V. Prasad Shastri Vanderbilt University
Andreas Lendlein Institute of Polymer Research
LinShu Liu U. S. Dept of Agriculture
Samir Mitragotri University of California-Santa Barbara
Antonios Mikos Rice University
HH1: Advanced Biomaterials I
Monday PM, December 01, 2008
Room 310 (Hynes)
9:00 AM - **HH1.1
Citric Acid-based Biomaterials: Teaching an Old Compound New Tricks.
Guillermo Ameer 1 Show Abstract
1 Department of Biomedical Engineering and the Department of Surgery, Northwestern University, Evanston, Illinois, United States
9:30 AM - HH1.2
Dual and Triple Shape Capability of Poly(ε-caprolatone)dimethacrylate Networks with Dangling PEG Chains.
Marc Behl 1 , Ingo Bellin 1 , Andreas Lendlein 1 Show Abstract
1 Center for Biomaterial Development, Institute of Polymer Research, GKSS Forschungszentrum Geesthacht GmbH, Teltow Germany
Shape-memory polymers are an emerging class of functionalized materials, which are able to change their shape in a predefined way upon appropriate stimulation . Therefore an attractive application area for shape-memory polymers is their use in active medical devices [2, 3]. Shape-memory polymer research was focused on the implementation of different stimuli for triggering the shape-memory effect . All these systems are dual-shape materials, which can transform from a first shape (A) to a second shape (B). Recently, polymeric materials with a triple-shape capability have been introduced. These polymer networks are able to change from a first shape (A) to a second shape (B) and from there to a third shape (C) . Here we highlight this new kind of polymeric triple-shape materials. As the triple-shape effect is a general concept, we will introduce suitable polymer architectures and their appropriate programming. While the permanent shape is determined by the chemical crosslinks formed during network preparation in these materials, distinct domains can be used to fix the two temporary shapes either by crystallization or vitrification. When programmed appropriately in a two-step thermomechanical process, these materials exhibit a triple-shape effect. Triple shape-memory polymers can also be functionalized like dual shape materials . Here, the two switching domains formed by two different switching segments can be used either individually or simultaneously to fix the temporary second shape. In graft polymer networks with poly(ε-caprolactone) segments and poly(ethylenglycol) side chains, the switching temperature, which needs to be exceeded for inducing the shape-memory effect, correlates with the melting transition of the related domain, if one domain is used for fixation. If both domains are used, the switching temperature correlates with the higher melting temperature.A. Lendlein, S. Kelch, Angew. Chem. Int. Ed. Engl. 41 (2002) 2034.F. El Feninat, G. Laroche, M. Fiset, D. Mantovani, Adv. Eng. Mat. 4 (2002) 91.R. Langer, D. A. Tirrell, Nature 428 (2004) 487.M. Behl, A. Lendlein, Mater Today 10 (2007) 20.I. Bellin, S. Kelch, R. Langer, A. Lendlein, Proc.Natl.Acad.Sci.USA 103 (2006) 18043.I. Bellin, S. Kelch, A. Lendlein, J. Mater. Chem.17 (2007) 2885.
9:45 AM - HH1.3
Fluorescent Core-Shell Silica Nanoparticles as Probes for in Vitro and in Vivo Imaging and Sensing.
Andrew Burns 1 , Erik Herz 1 , Barbara Baird 2 , Jin Hyang Choi 3 , Gabriela Hidalgo 4 , Alexander Nikitin 3 , Len Lion 4 , Anthony Hay 5 , Michelle Bradbury 6 , Ulrich Wiesner 1 Show Abstract
1 Materials Science & Engineering, Cornell University, Ithaca, New York, United States, 2 Chemistry & Chemical Biology, Cornell University, Ithaca, New York, United States, 3 Biomedical Science, Cornell University, Ithaca, New York, United States, 4 Civil & Environmental Engineering, Cornell University, Ithaca, New York, United States, 5 Microbiology, Cornell University, Ithaca, New York, United States, 6 Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York, United States
Amorphous sol-gel derived silica has shown itself to be an excellent host material for functional nanoparticles, particularly for application as probes and sensors in biology and nanomedicine. The facile and versatile chemistry of silica allows architectures to be tuned to specific applications, as well as the incorporation of diverse functional groups including dyes, chelators, polymers and targeting moieties. Our earlier work demonstrated core-shell fluorescent nanoparticles containing a core of silica-bound dye molecules surrounded by a pure silica shell, which exhibit exceptional brightness and stability compared to the constituent dyes as a general trend for dyes across the UV/visible spectrum. These particles have been applied to address a wide variety of questions both in vitro, as well as in vivo investigating the biodistribution and application of these particles to clinically-relevant tasks including sentinel lymph node imaging. Further, this core/shell concept lends itself particularly well to the development of quantitative ratiometric sensors. The co-localizaton of reference and sensor dye molecules in separate layers of a core-shell particle yields quantitative sensors with high surface area for analyte interaction, while protecting the reference signal within. We have generated core-shell sensor particles with average radii below 6 nm, capable of delivering high local concentrations of pH or Ca+2 sensor dye to biological microenvironments and have applied them to multi-dimensional chemical imaging in a variety of biological systems.
10:00 AM - HH1.4
Optimised Synthetic Route for Tuneable Shell SiO2@Fe3O4 Core-Shell Nanoparticles.
