be dispersed very well in the organic phase. In order to make them suitable for biomedical applications, various amphiphilic molecules have been used as phase transferring agents. Through detailed investigation, it is found that the quantum yield and lifetime of transferred PbS QDs are very sensitive to the initial surface ligand structure and the structure of amphiphilic molecules. Under certain circumstances, significant structure deterioration after the phase transfer results in the complete loss of the photoluminescence of PbS QDs. By forming a compact, protective surface layer, the structural integrity has been maintained and the quantum efficiency as high as that of the initial PbS QDs in the organic phase has been achieved in the aqueous phase.
4:30 PM - **XX2.6
Hydrophilic Polymer Ligands for Semiconductor Quantum Dots.
Francisco Raymo 1
1 Chemistry, University of Miami, Coral Gables, Florida, United States
Show AbstractThe outstanding photophysical properties of semiconductor quantum dots suggest that these inorganic nanoparticles can become valuable alternatives to conventional organic dyes in a diversity of bioimaging applications. These nanostructured assemblies, however, are not soluble in aqueous environments in their native form and must be passivated with hydrophilic coatings to ensure biocompatibility. In particular, their native hydrophobic surfactants can be replaced with hydrophilic thiols or coated with amphiphylic polymers to impose aqueous solubility. Nonetheless, the first strategy produces nanoparticles with poor quantum yields and limited stabilities, while the second approach increases significantly their physical dimensions. In order to overcome these limitations, we designed a series of ligands incorporating multiple thiol groups and poly(ethylene glycol) chains along a common polymer backbone. These macromolecular constructs adsorb on the surface of preformed CdSe/ZnS core-shell quantum dots to produce hydrophilic nanoparticles with compact dimensions, excellent quantum yields and long-term stabilities. Furthermore, these luminescent probes can cross cell membranes and are not cytotoxic. Thus, our novel polymer ligands can eventually lead to the development of valuable biocompatible quantum dots for the convenient investigation of cellular processes and visualization of subcellular structures.
5:00 PM - XX2.7
Aniline-Catalyzed Hydrazone Ligation: An Alternative Chemistry for the Multivalent Display of Biomolecules on Quantum Dot Surfaces.
Duane Prasuhn 1 , Juan Blanco-Canosa 3 , Kimihiro Susumu 2 , Gary Vora 1 , James Delehanty 1 , Hedi Mattoussi 2 , Philip Dawson 3 , Igor Medintz 1
1 Center of Bio/Molecular Science & Engineering - Code 6910, US Naval Research Laboratory, Washington, District of Columbia, United States, 3 Department of Cell Biology and Chemistry, Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States, 2 Division of Optical Sciences - Code 5611, US Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractWith their unique photoluminescent properties, semiconductor quantum dots (QDs) are promising nanoparticle-based scaffolds for biosensing and biomedical applications. One of the principle hurdles for the wider incorporation of QDs in biology continues to be the lack of facile linkage chemistries that allow the multivalent display of biomolecules such as proteins, peptides, and DNA on the QD surface in a controlled manner. Current methodologies are based on a limited set of functional groups and allow only minor control over the number and spatial orientation of the attached biomolecules. Aniline-catalyzed hydrazone coupling which has recently been demonstrated for modifying peptides and proteins may be a viable alternative for attaching biomolecules onto QD surfaces. This arises from the inherent regio-selectivity of the chemical ligation chemistry itself. Further, high reaction rates that approach >90% completion in less than one day using equimolar reactant concentrations can be carried out in mild, aqueous conditions of slightly acidic to neutral pH. We have tested two versions of this chemical approach. In the first, a polyhistidine ‘starter’ peptide is ligated to the targeted peptide or DNA of interest and facilitates subsequent self-assembly to the QD surface. The modularity of this approach was demonstrated by utilizing the final QD conjugates in sensing, cellular delivery, and DNA hybridization assays. It was also used to investigate resonance energy transfer in QD-assemblies with complex architectures. Examples of each will be discussed along with their utility. The second approach to this chemistry ligates targeted peptides or DNA directly to modified capping ligands already present on the QD surface. This methodology may be a viable approach for the controlled engineering of not only hybrid QD-biological systems, but is applicable to other types of nanoparticle materials.
5:15 PM - XX2.8
Study of Diamond photoluminescent Nanoparticles Uptake Mechanism in Cultured Cells.
Orestis Faklaris 1 , Vandana Joshi 2 , Abdallah Slablab 1 , Yan-Kai Tzeng 3 , Geraldine Dantelle 1 , Hugues Girard 4 , Celine Gesset 4 , Jean-Paul Boudou 2 , Mohamed Sennour 5 , Alain Thorel 5 , Jean-Charles Arnault 4 , Patrick Curmi 2 , Francois Treussart 1
1 Laboratoire de Photonique Quantique et Moléculaire, Ecole Normale Supérieure de Cachan, CNRS UMR 8537, Cachan France, 2 Laboratoire Structure et Activité des Biomolécules Normales et Pathologiques, Université d’Evry-Val-d’Essonne, INSERM U829, Evry France, 3 Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei Taiwan, 4 Diamond Sensor Laboratory, CEA LIST, Gif-sur-Yvette France, 5 Laboratoire Pierre-Marie Fourt, CNRS UMR 7633, Centre des Matériaux de l’Ecole des Mines de Paris, Evry France
Show AbstractSingle molecule observation is of great importance to study biomolecules interactions. Organic dyes are widely used as biomarkers but lack of photostability. One of the most used alternative system are the semiconductor Quantum Dots (QDs). Although very efficient for multicolour staining, they suffer of blinking and may be cytotoxic. In contrast, diamond nanoparticles containing nitrogen-vacancy (NV) color centers are a promising alternative. NV-centers neither photobleach nor blink and nanodiamonds are biocompatible. Here we investigate the uptake mechanisms of 35 nm photoluminescent nanodiamonds (PNDs) at the single particle level in culture cells. Moreover, we study and compare the photophysical properties of single PNDs and QDs.Nanodiamonds are made photoluminescent by particle beam irradiation creating vacancies and subsequent annealing. HeLa cells were grown in standard conditions and mounted on microscope slides or prepared for TEM observations. For endosomal and lysosomal labeling fluorescein was used. Colocalization was examined by either a home-made confocal microscope with single-photon detectors or with a SPC2 Leica microscope. Endocytosis was blocked by incubating cells at 4°C or by drug treatment. For single particle observations, the nanoparticles were spin-coated on glass coverslips.By endosomal and lysosomal staining and by hindering endocytosis uptake with drugs we find that PNDs are internalized by receptor-mediated endocytosis. With colocalization analysis we find a perfect colocalization of PNDs-aggregates in endosomal or lysosomal vesicles while for single PNDs the colocalization is partial. We verify these results by HR-TEM measurements. Moreover, we show that a single NV-center is 3-4 times less bright than a single QD, but that optimization of PNDs preparation leads to 20 nm PNDs containing up to 6-7 NV-centers, that are brighter than a single QD at the end.To summarize, we determined the internalization mechanism of PNDs. Thanks to their higher brightness and photostability compared to other biomarkers, PNDs are promising intracellular markers, which could also serve as drug delivery devices.
5:30 PM - XX2.9
Conjugating Luminescent CdTe Quantum Dots with Biomolecules.
Christina Gerhards 1 , Christian Schulz-Drost 1 , Vito Sgobba 1 , Dirk Guldi 1
1 Department of Chemistry and Pharmacy , Friedrich-Alexander University Erlangen-Nuernberg, Erlangen Germany
Show AbstractThe interest in semiconductor quantum dots (QD) has been continuously increasing during the last two decades. As the physical and chemical properties of semiconductor QDs differ greatly from those of their corresponding bulk materials numerous applications have emerged (i.e. photodiodes/solar cells, phototransistors, integrated optical circuit elements, lasers). [1, 2] Furthermore QDs have unique optical properties such as high emission quantum yields, broad absorption and narrow, symmetric photoluminescence, high molar extinction coefficients, remarkable resistance to chemical- and photodegradation as well as to photobleaching. [3] Considering, for example, the emission features, a key asset is that they span the full visible region of the solar spectrum as a result of tunable band gaps together with a very broad excitation wavelength range. Important is in this context that traditional markers based, for example, on organic molecules fall short of providing long-term stability and simultaneous detection of multiple signals. [4]Biological labeling by conjugation of inorganic nanostructures with biomolecules represents a significant milestone. These inorganic nanostructure / biomolecule conjugates combine the properties of both materials, namely exhibiting the spectroscopic characteristics of the QDs, while preserving the function of the biomolecules. [5] I will present interactions between water soluble, luminescent CdTe QDs and different redoxactive proteins (i.e., cytochrome c). [6] Characterization spans from simple UV-Vis absorption assays to transient absorption, steady-state and time-resolved photoluminescence spectroscopy as well as HR-TEM.References:[1] D. V. Talapin, S. Haubold, A. L. Rogach, A.Kornowski, M.Haase, H. J. Weller, Phys. Chem. B 2001, 105, 2260. [2] M.Gao, S. Kirstein, H. Mohwald, A. L. Rogach, A.Kornowski, A. Eychmueller, H. Weller, J. Phys. Chem. B 1998, 102, 8360. [3] B. Dubertret, P. Skourides, D. J. Norris, V. Noireaux, A. H. Brivanlou, A. Libchaber, Science 2002, 298, 1759.[4] W. C. W. Chan, D. J. Maxwell, X. Gao, R. E. Bailey, M. Han, S. Nie, Curr. Opin. Biotechnol. 2002, 13, 40.[5] I. L Medinitz,. H. T. Uyeda, E. R. Goldmann, H. Mattoussi, Nature Mat. 2005, 4, 435. [6] C. Gerhards, C. Schulz-Drost, V. Sgobba, D. M. Guldi, Phys. Chem. B 2008, 112, 14482.
5:45 PM - XX2.10
Chiral Quantum Dots.
Yurii Gun ko 1
1 Chemistry, Trinity College Dublin, Dublin Ireland
Show AbstractQuantum dots (QDs) are fluorescent semiconductor (e.g. II-VI) nanocrystals, which have a strong characteristic spectral emission. This emission is tunable to a desired energy by selecting variable particle size, size distribution and composition of the nanocrystals. QDs have recently attracted enormous interest due to their unique photophysical properties and range of potential applications in photonics and biochemistry.The main aim of our work is develop new materials based chiral quantum dots (QDs) and establish fundamental principles influencing the structure and properties of chiral QDs. Here we present the synthesis and characterisation of various chiral II-VI (CdS, CdSe and CdTe) semiconductor nanoparticles. The most interesting are penicillamine stabilised CdS and CdSe nanoparticles, which have shown both very strong and very broad luminescence spectra. Circular dichroism (CD) spectroscopy studies have revealed that the D- and L- penicillamine stabilised CdS and CdSe QDs demonstrate circular dichroism and possess almost identical mirror images of CD signals [1, 2]. Studies of photoluminescence and CD spectra have shown that there is a clear relationship between defect emission and CD activity. We believe that these new QDs could find important applications as fluorescent assays and sensors (or probes) in asymmetric synthesis, catalysis, enantioseparation, biochemical analysis and medical diagnostics. Also chiral QDs with an appropriate functionality could potentially serve as materials for the fabrication of circularly polarised light emitting devices. These devices are necessary components of chiroptical detectors used in polarimetry and CD spectrometers. Finally, circular polarized light emitters might have a potential application in colour displays.References1. M. M. Moloney, Y. K. Gun’ko, J. M. Kelly, Chem.Comm. 2007, 3900 – 3902.2. S. D. Elliott, M. P. Moloney and Y. K. Gun’ko, Nano lett , 2008, 8(8), 2452-2457.
XX3: Poster Session
Session Chairs
Antigoni Alexandrou
Hedi Mattoussi
Vincent Rotello
Tuesday AM, December 01, 2009
Exhibit Hall D (Hynes)
9:00 PM - XX3.1
Non-blinking and Non-bleaching Upconverting Nanoparticles as Optical Imaging Nanoprobe and T1 MRI Contrast Agent.
Yong Il Park 1 , Taeghwan Hyeon 1
1 School of Chemical and Biological Engineering, Seoul National University, Seoul Korea (the Republic of)
Show AbstractNanoparticles have been extensively studied for their unique size-dependent electronic, optical, and magnetic properties and their potential applications as probes in biomedical imaging. Recently, various multimodal imaging probes have been fabricated by combining different functional nanoparticles for more accurate imaging and diagnosis. For example, the combination of fluorescent semiconductor quantum dots and superparamagnetic magnetite nanoparticles yielded bimodal imaging probes that can provide the high sensitivity and resolution of fluorescence imaging as well as non-invasive and real-time monitoring abilities of magnetic resonance imaging (MRI). We demonstrated that NaGdF4:Er3+,Yb3+/NaGdF4 upconverting nanoparticles (UCNPs) can serve as multimodal imaging probe not only for background-free optical imaging but also for MRI. UCNPs absorb near-infrared (NIR) photons and emit visible or near UV photons. Non-blinking and non-bleaching property of UCNPs is unraveled by combined wide-field epi-luminescence imaging and atomic force microscopy analysis. The sturdy and persistent luminescence of UCNPs will minimize possible artifacts related to photoblinking and photobleaching of fluorescent probes in long-term imaging experiments. Bright-field and luminescence images of cancer cells incubated with UCNPs show complete absence of autofluorescence with NIR excitation at 980 nm and detection at 400-700 nm. Owing to Gd3+ ions on the surface, imaging contrast is clearly enhanced by UCNPs in T1-weighted MRI. Our UCNPs, endowed with multimodality, are expected to contribute to unerring diagnosis in biomedical applications.
9:00 PM - XX3.10
Luminescent Silicon Nanoparticles as Possible Agents for Bio-Imaging.
Nathalie Herlin Boime 1 , Ilaria Rivolta 4 , Rosaria D'Amato 2 , Vincent Maurice 1 , Valentina Bello 3 , Mauro Falconieri 2 , Giovanni Mattei 3 , Giulio Sancini 4 , Yarue Nie 5 , Olivier Sublemontier 1 , Enrico Trave 3 , Dayang Wang 5 , Giuseppe Miserocchi 4 , Elisabetta Borsella 2
1 IRAMIS/SPAM, CEA, Gif/Yvette Cedex France, 4 environmental medicine and biotechnology, Univ Milano-Bicocca, Milano Italy, 2 FIM, ENEA, Rome Italy, 3 Physics, Univ Padova, Padova Italy, 5 colloids and interface, MPI of colloids and interfaces, Potsdam Germany
Show AbstractVisible light emission from silicon nanoscaled structures has motivated an intense research for 15 years. Nevertheless, significant quantities of such particles could not be supplied in order to develop silicon nanocrystals-based applications which are now emerging. For labelling applications, organic dye based fluorophores are most often used. However, these dyes have several drawbacks such as rapid photo-oxidation, limited lifetime, need of different wavelengths to activate each dye... More recently, semiconductor nanocrystals (quantum dots-QDs) have been introduced for bio-labelling. As a result of the quantum confinement, such NPs (nanoparticles) exhibit intense, size-tuneable emission in the visible and near-infrared optical range. One main advantage of using luminescent NPs for imaging rests on their photostability, increased sensitivity through longer life time, and excitability by a single wavelength, which makes semiconductor NPs glow in a rainbow of colours depending on their size. However, as most widely used QDs (II-VI semiconductor QDs) are highly cytotoxic, limitations occur for in vivo application in living organisms and Si QD can offer a valuable alternative studied in the frame of the Bonsai euro project. Using the laser pyrolysis method, we are now able to obtain silicon nanocrystals with sizes between 4 and 9 nm and with a production rate between 0.2 g/h and 1 g/h respectively. The powders exhibit an intense photoluminescence (PL) after some days of passivation under ambient atmosphere or soft oxidation treatments in liquids and PL remains stable for months. The PL emission of Si NPs falls in the range 600-1000 nm and typical radiative lifetimes are in the range 0.05-0.3 ms. Using two-photon excitation we were able to excite Si NPs in the IR (at about 900 nm) where the human skin transmittivity is high. In order to use these NP for bio-labelling, the elaboration of stable and biocompatible colloids of Si NPs is necessary. The stability of NP Si suspensions in aqueous media was greatly improved by coating a silica shell at the surface of the NP and grafting with functional silanes terminated with amine or epoxy groups, for example efficiency of APTS grafting was measured in the range 6-10 functions per Si NP. NP were conjugated with poly(ethyleneglycol) and negligible cytotoxicity of PEGylated Si NPs was observed by vitality tests on epithelial cell lines known to be fairly sensible to noxious agents, i.e. A30 cells (located at the air/blood barrier). At first sight it was also found that cell proliferation is differently affected by S-PEGylated and E-PEGylated Si NPs (strongly in the first case, mildly in the second). First images of cells labelled with Si NP could also be obtained. Detailed results concerning these different points (passivation, surface functionnalization, toxicity and imaging) will be shown and discussed.
9:00 PM - XX3.11
Nontoxic Silicon Nanocrystals and Nanodiamonds as Substitution of Harmful Quantum Dots.
Anna Fucikova 1 2 , Jan Valenta 1 , Ivan Pelant 2 , Vitezslav Brezina 3
1 Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague, Prague Czechia, 2 , Institute of Physics AS CR, v. v .i., Prague Czechia, 3 , Institute of Systems Biology and Ecology AS CR, v. v .i.,, Nove Hrady Czechia
Show AbstractCommercially available semiconductor quantum dots (CQD) (e.g. cadmium containing quantum dots like CdS, CdSe, CdTe etc.) are toxic according to recent publications. They cannot be used in long-term biological studies in vitro and there is no safe method how to remove them after application in vivo. We are developing new non-toxic nanocrystalline silicon (Si-NCs) fluorescence labels which are biodegradable in living body and fluorescent nanodiamonds which are long-term stable (mainly for in vitro use). Light-emitting silicon nanocrystals (Si-NCs) have a crystalline core with size between 1-5 nm and their surface is naturally covered by SiO2 or functionalized by various compounds with respect to desirable use. Photoluminescence (PL) emission bands of Si-NCs range from ultraviolet to near infrared spectral region, depending on the Si-NC size and surface passivation. We present mesurements of luminescence spectra of single nanocrystals at room temperature in various environments including animal cells. There is a slight shift of the PL emission in the spectra when Si-NCs are interacting with internal environment of cells. Nanodiamond (ND) particles with diameter of 10 nm emit in the visible part of the spectrum with PL peak between 600-800 nm. Their cytotoxicity was studied in culture of L929 mouse fibroblast and HeLa cells. The bio-interaction of nanoparticles is studied by optical transmission microscopy, time-lapse microphotography of cell culture evolution, fluorescence microscopy, fluorescence micro-spectroscopy, confocal microscopy and scanning electron microscopy. The size and shape of nanocrystals were determined using atomic force microscopy and dynamic light scattering.
9:00 PM - XX3.12
Quantum Dots Delivery into Living Cells and High Resolution 3D Microscopy.