Carmen Vogt 1 , Muhammet Toprak 1 , Jingwhen Shi 2 , Bengt Fadeel 2 , Stefan Brene 3 , Rouslan Sitnikov 3 , Mamoun Muhammed 1 Show Abstract
1 Functional Materials, Royal Institute of Technology, Stockholm Sweden, 2 Institute of Environmental Medicine, Karolinska Institutet, Stockholm Sweden, 3 Experimental MR Center, Karolinska Institutet, Stockholm Sweden
Nanoparticles are subject for intensive research activities as they find a large variety of applications in numerous biomedical fields from enhancement of image contrast in MRI to different magnetically controllable drug delivery systems. Size limitation (below 100 nm to avoid endocytosis by macrophages and to be able to pass internal biological membranes) is one of the most important factors when considering targeting different types of tissues / organs (among other factors i.e. surface coatings functionalisation/activation). Silica is one of the preferable materials for surface coating when high biocompatibility, stability and increase in residence time is desired. This investigation is on the optimisation of a synthetic route for tuneable shell thickness SiO2@Fe3O4 core-shell nanoparticles for biomedical applications. Water in oil microemulsion synthesis is a well known technique for producing monodisperse particles, however, the application of this technique in producing well-dispersed single core-shell nanoparticles in large quantities is still challenging. In this study we report on the synthesis of well-separated, monodisperse single core-shell SiO2@Fe3O4 nanoparticles with an overall diameter of ~30 nm. The influence of different parameters (i.e. the nanoparticles size, nanoparticles concentration in the oil phase, the water/surfactant molar ratio, condensation time, etc.) on synthesis of tuneable shell thickness core-shell nanoparticles is reported. Particles’ cell toxicity and performance as MRI contrast agents were also undertaken due to their promising biological applications (as contrast agents, cell labelling and separation, drug delivery systems, etc.) and results are presented.
10:15 AM - HH1.5
Antimicrobial Nanostructured Hydrogel Webs with Controlled Silver Release.
Jian Wu 1 , Shuyu Hou 1 , Dacheng Ren 1 , Patrick Mather 1 Show Abstract
1 Department of Biomedical and Chemical Engineering and Syracuse Biomaterials Institute, Syracuse University, Syracuse, New York, United States
We have prepared new electrospun nano-fibrous scaffolds featuring excellent antimicrobial properties. Specifically, poly(ethylene glycol)(PEG)-based multi-block thermoplastic polyurethanes (TPUs) incorporating polyhedral oligomeric silsesquioxane(POSS) moieties were co-dissolved with silver nitrate(AgNO3) and subsequently electrospun to yield durable hydrogel webs capable of controlled silver ion release for effective antimicrobial behavior, which was analyzed quantitatively. Due to significant thermodynamic incompatibility between POSS moieties and ethylene oxide units, POSS nanocrystals, resulting from micro-phase separation, serve as physical crosslinking points within an inorganic-organic hybrid network, in turn affording novel hybrid organic-inorganic hydrogels in the water-swollen state. The resulting organic-inorganic hybrid hydrogel scaffolds not only feature excellent mechanical properties, but also display a desirable prolonged antimicrobial effect. For instance, our antimicrobial tests demonstrated that the electrospun nano-fibrous scaffolds (fiber diameter = 170±30 nm) prepared from TPUs incorporating 1.0 wt-% AgNO3 loading can effectively suppress Escherichia coli (E. coli) biofilm formation for 12 days, which is much longer than its cast (non-porous) film counterpart that suppressed E. coli biofilm formation for only 1 day. In contrast to conventional hydrogels, we observed that our electrospun nano-fibrous scaffolds hydrate with minimal change in macroscopic dimensions, perhaps due to a nano-confinement effect. We suggest that this arrested swelling behavior could enable us to control the rate of silver ion release from the electrospun hydrogel scaffold. We will discuss applications in wound dressing and reconstructive oral and bone surgery that can directly benefit from the properties of the new materials.
10:30 AM - HH1.6
Engineering Biomimetic Polymersomes for Effective Cytosolic Delivery.
Giuseppe Battaglia 1 Show Abstract
1 Engineering Materials, University of Sheffield, Sheffield United Kingdom
One of the most challenging aspects of drug delivery is the intra-cellular delivery of active agents. Several drugs and especially nucleic acids all need to be delivered within the cell interior to exert their therapeutic action. Small hydrophobic molecules can permeate cell membranes with relative ease, but hydrophilic molecules and especially large macromolecules such as proteins and nucleic acids require a vector to assist their transport across the cell membrane. This must be designed so as to ensure intracellular delivery without compromising cell viability. We have recently achieved this by using pH-sensitive poly(2-(methacryloyloxy)ethyl-phosphorylcholine)- co -poly(2-(diisopropylamino)ethyl methacrylate) (PMPC-PDPA) diblock copolymers that self-assemble to form vesicles in aqueous solution. These vesicles combine a non-fouling PMPC block with a pH-sensitive PDPA block and have the ability to encapsulate both hydrophobic molecules within the vesicular membrane and hydrophilic molecules within their aqueous cores. It is particularly noteworthy that PMPC-PDPA diblock copolymers form stable vesicles at physiological pH but that rapid dissociation of these vesicles occurs between pH 5 and pH 6 to form molecularly dissolved copolymer chains (unimers). We used PMPC-PDPA vesicles to encapsulate small and large macromolecules and these were successfully delivered intracellularly. Dynamic light scattering, zeta potential measurements, and transmission electron microscopy were used to study and optimize the encapsulation processes. Confocal laser scanning microscopy and fluorescence flow cytometry were used to quantify cellular uptake and to study the kinetics of this process in vitro and in vivo. We show the effective cytosolic delivery of nucleic acids, proteins, hydrophobic molecules, amphiphilic molecules, and hydrophilic molecules without affecting the viability of cells or even triggering inflammatory pathways.
10:45 AM - HH1.7
Single Component Polymer Capsules for Biomedical Applications.
Alexander Zelikin 1 , Siow Feng Chong 1 , Sri Sivakumar 1 , Amy Sexton 2 , Robert De Rose 2 , Stephen Kent 2 , Remy Robert 3 , Kim Wark 3 , Frank Caruso 1 Show Abstract
1 Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria, Australia, 2 Department of Microbiology and Immunology , The University of Melbourne, Parkville, Victoria, Australia, 3 Preventative Health Flagship and Division of Molecular and Health Technologies, CSIRO, Parkville, Victoria, Australia
Encapsulation of drugs and reagents for diverse applications ranging from encapsulated catalysis and sensing to drug delivery requires the creation of colloidally stable nano- and micro-capsules. Among the requirements for a successful capsule, monodispersity in size ensures the uniform properties of capsules and the degradable nature delivers the means to recover the reaction product or, in the case of biodegradable capsules, deliver the cargo therapeutics. Within the size range from 300 nm to several microns, a promising technique to produce said capsules in high yield is the facile layer-by-layer approach, in which interacting polymers are sequentially deposited onto a sacrificial colloidal template to form a thin polymer film. The latter becomes the wall of the capsule upon dissolution of the core particle. In this work, we describe the preparation of monodisperse colloidally stable degradable polymer capsules with sizes as small as 300 nm. The capsules consist of chains of poly(methacrylic acid), PMA, crosslinked via biodegradable disulfide linkages and deconstruct in the presence of a physiological concentration of the intracellular reducing agent, glutathione, GSH. The first step in the preparation of disulfide stabilized PMA capsules is the sequential deposition of poly(vinyl pyrrolidone), PVP, and thiolated PMA, PMASH, on colloidal template particles such as silica, as it is commercially available as monodisperse samples with varied sizes. The linear build-up of polymer multilayers provides control over the thickness of polymer film, which then translates to the thickness of the capsule wall which, in turn, determines properties permeability and stability of the capsules. After the desired number of polymer layers was deposited, the thiol groups are converted into bridging disulfide linkages. Removal of the core particles produces hollow capsules, and transferring the capsules into pH 7 results in ionization of PMASH and release of PVP from the capsules wall. The resulting single component PMA capsules are stabilized via the disulfide linkages and remain intact in a wide range of pH; the capsules exhibit reversible swelling in response to external pH and remain colloidally stable over a range of physiologically relevant experimental conditions (e.g., in the presence of serum proteins).We demonstrate that the capsules and the constituting polymers are non-toxic, as verified by the cell viability and proliferation assays, and are effectively taken up by the cells of varied types and function. When loaded with lipophilic anticancer drugs, the capsules exhibit minimal passive release of the therapeutic and are effective in delivering the cargo to cause cell death. In the whole human blood, the capsules are taken up by white blood cells, including monocytes and dendritic cells, deliver the functionally active oligopeptide cargo to the antigen presenting cells and stimulate an immune response.
11:00 AM - HH1: ADBIOMAT
HH2: Drug Delivery Systems I
Monday PM, December 01, 2008
Room 310 (Hynes)
11:30 AM - HH2.1
Micelles for Delivery of Nitric Oxide.
Yun Suk Jo 1 , Jay Gantz 1 , André van der Vlies 1 , Tyler Thacher 1 , Sasa Antonijevic 2 3 4 , Simone Cavadini 2 , Davide Demurtas 5 , Nikolaos Stergiopulos 1 , Jeffrey Hubbell 1 2 Show Abstract
1 Institute of Bioengineering (IBI), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne Switzerland, 2 Institute of Chemical Sciences and Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne Switzerland, 3 Department of Chemistry, University of California Berkeley, Berkeley, California, United States, 4 Division of Materials Science, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 5 Centre Intégratif de Génomique, Université de Lausanne, Lausanne Switzerland
Coronary arterial atherosclerosis is closely related to endothelial dysfunction and pathophysiologically altered homeostasis. Surgically, PTCA is performed to restore blood flow and nutrient transport in occluded lesions. However, this interventional surgery can still cause another incidence, namely post-PTCA restenosis due to the mechanical stimuli of catheter or metallic stent to the intact endothelium. In order to treat post-PTCA restenosis, the importance of local drug delivery has been focused upon due to the limited success of systemically administrated pharmaceutical drugs. Endogenous NO generated from endothelial nitric oxide synthase (eNOS) induces endothelial-dependent relaxation of blood vessels and modulates the tone of arterial vascular smooth muscle cells (VSMCs). Thus, NO-releasing drugs, namely NO donors would be very interesting for various cardiovascular therapies. However, most NO donors are decomposed much too fast to properly act as an anti-restenotic drug, which would require NO release over a longer time frame, ca. a few weeks after deployment of stent. Despite a number of NO-releasing drugs developed thus far, their ultra-rapid decomposition rate in contact with water has been always a major obstacle before possible implementation as pharmaceutical agents. Taking these requirements into consideration, we conceived NO-releasing micelles, which (1) release NO in a sufficiently slow pattern, (2) are of favourable size (e.g. less than 100 nm), and (3) are self-assembled structures to be eventually secreted after all NOs are delivered. Amphiphilic block copolymers can be assembled into a specific supramolecular structure by thermodynamically driven process. Self-assembled micelles likewise are attributed in a core-shell structure and considered an ideal platform to deliver pharmaceutical payloads in a controlled rate. Here we present the formation of micelles directed by in situ reaction of pressurized nitric oxide (NO) gas with intact hydrophilic moiety of diblock copolymers, i.e. polyamines. In contact with water, worm-like micelles (diameter: 50-80 nm) reversibly release NO, a key signaling molecule in the body, during remarkably long time period, ca. over three weeks. NO-bound secondary amines are conserved in a hydrophobic core, protected from proton transfer, and thus acid-triggering hydrolysis is slowed down, which benefits us this strikingly long release pattern. Micelles infused into the rabbit artery ex vivo readily penetrate the arterial wall at which point their therapeutic aspects could be exploited, namely slow delivery of NO to restenotic lesions.