Alexandra Fragola 1 , Eleonora Muro 1 , Roli Richa 1 , Pierre Vermeulen 1 , Pedro Felipe Gardeazabal 1 , Pierre Blandin 1 , Eduardo Sepulveda 1 , Ivan Maksimovic 1 , Vincent Loriette 1 , Benoit Dubertret 1
1 , LPEM, Paris France
Show AbstractQuantum dots (QD) present several advantages for high resolution 3D fluorescence imaging of biological samples:-they allow simultaneous multicolor imaging-thanks to a great absorption cross section, a high quantum yield, a recently reduced blinking and a good resistance to photobleaching, QDs become promising probes for single molecule imaging during a long time observation-they can be functionalized for specific targeting.Nevertheless, quantum dots delivery into living cells remains a critical step for many biological applications. We will show how pinocitosys allow to introduce into the cytoplasm QD at high concentration that are still bright and diffuse freely, even several days after.We will also present the development of a new method for quantum dot delivery based on pseudo-virus production as QD cargos. Those pseudo-viruses are 120nm particles with an envelope allowing fusion with target cells ; therefore, main applications could be specific staining, for cancer cells for example, or QD delivery in weak cells (neurons or stem cells).To observe cells stained with QD, we developed a structured illumination microscope that can perform both fast optical sectioning or super resolution imaging. The principle consists in collecting high spatial frequencies of the sample through the optical transfer function of the microscope using moiré effect. Based on Gustafsson's set-up (J. Microsc. 2000), our microscope uses two interfering beams to introduce a spatial modulated intensity pattern in the focal plane, which is displaced laterally with no mechanical elements, using a second spatial light modulator. An enhancement of the lateral resolution by a factor of two can then be achieved and allows super-resolution fluorescence imaging of multicolor QD-labeled cells for co-localization applications.This versatile set-up also permits fast acquisition of classical wide field and structured illuminated fluorescence images in order to obtain an optical section of the sample with only two images. This recent technique, called HiLo microscopy (J. Mertz, JBO 2009), allows 3D observation of QD-labeled biomolecules with good lateral and axial resolutions and increased temporal resolution.
9:00 PM - XX3.14
Synthesis of Multifunctional Monodisperse MnO Nanocrystals as Potential Hybrid Materials for Biomedical Applications.
Thomas Schladt 1 , Kerstin Schneider 1 , Tanja Graf 1 , Wolfgang Tremel 1
1 Institute for Inorganic and Analytical Chemistry, Johannes Gutenberg University Mainz, Mainz, RLP, Germany
Show AbstractMagnetic nanoparticles of 3d transition metal oxides have gained enormous interest as new materials for biomedical applications[1] such as magnetic separation,[2] sensing,[3] and as contrast agents for magnetic resonance imaging (MRI).[4] Although scalable preparative routes to high-quality magnetic nanoparticles are well-established, synthetic routes for surface modification are far less developed, which limits the utility of nanoparticles in biological applications. Two common problems are confronted when applying these particles in vivo: their destabilization due to the absorption of plasma proteins and non-specific uptake by reticular-endothelial system (RES), like macrophage cells.[5] Poly(ethylene glycol) (PEG) and PEGylated materials are well-known for their biocompatibility, thus PEGylation of colloidal nanoparticle surfaces has been shown to reduce cytotoxicity and nonspecific protein binding.[6]In this contribution we present single crystalline, highly monodisperse MnO nanoparticles of various sizes which were synthesized by decomposition of a manganese oleate complex in high boiling non-polar solvents.[7] Transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) confirmed phase purity and homogeneity of the particles. Magnetic measurements showed that the magnetic properties strongly depend upon the size of the nanoparticles. Both magnetic moment and blocking temperature increase when the particle size is decreased.[7]The as-prepared MnO nanocrystals were modified by ligand exchange of the oleate groups by novel multifunctional PEGylated polymers. These polymers allow further functionalization of the nanoparticles, e.g. cell-specific biomolecules. The coated MnO nanocrystals are extremely stable in various aqueous media (e.g. PBS-buffer, human blood serum), exhibit no cytotoxicity, and high T1 relaxivity coefficients. Therefore, our multifunctional MnO nanoparticles demonstrate a strong potential for a variety of bioapplications such optical/magnetic resonance imaging and specific cell targeting.References[1] Katz, E.; Willner, I. Angew. Chem., Int. Ed. 2004, 43, 6042. [2] Xu, C.; Xu, K.; Gu, H.; Zhong, X.; Guo, Z.; Zheng, R.; Zhang, X.; Xu, B. J. Am. Chem. Soc. 2004, 126, 3392.[3] Zhao, M.; Josephson, L.; Tang, Y.; Weissleder, R. Angew. Chem., Int. Ed. 2003, 42, 1375.[4] Park, J.; Joo, J.; Kwon,S.G.; Jang, Y.; Hyeon, T.; Angew. Chem. Int. Ed. 2007, 46, 4630.[5] (a) Q. A. Pankhurst, J. Connolly, S. K. Jones, J. Dobson, J. Phys. D Appl. Phys. 2003, 36, R167. (b) C. C. Berry, A. S. G. Curtis, J. Phys. D, Appl. Phys. 2003, 36, R198. (c) S. M. Moghimi, A. C. Hunter, J. C. Murray, Pharm. Rev. 2001, 53, 283.[6] (a) Harris M. J., Zalipsky, S., Eds. Poly(ethylene glycol): Chemistry and Biological Applications; American Chemical Society: Washington, DC, 1997. (b) Kohler, N.; Fryxell, G.; Zhang, M. J. Am. Chem. Soc. 2004, 126, 7206.[7] Schladt, T. D.; Graf, T.; Tremel, W.; Chem. Mater. 2009, in press.
9:00 PM - XX3.15
Nanocomposites of Highly Luminescent CdTe Quantum Dots with Nanoporous Gold.
Minho Kim 1 , Sunghoon Kim 2 , Jaebeom Lee 2 , Dongyun Lee 1
1 Nanomaterials Engineering, Pusan National University, Busan Korea (the Republic of), 2 Nanomedical Engineering, Pusan National University, Busan Korea (the Republic of)
Show AbstractSemiconductor nanocrystals (NCs), also known as quantum dots (QDs) are very attractive materials because of their many desirable properties, such as a wide absorption band, strong emission, possibility for controlling band gap, and their durability when exposed to light irradiation. Nanoscaled gold is also well known for enhancing the surface sensitivity of spectroscopic measurements. In this study, attempts to combine these two materials to synthesize nanocomposites have been performed. We used gold as nanoporous form on glass substrate that is fabricated from gold-silver alloy thin film by dealloying process using chemical or electrochemical technique. We prepared various sizes of the CdTe QDs and different pore sizes of the nanoporous gold films. And then, the CdTe QDs are embedded into the nanoporous gold films by electrophoretic or dip coating method. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) are used to explore microstructures of the nanocomposites, and Raman spectroscopy and photoluminescence (PL) are employed to analyze optical properties of the nanocomposites. Implications for the applications of the nanocomposite are discussed.
9:00 PM - XX3.16
High-Resolution Long-Range Scanning Magnetic Imaging of Nanoparticles.
Li Yao 1 , Shoujun Xu 1
1 Department of Chemistry, University of Houston, Houston, Texas, United States
Show AbstractMagnetic nanoparticles are widely used as biochemical markers, drug delivery carriers, and imaging contrast agents. Precise determination of the position and amount of the particles at a given time is vital for these purposes. In many applications, such as assay analysis on microchips and in vivo imaging, one characteristic is that the magnetic particles being used are far away from the detectors, on the order of several millimeters to a few centimeters. This makes it challenging to obtain a high sensitivity and sufficient spatial information because of the r^-3 dependence of magnetic field strength. Here we show a scanning magnetic imaging technique that possesses both a large detection range and high spatial resolution. This technique couples a novel scanning imaging scheme with a sensitive atomic magnetometer, which operates at a low temperature of 37 oC. We achieved a spatial resolution of 20 micrometers with a detection distance of nearly one centimeter, while only using ~30 nl of magnetic particles. The absolute magnetization and hence the amount of the particles is simultaneously determined. Such a combination enables imaging of magnetic nanoparticles in various situations where a large separation between the magnetic sample and the detector is inevitable. Our technique thus fills the gap between microscopic magnetic imaging and long-distance magnetic sensing. It will be applicable for scenarios that are not easily achievable before. Of particular interest are microfluidic applications of magnetic nanoparticles. We will be able to distinguish in which channel the magnetic particles flow and at what time and flow rate. The magnetization of the particles will reveal the amount of labeled chemical of interest, which serves as an indicator of the degree of the biomedical interaction has proceeded. We expect the resolution and detection limit be further improved based on projection from the intrinsic sensitivity of our atomic magnetometer.
9:00 PM - XX3.2
Quantum Dot Conjugation to Aptamers for Biological Probes using Cu(I)-catalyzed Azide-alkyne Cycloaddition.
Sungwook Jung 1 , Hyungu Kang 2 , Joonhyuck Park 1 , Jutaek Nam 3 , Nayoun Won 3 , Ho Jin 3 , Sungho Jung 3 , Sungjee Kim 1 3
1 School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang Korea (the Republic of), 2 Aptamer Unit, Postech Biotech Center, Pohang University of Science and Technology, Pohang Korea (the Republic of), 3 Department of Chemistry, Pohang University of Science and Technology, Pohang Korea (the Republic of)
Show AbstractSemiconductor quantum dots (QDs) are promising fluorescent probes for cellular imaging. On the other hand, aptamers can be easily synthesized by systematic evolution of ligands by exponential enrichment, and can show bindings to a broad range of targets with extremely high affinity and specificity. CdSe/CdS/ZnS (core/shell/shell) QDs were used as they can retain high fluorescence quantum yields in biological media. We have conjugated QDs to single stranded RNA aptamers that have been screened for human epidermal growth factor receptors 2 (HER2) which are known to be overexpressed in 15-20 percent of breast cancer cells. Cu(I)-catalyzed azide-alkyne cycloaddition, ‘click’ reaction, was employed for the conjugation. This approach provided us with robust QD-aptamer conjugate probes. The conjugate size was characterized by the dynamic light scattering and electrophoresis studies. The QD conjugates were used for cellular imaging with HER2-overexpressing human breast cancer cell line SKBr3. As controls, Hela and MCF7 cell lines were used as they have negligible or moderate expression level of HER2. Interactions of the QD conjugates with various types of cells were investigated using confocal laser scanning microscopy and fluorescence-activated cell sorting analysis. We will discuss applications of the QD conjugates for long-term single molecule imaging such as cell membrane protein trafficking.
9:00 PM - XX3.3
In vivo Real-time Multiplexed Infrared Quantum Dot Imaging Toward Tumor Growth and Development Studies.
Nayoun Won 1 , Joonhyuck Park 2 , Sanghwa Jeong 1 , Jiwon Bang 1 , Sungjee Kim 1 2
1 Chemistry, Pohang University of Science and Technology, Pohang Korea (the Republic of), 2 School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang Korea (the Republic of)
Show AbstractInfrared (IR) quantum dots (QDs) can promise a new modality for in vivo bio-imaging and future medical imaging applications. QDs have proven the potential for imaging contrast agents by the bright luminescence, resistance against photobleaching, and the multiplexing capability. IR wavelengths can provide maximal tissue penetrations by the minimal interferences from water and biomolecules and the reduced auto-fluorescence. IR QDs are used for in vivo imaging of tumor growth and development in a mouse model. We xenograft cancer cells that are labeled by IR QD internalization, and observe the growth and development of tumor by home-built IR imaging setup. Penetration depth of the QD imaging is simulated by optical phantom experiments using biological tissues such as bovine liver and porcine skin. We investigate into the imaging parameters that affect contrasts and signal to noise ratios. We report changes in penetration depths by the incidence angle, polarization, and excitation and emission wavelengths. We will also discuss camera specificities between Si and InGaAs CCDs for the in vivo imaging applications.
9:00 PM - XX3.4
Monofunctional Quantum Dot Probes for Cell Imaging and Nano-Architecture.
Samuel Clarke 1 , F. Pinaud 1 , A. Sittner 1 , G. Gouzer 1 , O. Beutel 2 , J. Piehler 2 , M. Dahan 1
1 Physics and Biology, ENS Paris, Paris France, 2 Biology, Universitat Osnabruck, Osnabruck Germany
Show AbstractRecently, it has been shown that the optical properties of quantum dot (QD) nanoparticles enable novel experiments at the single-molecule level in live cells, thereby opening new prospects for the understanding of cellular processes. One difficulty with these experiments is that complex biological environments impose stringent design requirements on fluorescent probes, necessitating the development of smaller and more biocompatible QDs. In this work, we present our efforts towards minimizing the size and controlling the surface functionality of QDs. We show that an engineered peptide surface coating and a purification method based on gel electrophoresis are sufficient to produce compact monofunctional QDs covalently conjugated to streptavidin, biotin or antibodies. To further characterize these QD probes, we apply techniques such as HPLC, ultracentrifugation and live cell assays. Aside from applications in biological imaging, we demonstrate the utility of monofunctional QDs to form controlled assemblies of nanoparticles, such as dimers and higher-order structures, which are confirmed by electron and single-molecule spectroscopy.
9:00 PM - XX3.5
In vivo NIR Up-conversion Luminescent Bioimaging Using Lanthanide Doped Nanocrystals and their Surface Modification.
Sanghwa Jeong 1 , Nayoun Won 1 , Sungjee Kim 1 2
1 Chemistry, POSTECH, Pohang Korea (the Republic of), 2 School of Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang Korea (the Republic of)
Show AbstractLanthanide doped nanocrystals (LDNCs) have attracted much attention for a decade owing to their advantageous features for bio-imaging such as strong chemical stability, low toxicity, narrow emission profile, and robustness against photobleaching. Especially, LDNCs that can be excited by near-infrared (NIR) are optimal for in vivo imaging probes. They can promise deep tissue penetrations, minimal auto-fluorescence, and reduced light scattering. Monodisperse NaYF4:Yb3+,Tm3+ up-conversion luminescent LDNCs have been successfully synthesized in fatty acid condition. The LDNCs are spherical with a mean diameter of 30 nm, and are dispersed in aqueous media through ligand exchanging by amines with long alkyl chains. The surface modified LDNCs show outstanding colloidal stability under a wide pH range from 2 to 8. The LDNCs show bright blue up-conversion luminescence in aqueous media under the illumination at 980 nm. They are further used for in vivo imaging studies on small animal models as exploiting the deep penetration depth, high signal-to-noise, and low toxicity.
9:00 PM - XX3.6
Quantum Dot Micelle Conjugates.
Olivier Carion 1 , Emilie Genin 2 , Benoit Mahler 1 , Eric Larquet 3 , Eric Doris 2 , Benoit Dubertret 1
1 LPEM, ESPCI, Paris France, 2 iBiTecS, CEA, Gif sur Yvette France, 3 IMPMC, UMR 7590, Paris France
Show AbstractColloidal nanocrystal quantum dots (QDs) consist of an inorganic nanoparticle core surrounded by a layer of organic ligands. Since their discovery, intensive studies have been carried out suggesting great potential for applications in electronic material science and more recently in biology. Indeed, the development of sensitive and specific probes that circumvent the intrinsic limitations of fluorogenic organic dyes is of considerable interest in many fields of research from molecular and cellular biology to medical imaging and diagnosis. Semiconductor nanocrystals have thus received considerable attention thanks to their unique optical properties which include high quantum yield, large molar extinction coefficient, tunable fluorescence emission, and photostability. Hydrophilic QDs have already been conjugated to biomolecules such as peptides, antibodies, nucleic acids, or small ligands for applications as targeted fluorescent labels. Applications of QDs in biology are increasingly widespread, giving a new impetus to this nano-material. Control over the photophysical and chemical properties of QDs require an extensive understanding of these properties, of their advantages and limitations. This knowledge allows the optimization of the coating and material composition to obtain the most reliable and reproducible results during biological experiments. The preparation of controlled and stable hydrophilic QDs is still a major challenge. This first step determines bioconjugate formation, controls the size, the robustness and quantum efficiency of the future biological probe. Here we will present the preparation and characterization of functionalized phospholipid QD micelles. These self-assembled probes consist in hydrophobic QDs incorporated into amphiphilic phospholipid micelles. The hydrophobic chains interdigitate with the QD hydrophobic ligands and the hydrophilic part of the lipid ensures water solubility. We will show details about quantum dot micelles characterization and procedures for obtaining stable conjugated QDs in aqueous buffers. We will present techniques for QD purification, encapsulation, and their effect on the QD optical properties. We will detail the preparation of Quantum dots bioconjugated with various biomolecules, such as proteins, DNA, antibodies. For the first time to our knowledge, we will present a full characterization of QD micelles in aqueous medium using cryogenic electron microscopy. We will also present QDs conjugated with CrAsH, a bisarsenical affinity probe. These organic dyes have selective and complementary interactions with proteins that incorporate a tetracystein tag (Cys2-(X)n-Cys2). The interaction between 4Cys tag of the protein and the bisarsenical probe induces a significant increase in the fluorescence of the probe. CrAsH-QD conjugate enables binding of 4Cys tag proteins and tracking probes.
9:00 PM - XX3.7
Conjugated Quantum Dots as Probes for the Localization of GABAA Receptors and VGLUT1 Transporters in Rat Cerebellum Slices.
Abdel Illah El Abed 1 , Anne Baudot 1 , Sanaa Ben Khalifa 1 , Mireille Chat 2 , Gerard Louis 1
1 Lab. Neuro-Physique Cellulaire, Paris Descartes University, Paris France, 2 Lab. Phsyiologie Cérébrale, Paris Descartes University, Paris France
Show AbstractThanks to their unique optical properties and nanoscopic size, quantum dots represent a new powerful tool in the field of imaging in cell biology. Besides their well known long term resistance to photobleaching, they possess also large Stokes shifts which enable to separate their fluorescence from background autofluorescence, making them hence good candidates for labelling tissues and slices. The formers represent a better material system in the field of neurobiology. However, because of the heterogeneous and complex structure of tissues and slices and also because of the relative big size of functionalized quantum dots by regards to organic fluorescents dyes, few applications of quantum dots in staining tissues and slices have been reported up to date [1].We report in this study a new application of conjugated quantum dots to specifically and efficiently label two endogenous synaptic proteins, namely R-GABAA-alpha1 receptors (GABAA Rs) and VGLUT1 transporters within the molecular layer of fixed young and adult rat cerebellum slices. GABA and glutamate are known respectively as the principal inhibitory and excitatory neurotransmitters in the vertebrate central nervous system. Nevertheless, recent electrophysiological data obtained by Stell et al. [2] in rat cerebellum molecular layer indicate that GABAA Rs may undergo also an excitatory action depending on the experimental conditions. Such an unpredicted result was corroborated by immunogold data which reveal clearly the presence of GABAA Rs on the glutamatergic 0.2 micron thick parallel fibers (PF) varicosities, whereas immunohistchemistry assays using organic fluorescent dyes failed to show a clear localization of these receptors around these presynaptic varicosities. The parallel fibers correspond to the horizontal portions of the glutamatergic granule cells axons; presynaptic varicosities correspond to the sites of the PF and the dendrites of either the gabaergic Purkinje cells or the also gabaergic molecular layer interneurons.We investigated different experimental approaches in order to optimize labeling of GABAA Rs and VGLUT1 transporters with quantum dots. Our results allowed us, using fluorescence and confocal microscopy, to show the localization within the molecular layer of GABAA Rs, not only around interneurons but also around the parallel fibers of granule cells in agreement with the results shown by Stell et al. [2] using electrophysiological and immunogold data.[1] B. N. Giepmans, T. J. Deerinck, B. L. Smarr, Y. Z. Jones, M. H. Elisman, Nature Methods 2, 743 (2005). [2] B. M. Stell, P. Rostaing, A. Triller and A. Marty, J. Neuroscience 27, 9022 (2007).
9:00 PM - XX3.8
Transfection of Aqueous Quantum Dots using Polyethylenimine for Live Cell Labeling.
S-Ja Tseng 2 3 , Yu-Chieh Lu 1 3 , Hui Li 1 , Shiue-Cheng (Tony) Tang 3 , Wan Shih 2 , Wei-Heng Shih 1
2 School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania, United States, 3 Department of Chemical Engineering, National Tsing Hua University, Hsinchu Taiwan, 1 Department of Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania, United States
Show AbstractQuantum dots (QDs) are widely used as a photoluminescent marker for bioimaging applications. Due to their superior brightness and photostability as compared to organic fluorophores, QDs offer great potential for cellular labeling and deep-tissue imaging. Recently we demonstrated the transportation of aqueous CdS QDs inside PC12 neuronal cells without QDs aggregation using commercial polyethylenimine (PEI) as an effective and endosomolytic carrier. With PEI they formed complexes by electrostatic attraction. Confocal microscopy showed that PEI–QD complexes of an optimized PEI/QD number ratio were successfully internalized and uniformly distributed inside the cells, indicating that the PEI–QD complexes were able to rupture the vesicles to enter the cytoplasm without aggregation. More recently, we have also explored the use of near-infrared (NIR) QDs for deep-tissue bioimaging applications.
9:00 PM - XX3.9
Resolving Sub-Diffraction Limit Encounters in Nanoparticle Tracking Using Coupling Microscopy.
Guoxin Rong 1 2 , Hongyun Wang 1 2 , Lynell Skewis 1 2 , Bjoern Reinhard 1 2
1 Department of Chemistry , Boston University, Boston, Massachusetts, United States, 2 Photonics Center, Boston University, Boston, Massachusetts, United States
Show AbstractWe demonstrate that plasmon coupling between individual gold nanoparticle labels can be used to monitor sub-diffraction limit distances in live cell nanoparticle tracking experiments. While the resolving power of our optical microscope is limited to ≥ 500 nm, we improve this by more than an order of magnitude by detecting plasmon coupling between individual gold nanoparticle labels bound to specific cell membrane proteins using a ratiometric detection scheme. We apply this plasmon coupling microscopy to resolve the interparticle separations during individual encounters of gold nanoparticle labeled fibronectin-integrin complexes in living HeLa cells.
Symposium Organizers
Antigoni Alexandrou Ecole Polytechnique
Jinwoo Cheon Yonsei University
Hedi Mattoussi Florida State University
Vince Rotello University of Massachusetts
XX4: Single Molecule Studies of Specific Biological Processes
Session Chairs
Maxime Dahan
Benoit Dubertret
Tuesday AM, December 01, 2009
Room 309 (Hynes)
9:30 AM - **XX4.1
Non Blinking Colloidal Quantum Dots and Atomically Controlled CdSe Platelets : Description and Potential Use for Biomedical Imaging.
Benoit Mahler 1 , Sandrine Ithurria 1 , N. Lequeux 1 , P. Spinicelli 2 , S. Buil 2 , X. Quelin 2 , J. Hermier 2 , Benoit Dubertret 1
1 Laboratoire de Physique et d'Etude des Materiaux, CNRS UPR5, Paris France, 2 Groupe d'etude de la Matiere Condensee, Universite de Versailles Saint Quentin, CNRS UMR8635, Versailles France
Show AbstractWe will present the synthesis of thick shell (up to 10 nm) CdSe/CdS quantum dots. We will focus on the roles of the ligands regarding the crystal structure transformation during shell growth. Synthesis pathways to obtain thick shell CdSe/CdS QDs in either wurtzite or cubic crystal structure will be discussed, and the influence of the lattice mismatch between the core and the shell will be highlighted [1].When compared to standard colloidal nanocrystals, individual thick shell CdSe/CdS nanocrystals exhibit strongly reduced blinking [2]. Analyzing the photon statistics and lifetime of the ”on” state, we first demonstrate [3] that brilliant periods correspond to single photon emission with a fluorescence quantum efficiency of the monoexcitonic state greater than 95 %. We also show that low emitting periods are not dark. Measuring their fluorescence quantum efficiency (19 %), we deduce the radiative lifetime (45 ns) and Auger lifetime (10.5 ns) of the ”grey” state. The grey state is attributed to a trion state, where as the bright state to a mono exciton. Potential use of this novel class of switchable QDs in biomedical imaging will be discussed.We have recently synthesized the first CdSe platelets with a thickness controlled at the atomic level[4]. These platelets are similar to perfect quantum wells with full width half maximum of their emission spectra close to 1.2kT (6.7nm) at room temperature. The physics and potential applications of these objects for biomedical imaging will be discussed. 1.Ithurria, S., et al., Mn2+ as a radial pressure gauge in colloidal core/shell nanocrystals. Physical Review Letters, 2007. 99(26): p. 4.2.Mahler, B., et al., Towards non-blinking colloidal quantum dots. Nature Materials, 2008. 7(8): p. 659-664.3.Spinicelli, P., et al., Bright and Grey States in CdSe-CdS Nanocrystals Exhibiting Strongly Reduced Blinking. Physical Review Letters, 2009. 102(13): p. 4.4.Ithurria, S. and B. Dubertret, Quasi 2D Colloidal CdSe Platelets with Thicknesses Controlled at the Atomic Level. Journal of the American Chemical Society, 2008. 130(49): p. 16504-+.
10:00 AM - XX4.2
Non-blinking and Photostable Single Lanthanide-doped Upconverting Nanocrystals as Potential Background-free Bio-imaging Probes.
Gang Han 1 , Shiwei Wu 1 , Delia Milliron 1 , Dmitri Talapin 2 , Bruce Cohen 1 , James Schucka 1
1 The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 Chemistry, University of Chicago, Chicago, Illinois, United States
Show AbstractThe development of probes for single-molecule imaging has dramatically facilitated the study of individual molecules in cells. A ideal single-molecule probe is required to exhibit good brightness, uninterrupted emission, resistance to photobleaching, and minimal spectral overlap with cellular autofluorescence. However, most single-molecule probes are imperfect in several of these aspects. Here we show that individual lanthanide-doped upconverting nanoparticles (UCNPs)- hexagonal phase NaYF4 with multiple Yb3+ and Er3+ dopants—emit bright anti-Stokes visible upconverted luminescence with exceptional photostability when excited by a 980-nm continuous wave laser. Individual UCNPs exhibit no on/off emission behavior, or “blinking,” down to the millisecond timescale, and no loss of intensity following an hour of continuous excitation. Amphiphilic polymer coatings permit the transfer of hydrophobic UCNPs into water, resulting in individual water-soluble nanoparticles with undiminished photophysical characteristics. These UCNPs are endocytosed by cells and show strong upconverted luminescence, with no measurable anti-Stokes background autofluorescence, suggesting that UCNPs are ideally suited for single-molecule imaging experiments.The extension of the use of UCNPs to sensing, energy transfer and other imaging applications, through surface conjugation of organic or biological molecules, will also be discussed.
10:15 AM - XX4.3
Temporal Pattern of Reactive Oxygen Species Signaling Revealed by Single Europium-doped Nanoparticle Imaging.
Cedric Bouzigues 1 , Thanh-Liem Nguyen 1 , Didier Casanova 1 , Rivo Ramodiharilafy 1 , Genevieve Mialon 2 , Thierry Gacoin 2 , Jean-Pierre Boilot 2 , Pierre-Louis Tharaux 3 , Antigoni Alexandrou 1
1 Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Palaiseau France, 2 Laboratoire de Physique de la Matière Condensée, Ecole Polytechnique, Palaiseau France, 3 INSERM U970, Paris-Cardiovascular Research Centre, Paris France
Show AbstractReactive oxygen species (ROS) and in particular hydrogen peroxide (H2O2) have long been known for their microbial killing role in defence mechanisms of immune cells and have been thought to be deleterious for cells. However, it is now well documented that other types of cells produce H2O2 in much lower concentrations for signaling purposes and that H2O2 mediates various physiological processes. The cell response is expected to be finely tuned by the timing, amplitude and compartmentalization of the H2O2 production. However, no reliable method for the dynamic and local measurement of its concentration within the cell is available for the moment.Here we propose a new method based on the imaging of single lanthanide-doped oxide nanoparticles (Y1-xEuxVO4) loaded in living cells by pinocytic influx allowing a quantitative and time resolved measurement. Y1-xEuxVO4 nanoparticles are photostable probes presenting a continuous emission due to luminescence of Eu3+ ions. These nanoparticles show a luminescence decrease due to a laser-induced Eu3+ reduction process. The presence of an oxidant like H2O2 oxidizes the reduced lanthanide ions back to their trivalent state leading to a luminescence recovery. We demonstrated that these processes are reversible and that the instantaneous H2O2 concentration can be extracted from the luminescence signal and its derivative with a 30-s resolution in the 1-45 µM range [1]. In addition, the capability of single particle detection [2] allows spatial resolution.We then used this sensor to measure the intracellular H2O2 produced in mouse vascular smooth muscle cells upon stimulation by two of the main effectors in the vascular system: platelet-derived growth factor (PDGF-BB) and endothelin-1 (ET-1) which regulate migration and contraction, respectively. Control experiments show that H2O2 is the only oxidant acting on the nanoparticles in these signaling pathways. The results highlight the capability of the cell to temporally regulate its response: while H2O2 is produced quasi-instantaneously upon ET-1 stimulation, a 5-10 min latency time is observed after PDGF-BB stimulation [1]. Inhibition of the epidermal growth factor receptor (EGFR) induces a decreased response (3.7 versus 7.1 µM H2O2) and an increased latency time illustrating the role of EGFR receptor transactivation upon stimulation by PDGF-BB. These results constitute the first quantitative, time resolved monitoring of ROS production in living cells and open new perspectives for the deciphering of complex signaling pathways in a variety of biological systems. [1] D. Casanova, C. Bouzigues, T.-L. Nguyên, R. O. Ramodiharilafy, L. Bouzhir-Sima, T. Gacoin, J.-P. Boilot, P.-L. Tharaux, A. Alexandrou, Nature Nanotech. (in press).[2] E. Beaurepaire, V. Buissette, M.-P. Sauviat, D. Giaume, K. Lahlil, A. Mercuri, D. Casanova, A. Huignard, J.-L. Martin, T. Gacoin, J.-P. Boilot, A. Alexandrou, Nano Lett. 4, 2079 (2004).
10:30 AM - **XX4.4
Visualizing Cellular Events, One Quantum Dot a Time.
Maxime Dahan 1
1 Physics and Biology Department, Ecole normale supérieure, Paris France
Show AbstractExperiments on membrane molecules have demonstrated the potential of single quantum dot (QD) tracking to decipher the dynamics of complex cell events and to study biochemical reactions at the single molecule level. I will first discuss the principles and methods of single QD tracking. I will then present our current effort to go beyond membrane dynamics and address intracellular processes, in order to make QD imaging a standard imaging technique in cell biology. First, I will discuss how QDs can be internalized into live cells, how their colloidal properties affect their intracellular behavior and how QDs can be targeted to specific biomolecules or organelles. Next, I will show the results of recent experiments on the localization of cell-fate determinants during the division of neuroblasts and on the motion of molecular motors kinesin and myosin V in the cytoplasm of live cells. These latter experiments give access to important parameters such as the velocity, the processivity or stepping characteristics of the motor, directly in its cellular environment. Finally, I will present the challenges that need to be met to improve the properties of QDs as biological probes and the strategies that we are implementing to prepare small functional nanoparticles with controlled valency using peptide-coated QDs. In conclusion, I will argue that the combination of tracking measurements and emerging high-resolution imaging techniques offer exciting possibilities to probe the formation and maintenance of supramolecular assemblies in live cells.
11:30 AM - **XX4.5
Single Quantum Dot Imaging: Progresses and Perspectives.
Xavier Michalet 1 2 , F. Pinaud 1 2 , G. Iyer 1 2 , Y. Chang 1 2 , J. Antelman 1 2 , C. Wilking-Chang 1 2 , R. Colyer 1 2 , O. Siegmund 1 2 , A. Tremsin 1 2 , J. Vallerga 1 2 , S. Weiss 1 2
1 Chemistry and Biochemistry, UCLA, Los Angeles, California, United States, 2 Space Sciences Laboratory, University of California at Berkeley, Berkeley, California, United States
Show AbstractQuantum dots (QDs) have proven their value in a variety of biological applications, among which the most exciting involve the detection of individual QDs. Achieving single-QD detection is however only the first step in fully exploiting their potential. A thorough characterization of their properties is also necessary to confidently use them for advanced biological imaging applications. This talk will review several themes, such as functionalization stoichiometry, shape and size effects or photophysical characteristics, illustrating them with recent results from our group, including the development of a new detector specifically designed to take advantage of QDs’ unique properties.
12:00 PM - XX4.6
Smart Quantum Dot Sensing.
Andrew Greytak 1 , Rebecca Somers 1 , Ryan Lanning 2 , Emily McLaurin 1 , Wenhao Liu 1 , Peter Curtin 1 , Rakesh Jain 2 , Moungi Bawendi 1 , Daniel Nocera 1
1 Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Edwin L. Steele Laboratory for Tumor Biology, Massachusetts General Hospital, Boston, Massachusetts, United States
Show AbstractThe high per-particle brightness and photostability of colloidal quantum dots (QDs) suggests important applications as fluorophores in biological imaging and microscopy. By designing specific, reversible interactions with the local environment, we can develop "smart" QDs as optically-reporting fluorescent sensors. We will present recent work on QD surface modification to control the size, charge, and reactivity of aqueous QD sensor scaffolds. Additionally we will describe QD-based sensors adapted to sensing and imaging of biochemical parameters in living systems, for example in metabolic profiling of murine tumor models via intravital multiphoton laser-scanning microscopy (MPLSM).
12:15 PM - XX4.7
Deciphering 3D Rotational Motion in Live Endocytosis and Intracellular Transport.
Ning Fang 1 2 , Gufeng Wang 1 2 , Wei Sun 1 2
1 Chemistry, Iowa State University, Ames, Iowa, United States, 2 , Ames Laboratory-US Department of Energy, Ames, Iowa, United States
Show AbstractWe introduce a novel methodology to study 3D rotations in nanodomains for live-cell imaging over arbitrarily long periods of time. We revealed 3D rotations of single cell-penetrating peptide conjugated gold nanorods during receptor-mediated endocytosis and subsequent transport on the microtubule network by differential interference contrast microscopy. The gold nanorod went through stages of random rotation due to single-point attachment, in-plane rotation with a fixed tilting angle, and tumbling into the cell, shedding new light on the TAT-mediated endocytosis. After being endocytosed by the cell, the nanorod-containing vesicle either diffuses in the cytoplasm or is transported on the microtubule networks. We observed that 70% of the vesicles do not rotate around the microtubule or itself while the rest 30% may involve periodic rotation of the vesicle around the MT track when being transported. More importantly, we find that in the non-rotating cases, gold nanorod-containing vesicles adopt a fixed angle with the microtubule track even when being transferred from one microtubule to another. Our method is complementary to fluorescence-based studies for understanding cell trafficking.
12:30 PM - **XX4.8
Single-molecule Studies in Live Neurons with Luminescent and Non-luminescent Nanoparticles.
Laurent Cognet 1
1 CPMOH, Universite de Bordeaux & CNRS, Bordeaux France
Show AbstractThe optical microscopy of individual nano-objects has recently been beneficial for many applications and especially in biology. Indeed, it completely removes ensemble averaging, so that the heterogeneity of populations and the dynamical fluctuations of individuals come to light. It also allows a sub-wavelength localisation of the nano-objects. Applications in neurosciences that make use of fluorescence based methods with organic dyes or quantum dots will be presented. Such studies revealed the mobility of glutamate receptors in synapses (1-2) and allowed the identification of a new mechanism for fast communication between neurons based on the receptor mobility(3). A new far-field optical methods based on absorption instead of luminescence will then be introduced. Such approaches do not suffer from the inherent photophysical limitations of luminescent objects and allows the ultra-sensitive detection of tiny absorbing individual nano-objects such as gold nanoparticules down to 1.4nm(4). Two approaches were further developed to measure the diffusion of proteins labelled with gold nanoparticles in living neurons. The first one uses a triangulation scheme to track and record on living cells the trajectory of individual nanoparticles as small as 5 nm for arbitrary long times(5). The second one, called Photothermal Absorption Correlation Spectroscopy (PhACS) measures the signal fluctuations arising from diffusing nanoparticles in the focal spot of the photothermal microscope akin to fluorescence correlation spectroscopy(6). Due to the exceptional photostability of gold nanoparticles, PhACS has the advantage to give access with great precision to extremely slow dynamics. (1)Tardin, C. et al EMBO J. (2003), 22, 4656-4665.(2)Groc, L.et al D. Nat Neurosci. (2004), 7, 695-696.(3)M. Heine et al., Science (2008), 320, 201.(4)Berciaud, S.et al Phys Rev Lett (2004), 93, 257402.(5)Lasne, D. et al Biophysical Journal (2006), 91, 4598.(6)Octeau, V. et al, ACS Nano (2009), 3, 345.
XX5: Development of Multfunctional Nanoparticles (Magnetic and Others) for Imaging and Other Applications
Session Chairs
Mathias Brust
Jinwoo Cheon
Souheng Sun
Tuesday PM, December 01, 2009
Room 309 (Hynes)
2:30 PM - **XX5.1
Developing Multifunctional Magnetic Nanoparticles for Imaging and Delivery Applications.
Shouheng Sun 1
1 , Brown University, Providence, Rhode Island, United States
Show AbstractI will summarize our recent efforts in the synthesis and functionalization of monodisperse magnetic nanoparticles for biological imaging and therapeutic applications. We have developed various monodisperse magnetic nanoparticles of iron oxide MFe2O4 (M = Fe, Co, Mn), core/shell structured M/Fe3O4 (M = Co, Fe), and dumbbell-like Au-Fe3O4 with tunable sizes and magnetic properties. The particles coated with polyethylene glycol and the selected peptide, antibody and anticancer drug are stable in physiological conditions. They are able to target the specific cancer cells with drugs being released in a pH controlled manner. These nanoparticles can be used as sensitive labels for cancer diagnostics and as efficient delivery tools for therapeutics.
3:00 PM - XX5.2
New-Generation Magnetic Nanoparticles as Ultra-sensitive and Versatile Platform Materials for NanoBiotechnology.
Jinwoo Cheon 1 , Jae-Hyun Lee 1 , Jin-sil Choi 1 , Eun-joo Choi 1
1 Departmeny of Chemistry, Yonsei University , Seoul Korea (the Republic of)
Show AbstractThe development of next generation nanomaterials for the study of biological targets is of interest. In this talk, I will discuss our recent studies on the chemical design of ultra-sensitive MRI and multi-modal nanoparticle probes. Nanoscale magnetism effects of size, dopant, and magnetocrystallity on the MR signal enhancements are to be described. Currently developed new MEIO magnetic nanoparticles provide the highest MR contrast effects (r2=860 mM-1s-1) reported to date which is roughly 8-14 times larger than conventionally iron oxide contrast agents. Hence, magnetism optimized nanoparticles are very useful as key platform materials for high performance multi-modal imaging (e.g. MRI-optical, MRI-PET), drug and gene delivery, cell trafficking, and bio-sensing and actuations. I will show a few examples of how these were successfully utilized for in vitro and in vivo imaging and therapeutics.
3:15 PM - XX5.3
Functionalized Magnetic Nanoparticles for Selective Targeting of Cells.