11:45 AM - HH2.2
Triterpene Saponin Glycosides: a New Class of Chemical Penetration Enhancers.
Christopher Pino 1 , Jordan Gutterman 2 , V. Shastri 1 Show Abstract
1 Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, United States, 2 Department of Molecular Therapeutics, M.D. Anderson Cancer Center, Houston, Texas, United States
The uppermost layers of the epidermis, the stratum corneum, provides the barrier properties to skin and plays a critical role in the regulation of the transport and retention of many important molecules, such as water, oxygen and sodium. Changes to the permeability of skin toward these molecules can seldom be achieved without altering the barrier function of skin. For example, an increase in evaporative water loss accompanies chronic skin conditions such as psoriasis and eczema. Triterpene saponin glycosides (TSGs) are a class of macromolecules that have been shown to interact favorably with synthetic lipid bilayers. Due to its size (several hundred Daltons), these molecules would be considered poor candidates for transdermal (TD) transport. We found that in spite of their molecular weight (MW) exceeding the theoretical cut-off for TD transport, TSGs exhibit appreciable percutaneous adsorption and transport through full thickness pig skin. Additionally, TSGs are also capable of enhancing the transport of both hydrophilic and hydrophobic compounds (Estradiol) without significantly impacting their partitioning behavior. This suggests that TSGs might be promoting TD transport of these molecules through secondary pathways that have been hitherto unexplored and may be used to modulate homeostasis.
12:00 PM - HH2.3
Structure and Mechanical Properties of Nucleic Acid Lipid Films and Their Application as Drug Delivery Vehicles Towards Human Breast Cancer Cells.
Surekha Gajria 1 2 , Thorsten Neumann 2 1 , Matthew Black 3 2 , Wirasak Smitthipong 2 3 , Luc Jaeger 1 2 , Matthew Tirrell 3 2 Show Abstract
1 Chemistry, UC Santa Barbara, Santa Barbara, California, United States, 2 Materials Research Laboratory, UC Santa Barbara, Santa Barbara, California, United States, 3 College of Engineering, UC Santa Barbara, Santa Barbara, California, United States
Negatively charged nucleic acids such as RNA and DNA can self-assemble with cationic lipids via electrostatic complexation to form water-insoluble complexes capable of forming self-standing films when cast from an organic solvent such as isopropanol, as previously reported1,2. We have investigated their structure by X-ray scattering, X-ray reflectivity, and AFM, as well as their tensile strength and mechanical properties. If didodecyldimethylammonium bromide (DDAB) is chosen, the films have a lamellar structure of nucleic acid strands sandwiched between bilayers of the cationic lipid which are thought to be fully interdigitated. Since nucleic acids are able to intercalate certain drugs within their double helical strands, the films can act as local carriers for these drugs when placed in the vicinity of a diseased area, such as a tumor. One example of such a drug is daunorubicin, a drug commonly used in breast cancer therapy, which targets DNA replication in fast growing cells such as cancer cells. These drugs could be released by local enzyme degradation of the nucleic acid-lipid scaffold within the body while the remaining film components can be easily degraded to monomer units. We have also investigated the biodegradability and biocompatibility of the films and found them suitable for insertion within the body, particularly when blended with a neutral biocompatible biodegrdable polymer such as PEG, and the time and extent of degradation can be varied depending on the composition of the nucleic acid within the film. The films are fairly simple to prepare and can be produced on a large scale. We present these films as a novel type of biomaterial capable of mediated local drug delivery to human breast cancer cells rather than normal human breast tissue cells in vitro. 1.ljiro, K. and Okahata, Y. “A DNA-Lipid Complex Soluble in Organic Solvents.” J. Chem. Soc., Chem. Commun., 1992, 1339 – 1341.2.Hoshino, Y. et al. “RNA-Aligned Film Prepared from an RNA/Lipid Complex.” Macromol. Rapid Commun. 2002, 23, 253-255.
12:15 PM - HH2.4
IMAC Surface Modification of Polyketal Microparticles for Dual-Mode Drug Release.