Ibrahim Shukoor 1 , Matthias Barz 2 , Stefan Weber 3 , Rudolf Zentel 2 , Laura Maria Schreiber 3 , Juergen Brieger 3 , Wolfgang Tremel 1
1 Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität, Mainz Germany, 2 Universitätsklinikum, Johannes Gutenberg-Universität, Mainz Germany, 3 Institut für Organische Chemie, Johannes Gutenberg-Universität, Mainz Germany
Show AbstractOne of the emerging goals for biomedical applications of nanoparticles is their functionalization to impart precise biological functions. Nanomaterials can be loaded with traditional low molecular drugs or ribonucleic acids (RNA) which are inherently difficult to deliver due to their size and polarity. Nanoparticles are attractive probe candidates because of their (i) size and large surface-to-volume ratio, (ii) chemically tailorable physical properties which directly relate to size, composition, and shape, (iii) unusual target binding properties, and (iv) structural robustness. We have developed biocompatible materials for surface coating and functionalization of nanoparticles using multifunctional polymers that simultaneously bind to inorganic nanoparticles, target molecules through specific anchor groups and carry a fluorophor for optical detection. MnO nanoparticles were functionalized and protected using a functional copolymer [1] carrying (i) anchor groups for surface binding, (ii) free amino groups for the attachment of target ligands (poly(I:C), CpG, etc.) and (iii) fluorescent tags for optical detection [2]. The cytotoxicity was evaluated by an electric cell-substrate impedance sensing (ECIS) micromotion assay. The biological activity of these poly(I:C) coated magnetic nanoparticles was demonstrated on various cell lines [3]. The ssDNA coupled nanoparticles were used to target Toll-like receptors 9 (TLR9) receptors inside the cells and to activate the classical TLR cascade [4]. The trimodal nanoparticles allow the imaging of cellular trafficking by different means and simultaneously are an effective drug carrier system. The magnetic properties of the MnO core make functionalized MnO nanoparticles also potential diagnostic agents for magnetic resonance imaging (MRI). For in vivo MRI imaging, the water-dispersible functionalized MnO nanoparticles were injected into a tumor (squamous cell carcinoma) implanted into nude rats. The manganese oxide nanoparticle contrast-enhanced T1-weighted MRI showed contrast-enhanced regions following accumulation of MnO nanoparticles in the tumor [5].In addition, Au/ MnO hybrid nanocrystals were synthesized by thermal decomposition of Mn2+ salts in the presence of Au colloids. By changing the molar ratio of the precursors, the morphologies of the composite NPs can be varied from dumbbells to ‘‘flowers’’ having up to four MnO ‘‘leaves’’ around the gold core. The Au and MnO components could be functionalized selectively, where tumor cells were addressed by ssDNA ligands while an effective killing of the cells could be achieved under illumination with NIR light [6]. [1] M. N. Tahir et al., Angew. Chem. Int. Ed. 2006, 45, 4803.[2] M. I. Shukoor et al., Angew. Chem.Int. Ed. 2008, 47, 4748. [3] M. I. Shukoor et al., Small 2007, 3, 1374.[4] M. I. Shukoor et al., Adv. Funct. Mater. 2009, in press. [5] M. I. Shukoor et al., Small 2009, submitted. [6] M. I. Shukoor et al., Adv. Mater. 2009, submitted.
3:30 PM - XX5.4
Magneto Theranostics: Multi-functional Magnetic Cationic Liposomes (MagCLIPs) for Targeting, MRI Contrast Enhancement and Therapy.
Dattatri Nagesha 1 , Evin Gultepe 1 , Francisco Reynoso 1 , Aditi Jhaveri 2 , Robert Campbell 2 , Praveen Kulkarni 2 , Craig Ferris 2 , Srinivas Sridhar 1
1 Physics, Northeastern University, Boston, Massachusetts, United States, 2 Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts, United States
Show AbstractWe describe the development and use of multi-functional magnetic cationic liposomes (MagCLIPs) for theranostics - diagnostics, imaging and therapeutic applications. Water soluble superparamagnetic iron oxide nanoparticles (SPIONS) were encapsulated within poly-ethyleneglycol (PEG) coated cationic liposomes to form the MagCLIPs. These liposomes were characterized for their size, surface charge and magnetic properties. In-vivo studies were carried out in mice bearing a carcinoma in the posterior right flank and were imaged under MRI. The MRI results show that these liposomes are an exceptional contrast agent with the PEG coating dramatically reducing uptake by the mononuclear phagocyte system (MPS). This results in increased blood circulation time thereby allowing the liposomes to accumulate in the tumor. The magnetic properties of the nanoparticles were further exploited to selectively accumulate these liposomes in the tumor using external magnetic fields. This type of targeting can be highly advantageous for localized drug delivery of chemotherapy agents by minimizing harmful side effects in healthy tissue. Quantitative analysis of the in vivo MRI images show a two fold increase in tumor accumulation of these liposomes through magnetic targeting and are attributed to Enhanced Permeability and Retention (EPR) effect. Furthermore for enhanced therapeutic effects, MagCLIPs were loaded with Doxorubicin and in vitro triggered release of this drug was achieved through magnetic hyperthermia. Results from these studies will be presented. This work was supported by IGERT Nanomedicine Science and Technology Program (NSF-0504331) and by Northeastern University.
3:45 PM - XX5.5
Dopant Controlled Magnetism Tuning of Metal Oxide Nanoparticles for High Performance Magnetic Resonance Imaging and Hyperthermic Effects.
Jung-tak Jang 1 , Seung Ho Moon 1 , Eun-joo Choi 1 , Jae-Hyun Lee 1 , Min Gyu Kim 2 , Jinwoo Cheon 1
1 Department of Chemistry, Yonsei University , Seoul Korea (the Republic of), 2 Beamline Research Division , Pohang Accelerator Laboratory (PAL), Pohang Korea (the Republic of)
Show AbstractNewly discovered nanoscale phenomena of magnetic nanoparticles reveal that magnetic properties such as coercivity, blocking temperature, and saturation magnetization are greatly dependent on their size, shape and composition. When interfaced with biomedical sciences, they have been widely used for the applications such as magnetic resonance imaging (MRI), drug delivery, cellular signaling and hyperthermia. For decades, iron oxide (Fe3O4) nanoparticles have been the representative materials in these research fields. However, since sensing and magnetic manipulation performances of the nanoparticle probes are critically dependant on their magnetic characteristics, it is particularly important for the development of new types of nanoparticles. In this talk, we show the proper positioning of Zn dopants in Td site in metal ferrite nanoparticles, which ultimately leads to successful magnetism tuning. These Zn doped metal ferrite nanoparticles exhibit an extremely high magnetization value (175 emug-1) and provide the largest MRI contrast effects (r2 = 860 mM-1S-1). They have an eight- to fourteenfold increase in MRI contrast and a fourfold enhancement in hyperthermic effects compared to conventional iron oxide nanoparticles.
4:30 PM - **XX5.6
Intracellular Colloidal Gold: Uptake, Reactivity and Applications.
Mathias Brust 1
1 Chemistry, University of Liverpool, Liverpool United Kingdom
Show AbstractThe use of nanoparticles as intracellular probes and agents is a rapidly advancing field with the exciting promises of developing new experimental tools for research, diagnostics and therapeutics. For a number of reasons, nanoparticles of gold are of particular interest in this context. They are easy to prepare, stable at ambient conditions, readily detected to single particle level by a number of different techniques, presumably non-toxic under most conditions, and they can be chemically functionalised to carry any molecular or bio-molecular surface feature of choice. Ideally, gold nanoparticles can be programmed to enter a cell by a specific uptake mechanism, reach a predetermined intracellular target and either report by sending a diagnostic signal, or react, for example, by the site specific delivery of a drug molecule. In order to achieve this, a number of important open questions have to be addressed first. For example, it is generally not well-understood by which mechanism nanoparticles are taken up by cells and how this can be controlled. From this it follows that controlling the intracellular fate of the particles is not usually possible and that in most cases practically all particles remain confined to the endosome where they are of limited practical use. Another important problem is the stability of the ligand shell of the particles inside the cell, which represents a relatively harsh medium in which enzymatic digestion or exchange of ligands may occur quite rapidly. Here our recent advances towards dealing with these questions are presented. In particular, the use of cell penetrating peptides (CPPs) and signal sequences to control uptake and final destination of the particles is discussed. It is also shown that the presence of certain small molecules such as acrylate in the cellular medium can have a profound influence on cellular uptake of gold nanoparticles. Based on the understanding gained from these experiments, targeted drug delivery to the nucleus using programmed gold nanoparticles as carriers has been attempted. Finally, the mechanisms of inflicting highly localised damage to intracellular structures by exposure of intracellular gold nanoparticles to laser irradiation is revisited.
5:00 PM - XX5.7
Design of Maleimide-functionalized Au Nanoparticles and their use for Surface Ligand Counting and Controlled Conjugation to Biomolecules.
Eunkeu Oh 1 , Kimihiro Susumu 1 , Igor Medintz 1 , Hedi Mattoussi 1
1 Division of Optical Sciences and Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractMaleimide-to-cysteine thiol coupling has been widely used for labeling biomolecules (e.g., proteins and peptides) with dyes, due to the efficiency of the reaction and its specificity. The remarkable growth of Au nanoparticle (AuNP) use in a wide range of biological applications has increased the need and desire to prepare maleimide-functionalized AuNPs. However, because most available capping strategies of AuNPs rely on the use of thiol-appended ligands, maleimide-functionalization of these NPs is fraught with problems. Chain reaction of maleimide with thiols can occur with free ligands; this prevents transformation of the ligands prior to cap-exchange on the NPs. Maleimide-transformation applied to capped-NPs require multistep reactions,1 which reduces the effectiveness of this strategy. We have previously reported the design of modular ligands based on thioctic acid (TA) coupled to poly(ethylene glycol), TA-PEG, to promote the transfer of AuNPs to buffer media.2 Here we will describe the synthesis of maleimide-terminated TA-PEG (TA-PEG-Mal) ligands and their use for the controlled functionalization of AuNPs. The strong affinity of disulfide of TA to Au, coupled with aqueous affinity of PEG provided maleimide-functionalized AuNPs that are easily coupled to cysteine-containing biomolecules. NPs stable in high electrolyte concentrations and against dithiothreitol competition have been prepared. We will describe the synthesis of TA-PEG-Mal ligands, surface functionalization of AuNPs, and the use of maleimide coupling to controllably assemble AuNP-peptide conjugates. We then detail the use of these assemblies to count the number of surface ligands per nanoparticle. Additional use of AuNPs conjugated to cell penetration peptide (CPP) to monitor nanoparticle intracellular uptake will also be discussed.1.Zhu, J.; Kell, A. J.; Workentin, M. S. Org. Lett. 2006, 8, 4993-4996.2. Mei, B. C.; Susumu, K.; Medintz, I. L.; Delehanty, J. B.; Mountziaris, T. J.; Mattoussi, H. J. Mater. Chem. 2008, 18, 4949-4958.
5:15 PM - XX5.8
Surface Functionalized Hollow Manganese Oxide Nanoparticles for Cancer Targeted siRNA Delivery and Magnetic Resonance Imaging.
Ki Hyun Bae 1 , Kyuri Lee 1 , Jaewon Lee 2 , In Su Lee 3 , Chunsoo Kim 1 , Jung Hee Lee 2 , Tae Gwan Park 1
1 Department of Biological Sciences, KAIST, Daejeon Korea (the Republic of), 2 Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul Korea (the Republic of), 3 Department of Chemistry & Advanced Material Sciences, Kyung Hee University, Yongin Korea (the Republic of)
Show Abstract Small interfering RNAs (siRNAs) have recently emerged as promising therapeutic agents for cancer treatment due to their superior ability to silence target genes in a specific manner. For efficient cancer therapy, siRNAs should be stably and efficiently delivered into the tumor tissue and readily taken up by cancer cells. To address these issues, various cationic lipids, polymers, and peptides have been widely explored as siRNA carriers. Among them, polyethylenimine is the most popular cationic polymer currently used in non-viral gene therapy owing to its ability to escape from endosomes and superior transfection efficiency. In the present study, we report the development of polyethylenimine-coated hollow manganese oxide nanoparticles using 3,4-dihydroxy-L-phenylalanine (DOPA) as a bio-inspired adhesive, and their utility for cancer targeted siRNA delivery and simultaneous magnetic resonance imaging (MRI). The surface coating of DOPA-conjugated polyethylenimine led to the formation of positively charged manganese oxide nanoparticles, which can form stable polyelectrolyte complexes via electrostatic interactions with siRNA. Moreover, the conjugation of a therapeutic anti-HER2 antibody (Herceptin) onto the siRNA-incorporated nanoparticles facilitated their intracellular uptake and gene silencing effect against the cancer cells over-expressing HER2 receptors. These novel nanomaterials could be potentially utilized as multi-functional agents for cancer therapy using therapeutic siRNAs and MRI-based diagnosis.
5:30 PM - XX5.9
Mononucleotide-Mediated Multi-Functionalization of Gold Nanoparticles for Enzyme Sensing.
Wenting Zhao 1 , I-Ming Hsing 1 2
1 Bioengineering Graduate Program, Hong Kong University of Science and Technology, Hong Kong S. A. R. China, 2 Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Hong Kong S. A. R. China
Show AbstractTaking advantages of the size-related properties, gold nanoparticles with biomolecular functionalization have been intensively studied as reporters and carriers in developing molecular diagnostic methods and regulating intracellular gene expressions. The most popular chemistry for the synthesis of bio-functionalized gold nanoparticles is the immobilization of thiol-terminate biomolecules via gold-sulfide bond. However, long incubation (~ 2days) and delicate control on ionic strength are inevitable in current approaches due to the challenge in minimizing the charge repulsion between biomolecules and nanoparticles and protecting the nanoparticle from salt-induced aggregation in biological conditions, which consequently affect the nanoparticle stability and the biomolecule loading density. Moreover, the application schemes are generally limited by the functional biomolecules on the particles. Therefore, a facile approach for the synthesis of multi-functional gold-nanoparticles will certainly be beneficial to the field.In this study, we report a mononucleotide-mediated method for the synthesis of DNA and peptides co-functionalized gold nanoparticles. Mononucleotides, by forming an adsorption layer on particle surface, provide a sufficient stabilization effect on gold nanoparticles in salt solutions. [1] The adsorption is thermally tunable and mononucleotides detach from particle surface when temperature elevated. Mediated by mononucleotide stabilization layer, thiol-DNA can be conjugated to gold nanoparticles in just a few hours (< 4 h). [2] The achieved DNA surface coverage can be easily tuned over a wide range (from a few strands to 80 strands per particle). Besides DNA, peptides are also linked to nanoparticles in a similar way; and the sequential and simultaneous strategies for the synthesis of DNA/peptide multi-functionalized gold nanoparticles are investigated. A novel enzyme detection scheme using multi-functionalized gold nanoparticles is developed. We believe that the mononucleotide-mediated functionalization strategy will be an attractive alternative to prepare biomolecules/gold nanoparticle conjugates. The ability to modify gold nanoparticles with DNAs and peptides in a controlled manner will open up new opportunities in medical diagnosis and biological sensing applications.Reference:1.W. T. Zhao, T. M. H. Lee, S. S. Y. Leung and I. M. Hsing, Langmuir, 2007, 23, 7143-7147. 2.W. T. Zhao, L. Lin and I. M. Hsing, Bioconjugate Chem., 2009, 20, 1218-1222.
XX6: Poster Session
Session Chairs
Jinwoo Cheon
Hedi Mattoussi
Wednesday AM, December 02, 2009
Exhibit Hall D (Hynes)
9:00 PM - XX6.1
Nanoparticle-modified Polymer Capsules as Multifunctional Systems for Biosensing and Drug Delivery Applications.
Azhar Abbasi 1 , Loretta del Mercato 1 , Markus Ochs 1 , Pilar Rivera-Gil 1 , Almudena Munoz-Javier 1 , Pablo del Pino 1 , Wolfgang Parak 1
1 Physics, Philipps Universitaet Marburg, Marburg Germany
Show AbstractOne of the possible contributions of nanomedicine consists in building biocompatible multifunctional carrier systems that are able to navigate within living organisms using remote guidance and activation for the local release of their cargo. Such carrier systems can be used to improve cargo stability, to sustain and control their release rates, to increase the bioavailability of cargo substances, and to target them to specific sites within the body.Multilayer polyelectrolyte capsules are spherical microcontainers based on layer-by-layer adsorption of oppositely charged polyelectrolyte polymers onto a sacrificial template followed by the decomposition of this template. Compared to other systems (such as liposomes, block copolymers, and dendrimer polymers) polymer capsules have many advantageous properties which make them attractive candidates for medical applications including biosensing and drug delivery. Firstly, they can be synthesized under mild conditions by using numerous different materials. Secondly, their functional properties can be well-defined by embedding different nanoscale building blocks (as colloidal inorganic nanoparticles or biomolecules) within and on top of their wall. Thirdly, they can efficiently host (biological) macromolecules within their cavity for numerous biomedical applications. Finally, they can be composed of biocompatible materials for the delivery of encapsulated materials into cells1.In this work the main concepts concerning the fabrication of polyelectrolyte capsules based on calcium carbonate cores are described and their applications for delivery and sensing in cells are showed. The use of these systems is envisioned to open new ways in a broad range of disciplines since their properties may be promptly tailored to specific applications by varying the nature of the encapsulated material and the polymer shell composition.1Rivera G. P., del Mercato L. L., del Pino P., Munoz J. A., Parak W. J. “Nanoparticle modified polyelectrolyte capsules”, Nano Today, 3, 12-21, 2008.
9:00 PM - XX6.10
Protease-triggered Targeted Delivery of Gold Nanorods into Tumor.
Takuro Niidome 1 2 3 , Akira Ohga 1 , Tsuyoshi Ando 1 , Yasuro Niidome 1 , Takeshi Mori 1 2 , Yoshiki Katayama 1 2
1 Department of Applied Chemistry, Kyushu University, Fukuoka, Fukuoka, Japan, 2 Center for Future Chemistry, Kyushu University, Fukuoka, Fukuoka, Japan, 3 PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
Show AbstractGold nanorods, rod-shaped gold nanoparticles, have unique optical properties. They show two surface plasmon bands corresponding to the transverse and longitudinal surface plasmon bands in the visible (~ 520 nm) and the near infrared regions (~ 900 nm), respectively. The near infrared region (650 – 900 nm) is ideally suited for in vivo imaging and phototherapy due to minimum light absorption by intrinsic chromophores, hemoglobin, and water. Recently, we succeeded in preparing biocompatible gold nanorods by modifying PEG chain (T. Niidome et al., J. Control. Release, 114, 343-347, 2006). As a demonstration of photothermal tissue damage, the PEG-modified gold nanorods were directly injected into subcutaneous tumors in mice, then, near infrared pulsed laser lights were irradiated on the tumors. Significant suppression of the tumor growth was observed. In the case of intravenous injection of the gold nanorods, the suppression was weaker than in case of the direct injection, indicating that targeted delivery of the gold nanorods to the tumor tissue is an important key to improve the therapeutic effect (T. Niidome et al., J. Biomater. Sci.-Polym. Ed., 20, 1203-1215, 2009). In this study, we developed a functional surface modification that allows the gold nanorods to accumulate into tumor tissues.
To deliver the gold nanorods to the tumor, we modified them with a PEG-peptide instead of the simple PEG chain. A substrate peptide (LGGSGRSANAILE-Cys) for urokinase-type plasminogen activator (uPA), which specifically expresses in tumor tissue, was conjugated with PEG chain, then, the PEG-modified peptide was modified on the surface of the gold nanorods. When purified uPA was added to the PEG-peptide-modified gold nanorods, aggregation of the nanorods was confirmed by measuring absorption change at the near infrared light region and under the electron microscopy. Decrease of the absorption depended on concentration of uPA and density of PEG-peptide on the nanorods. It is expected that the PEG-peptide-gold nanorods accumulate in the tumor due to the aggregation triggered by the site-specific enzyme activity. The targeted delivery of the gold nanorods to the tumor won’t be utilized only for diagnosis of cancer but also improve the effect of the photothermal therapy.
9:00 PM - XX6.11
Monitoring Simultaneous Distance and Orientation Changes in Discrete Dimers of DNA Linked Gold Nanoparticles.