Jay Sy 1 , Niren Murthy 1 2 , Michael Davis 1 3 Show Abstract
1 Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, Georgia, United States, 2 Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States, 3 Division of Cardiology, Emory School of Medicine, Atlanta, Georgia, United States
Many inflammatory diseases are progressive, with different treatments being needed during various phases of the disease. Microparticles have widely been used as drug delivery devices for the sustained delivery of numerous therapeutics. Work in our laboratory has shown that the polyketal microparticles, formulated from poly(cyclohexane-1,4-diyl acetone dimethylene ketal) (PCADK), exhibits excellent properties for sustained delivery of hydrophobic, anti-inflammatory drugs to a myocardial infarction animal model. Polyketals are ideal for treating inflammatory diseases due to their nontoxic and neutral degradation products. Hydrophilic therapeutics, such as proteins and RNAi, hold promise for treating diseases, however delivery through microparticle systems have been hindered due to low loading efficiencies and the large amount of material required for formulations. We hypothesized that by adapting immobilized metal affinity chromatography (IMAC) chemistry for drug delivery, we could efficiently load proteins in a quantitative manner to the surface of PCADK microparticles while maintaining sustained release of hydrophobic drugs from the bulk of the microparticle.We have fabricated PCADK microparticles bearing nitrilotriacetic acid (NTA) on the surface of the particle. NTA is routinely used to chelate nickel ions and purify recombinantly-expressed proteins with the His6-tag. We investigated the binding properties of the microparticles using His6-tagged green fluorescent protein (GFP). At 10% NTA, we found a maximum loading of 45 ng GFP per mg particle in a dilute solution (<1.5 μg/mL). This corresponded to a loading efficiency of 40%. Similar efficiencies were achieved using 1% NTA, though particles saturated at 30 ng GFP per mg particle. Binding was shown to be nickel-dependent and fully reversible with the addition of immidazole. In prior studies from our laboratory, the small molecule p38-inhibitor SB239063, had a release half-life of approximately one week from the bulk of the microparticle. In vitro studies using the NTA-Ni particles indicated that the release half-life of GFP was approximately 24h under physiological conditions (pH 7.4, 10% serum, 37°C). Ongoing work in our laboratory focuses on using the NTA-Ni microparticle chemistry to deliver growth factors as well as adding targeting ligands for cell surface receptors.Polyketal microparticles hold great promise for drug delivery applications. In this work, we investigated the use of IMAC strategies to reversibly bind His6-tagged proteins to the surface of microparticles. The ability to have quantitative dual release kinetics from a single microparticle could have an impact in treating progressive diseases by controlled delivery of different drugs at specific times. Since many commercially available proteins are recombinantly expressed with His6-tags, NTA-functionalized microspheres should prove to be a flexible platform for dual-mode delivery of bioactive compounds.
12:30 PM - HH2.5
Nanoparticles of Porous Iron Carboxylates as New Drug Carriers.
Patricia Horcajada 1 , Christian Serre 1 , Ruxandra Gref 2 , Tamim Chalati 2 , Gerard Ferey 1 , Patrick Couvreur 2 Show Abstract
1 Institut Lavoisier, University of Versailles, Versailles France, 2 Faculty of Pharmacy, University Paris XI, Chatenay Malabry France
The need of molecules of very high molecular weight and/or with a low aqueous solubility in chemotherapy makes indispensable the development of new drug carriers. Polymeric and mixed systems have been recently proposed for controlled release of drugs with higher efficiency(1). However, the actual delivery systems are not able to satisfy the necessary requirement for a large number of molecules of high therapeutic interest such as Busulfan (Bu; antitumoral agent)(2) and Azidothimidine triphosphate (AZT-TP; antiretroviral drug), which show important problems as a poor stability(3), toxicity effects(4) or a low bioavailability(5,6). A new alternative to encapsulate drugs, never tried before, is the use of nanoparticles of porous Metal-Organic-Frameworks (MOFs). These solids combine a high pore volume and a regular porosity, as well as the presence of organic groups easily tuneable within the framework(7). Thus, very high drug storage capacities, up to 1.4 g of Ibuprofen/g of MOF, with a complete drug controlled release under physiological conditions from 3 to 6 days were achieved using rigid MOFs(8). In addition, the use of the flexible porous MOFs led to an unsually long drug release(3 weeks) with a loading capacity of 20% (wt/wt).(9) Moreover, according to their composition, these materials possess a priori a low toxicity and a hydrophobic/hydrophilic internal microenvironment conveniently adapted to host a large number of different molecules(10). This work reports the use for the first time of nanoparticles of porous iron (III) carboxylates as new drug delivery systems(11). The encapsulation and release of different antitumoral and retroviral drugs into these porous hybrids solids were studied. Drug loadings 60 times more effective than in liposomes and 4 times more effective than the best systems polymer-based were achieved (up to 20 %wt) with a controlled release of the drug, which makes their use very promising for a better administration of cytotoxic drugs. In addition, the design of the porous hybrid solids, playing with the wide range of compositions and topologies, will allow adapting these porous hybrid matrices to the host molecule, according to its structure and its dosage requirements. 1. Freiberg S. et al. Internat. J. Pharmac. 2004, 282, 12. Nashyap A. et al. Biol. Blood Marrow Transplant., 2002, 8, 4933. Li X., Chan W. K., Advanced Drug Delivery Reviews 39,1999, 81 4. Baron F. et al. Haematologica 1997, 82, 7185. M. Kukhanova et al. Curr. Pharm. Des. 6, 2000, pp. 5856. Hillaireau H. et al. J. Controlled Release 116, 2006, 3467. Serre C. et al. Science, 2007, 315, 1828; Férey G. et al. Science, 2005, 309, 2040.8. Horcajada P. et al.Angew. Chem. Int. Ed., 2006, 45, 5974.9. Horcajada P. et al. J. Am. Chem. Soc.,2008, 130, 6774.10. Ghermani N.E. et al.Pharmac. Research, 2004, 21, 598.11. Horcajada P., Serre C., Gref R., Férey G., Couvreur P., FR 07/06873, 01 october 2007 and FR 07/06875, 01 october 2007
12:45 PM - HH2.6
Protein-Nanoparticle Conjugates As Neuroprotective Agents.
Vladimir Reukov 1 , Victor Maximov 1 , Alexey Vertegel 1 Show Abstract
1 , Clemson University, Clemson, South Carolina, United States
Neurons continue to die for hours following traumatic spinal cord injury. Secondary injury is a combination of several factors contributing to cell death, including free radical damage and glutamatergic excitotoxicity. Here we study attachment of superoxide dismutase (SOD) and glutamate receptor antibody to poly(butylcyanoacrylate) (PBCA) nanoparticles with the ultimate goal to design biomedical nanodevices for treatment of secondary spinal cord injury. Ability to penetrate the blood-brain barrier (BBB) is a unique property of PBCA nanoparticles that can be used for drug delivery to the central nervous system (CNS). Synthesis of monodispersed 100 nm PBCA nanoparticles was performed using polymerization at pH 2.0 using Dextran-70 as the stabilizer. Sulfo-HSAB spacers were used to covalently attach superoxide dismutase and anti-NR1 glutamate receptor antibodies to the nanoparticles. Aggregation of protein-nanoparticle conjugates was not observed. Composition of the protein-nanoparticle conjugates can be controllably changed by varying protein concentrations in the initial mixtures. Activity of covalently attached SOD consisted of 70-80% of that of the free enzyme even after 3 week storage at 4°C. The observed high activity and storage stability are very important for future therapeutic applications. Strong binding of the protein-nanoparticle conjugates containing NR1 glutamate receptor antibody to rat dorsal ganglion neurons was observed. The effectiveness of such conjugates against generated superoxide was studied on primary rat neurons cell culture. About 200 uL of conjugate suspension was added to the well with neurons, and than xanthine(25uM) and xanthine oxidase(10 mU/mL) solution were added into the same well. Cell viability was determined using a fluorescent live / dead cell assay. We found that superoxide dismutase (SOD) and glutamate receptor antibody to poly(butylcyanoacrylate) (PBCA) nanoparticles shows high activity against generated superoxide radicals.This work was supported by South Carolina Spinal Cord Injury Research Fund grant # 0206.
HH3: Advanced Biomaterials II
Monday PM, December 01, 2008
Room 310 (Hynes)
2:30 PM - HH3.1
Shape-memory Properties of Multiblock Copolymers Consisting of Poly(ω-pentadecalactone) Hard Segments and Crystallisable Poly(ε-caprolactone) Switching Segments.
Karl Kratz 1 2 , Ulrike Voigt 2 , Wolfgang Wagermaier 2 , Andreas Lendlein 1 2 Show Abstract
1 , Center for Biomaterial Development and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Teltow Germany, 2 , GKSS Forschungszentrum Geesthacht GmbH, Teltow Germany
2:45 PM - HH3.2
Magnetron-Sputtered Zinc Doped Hydroxyapatite Thin Films for Orthopedic Applications.
Patrick Marti 1 , Serena Best 1 , Zoe Barber 1 , Roger Brooks 2 , Neil Rushton 2 Show Abstract
1 Department of Materials Science & Metallurgy, University of Cambridge, Cambridge United Kingdom, 2 Department of Surgery, University of Cambridge, Cambridge United Kingdom
The coating of metallic bone and joint implants with hydroxyapatite (HA) has been shown to improve bone apposition and growth in vivo. Magnetron sputtering has attracted great interest due to its ability to produce dense, uniform thin coatings on metallic substrates. Furthermore, magnetron co-sputtering provides a straightforward method of incorporating elements into HA coatings, as has been done previously with silicon doped HA coatings, which out-performed regular HA coatings in vitro. Zinc is a trace element found in bone which has been shown to improve osteoblast proliferation and inhibit osteoclast growth in vitro. As a result, several investigations have produced and characterized zinc-substituted calcium phosphates with positive results. However, to date there have been no studies which have looked at the incorporation of zinc into HA coatings. The aim of this study was to produce and characterize zinc-doped HA thin films using rf-magnetron sputtering as a potential coating for metallic bone and joint replacement implants.For each sputtering run, radio-frequency power was supplied to a phase-pure sintered HA target at 60 W, and a direct current was applied to a zinc target at a power of either 1.5 W or 3.0 W. Ti-6Al-4V discs (10 mm diameter) were ground with 1200 grit SiC paper and cleaned prior to sputtering for 4 hours at a pressure of 0.8 Pa. Samples were heat-treated at 600 C for 3 hours in an Ar/Water atmosphere to ensure crystallization of the coatings.Uniform thin films of zinc-doped HA were produced with an approximate thickness of 600 nm. EDS was used to determine that the zinc content of the coatings produced with Zn target DC powers of 1.5 W and 3.0 W were 3.8 wt. % and 7.0 wt. % zinc, respectively. XRD revealed that the as-coated films were amorphous, and that heat treatment at 600 C resulted in the formation of a highly crystalline coating.Human osteoblast precursor cells were plated onto uncoated Ti-6Al-4V discs and Zn doped HA coated discs at a concentration of 10000 cells/disc. After 1, 4, and 7 days, cells were fixed with 4% paraformaldehyde, made permeable with Triton-X 100, and stained with Phalloidin TRFC and DAPI. Fluorescent microscopy showed significant attachment and growth of cells on each surface after 1 day. After 7 days, the 3.8 wt. % Zn doped HA coatings showed greater cell proliferation than both the Ti-6Al-4V and 7.0 wt. % Zn doped HA surfaces. This study demonstrates that a novel zinc doped HA coating produced using a magnetron co-sputtering process may have great promise for applications in the field of orthopedic biomaterials.