Hongyun Wang 1 2 , Bjoern Reinhard 1 2
1 Department of Chemistry, Boston University, Boston, Massachusetts, United States, 2 The Photonics Center, Boston University, Boston, Massachusetts, United States
Show AbstractImportant optical properties of discrete pairs of DNA tethered gold nanoparticles, including their scattering cross section and resonance wavelength, depend on both the dimer structure and the refractive index of their immediate environment. We show that far-field polarization microscopy aids the optical identification and interpretation of structural changes including hinge motions and nanoscale distance changes in individual assemblies. Previous theoretical studies have shown that the interparticle separation dependent polarization anisotropy of discrete nanoparticle dimers enables nanoscale distance measurements. Here we implement this approach experimentally and evaluate measured polarization anisotropies in the framework of a dipolar coupling model. We use polarization sensitive dark-field microscopy to resolve simultaneous distance and orientation changes during the compaction of discrete pairs of DNA tethered gold nanoparticles by fourth generation polyamidoamino (PAMAM) dendrimers. The relative contributions from interparticle separation and refractive index variations to changes in the light polarization and scattering intensity are quantified and compared.
9:00 PM - XX6.12
Four-in-One Targeted Gene Suppression Using Magnetic Nanoparticles for Simultaneous Molecular Imaging and siRNA Delivery.
Seung Ho Moon 1 , Eun-joo Choi 1 , Jae-Hyun Lee 1 , Kyuri Lee 2 , Tae Gwan Park 2 , Jinwoo Cheon 1
1 Department of Chemistry, Yonsei University , Seoul Korea (the Republic of), 2 Department of Biological Sciences, Korea Advanced Institue of Science and Technology, Daejeon Korea (the Republic of)
Show AbstractRecently nanomedicine based on novel magnetic nanoparticles is of considerable interest in bio-medical technologies including magnetic resonance imaging (MRI) and magnetic targeting, cell or protein separations, heat generation, and magnetism induced cellular mechanotransductions. Extensive studies on the synthesis, stabilization and surface tailoring of these robust magnetic nanoparticles have revealed that the magnetic nanoparticles can be an excellent building platform for multifunctional nanomedicine with two or more multiple components. In here, we show the basis for a “four-in-one” platform for siRNA delivery and multi-modal imaging system, in which magnetic nanoparticle is conjugated with siRNAs, cancer cell specific targeting moieties, and fluorescent dyes. In our study, this nanoparticle exhibited actively targeted cancer gene therapy to specific malignant tumors with high specificity and this targeting phenomenon was imaged by both MRI and fluorescence as well providing macroscopic cancer detection and microscopic single- or sub-cellular imaging, respectively.
9:00 PM - XX6.13
The Effect of PEG Grafted on Gold Nanorods and Their Injection Dose on Biodistribution in Tumor-bearing Mice.
Yasuyuki Akiyama 1 , Takeshi Mori 1 2 , Yoshiki Katayama 1 2 , Takuro Niidome 1 2 3
1 Department of Applied Chemistry, Faculty of Engineering, Kyushu University, Fukuoka Japan, 2 Center for Future Chemistry, Kyushu University, Fukuoka Japan, 3 PRESTO, Japan Science and Technology Corporation, Kawaguchi Japan
Show AbstractGold nanorods have strong absorbance in the near infrared region, at which light penetrates deeply into tissues, where the absorbed light energy is converted into heat. Therefore, gold nanorods are expected to act as an effective contrast agent for in vivo bioimaging and as a thermal converter for photothermal therapy. However, gold nanorods had not been applied in the bioscience field because hexadecyltrimethylammonium bromide (CTAB), a strongly cytotoxic cationic detergent, is used in their preparation. We grafted polyethylene glycol (PEG) onto the surface of gold nanorods for removing CTAB from solution and producing biocompatible gold nanorods (T. Niidome et al., J. Control. Release, 114, 343-347, 2006). Targeting of gold nanorods to a specific site is a critical aspect of bioimaging using gold nanorods as a contrast agent and for achieving efficient photothermal therapy without side effects, especially after intravenous injection. In this study, we investigated the effects of PEG grafted on gold nanorods and their injection dose on the biodistribution in tumor-bearing mice after intravenous injection and enhanced permeability and retention (EPR) effect.
In order to know the optimum length of the PEG chain for stabilizing the gold nanorods in the blood circulation, the several lengths PEG-modified gold nanorods were intravenously injected into normal mice. At 0.5 h after intravenous injection, we collected the blood and quantified the amount of Au in the blood by inductively coupled plasma mass spectrometry (ICP-MS). The PEG5,000- and PEG10,000-modified gold nanorods showed higher stability in the blood circulation compared with PEG2,000- and PEG20,000-modified gold nanorods. It is probably due to that the PEG5,000- and PEG10,000-modified gold nanorods achieve effective inhibition of protein adsorption.
To clarify the effect of the amount of PEG5,000 grafted onto the gold nanorods and injection dose on biodistribution, at 72 h after their intravenous injections, we collected major organs (blood, liver, lung, spleen, kidney, tumor and skin) from tumor-bearing mice injected Colon-26 cells (mouse rectum carcinoma) subcutaneously, then, quantified the amount of Au in the samples by ICP-MS. Higher PEG grafting levels were advantageous for reticuloendothelial system (RES) avoidance and suppression of aggregation of the gold nanorods in the circulation. Modification with a PEG:gold molar ratio of 1.5 was sufficient to show both prolonged circulation and the EPR effect. When the injection dose was increased above 39.0 μg of gold, the RES uptake in the liver was saturated and surplus gold nanorods were distributed to other tissues, especially the spleen and the tumor. This information is expected to provide an important basis for the successful application of gold nanorods in the field of nanomedicine.
9:00 PM - XX6.14
Phosphorescence-Based Dissolved Oxygen Sensing Films for Biological Applications via Metal-Halide Nanoparticles Dispersed in a Polymer Matrix.
Sage Kramer 1 3 , Per Askeland 2 , Reza Loloee 1 , Christopher Weeks 4 , Ruby Ghosh 1
1 Physics and Astronomy, Michigan State University, East Lansing, Michigan, United States, 3 Physiology, Michigan State University, East Lansing, Michigan, United States, 2 Composite Materials and Structures Center, Michigan State University, East Lansing, Michigan, United States, 4 Fisheries and Wildlife, Michigan State University, East Lansing, Michigan, United States
Show AbstractThe capability to precisely measure dissolved oxygen (DO) in aqueous environments is valuable for both the medical field and many biological industries. We are developing a portable phosphorescence based oxygen sensing unit for biological applications. The sensor will allow for in-vivo, accurate (0.5 – 18 mg/L), real-time measurements of DO. The 11Å x 11Å x 14Å luminophore is composed of a K2Mo6Cl12L2 monomer, where L is a ligand molecule. It is then dispersed in a silicone polymer matrix to make the sensing film. Since the exposed monomer is irreversibly fouled by water, we have developed a hydrophobic supportive matrix that is permeable to oxygen; the focus of this paper is on the process of embedding the nanoparticles in the protective matrix while maintaining the optical properties of the monomers in solution. In the range of 0.16 – 5.6 x 10-4 [M] a linear fit to the Stern-Volmer (SV) equation was obtained in water which demonstrates successful immobilization of the lumininophore in the sensing film. As a monomer dissolved in acetonitrile, the red luminescence in response to ultra-violet excitation is quenched by the presence of ground state 3O2 as described by the Stern-Volmer equation τo/τ = 1 + KSV[O2] , where τo and τ are the lifetimes in the absence and presence of oxygen respectively, KSV is the SV coefficient and [O2] is the molar concentration of oxygen. In solution, τo ~160 µs and τ ~13 µs in 21% oxygen. As an inorganic-metallic salt, the luminophore exhibits long term stability with no observed effects of photo bleaching as well as quantum efficiencies of ~0.2. The large, 300 nm Stokes shift, allows for simple filtering techniques to separate the original pump beam from the emission beam. Our goal is to develop a practical and relatively inexpensive DO probe, we utilize the frequency domain method to measure lifetime, as opposed to the time domain method due to the availability of inexpensive fluorimeters. The sensing film has both promising physical characteristics and optical properties comparable to the original molybdenum nanoparticles; further optimization is in progress. Lifetimes in solution are 160 and 13 µs in 0.0001 % and 21% O2 respectively. For the polymer sensing film in water τo is 80 µs and 20 µs in 21 % oxygen. A linear fit to the Stern-Volmer equation was obtained in the 0.5 to 18 mg/L DO range with KSV = (0.235 ± 0.007) L/mg. From a practical perspective this allows for a fast and inexpensive two point calibration of the device. The matrix is demonstratively gas permeable as t90 values in gas are on the order of one to two minutes. Following several weeks of testing in heavily populated fish ponds the sensing film shows no signs of permanent biofouling or degradation due to photobleaching. Both the synthesis procedure and the measurement instrumentation are efficient and inexpensive; which will enable commercialization and use of our device in a wide range of dissolved oxygen applications.
9:00 PM - XX6.15
Development of Protein-Based Taggants for Chemical and Biological Agent Detection.
William Burke 1 , Richard Chapleau 1 , David Liptak 1 , Melinda Ostendorf 1 , Malcolm Miranda 2 , Tayfun Ozdemir 2 , Melanie Tomczak 1
1 Biotechnology, UES, Inc, Dayton, Ohio, United States, 2 , VirtualEM, Ann Arbor, Michigan, United States
Show AbstractCurrent technologies for the detection of chemical and biological warfare (CBW) agents rely on several step processes and require extensive blocking and washing for positive identification. Currently, there is no deployable sensor that can detect and identify CBW agents in real-time in a field setting from a stand-off distance, which would be a significant technical advantage for the Departments of Defense and Homeland Security. Furthermore, the traditional ligands for identification of the targets of interest are antibodies, which are large proteins that are not inherently stable under battlefield or other real-world conditions. Here, we describe a novel detection system that specifically captures and identifies CBW agents in real-time in a field-deployable setting. This system utilizes nanoscale peptide ligands that have been identified and engineered to bind tightly and specifically to targets of interest. Peptides were used to capture and detect biological warfare analogues bacteriophage MS2 (a size analog of the smallpox virus), Bacillus subtilis and Bacillus cereus (close relatives of Bacillus anthracis the causative agent of Anthrax). Upon detection of a CBW agent, this system is capable of reporting detection to remote personnel via wireless communication.
9:00 PM - XX6.16
GEPI-based Genetically Engineered Fusion Proteins for Bionanotechnology Platform.
Banu Taktak 1 , Marketa Hnilova 2 , Carol Jia 2 , Whitney Allen 2 , Hanson Fong 2 , Mehmet Sarikaya 1 2 , Candan Tamerler 1 2
1 Molecular Biology and Genetics and MOBGAM, Istanbul Technical University, Istanbul Turkey, 2 Departmentof Material Science and Engineering, University of Washington, Seattle, Washington, United States
Show AbstractHighly ordered and specific immobilization of proteins and other biomolecules onto the solid surfaces is a major challenge in building nanosensing devices and developing proteomic arrays. Currently immobilization of biomolecules onto solid substrates is usually accomplished using covalently bound chemical linkers, e.g. thiols and silanes. Utility of combinatorially selected genetically engineered peptides for inorganics (GEPIs) that bind to solid surfaces with high affinity and specificity are potentially appealing as environmental- and bio-friendly alternatives to conventional chemical methods. In addition to specific recognition of inorganic surfaces, the GEPIs, which have short amino acid sequences, are robust building blocks that can be genetically engineered or chemically modified to tailor their functionalities such as binding, erecting and linking, producing bifunctional protein-based constructs. Here, we use novel recombinant maltose-binding proteins (MBP) genetically fused to inorganic-binding peptides (e.g., gold binding and quartz binding, AuBPs and QBPs, respectively) and demonstrate their specific immobilization onto various solid surfaces utilizing these specific peptide linkers using a combination of self assembly and soft lithography processes. Moreover, we demonstrate formation of multifunctional water-dispersible metallic nanostructures via gold-binding motif in a single step reaction. Materials and nanostructures are characterized using dark field optical microscopy, scanning electron microscopy and atomic force microscopy. Both presented biomimetic approaches of peptide-directed assembly and synthesis of multifunctional hybrid nanostructures have implications in a wide range of potential practical applications such as controlled bottom-up assembly of hybrid nanostructures, bionanophotonic and biosensing platforms. Research is supported by GEMSEC, an NSF-MRSEC and an NSF-IRES Programs at the University of Washington GEMSEC.
9:00 PM - XX6.17
Biological Nitric Oxide Detection with Single-walled Carbon Nanotube/Polymer Hybrid Fluorescent Sensor.
Jong-Ho Kim 1 , Daniel Heller 1 , Hong Jin 1 , Jingqing Zhang 1 , Michael Strano 1
1 Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractNitric oxide (NO) is a gaseous, free radical, which plays a role as an intracellular and intercellular messenger for signaling. To selectively detect NO in living cells, a 3,4-diaminophenyl-functionalized dextran (DAP-dex) was synthesized for wrapping single-walled carbon nanotubes (SWNT), which imparts rapid and selective fluorescence detection of NO. The near infrared (nIR) fluorescence of SWNTDAP-dex is immediately and directly bleached by NO, but not by other reactive nitrogen and oxygen species. This bleaching is reversible and shown to be caused by electron transfer from the top of the valence band of SWNT to the lowest unoccupied molecular orbital (LUMO) of NO. The SWNTDAP-dex optical sensor is capable of real-time and spatially resolved detection of NO produced by stimulating NO synthase (iNOS) in macrophage cells. We also demonstrate the potential of the optical sensor for in-vivo detection of NO in a mouse model.
9:00 PM - XX6.3
Design of New Contrasting Agents for MRI: Water Soluble Metal Oxide Nanoparticles for in vitro and in vivo Studies.
Kerstin Schneider 1 , Thomas Schladt 1 , Mohammed Shukoor 1 , Karl Fischer 3 , Florian Jochum 2 , Laura Schreiber 4 , Rudolf Zentel 2 , Manfred Schmidt 3 , Wolfgang Tremel 1
1 Inorganic Chemistry, Johannes-Gutenberg University, Mainz Germany, 3 Physical Chemistry, Johannes-Gutenberg University, Mainz Germany, 2 Organic Chemistry, Johannes-Gutenberg University, Mainz Germany, 4 medical Physics, Johannes-Gutenberg University, Mainz Germany
Show AbstractMagnetic resonance imaging (MRI) provides non-invasive, three-dimensional examination of biological processes in living organisms. An active field of research in MRI is the development of MRI contrast agents for image enhancement [1]. Superparamagnetic metal oxide nanoparticles are effective in enhancing magnetic resonance image contrast [2]. The applications of metal oxides in MRI have ranged from nontargeted detection of diseases by accumulating at certain tissues to targeted detection of biomolecular markers in cells. Target-specific MRI detection using SPIOs helps to monitoring cellular or molecular processes [3]. We have functionalized and surface protected superparamagnetic MnO and Fe2O3 nanoparticles with a multidentate functional copolymer [4] carrying (i) anchor groups for surface binding, (ii) free amino groups for attachment of target ligands and (iii) fluorescent tags for optical detection [5]. The biological activity of poly(I:C) coated magnetic nanoparticles allows specific targeting of cancer cells. Caki1, as well as Caco2 cell lines feature toll like receptor 3 (TLR3), known to bind Poly(I:C). In vitro studies already showed promising results [6]. The in vivo applicability of these particles, requires a functionalization that is compatible with body fluids, i.e. an aggregation with polyelectrolytes in the serum has to be avoided in order to prevent inactivation. This could be achieved through PEGylation. MnO nanoparticles functionalized with PEGylated polymer were soluble and stable in aqueous solution for several days without noticeable aggregation as demonstrated by light-scattering experiments [7]. In vitro experiments were used to test for toxicity as well as allocation of the particles in the cell cultures. [1]A. E. Merbach, E. Toth, Editors, The Chemistry of Contrast Agents in Medical Magnetic Resonance Imaging, John Wiley and Sons, Chichester, 2001.[2]H. B. Na, J. H. Lee, K. An, Y. I. Park, M. Park, I. S. Lee, D.-H. Nam, S. T. Kim, S.-H. Kim,; S.-W. Kim,; K.-H. Lim, K.-S. Kim, S.-O. Kim, T. Hyeon, Angew. Chem., Int. Ed. 2007, 46, 5397.[3]M. Lewin, N. Carlesso, C.-H. Tung, X.-W. Tang, D. Cory, D. T. Scadden, R. Weissleder, Nat. Biotechnol. 2000, 18, 410–414. (b) Grimm, Medical Solutions, 2003, 1, 74.[4] M. N. Tahir, M. Eberhardt, P. Theato, S. Faiss, A. Janshoff, T. Gorelik, U. Kolb, W. Tremel, Angew. Chem. Int. Ed. 2006, 45, 4803.[5] M. I. Shukoor, F. Natalio, V. Ksenofontov, M. N. Tahir, M. Eberhardt, P. Theato, H. C. Schröder, W. E. G. Müller, W. Tremel, Small 2007, 3, 1374. T. D. Schladt, T. Graf, W. Tremel, Chem. Mater. 2009, in press.[6] M. I. Shukoor, F. Natalio, N. Glube, M. N. Tahir, H. A. Therese, V. Ksenofontov, N. Metz, P. Theato, P. Langguth, J.-P. Boissel, H. C. Schröder, W. E. G. Müller, W. Tremel, Angew. Chem. Int. Ed. 2008, 47, 4748. [7]K. Schneider, T. D. Schladt, M. I. Shukoor, K. Fischer, F. Jochum, L. M. Schreiber, W. Zentel, M. Schmidt, W. Tremel, ACSNano. 2009, submitted.
9:00 PM - XX6.4
Applicability of Gold Nanoparticle for Prevention of Respiratory Syncytial Virus.
Nidhi Joshi 1 , Rakesh Joshi 1 , Seyhan Boyoglu 2 , Shree Singh 2 , Ashok Kumar 1
1 , University of South Florida, Tampa, Florida, United States, 2 Math and Science, Alabama State University, Montgomery, Alabama, United States
Show AbstractWe present the applicability of Au nanopartiles of different shapes and sizes for prevention of Respiratory Syncytial Virus (RSV) infection. RSV is known to be the main cause of Pneumonia and other severe respiratory disorders causing serious illness to the children. We have synthesised gold nanoparticles in the range 3 to 30 nm by reducing HAuCl4 solution with sodium citrate in the presence of polyvinyl pyrrolidone PVP. Gold nanoparticles were also grown in different shapes such as, nanorods, nanocubes, nanotriangles, nanooctagans and nanohexagons. The nanoparticles were characterized by using high resolution transmission electron microscopy, scaning electron microscopy atomic force microscopy and absorption spectroscopy. Variation in surface plasmon resonance band peak position in wavelength scale from 525 nm to 975 nm was observed on chaninging the nanoparticle shape from spherical to cubic. The nanostructures were used for studying Inhibition of RSV viral infection in cell culture protocal. The gold nanoparticle conjugates were mixed with RSV and subsequently introduced into the HEp-2 cells. Role of Au nanoparticle size and shape on the prevention of RSV infection and toxicity for HEp-2 cells will be presented.
9:00 PM - XX6.5
Functional Controlled Release Systems Triggered by Photothermal Effect of Gold Nanorods.
Shuji Yamashita 1 , Hiromitsu Fukushima1 1 , Yasuro Niidome 1 , Yoshiki Katayama 1 2 , Takuro Niidome 1 2 3
1 Department of Applied Chemistry, Faculty of Engineering, Kyushu University, Fukuoka Japan, 2 , Center for Future Chemistry, Fukuoka Japan, 3 , Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi Japan
Show AbstractGold nanorods, rod-shaped gold nanoparticles, have transverse and longitudinal surface plasmon (SP) bands at visible and near-infrared (IR) regions, respectively. The near-IR light can penetrate tissues. In addition, since the absorbed light energy is converted into heat, photothermal effect of gold nanorods can be triggered without damage the tissues in the path of near-IR laser light. In this study, we tried to construct controlled release system of functional molecules from surface of gold nanorods mediated by the photothermal effect.