3:15 PM - HH3.4
Novel Biologically-inspired KRSR and RGD Modified Rosette Nanotube Coatings on Orthopedic Implants.
Lijie Zhang 1 , Usha Hemraz 2 , Hicham Fenniri 2 , Thomas Webster 1 Show Abstract
1 Engineering, Brown University, Providence, Rhode Island, United States, 2 National Institute for Nanotechnology and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
Due to the increasing number of patients who suffer various bone diseases and problems (such as implant loosening, etc.) related to conventional orthopedic implant materials (i.e., titanium), it is desirable to develop novel biomaterials which can significantly lengthen the service lifetime of orthopedic implants and, thus, dramatically reduce the relatively high percentage of orthopedic revision procedures performed around the world. The aim of this study was to create a novel biologically-inspired coating based on the self-assembly properties of helical rosette nanotubes (HRNs) with favorable cytocompatibility properties for improving orthopedic implants. HRNs are a series of biocompatible nanomaterials which spontaneously form in water or various solvents by the self-assembling of guanine-cytosine DNA motifs. Several types of novel HRNs with unique surface chemistry were synthesized and characterized in this study: HRN-K, HRN-RGD-K, HRN-KRSR, which were conjugated with respective cell-adhesive domains lysine (K), RGD, and KRSR peptide sequences. After coating these biomimetic HRNs on currently implanted titanium, the results of this study showed greatly improved osteoblast (bone-forming cell) adhesion after 4 hours compared to uncoated titanium. Additionally, HRNs performed much better towards improving bone cell adhesion than poly lysine, collagen, and KRSR peptides. Since other cells (such as endothelial cells for vascularization and fibroblasts for forming fibrous tissue capsule) also play important roles in new bone formation, the responses of vascular endothelial cells and skin fibroblasts towards these new KRSR and RGD modified HRN coatings were investigated. In total, this study created a novel nanostructured coating which can significantly improve bone cell adhesion and stimulate new bone growth, and thus, are worth further investigation.
3:30 PM - HH3.5
Activatable Nanoparticle-Tagged Perfluorocarbon Droplets for Medical Imaging.
Naomi Matsuura 1 , Ivan Gorelikov 1 , Ross Williams 1 , Kelvin Wan 1 , Siqi Zhu 1 , James Booth 2 , Peter Burns 1 , Kullervo Hynynen 1 , John Rowlands 1 Show Abstract
1 Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada, 2 Molecular and Cellular Biology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
There is interest in designing multifunctional constructs for clinical medical imaging that can both amplify weak native contrast at disease sites and be activated through means external to the patient to deliver localized therapy. Perfluorocarbon (PFC) droplets have been shown to be effective medical imaging contrast agents, and nanoparticles have been used as both imaging and therapy agents. In this work, the combination of PFC droplets and nanoparticles as hierarchical, composite constructs that may be activated by ultrasound energy was investigated for multifunctional imaging/therapy applications. Silica-coated, CdSe/ZnS, quantum dot (QD) nanoparticles were dispersed in PFC after surface fluorination, and were subsequently emulsified using synthetic fluorosurfactants to form sub-micron, QD-tagged PFC droplets in water. QD fluorescence and transmission electron microscopy were used to confirm that the QD-tagged PFC droplets successfully labeled live macrophage cells in vitro. To activate the QD-tagged PFC droplets, ultrasound pulses (peak negative pressures from 0 to 2 MPa) were applied to convert them to gas bubbles, which were rapidly driven to collapse. At ultrasound pressures greater than 1.6 MPa, the activation of the PFC droplets in the cells resulted in cell membrane disruption and dispersion of the cell contents into surrounding media. Activation of the PFC droplets was further validated by the decrease in total cell count of PFC-loaded cells after ultrasound exposure. This work reveals the potential of using ultrasound-activatable nanoparticle-PFC constructs to track transplanted ex vivo-labeled cells in vivo or to image acoustically the cellular target of similarly labeled constructs.
3:45 PM - HH3.6
Maghemite Nanoparticles Embedded in a Silica Shell as Enhanced T2 Contrast Agent for MRI.
Elena Taboada 1 , Anna Roig 1 , Elisenda Rodriguez 2 Show Abstract
1 Crystallography Dpt., Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Bellaterra Spain, 2 Center for Molecular Imaging Research, MGH-Harvard Medical Hospital, Boston, Massachusetts, United States
4:00 PM - HH3: ADBIOMAT
HH4: Drug Delivery Systems II Gene and Peptide Delivery
Monday PM, December 01, 2008
Room 310 (Hynes)
4:30 PM - **HH4.1
A Multilayered Approach to Surface-Mediated DNA Delivery.