First, we evaluated controlled release of poly(ethyleneglycol) (PEG) chains from PEG-modified gold nanorods (PEG-NR). Pulsed-laser irradiation significantly induced release of the PEG chains from the gold nanorods. On the other hand, continues wave (CW)-laser irradiation did not release any PEG chains; however, it was effective to increase temperature of the solution of the gold nanorods.
Next, we employed double stranded oligonucleotide as a thermo-responsive dissociating group. The double stranded oligonucleotide was modified on the gold nanorods using thiol group at a terminal of one strand of the oligonucleotide (DNA-NR). CW-laser irradiation induced the photothermal release of the other strand. The release depended on laser irradiation time.
We evaluated photothermal release mediated retro-Diels-Alder reaction. PEG derivative, of which terminal contains retro-Diels-Alder reaction system (furan-SH and maleimide) (PEG-DA-SH) was synthesized, then, it was modified on the gold nanorods. CW-laser irradiation induced release of the PEG chains.
For construction of controlled release system of functional molecules, these studies will provide important information about the photothermal reactions of surface molecules on the gold nanorods triggered by near-IR light irradiation.
9:00 PM - XX6.6
Synthesis of Highly-dispersive Gold/iron-oxide Magnetic Nanoparticles.
Yuki Fujikawa 1 , Motohiro Yoshikawa 1 , Takuya Kinoshita 1 , Motoaki Adachi 1 , Satoshi Seino 2 , Takao Yamamoto 2
1 Department of Chemical Enginnering, Graduate School of Engineering, Osaka Prefecture University, Sakai Japan, 2 , Graduate School of Engineering, Osaka University, Suita Japan
Show AbstractWe have succeeded in developing highly-dispersive gold/iron-oxide magnetic composite nanoparticles for biomedical applications. Firstly, we synthesized iron-oxide nanoparticles in coprecipitation method. Ferric and ferrous chloride were dissolved in distilled water with polyvinyl alcohol (PVA) as inhibitor of particle growth. After dropping ammonia water, the aqueous solution was agitated for half an hour. The obtained iron-oxide nanoparticles were collected by a magnet. Secondly, iron-oxide nanoparticles were dispersed in an aqueous solution containing HAuCl4, 2-propanol and PVA. The dispersion was filled into a glass vial and irradiated with gamma rays or electron beams to deposit metallic gold. The average sizes of the iron-oxide and Au grains determined from TEM observation were 10 - 20 nm. The secondary particle size of composite particles in the solution determined by dynamic light scattering was controlled in the range of 60 nm to 150 nm by arranging the synthesis parameter. We have performed magnetic separation tests using amino acids as model biomolecules in order to demonstrate that our particles absorb them via Au-S bond and are attracted by a magnet. Only two amino acids with sulfur, cystine and methionine, out of 17 α-amino acids were preferably separated by our particles. These characters show that our gold/iron-oxide magnetic nanoparticles have great potential for biomedical application such as drug delivery and DNA and RNA separation, MRI imaging, immunoassays, cell separation and hyperthermia in the future.
9:00 PM - XX6.7
Synthesis and Cell Uptake of Gold Nanostars with Magnetic Cores.
Hyon-Min Song 1 , Quy Ong 1 , Qingshan Wei 1 , Alexander Wei 1
1 Chemistry, Purdue University, West Lafayette , Indiana, United States
Show AbstractGold nanostars with magnetic cores have been synthesized by a two-step method, using core-shell Fe3O4@Au nanoparticles as intermediates. The nanostars were prepared in micellar surfactant (CTAB) solutions and their dimensions were varied by the concentration of HAuCl4, the size of the core-shell seeds, and the amount of AgNO3 (a growth additive). Composite Fe3O4-Au nanoparticles could also be used as seeds, and produced nanostars with similar shape characteristics. The core and shell thicknesses of the Fe3O4@Au nanoparticles could be varied to produce seed particles with diameters ranging from 11 to 29 nm, and had significant impact on nanostar growth. Nanostars were cleansed and functionalized for cell uptake studies using KB cells and macrophages. These were found to have low cytotoxicity, however macrophages responded to high nanoparticle loadings with gross changes in their adhesion and morphology. This implies that even nontoxic nanomaterials may affect the immune response of macrophages.
9:00 PM - XX6.8
SERS Study of Alizarin Red Dye on Colloidal Silver Nanoparticles.
Raj Swarnkar 1 , Subhash Singh 1 , Ram Goapl 1
1 Department of Physics, Allahabad University, Allahabad, Uttar Pradesh, India
Show AbstractThe present paper deals with surface enhanced Raman scattering (SERS) study of an organic red dye Alizarin on colloidal silver nanoparticles. The colloidal solution of nanoparticles is synthesized by pulsed laser ablation of silver rod in pure deionized water using focused out put of 1064nm wavelength of Nd:YAG laser having 35mJ/ pulse energy. Sodium chloride is used as aggregating agents. It is observed that SERS enhancement factor varies strongly depending on concentration of used aggregating agent (especially on the concentration of Cl- ions). These changes in SERS efficiency of colloid are reflected through changes on the absorption spectra. The possible mechanism of SERS will be also discussed.
9:00 PM - XX6.9
Metal Enhanced Fluorescence Mediated Detection of Biological Contaminants.
Melinda Ostendorf 1 , William Burke 1 , David Liptak 1 , Richard Chapleau 1 , Melanie Tomczak 1
1 Biotechnology, UES, Inc, Dayton, Ohio, United States
Show AbstractIdentification of bacterial and viral agents in water, soil and airborne sources is essential to protecting public health and safety. Proteins and peptides are capable of highly sensitive and specific recognition of biological and chemical targets. The ability to synthetically produce peptides allows for conjugating myriad reporting groups and incorporating the specific recognition abilities into biosensor platforms. Here we describe the construction of a portable sensor suitable for the direct measurement of target organisms utilizing metal enhanced fluorescence (MEF). The fully self-contained sensor is capable of unsupervised monitoring for an extended period of time. Detection events are automatically reported over a wireless network. Peptides were used to capture and detect the biohazardous organisms and analogues bacteriophage MS2, Bacillus subtilis and Bacillus cereus. All steps, from detection to reporting to information transmission, occur in real-time and in real-world environments. This technology can readily be multiplexed for the specific detection of multiple targets from “dirty” real-world samples by the choice of fluorophores attached to the reporting peptide. Coupling the biosensor technology to a miniature spectrometer provides for the high-resolution distinguishing between individual contaminants in a shoe-box sized instrument.
Symposium Organizers
Antigoni Alexandrou Ecole Polytechnique
Jinwoo Cheon Yonsei University
Hedi Mattoussi Florida State University
Vince Rotello University of Massachusetts
XX7: Multifunctional Nanoparticles and Nano-architectures as Sensing Tools
Session Chairs
Wednesday AM, December 02, 2009
Room 309 (Hynes)
9:30 AM - **XX7.1
A General Approach to Generate Multifunctional Nano-architectures from DNA-based ABC Monomers for Biosensing and Drug-delivery-coupled Imaging.
Dan Luo 1
1 Biological and Environmental Engineering, Cornell University, Ithaca, New York, United States
Show AbstractAssembling different moieties onto a single core building block can create synergistic functions and enable real world applications including intelligent sensing and imaging. However, precise attachment of different moieties requires that the core block is both multivalent and anisotropic. In this talk, I will focus on our creation of anisotropic, branched, and crosslinkable building blocks (ABC monomers) from which multifunctional nano-architectures have been assembled. A target-driven polymerization process has also been developed based on ABC monomers. In this novel process, multiple signals within each ABC monomer get amplified upon polymerization, and polymers are generated only in the presence of a specific DNA molecule, enabling highly-sensitive pathogen detection. Using this ABC monomer system, we have also designed a biocompatible multi-drug delivery vector that delivers both drugs and imaging-tracers simultaneously. Our ABC approach provides a general yet versatile route towards creating a range of multifunctional nano-architectures that can be used in multiplexed biosensing and drug-delivery-coupled imaging.References:Nature Nanotechnology in press July (2009)Nature Materials (Article), 8, 519-527(2009)Nature Materials (Article) 8, 432-437 (2009)Nature Nanotechnology (Cover Article) 3, 693-696 (2008) Nature Materials 5, 797-801 (2006)Nature Protocols 1, 995-1000 (2006)Nature Biotechnology 23, 885-889, (2005)Nature Materials 3, 38-42, (2004)
10:00 AM - XX7.2
Multimodal Nanoparticles as Contrast Agents for Bioimaging Applications.
Amit Singh 1 , Parvesh Sharma 1 , Scott Brown 1 , Niclas Bengtsson 1 , Qizhi Zhang 1 , Glenn Walter 1 , Stephan Grobmyer 1 , Swadeshmukul Santra 2 , Huabei Jiang 1 , Edward Scott 1 , Brij Moudgil 1
1 , university of florida, Gainesville, Florida, United States, 2 , university of central florida, Orlando, Florida, United States
Show AbstractEach imaging modality, if used independently, provides limited structural and functional information. Different imaging modalities can be integrated synergistically to provide comprehensive and complementary information ranging from tissue structure to biological processes. For instance, multimodal MRI-PAT imaging contrast agents combine the high resolution and deep tissue penetration of MRI (magnetic resonance imaging) with the sensitivity of PAT (photoacoustic tomography). In this work we describe the synthesis, characterization and functional evaluation of MRI-PAT contrast agent for non-invasive imaging through both MRI and PAT. Novel gold speckled silica (GSS) nanoparticles doped with Gadolinium (Gd) were synthesized by a simple one pot procedure utilizing reverse micelles of nonionic microemulsions. The photo acoustic signal originates from the thermoelastic expansion of the discontinuous gold nano domains speckled across the silica surface, whereas the MR contrast is obtained from the Gd incorporated in the silica matrix. The bimodal imaging capabilities of these particles were demonstrated using in vitro studies.
10:15 AM - XX7.3
Gadolinium-Hydrogel-Lipid Hybrid Nanoparticles Provide `Off-On-Off’ MRI Signals for Non-Invasive Thermometry.
Adam Shuhendler 1 , Claudia Gordijo 1 , Robert Staruch 2 , Wendy Oakden 2 , Greg Stanisz 2 , Rajiv Chopra 2 , Xiao Yu Wu 1
1 Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada, 2 , Sunnybrook Research Institute, Toronto, Ontario, Canada
Show AbstractThermotherapy to treat localized solid tumors can be non-ablative, where tissue temperature is held at 42-43oC, or ablative, causing non-selective tissue necrosis at temperatures greater than 55oC. Since tissue temperature dictates the type of thermotherapy and thus very different therapeutic outcomes, the precise control of tissue temperature is crucial. Due to its non-invasiveness and multidimensional imaging capability, magnetic resonance imaging (MRI) has been pursued as an alternative to surgically invasive and potentially infectious probe thermometry. Existing temperature-sensitive contrast agents have failed to provide reliable temperature data due to low signal-to-noise ratio and the dependence of accurate interpretation of relaxivity data on tissue concentrations of the contrast agent. While temperature sensitive liposomes have been reported to overcome these limitations, a single formulation cannot provide real-time measurement of the therapeutic temperature window that demarcates the onset of non-ablative thermotherapy and differentiates between non-ablative and ablative temperatures. By synthesizing novel metal-chelating temperature-responsive ultrafine hydrogel nanoparticles and loading them into a solid lipid nanoparticle carrier, a temperature sensitive contrast agent was engineered with two consecutive temperature-dependent ‘off-on’ and ‘on-off’ step transitions, delimiting a window within which thermotherapy can be applied. A novel cross-linker was synthesized with metal chelation functionality, and used to formulate poly(acrylamide-co-N-isopropylacrylamide) nanoparticles 10 nm in diameter. Once loaded with gadolinium (Gd), which was stably chelated by these particles, a 3-fold enhancement of water proton relaxivity was observed over free gadolinium diethylenetriaminepentaacetic acid. The Gd-hydrogel nanoparticles were then incorporated into a solid lipid nanoparticle matrix resulting in solid Gd-hydrogel-lipid hybrid nanoparticles with average sizes ranging from 105 to 112 nm. When these nanoparticles were aliquoted, heated at various temperatures for 10 minutes in vitro and subsequently analyzed by MRI, an ‘off-on-off’ thermal response was observed. An ‘off-on’ step transition in contrast enhancement was detected at the melting point of the fatty acid matrix (42oC), and an ‘on-off’ step transition was noticed at the lower critical solution temperature (LCST) of the copolymer hydrogel (54oC). A single composite nanoparticle, as formulated here, can thus serve to indicate the onset of non-ablative thermotherapy (42-43oC) and to delineate the transition from non-ablative to ablative temperatures (>55oC) in real-time. Since both the melting point of the fatty acid matrix and the LCST of the hydrogel are tunable in terms of response temperature, the intelligent multiparticle relaxation-enhancing system can be engineered to designate the temperature window specific to the goal of the individual thermotherapy.
10:30 AM - XX7.4
Characterization of FePt Alloy Nanoparticles with Controllable Size and Conformation and their Biomedical Applications for MRI/CT Dual Contrast Agent.
Yu-Hong Shau 4 , Yusang Yang 1 , Tung-Yiu Wong 4 , Chia-Chun Chen 2 , Dar-Bin Shieh 3 4
4 Oral Medicine, National Cheng Kung University, Tainan Taiwan, 1 Material Science, National Tsing Hua University, Hsinchu Taiwan, 2 Chemistry, National Taiwan Normal University, Taipei Taiwan, 3 IIAS, National Cheng Kung University, Tainan Taiwan
Show AbstractFePt alloy nanoparticles have been developed for their applications in IT industry for high density recording due to their stability, magnetic property, high electron density and controllable sizes. Their biological properties and applications in biomedicine, however, has not been well documented. We were able to synthesize FePt nanoparticles in defined size from 3, 6, to 12nm. Their cellular and sub-cellular nuclear targeting, biodistribution and imaging contrast properties in X-ray computed tomography (CT scan) and magnetic resonance imaging (MRI) were explored. The biocompatibility evaluation revealed that both cytotoxicity and hemolysis was minimal in the application dosage ranges. The biological distribution of the particles in C3H/HEN mice showed that 12nm FePt NP mainly accumulated in the spleen and lung 12 hr after IV injection then gradually decreased toward normal level. The 6nm particles was accumulated in the lung followed by spleen and reached plateau at 48hr. 3nm FePt NP also preferentially accumulated in the spleen, lung and liver and reached peak value at 48hrs. The 12nm FePt NPs presented persisted high blood levels even at 48hr after IV injection. On the other hand, 3 and 6nm particles was significantly cleared from the circulation after 12hr. The nanoparticles were able to reach brain tissue and plateau at 24hr with highest concentration for 12 and 3nm particles. At equal iron concentration, 12nm FePt NP presented the highest image contrast in CT followed by 3nm and 6nm particles. All three nanoparticles show detectable image contrast at above 100μM. The 12nm particles presented the best T2* MRI contrast property with a detection limit at 1mM. 3 and 6nm particles required more than 25mM of iron concentration to be detected in MRI. The NLS-FePt-nps were able to be transported to the nucleus of Hela cell compared to the control. In conclusion, FePt NP presented to be a promising material for the development of multi-modal molecular imaging/nuclear targeting agent for MRI and CT.
10:45 AM - XX7.5
Nanoparticle-incorporated Microbubbles as Multifunctional Contrast Agents for Medical Imaging and Therapy.
Minseok Seo 1 2 , Ivan Gorelikov 2 , Naomi Matsuura 1 2
1 Department of Medical Biophysics, University of Toronto , Toronto, Ontario, Canada, 2 Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
Show AbstractThere is great interest in designing new medical imaging contrast agents that can permit multiple imaging and therapy applications using a single agent. This would provide concurrent contrast imaging for multiple modalities (e.g., magnetic resonance, x-ray computed tomography, ultrasound, and optical imaging) with complementary spatial, temporal and depth resolution for the more accurate diagnosis and local treatment of diseased tissue. Solid nanoparticles (NPs) are promising multifunctional imaging and therapy agents. Microbubbles have long been used as effective contrast agents for ultrasound imaging in patients. Here, we present a new strategy for the simple and robust incorporation of various medical nanoparticles into monodisperse microbubbles based upon the controlled pH-based regulation of the electrostatic attraction between NPs and the microbubble shell. Using this simple approach, microfluidic-generated, protein-coated, perfluorobutane microbubbles (2-8 μm) were incorporated with various NPs, including quantum dots, iron oxide NPs, and gold nanorods. This work reveals the potential of modular synthesis of a variety of NP-microbubble constructs to represent flexible, user-defined multifunctional imaging and therapy agents tailored for specific applications and disease types.
11:30 AM - **XX7.6
Development of a Tetrapod-based Fluorescent Strain Sensor for Biological Imaging.
Charina Choi 1 2 , Paul Alivisatos 1 2
1 Chemistry Department, University of California, Berkeley, Berkeley, California, United States, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractIn recent years, a new generation of quantum confined colloidal semiconductor structures has emerged, with more complex shapes than simple quantum dots. These include nanorods and tetrapods. Beyond shape, it is also now possible to spatially vary the electron and hole potentials within these nanoparticles by varying the composition. Examples of these new structures include seeded dots, rods, and tetrapods, which contain a CdSe core embedded within a CdS shell. These structures may have many uses beyond those envisioned for simple quantum dots, which are frequently employed in luminescent applications. This talk is concerned with changes in the optoelectronic properties of tetrapods when the arms are bent. We demonstrate that seeded tetrapods can serve as an optical strain gauge, capable of measuring forces on the order of nanonewtons. We anticipate that a nanocrystal strain gauge with optical readout will be useful for applications ranging from sensitive optomechanical devices to biological force investigations.
12:00 PM - XX7.7
Plasmonic Nanostructures in Biosensing: Applications from Plasmon Coupling Microscopy to Rapid Pathogen Detection using Nanoparticle Cluster Arrays.
Bjoern Reinhard 1 2 , Guoxin Rong 1 , Lynell Skewis 1 , Bo Yan 1 , Hongyun Wang 1
1 Chemistry, Boston University, Boston, Massachusetts, United States, 2 Photonics Center, Boston University, Boston, Massachusetts, United States
Show AbstractDiscrete assemblies of noble metal nanoparticles enable new imaging and improved sensing applications. The distance dependent interactions between individual noble metal nanoparticles can be used to engineer discrete plasmonic nanostructures for applications in microscopy, sensing and imaging. For instance, RNA tethered noble metal nanoparticles are active nanostructures which can indicate nanoscale distance changes through shifts in their resonance wavelength.[1] Plasmon coupling microscopy utilizes the distance dependent plasmon coupling to resolve close contacts between individual nanoparticle labeled membrane components during optical colocalization.[2] Direct near-field interactions between the particles red-shifts their resonance when the particles have approached within approximately one particle diameter. These shifts can be conveniently detected using a ratiometric detection scheme in a wide field microscope. The near-field interactions between closely coupled nanoparticles culminate in strong E-field localizations in the junction between the particles making these materials also interesting building blocks for photonic devices. In two dimensional nanoparticle cluster arrays (NCAs) near- and far-field interactions enable a multiscale field enhancement that can be tuned in a rational fashion by controlling size and separation of the clusters.[3] NCAs represent photonic plasmonic crystals with cascade E-field enhancement that have demonstrated the ability to identify different bacteria species using surface enhanced Raman spectroscopy (SERS). 1.Skewis, L.R. and B.M. Reinhard, Spermidine modulated ribonuclease activity probed by RNA plasmon rulers. Nano Letters, 2008. 8(1): p. 214-220.2.Rong, G.X., et al., Resolving Sub-Diffraction Limit Encounters in Nanoparticle Tracking Using Live Cell Plasmon Coupling Microscopy. Nano Letters, 2008. 8(10): p. 3386-3393.3.Yan, B., et al., Engineered SERS Substrates with Multiscale Signal Enhancement: Nanoparticle Cluster Arrays. ACS Nano, 2009. 3: p. 1190 - 1202.
12:15 PM - XX7.8
Solution Phase Triangular Silver Nanoplates for Highly Sensitive Surface Plasmon Resonance Sensing of C-reactive Protein.
Deirdre Ledwith 1 , Muriel Voisin 1 , Denise Charles 2 , Stephen Cunningham 3 , Patrick Fournet 1 , John Kelly 4 , Margaret Brennan Fournet 1
1 School of Physics, National University of Ireland, Galway, Galway Ireland, 2 School of Physics, Trinity College Dublin, Dublin Ireland, 3 National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Galway Ireland, 4 School of Chemistry, Trinity College Dublin, Dublin Ireland
Show AbstractSolution phase triangular silver nanoplates (TSNP) as highly sensitive ensemble localized surface plasmon (LSPR) sensors are presented. By controlling the TSNP edge length and therefore aspect ratio, the LSPR and LSPR sensitivity can be readily tuned along the theoretical upper sensitivity limit throughout the visible and near-infrared regions of the spectrum which are particularly relevant for biosensing. A novel one-step total solution phase bioassay for the detection of the acute phase protein and cardiac marker C-reactive protein (CRP) is demonstrated. Cytidine 5’-phosphocholine (PC) which binds to CRP in a calcium mediated process is used as a nonimmunological receptor molecule. A simple, one step in situ functionalization procedure was developed whereby the synthesis of PC coated TSNP was carried out in a one pot procedure. After centrifugation to remove any unbound receptor molecules and/or blocking agent a simple one-step direct capture assay method is used for the detection of CRP. UV-visible-NIR spectra of the PC functionalized TSNP solutions are recorded on the addition of CRP at concentrations ranging from 0 ng to 500 ng. The analyte concentration can be determined from the measured quantitative LSPR-shift in the spectrum within time durations of circa 3 minutes.In conclusion we have demonstrated high LSPR sensitive solution phase ensemble nanostructures featuring triangular silver nanoplates and their use for LSPR-shift based biosensing. The versatility of these high LSPR sensitive TSNP ensembles for one step homogenous phase sensing highlights their exceptional promise for bioassays.
12:30 PM - XX7.9
Fluorescence Quenching of CdSe/ZnS nanocrystals by Binding to copper Nanoparticles.
Sanchari Chowdhury 1 , Venkat Bhethanabotla 1 , Rajan Sen 2
1 Chemical and Biomedical Engineering Department, University of South Florida, Tampa, Florida, United States, 2 Civil and Environmental Engineering, University of South Florida, Tampa, Florida, United States
Show AbstractQuenching of luminescence due to the proximity of metal nanoparticles is efficiently utilized for many different applications. Quenching resulting due to metallic nanoparticles is successfully utilized for the improvement of homogeneous and competitive fluorescence immunoassay, optical detection of DNA hybridization , competitive hybridization assay, and in optoelectronics. Recently many researchers have utilized the quenching effect of gold nanoparticles on nanocrystals quantum dots for biological and solar cell application. Like luminophore molecules the fluorescence of quantum dots are similarly affected by the electromagnetic interaction with metal nanoparticles. The effect of metal nanoparticles on the luminescence of luminophore is decided by different properties of nanoparticles like dielectric constant, size and shape. Luminescence quenching by metal nanoparticles has been studied mostly using gold nanoparticles. The imaginary components of dielectric constants of copper and gold are comparable in the wavelength range of 400 nm to 500 nm and almost twice in the wavelength range of 500 nm to 625 nm. Hence, it is expected that in these wavelength range due to ohmic losses, Cu nanoparticles will show similar or better quenching effects in comparison to gold nanoparticles. This motivates us to choose copper nanoparticles for fluorescence quenching application.A pronounced fluorescence quenching of CdSe/Zns nanocrystals coated with mercaptoundecanoic ligands was realized at the close proximity of copper nanoparticles. Stable copper nanoparticle colloid with average particle size of 10 nm was synthesized by reducing copper salt precursor using ascorbic acid in the presence of Polyvinylpyrrolidone (PVP) polymer. The fluorescence quenching of the CdSe/Zns nanocrystals is sensitive to the nanomol concentration range of the copper nanoparticles. We also observed that the quenching rate increases as the spectral overlap between the CdSe/ZnS emission and the copper nanoparticles absorption increases. This suggests that the quenching is a result of Forster-type energy transfer processes. The mechanism of the fluorescence quenching on the copper nanoparticles surfaces has been treated in the light of electromagnetic interaction between nanoparticles and fluorophores which influences the both radiative and non-radiative decay rate of fluorophore. We will present theoretical calculation using Gersten-Nitzan (GN) model to provide insight into the influence of Cu nanoparticles on radiative and non-radiative decay rates of luminophore molecules at their close proximity. Quenching effect of copper nanoparticles will motivate the utilization of these nanoparticles as an inexpensive alternative to gold in some biological and optoelectronics applications.
12:45 PM - XX7.10
DNA-templated Nanowires: Mechanism of Formation and Their Application.
Albena Ivanisevic 1
1 , Purdue University, West Lafayette, Indiana, United States
Show AbstractIn biomedical applications, novel nanostructures can be designed to perform multiple functions, such as providing a platform for cell targeting as well as behaving as an MRI contrast agent. In recent years, our group has demonstrated that metallic and magnetic nanoparticles (NP) can be aligned along the DNA strand, creating a 1D linear nanowire. The high aspect ratio of length to diameter along with its affinity to cations makes DNA an efficient template for nanowire formation. Control over the fabrication method is needed in order to characterize its imaging and cellular recognition properties. First, circular dichroism (CD) spectroscopy technique was used to probe changes in the structure of the DNA-templated nanowires. The mechanism of nanowire formation was studied by examining the arrangement effects of nanoparticle (Au and Fe_2 O_3 ) assembly on the DNA double helix and analyzing the structural influence after enzyme manipulation. Multi-component nanowires constructed with 1:1 DNA:NP mass ratio displayed a similar CD signal as the B-form bare DNA, with optimal enzyme activity and no sign of template denaturation. Second, to test whether nanowires are effective MR contrast agents, relaxation times were measured at different NP concentrations through nuclear magnetic resonance (NMR). In addition, in vitro experiments were performed to understand the cytotoxicity effects of the nanowires. Initial results from NMR and in vitro experiments demonstrate that DNA template enhanced the MR relaxivity and did not harm the cell viability.
XX8: Detection Technologies: MRI, Hybridization, and Colorimetric Assays
Session Chairs
Christof Niemeyer
Geoffrey Strouse
Wednesday PM, December 02, 2009
Room 309 (Hynes)
2:30 PM - **XX8.1
DNA-Protein Conjugates of Semiconductor Nanoparticles – Toward Rational Fabrication of Devices.
Christof Niemeyer 1 2 , Oliver Schoeps 1 2 , Ulrike Woggon 1 2 , Huachang Lu 1 2
1 Fakultaet Chemi, LS Biologisch-Chemische Mikrostrukturtechnik, Technische Universitaet Dortmund, Dortmund Germany, 2 Institut fuer Optik und Atomare Physik, Technische Universitaet Berlin, Berlin Germany
Show AbstractThe biomimetic "bottom-up" assembly of programmed molecular building blocks into larger superstructures represents a highly attractive strategy for the generation of functional nanomaterials. With respect to this approach, DNA oligomers are powerful building blocks for the self-assembly of nanostructured architecture. We here report on the DNA-functionalization of proteins and nanoparticles toward rational fabrication of model devices. For instance, we have used DNA oligomers to assemble fluorescent proteins into well defined architecture to model antennae and light-switchable devices. Decoration of semiconductor quantum dots with DNA-fluorescent protein conjugates was investigated. The resulting supramolecular assemblages enabled FRET detection over significantly longer distances than the traditional approach. Moreover, quantum dots were modified with cytochrome P450 enzymes to yield a novel class of photoswitchable biocatalysts. [1] Mirkin, C. A., Niemeyer, C. M., NanoBiotechnology II: More Concepts and Applications, Wiley-VCH, Weinheim 2007.[2] Kukolka, F., Schoeps, O., Woggon, U., Niemeyer, C. M. (2007) DNA-Directed Assembly of Supramolecular Fluorescent-Protein Energy-Transfer Systems. Bioconjug. Chem. 18, 621 - 627.[3] Ipe, B. I., Niemeyer, C. M. (2006) Nanohybrids Composed of Quantum Dots and Cytochrome P450 as Photocatalysts. Angew. Chem. Int. Ed. 45, 504-507.[4] Hazarika, P., Kukolka, F., Niemeyer, C. M. (2006) Reversible binding of fluorescent proteins at DNA-gold nanoparticles. Angew. Chem. Int. Ed. 45, 6981-6984[5] Lu, H., Schoeps, O., Woggon, U., Niemeyer, C. M. (2008) A Self-Assembled Donor Comprising Quantum Dots and Fluorescent Proteins for Long-Range Fluorescence Resonance Energy Transfer. J. Am. Chem. Soc. 130, 4815-4827.
3:00 PM - XX8.2
Colorimetric Detection of Small Molecules based on Aptamer-Linked Gold Nanoparticles.
Jorge Chavez 1 , Carter East 2 , Wanda Lyon 1 , Nancy Kelley-Loughnane 1 , Morley Stone 1
1 Applied Biotechnology Branch, Human Effectiveness Directorate, Air Force Research Laboratories, Wright-PAtterson Air Force Base, Ohio, United States, 2 Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio, United States
Show AbstractDifferent approaches have been proposed to develop sensors that show high specificity and minimal chances of false positives. Naturally occurring biomolecules that have evolved for a specific function are logical candidates to be used as recognition units in different sensing platforms. Coupling such biomolecules with materials that can produce an optical or electronic signal upon the recognition event can lead to the development of sensors with superior responses. Nanoparticles, due to their size and high surface areas offer exciting possibilities for development of new materials. Metal nanoparticles undergo colorimetric changes as a function of the interparticle distance, which has been used to develop colorimetric sensors. In this work, we used gold nanoparticles (AuNPs) as colorimetric reporters and aptamers as the recognition motif for the design of sensing materials for different targets. This design involves two sets of AuNPs coated each with a different oligonucleotide (DNA-AuNPs). Each set of particles contained a sequence complementary to contiguous parts of the 5’ end of an aptamer. Hybridization of the free aptamer and the complementary oligonucleotides immobilized on the DNA-AuNPs (3-piece system) produced purple nanoparticle aggregates. The aptamer was intended to be used as a tool to control the interparticle distance. In the aggregates, the aptamer acted as a crosslinker due to the complementary sequences used in the AuNPs. The binding to its target involved a change in the conformation of the aptamer, which was designed to promote the disassociation of the nanoparticle aggregates. The conformational change induced dehybridization of the DNA crosslinking AuNPs produced a change in the color of suspensions from purple to red. We designed two nanoparticle aggregates sensing systems, one based on an aptamer for theophylline, a drug for asthma treatment, and the other with an aptamer that binds riboflavin, a redox-cofactor. We observed that the qualitative response of the aggregates depended on the aptamer used as the recognition motif. Moreover, adding a sequence of 10 adenines to the DNA used to hybridize the particles to the theophylline aptamer dramatically affected the qualitative response of the aggregates. A simplified system was designed by immobilizing the riboflavin aptamer directly on one set of the AuNPs (Apt-AuNPs). The aggregates were obtained by hybridization of the Apt-AuNPs and a second set of DNA-AuNPs (2-piece system). We studied the response of these nanoparticle aggregates under different conditions, observing that they could be used at different salt concentrations and temperatures. This new design responded to riboflavin with high specificity and superior performance.
3:15 PM - XX8.3
Nanoshells with Targeted Simultaneous Enhancement of Magnetic and Optical Imaging and Photothermal Therapeutic Response.
Rizia Bardhan 1 , Wenxue Chen 2 , Carlos Perez-Torres 3 2 , Marc Bartels 2 , Ryan Huschka 1 , Liang Zhao 4 , Emilia Morosan 4 , Robia Pautler 3 2 , Amit Joshi 2 , Naomi Halas 1 5
1 Chemistry, Rice University, Houston, Texas, United States, 2 Radiology, Baylor College of Medicine, Houston, Texas, United States, 3 Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States, 4 Physics and Astronomy, Rice University, Houston, Texas, United States, 5 Electrical and Computer Engineering, Rice University, Houston, Texas, United States
Show AbstractIntegrating multiple functionalities into individual nanoscale complexes is of tremendous importance in biomedicine, expanding the capabilities of nanoscale structures to perform multiple parallel tasks. Here we combine the ability to enhance two different imaging technologies simultaneously- fluorescence optical imaging and magnetic resonance imaging (MRI), with antibody targeting, and photothermal therapeutic actuation all in the same nanoshell-based complex. The nanocomplexes are constructed by coating a gold nanoshell (silica core/Au shell) with a silica epilayer doped with Fe3O4 and the fluorophore Indocyanine green (ICG). ICG, the only FDA-approved near-infrared-emitting fluorophore, is extensively used in biomedical imaging. However, ICG is relatively weak with a quantum yield of only 1.3% in aqueous media. Recently we have shown that the fluorescence of ICG can be enhanced by 50X when placed near a Au nanoshell surface, when the nanoshell plasmon is tuned to the ICG emission wavelength.[1] The nanocomplexes fabricated here are bright (45X fluorescence enhancement of ICG) and have a high T2 relaxivity (390 mM-1sec-1). The antibody conjugated nanocomplexes target HER2 positive cells and show significant contrast in vitro both as an MR agent and a bright fluorescence probe. In addition, they induce photothermal cell death upon near-infrared illumination. We believe the properties of the nanocomplexes will provide a unique tool for the clinical scientist, enabling studies of pharmacokinetics and biodistribution of nanoparticles before, during, and after therapy in a manner compatible for minimally invasive human use.[1] R. Bardhan, N. K. Grady and N. J Halas, “Nanoscale Control of Near-Infrared Fluorescence Enhancement Using Au Nanoshells”, Small 2008, 4, 1716-1722.
3:30 PM - **XX8.4
Manipualting Gene Expression in-vitro Via a Non-viral QD Gene Therapeutic.
Geoffrey Strouse 1
1 Department of Chemistry an Biochemistry, Florida State University, Tallahassee, Florida, United States
Show AbstractNon-viral gene therapeutics represent a rapidly developing biomedical technology. The integration of QDs and nucleic acid therapeutics (DNA, siRNA, mRNA), as well as proteins, can offer a trackable platform for manipulating protein levels within mammalian cells. In this presentation I will discuss the control of protein expression in cells through the simultaneous delivery of siRNA and linearized plasmid DNA. Chemoselective coupling strategies are employed to control the timing of release and thus protein expression levels within the cell. The design of the materials, the delivery into the cells, and the impact on cell viability and metabolic pathways will be discussed. Using quantum dot materials modified by gene regulators, one can envision potentially individualized diagnostic and therapeutic approaches for biomedical science.
4:30 PM - **XX8.5
Release of Multiple Species from Gold Nanorods.
Kimberly Hamad-Schifferli 1
1 Biological Engineering and Mechanical Engineering, MIT, Cambridge, Massachusetts, United States
Show AbstractMany complex diseases such as cancer and HIV are best treated with a mixture of drugs which act synergistically. One of the major challenges in drug delivery is controlling release of each of the species independently and precisely, since each species can have vastly different chemical and biological properties. Often carriers must be engineered with complex architectures in order to release multiple drugs in different time windows, and still only passively. Gold nanorods offer the ability to control the release of multiple species because of their unique optical properties. Ultrafast laser irradiation in resonance with their longitudinal surface plasmon resonance can heat NRs to a high local temperature, inducing melting. This triggered melting has been exploited for controlled release of biomolecules bound to the nanorods. We exploit the fact that gold nanorods can be engineered to absorb light at different wavelengths by changing their shape. By using a laser tuned to their absorption peak, we are able to selectively melt nanorods of different shapes. We load two different shaped nanorods with two different DNA strands and by tuning the laser excitation, can release one strand or the other. Release is efficient, where 50-80% of loaded DNA is released selectively. Laser fluence governs the degree of nanorod melting, therefore specificity and degree of release are externally tunable. Since conjugation requires only a simple thiol, it is potentially applicable to a range of molecules. This method is expandable, as tuning nanorod synthesis parameters could extend this approach beyond two species. Nanord surface chemistry is customizable, so they can accommodate different physiological environments.
5:00 PM - XX8.6
LSPR Based Nanosensors Composed of Bifunctional Inorganic Binding Peptides and Molecular Constructs.
Turgay Kacar 1 2 , Matthew Rutherford 1 , Banu Taktak 2 , Mustafa Gungormus 1 , David Ginger 3 , Candan Tamerler 1 2 , Mehmet Sarikaya 1
1 Materials Science and Engineering, University of Washington, Seattle, Washington, United States, 2 Molecular Biology and Genetics, Istanbul Technical University, Maslak - Istanbul Turkey, 3 Chemistry, University of Washington, Seattle, Washington, United States
Show AbstractGenetically engineered peptides for inorganics (GEPIs) isolated via combinatorial biology approaches, such as phage- and cell surface-display protocols, can be used as molecular erectors to attach biomolecules and nanoparticles onto solid surfaces. In this study, an optical hybrid sensor composed of gold nanoparticles (NPs), GEPI and a molecular construct was developed for detecting biomolecules in solution. In contrast to conventional chemistry, AuNPs were attached to glass slide through bifunctional peptide in which individual Au and silica-binding peptide sequences were chemically linked with a flexible triple-amino acid bridging. Glass slides, functionalized with AuNPs were used as platform for nanophotonic detection of analytes since NPs exhibit strong UV-vis absorption band, known as localized surface plasmon resonance (LSPR). The light-absorptive properties of these NPs depends highly on the local environment. As a model experiment, Alkaline Phosphatase (AP) fused with five tandem repeats of gold binding sequence (5rGBP-AP) and Maltose Binding Protein (MBP) fused with another gold binding peptide AuBP1 (AuBP1-MBP), were chosen as probes for the assembly onto gold nanoparticles. For the control, probe proteins lacking gold binding sequences (AP and MBP) were used. Based on the red shift at LSPR Lambda-max, we demonstrate that GEPI-protein constructs have better affinity to AuNP surfaces compared to their corresponding control proteins. Consequently, nM-level concentration of target molecules, namely, Anti-AP and Anti-MBP, were detected through the coupling reaction to 5rGBP-AP and AuBP1-MBP, respectively. Our results highlight that GEPI can be an effective erector or a linker not only for the AuNP attachment but also for the protein immobilization on inorganic surfaces, yielding a hybrid multifunctional platforms for bionanotechnology. The research was supported by Genetically Engineered Materials Science and Engineering Center (GEMSEC), an NSF-MRSEC at UW, and NSF-IRES and TUBITAK (Turkey).
5:15 PM - XX8.7
Full Spectral Raman Flow Cytometry using SERS-Active Metal Nanoparticle Aggregates.
Leif Brown 1 , Gregory Goddard 2 , Christina Brady 1 , Stephen Doorn 1
1 Chemistry, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 Biosciences, Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractConventional flow cytometry uses detection by fluorescence, driven by inherently high emission intensities that provide for rapid in-flow identification of tagged material. However, because of broad fluorescence line widths, Surface Enhanced Raman Scattering (SERS) is an increasingly viable alternative method for detection and identification. In addition to signal intensities that are theoretically comparable to fluorescence, SERS supports spectroscopic bar coding and multiplexing[1] with a single excitation laser, by way of comparatively narrow line widths. Here, we provide an overview of work in preparing and optimizing silica-coated noble metal nanoparticle aggregate structures,[2-5] in which we produce a highly intense, stable system. We have successfully applied this platform to Raman flow cytometry, obtaining full spectral detection from microsecond transit times that are comparable to conventional cytometry.[6] Additional discussion will involve cytometry applications enabled by employing our ability to screen specific attributes of single particles, and to discriminate specific spectral signatures and barcodes.[1] Brady, C. I.; Mack, N. H.; Brown, L. O.; Doorn, S. K., submitted. [2] Doering, W. E.; Nie, S. Anal. Chem. 2003, 75, 6171-6176. Mulvaney, S. P.; Musick, M. D.; Keating, C. D.; Natan, M. J. Langmuir 2003, 19, 4784-4790. [3] Brown, L. O.; Doorn, S. K. 2007 MRS Fall Meeting, 11/29/2007. [4] Brown, L. O.; Doorn, S. K. Langmuir 2008, 24, 2178-2185. [5] Brown, L. O.; Doorn, S. K. Langmuir 2008, 24, 2277-2280. [6] Goddard, G; Brown, L. O.; Martin, J. C.; Graves, S. W.; Freyer, J. P.; Doorn, S. K., in preparation.
5:30 PM - XX8.8
High-throughput Detection of Protein Kinase Activities in Cell Lysate Based on the Aggregation of Gold Nanoparticles with Peptides.
Yoshiki Katayama 1 2 , Hirotaro Kitazaki 1 , Jeong-Hun Kang 1 , Xaoming Han 1 , Takeshi Mori 1 2 , Takuro Niidome 1 2
1 Applied Chemistry, Kyushu University, Fukuoka, Fukuoka, Japan, 2 Center for Future Chemistry, Kyushu University, Fukuoka, Fukuoka, Japan
Show AbstractProtein kinases play an important role in many regulatory cellular processes using cellular signal transduction. Since the regulational disruption of protein kinases is linked with many diseases, they are remarkable targets for the development of new drugs. Practically, many kinase inhibitors have been developed and are used in clinical treatments. Thus, the high-throughput screening (HTS) of kinase activity has been very important. For the HTS of kinase activity, traditional techniques such as enzyme-linked immunosorbent assays, gel-based assays, and filter-binding assays have been used widely, but these methods are time consuming. On the other hand, we have been developed a rapid and simple colorimetric assay system using the aggregation of gold nanoparticles (GNPs) with peptide to detect protein kinase activity. In this assay, cationic substrate peptides function as coagulants of citrate-coated GNPs with anionic surface charges, while phosphorylated peptides do not coagulate GNPs because of a net increase in total negative charge. Thus, Incubation of a substrate peptide of target protein kinase with sample solution and following addition of GNPs remain red in color of the GNP dispersion if the kinase in the sample solution is active, while the color changes to blue due to the aggregation if the kinase is inactive. Activities of the kinase in different sample also can be compared by using absorbance change in the GNP dispersion.Thus, we synthesized various cationic substrate peptides for various protein kinases and applied to this system. This system successfully detected all serine/threonine kinases we investigated (protein kinase A, protein kinase Cα and MAPK-activated protein kinase2) and also tyrosine kinase such as Src by optimizing the salt concentration. Another advantage of this system is applicability not only to enzyme solution but also to cell lysate or tissue extract using same procedure. We successfully monitored the change of Src activity in living cell against the dosage of Src inhibitors.Then we applied the system to cancer diagnosis by using PKCα as a cancer specific signal, because the kinase activity is directly related to cancer malignancy. Tissue extract form tumor tissue in mice and humans indicated PKCα activation with our system, while normal tissue didn’t indicate such activation. This assay may be useful for pre-medication diagnosis.Finally, we tried kinase inhibitor screening of chemical library by using our GNP assay. All known inhibitors and some unknown compounds were hit from the screening, and actual inhibitory activities were confirmed by MALDI-TOF MS assay using substrate peptide.Our assay system therefore would be useful for rapid monitoring of protein kinase activity and screening of kinase inhibitor.
5:45 PM - XX8.9
Kinetic Study of Binding of Multivalent Ligands on Size Selected Gold Nanoparticles.
Suguna Perumal 1 , Andreas Hofmann 1 , Christina Graf 1 , Eckart Ruehl 1
1 Physical and Theoretical Chemistry, Institute for Chemistry and Biochemistry, Free University , Berlin Germany
Show AbstractA kinetics study of the binding of multivalent ligands on different kinds of nanoparticles is presented. The enhanced binding of multiple ligands in one entity to multiple receptors is known as the multivalency effect. Flexible thiol functionalized multivalent ligands are synthesized by using reported procedures.(1-3) Pyrene bound 2.2 nm and 3.2 nm sized gold nanoparticles were prepared by wet colloidal chemistry and characterized by transmission electron microscopy.(4) The multivalency effects and size effects are investigated by exchanging monovalently bound pyrene molecules on gold nanoparticles by multivalent ligands and studying this process via fluorescence spectroscopy. The fluorescence of the pyrene moiety is completely quenched when it is directly bound to gold nanoparticles. It slowly recovers as a result of the exchanging by the mono- or multivalent ligands. The change of the fluorescence intensity of the pyrene moiety is measured as a function of time. Multivalency effects are observed by comparing the rate constants of monovalent with di- or trivalent thiol ligands. However, no enhancement multivalency effects are observed between trivalent and divalent thiol ligands on 3.2 nm gold nanoparticles. Hence, we assume that possibly only two thiol groups are binding in case of the trivalent ligands on 3.2 nm gold nanoparticles. Size effects are observed by comparing the rate constants of 2.2 nm and 3.2 nm gold nanoparticles. The reaction rates are significantly decreasing with decreasing the size of the particles. References [1] M. Matoba, T. Kajimoto, K. Nishide, and M. Node, Chem.Pharm. Bull, 2006, 54, 1, 141. [2] B. Weibull and M. Matell, Acta Chem. Scand, 1962, 16, 4, 1062.[3] K. Wojczykowski and P. Jutzi, Synlett , 2006, 1, 39.[4] M. Montalti, L. Prodi, N. Zaccheroni, R. Baxter, G. Teobaldi, and F. Zerbetto, Langmuir, 2003, 19, 5172.
Symposium Organizers
Antigoni Alexandrou Ecole Polytechnique
Jinwoo Cheon Yonsei University
Hedi Mattoussi Florida State University
Vince Rotello University of Massachusetts
XX9: Composite Nanoparticles, Interactions, Imaging and Sensing
Session Chairs
Alexander Govorov
Alexander Wei
Thursday AM, December 03, 2009
Room 309 (Hynes)
9:30 AM - **XX9.1
Exciton-Plasmon Interaction and Energy Transfer in Nanocrystal Complexes with Sensor Properties.
Alexander Govorov 1
1 , Ohio U., Athens, Ohio, United States
Show AbstractEnergy transfer and Coulomb interactions between optically-excited nanocrystals can be very efficient. There interactions can be utilized for sensing of temperature and chemical composition [1-2]. One particular class of structures with sensor properties comprises coupled metal and semiconductor nanocrystals and, correspondingly, exhibits both plasmon and exciton resonances [3]. The interaction of excitons and plasmons in such structures leads to several effects: energy transfer between nanoparticles (NPs), electromagnetic enhancement, reduced exciton diffusion in nanowires (NWs), exciton energy shifts, and interference [1-4]. Recent experiments with NW-NP complexes [1] showed that the exciton-plasmon interaction can lead to a blue shift of excitonic emission. This behavior was explained in terms of exciton diffusion along a NW and energy transfer. The sensor mechanism in NP-NP and NW-NP complexes studied in refs. 1-3 is based on variation of inter-nanocrystal distance with temperature or chemical composition [1,2] . Exciton-plasmon interactions may also be used for detection of single NPs and molecules. Calculations [4] show that the exciton-plasmon interaction gives rise to interference effects (Fano-like asymmetric resonances and anti-resonances). The interference greatly enhances a visibility of relatively weak exciton signals coming from single NPs and molecules. Another class of hybrid structures involves NPs and photosynthetic molecules (reaction centers). Reaction centers have an important functionality – a charge separation. Modeling of the artificial light-harvesting complexes suggests an interesting opportunity of enhanced photosynthetic activity [5]. Optical enhancement in photosynthetic complexes may come from plasmon resonances, strong optical absorption by semiconductor NPs, and energy transfer from NPs to reaction centers. [1] J. Lee, P. Hernandez, J. Lee, A. Govorov, and N. Kotov, Nature Materials 6, 291 (2007). [2] J. Lee, A. O. Govorov, and N. A. Kotov, Angewandte Chemie 117, 7605 (2005). [3] A. O. Govorov, G. W. Bryant, W. Zhang, T. Skeini, J. Lee, N. A. Kotov, J. M. Slocik, and R. R. Naik, Nano Letters 6, 984 (2006). [4] J.-Y. Yan, W. Zhang, S. Duan, X.-G. Zhao, and A. O. Govorov, Phys. Rev. B 77, 165301 (2008). [5] A. O. Govorov and I. Carmeli, Nano Lett. 7, 620 (2007); A. O. Govorov, 20, 4330 (2008).
10:00 AM - XX9.2
Enzyme Immobilization into Magnetic Nanoparticles/Mesoporous Silica Core/Shell Nanocomposite for Applications to Biosensor.
Yu-Ho Won 1 , Ho Seong Jang 2 , Ravi Sinha 1 , Lia Stanciu 1
1 School of Materials Engineering, Purdue University, West Lafayette, Indiana, United States, 2 Department of Chemistry, Purdue University, West Lafayette, Indiana, United States
Show AbstractMagnetic nanoparticles (NPs) have received considerable attention because of their potential applications in drug delivery, magnetic resonance imaging (MRI) contrast enhancement, and magnetic immobilization. For many applications, the nanoparticles would benefit from having a mesoporous silica shell to impart uniform pores, wettability, and biocompatibility. Here, we report on the synthesis, characterization and biosensor applications of hybrid biomagnetic nanocomposites. Biomagnetic nanocomposites consist of magnetic NPs (Fe3O4) core, a mesoporous silica shell, and biomolecules (enzymes). Fe3O4 NP/mesoporous silica core/shell nanospheres (Fe3O4/m-silica) were synthesized and further used to immobilize acetylcholinesterase (AChE). These biomagnetic nanocomposites served as a platform for the fabrication of a pesticide (paraoxon) biosensor. The synthesized Fe3O4/m-silica was uniform in both size and shape, and highly water soluble. The size of Fe3O4 NPs and the thickness of mesoporous silica shell could be simply controlled by varying the synthesis conditions. The paraoxon biosensor showed higher current response and better stability when compared to free AChE. In addition, the biosensor showed superior detection limit (4.6 X 10-9 M of paraoxon) and high stability up to 30 days. These results indicate the biomagnetic nanocomposites are promising for applications to reliable biosensors.
10:15 AM - XX9.3
A New Platform for Single Molecule Studies: Quantum Dot-Magnetic Nanoparticle Composites Coupled with Magnetic Tweezers.
Jessica Winter 1 , Gang Ruan 1 , Dhananjay Thakur 1 , Greg Vieira 1 , Thomas Henighan 1 , Aaron Chen 1 , R. Sooryakumar 1
1 , Ohio State University, Columbus, Ohio, United States
Show AbstractStudying single nanoparticles and molecules has led to a number of important discoveries in biology and nanoscience. In particular, single quantum dots (semiconductor nanocrystals) have been successfully used to image and track biological processes at single molecule level in vitro and in vivo. On the other hand, magnetic tweezers have been used to apply force on micron-sized magnetic beads. Combining the fluorescence of quantum dots and the force of magnetic tweezers, we have achieved the first concurrent magnetic manipulation and fluorescent tracking of single nanoparticles (smaller than 100 nm). Quantum dots and superparamagnetic iron oxide nanoparticles were first loaded into nanocontainers of diameter 40 nm, forming nanocomposites with both fluorescence and superparamagnetism properties. Magnetic tweezers were then used to apply force on the composite nanoparticles, while the movement of these nanoparticles was tracked by a fluorescent microscope. It was found that the composite nanoparticles had fluorescent intermittency (e.g., blinking), indicating that they were single nanoparticles (rather than large aggregates of nanoparticles). Biomolecules such as antibodies and peptides were then conjugated to the composite nanoparticles for single molecule experiments. The ability of simultaneous magnetic manipulation and fluorescent tracking of single sub-100 nm nanoparticles could have broad impact in many areas, including biomechanics and nanofabrication.
10:30 AM - **XX9.4
Multiplexed Solid Phase Hybridization Assay Strategies for the Selective Detection of Nucleic Acids.
W. Russ Algar 1 , Ulrich Krull 1
1 Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
Show AbstractThe selective detection of nucleic acids is fundamental in studying cellular function, diagnosing disease, and protecting our food from pathogens. Although the microarray is the classic multiplexed platform for nucleic acid analysis, there are definite advantages in using biosensor technology designed to quickly screen for a smaller number of target sequences. We describe the development of a multiplexed solid-phase hybridization assay using quantum dots (QDs) and fluorescence resonance energy transfer (FRET). QDs were immobilized on the surface of an optical fiber via multidentate surface ligand exchange and oligonucleotide probes were conjugated to QDs using a Neutravidin bridge. Hybridization of the immobilized probes with dye labeled target oligonucleotides provided the proximity required for FRET, where the relative acceptor fluorescence was used as the analytical signal. This platform was capable of nanomolar detection limits, a dynamic range better than one order of magnitude, resolution of single nucleotide polymorphisms, and detection in complex matrices. It was also possible to avoid direct target labeling by using a sandwich assay. “One-pot multiplexing” was demonstrated through the creation of mixed films of two colors of QD and two probe oligonucleotides. The concentration dependent binding of two target nucleic acid sequences was simultaneously measured using two discrete QD-dye FRET pairs. The relative response of each FRET-pair to target concentration varied proportionally to the stoichiometry of the immobilized probe oligonucleotides. In addition to the above multiplexing strategy, we will also describe our ongoing work in: 1) developing two-plex biosensors based on a single QD donor simultaneously combined with two different acceptor dyes; and 2) developing a three-plex biosensor by combing two-plex FRET systems with a direct excitation “channel”. This work is an important step in capitalizing on the multiplexing advantages afforded by QDs: it potentiates the facile construction of miniaturizable sensors suitable for detecting multiple nucleic acid targets without discrete sensor elements, sorting technology, or multiple excitation sources.
11:30 AM - **XX9.5
Gyromagnetic Imaging using Gold Nanostars with Magnetic Cores.
Qingshan Wei 1 , Hyon-Min Song 1 , Alexei Leonov 1 , Kenneth Ritchie 2 , Alexander Wei 1
1 Chemistry, Purdue University, West Lafayette, Indiana, United States, 2 Physics, Purdue University, West Lafayette, Indiana, United States
Show AbstractPlasmon-resonant nanoparticles with optical scattering in the near-infrared (NIR) offer strong contrast for biophotonic imaging, but have limited effect in noisy environments when imaged under static conditions. Gyromagnetic imaging provides a dynamic mode of optical contrast, and can improve signal-to-noise ratios by as much as 25 dB. Here we use gold nanostars with Fe3O4 cores for polarization-sensitive NIR scattering in the presence of a rotating magnetic field gradient. Gyrating nanostars can produce a periodic "twinkling" that enables time-domain signals to be transformed into frequency-selective images of remarkable clarity. Gyromagnetic imaging of nanostars inside of tumor cells using broadband excitation can produce clearly resolved signals against a high background in under 1 second, while simultaneously suppressing brighter but static objects. The gyromagnetically active nanostars do not cause a loss in cell viability, and can even have a mild stimulatory effect on cell growth.
12:00 PM - XX9.6
Combined Atomic Force Microscopy and 3-D Optical Investigation of the Active Cytoskeletal Response of Living MHS Cells to Nanoscale Structures and Forces.
Vincent Palumbo 1 , Atif Rakin 1 , Arron Lucas 1 , Renee Gilberti 2 , David Knect 2 , Bryan Huey 1
1 Institute of Materials Science, University of Connecticut, Storrs, Connecticut, United States, 2 Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, United States
Show AbstractA unique combined Atomic Force Microscope (AFM) and 3-d optical system is employed to quantitatively record passive and active responses of live mouse lung macrophage (MHS) cells to picoNewton-scale interactions with nanometer-scale structures. These structures, either scanning probes themselves, particles attached to the probes, or chemically functionalized probes, are then contacted and/or indented into a cell at precise locations based on optical markers. Adhesion energies, forces during phagocytosis, and the significance of the foreign body shape and/or chemistry can thus be directly manipulated and measured. 3-d optical cross-sections based on green fluorescent protein actin markers are simultaneously acquired, linking the local measurements with the local cellular structure and dynamcis. Specifically, adhesion energy clearly increases for rabbit-anti-ovalbumin (RAO) antibody coated probes vs. non-specific binding proteins or uncoated probes. For picoNewton scale loads, the actin cytoskeleton also actively responds, polymerizing additional actin during loading and depolymerizing upon removal of the foreign nanostructure. Such research has implications for the fundamental process of phagocytosis, as well as the much broader issue of the cellular response to foreign bodies including micro and especially nanoscale particles.
12:15 PM - XX9.7
Wide-field in vitro Imaging of Breast Cancer Cells with Targeted Nanopyramids.
Colleen Nehl 1 , Warefta Hasan 1 , Christina Sweeney 1 , Teri Odom 1 2
1 Chemistry, Northwestern University, Evanston, Illinois, United States, 2 Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States
Show AbstractA critical barrier to widespread application of gold nanoparticles for biological imaging is the lengthy time and costly equipment necessary for spectral characterization. We have developed a new wide-field parallel imaging method for rapidly determining the orientation of gold nanopyramids on a substrate or in vitro. Our technique is >1000X faster than single particle spectroscopy, inexpensive, and applicable to real-time measurements in live cells. This new wide-field imaging technique is applicable to any noble metal nanoparticle with a sufficiently large scattering cross section. We demonstrate that our method effectively determines nanoparticle location, orientation, and composition in vitro for SK-Br-3 breast cancer cells.
12:30 PM - XX9.8
Modified Magnetic Nanoparticles with Multidentate Metal Complexing Surface Ligands.
Chad Dooley 1 , Chris Sichmeller 1 , Song Jin 1
1 Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States
Show AbstractA great deal of research over the last decade has produced a diverse library of surface modification chemistries for the functionalization of semiconductor, metallic and magnetic nanoparticles, largely directed at the interaction of these materials with biological targets. In the discussed work, we will present our findings on the modification of superparamagnetic metal ferrites (Fe3O4, CoFe2O4, etc.) with metal ion coordinating ligands and their interactions with other inorganic and biological substituents. Materials soluble in polar solvents with diameters from 4-15 nm were prepared from organic soluble particles by ligand exchange of the original oleic acid and oleylamine stabilizing ligands with short-chain alkoxysilanes and subsequent cross-linking to form a protective layer of siloxane. The solubilizing side-chain displayed on the surface of the siloxane shell was chosen such that secondary coupling reactions could be run to modify the surface with a number of different multidentate ligands for metal complexation. Mixtures of alkoxysilane derivatives were studied to allow multiple functionalities to cooperate in preserving particle stability as well as reactivity toward a desired analyte.