David Lynn 1 Show Abstract
1 Department of Chemical and Biological Engineering, University of Wisconsin - Madison, Madison, Wisconsin, United States
Methods for the layer-by-layer deposition of oppositely charged polymers on surfaces can be used to fabricate ultrathin, multilayered films using a broad range of natural and synthetic materials, including DNA. Provided that the individual components of these assemblies are designed appropriately, these methods provide opportunities to design thin films and coatings that provide control over the release of proteins, DNA, and other agents from surfaces.We will describe recent work from our laboratory on the fabrication of ultrathin multilayered films that provide tunable and, in some cases, sophisticated levels of spatial and/or temporal control over the release of DNA from the surfaces of macroscopic and microscopic objects. Our work has centered on two primary approaches. The first approach is based on the fabrication of multilayered films using synthetic cationic polymers designed to degrade hydrolytically. The incorporation of degradable polyamines into these films introduces a mechanism for promoting controlled film disruption and the surface-mediated delivery of DNA. We have demonstrated that films fabricated using these materials erode gradually and can be used to direct surface-mediated cell transfection in vitro and in vivo. We have also demonstrated that changes in polymer structure can be used to provide tunable control over film disassembly. For example, systematic changes in polymer hydrophobicity, side chain structure, or charge density can be used to tune film erosion and the release of DNA over periods ranging from several hours, several days, or several weeks.The second approach is based upon the synthesis and incorporation of new synthetic ‘charge-shifting’ cationic polymers that undergo gradual reductions in net charge (e.g., from ‘cationic’ to ‘less cationic’ or ‘anionic’) and introduce time-dependent destabilizing interactions in DNA-containing films. We will discuss two different approaches to the design of these ‘charge-shifting’ polymers and examples of how these new polymers can be used to (i) design ultrathin films that promote the long-term release of DNA (e.g., for up to 3 months) and (ii) design multilayered films with hierarchical structures that permit control over the release of two or more DNA constructs with separate and distinct release profiles (e.g., rapid release of one DNA construct, followed by the slower, sustained release of a second DNA construct, etc).We will also describe the results of experiments demonstrating the abilty of these thin film coatings to localize the release of DNA from the surfaces of implantable medical devices, such as intravascular stents, or from the surfaces of injectable polymer microspheres. These new materials could contribute to the design of thin films and coatings capable of delivering precise and well-defined quantities of multiple different DNA constructs (or combinations of other agents) in a range of fundamental and applied contexts.
5:00 PM - HH4.2
DNA Delivery Using pH-Sensitive Polymer Vesicles.
Hannah Lomas 1 , Irene Canton 1 , Marzia Massignani 1 , Adam Blanazs 2 , Steven Armes 2 , Andrew Lewis 3 , Giuseppe Battaglia 1 Show Abstract
1 Biomaterials and Tissue Engineering Group, Department of Engineering Materials, The Kroto Research Institute, The University of Sheffield, Sheffield United Kingdom, 2 Department of Chemistry, The University of Sheffield, Sheffield United Kingdom, 3 , Biocompatibles UK Ltd, Farnham Business Park, Farnham, Surrey United Kingdom
We present a novel non-viral gene delivery vector based on the ability of a synthetic amphiphilic block copolymer to mimic biological phospholipids by forming membrane-enclosed structures, specifically nanometer-sized vesicles.1,2 We report the use of a diblock copolymer which comprises a biocompatible, hydrophilic polymer, poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC), and a pH-sensitive polymer, poly(2-(diisopropylamino)ethyl methacrylate) (PDPA), which can bind nucleic acids. The block copolymer self-assembles into vesicles at physiological pH, and dissolves completely as unimers at endocytic pH. Plasmid DNA has been successfully encapsulated inside these vesicles, and delivered intracellularly. We report that plasmid DNA-loaded PMPC25-PDPA70 polymer vesicles are able to transfect human primary cells (human dermal fibroblasts [HDF]) and an animal cell line (Chinese hamster ovary cells [CHO]) via the pH-triggered collapse of the vesicle.3 When the PDPA block of the PMPC-PDPA copolymer is protonated (at pH values below its pKa) it can also bind the highly negatively charged nucleic acids. We have characterized the DNA-copolymer interactions by ethidium bromide displacement assays, dynamic light scattering, transmission electron microscopy, and analysis of the zeta potential.3 All these techniques have confirmed that the self-assembly of the copolymer into vesicles at neutral pH is not affected by the presence of DNA and that the nucleic acid can be physically encapsulated within the polymer vesicle aqueous core, with a maximum encapsulation efficiency of 55 %. At acidic pH, the copolymer interacts strongly with DNA leading to the formation of a copolymer-DNA complex. Both GFP- and luciferase- encoding plasmid DNA have been encapsulated inside the polymer vesicles, and delivered into HDF and CHO cells.3,4 Compared to the use of more traditional non-viral vectors, such as LipofectamineTM and calcium phosphate, the PMPC-PDPA vesicles displayed very high levels of cellular viability, resulting in a much higher transfection efficiency. Furthermore, levels of protein expression when using these polymer vesicles to transfect cells were comparable to transfection using calcium phosphate.REFERENCES1. Discher, D. E. and Eisenberg, A. Polymer vesicles. Science, 297, 967-73, 2002.2. Battaglia, G. and Ryan, A. J. Bilayers and Interdigitation in Block Copolymer Vesicles. J. Am. Chem. Soc., 127, 8757-8764, 2005.3. Lomas, H. et al. Biomimetic pH Sensitive Polymersomes for Efficient DNA Encapsulation and Delivery. Advanced Materials, 19, 4238-4243, 2007. 4. Lomas, H., Massignani, M. et al. Non-cytotoxic polymer vesicles for rapid and efficient intracellular delivery. Faraday Discuss., 139, 2008 (in the press).
5:15 PM - HH4.3
Role of Shell Structure and Surface Chemistry in the Cytosolic Delivery of SiRNA, Proteins, and Viral Particles into Cells using Endosome-escaping Core-shell Nanoparticles.
Darrell Irvine 1 3 2 , Yuhua Hu 4 , Prabhani Atukorale 3 , Eun Chol Choi 1 Show Abstract
1 Materials Sci. and Engineering, MIT, Cambridge, Massachusetts, United States, 3 Biological Engineering, MIT, Cambridge, Massachusetts, United States, 2 Koch Institute for Integrative Cancer Research, MIT, Cambridge, Massachusetts, United States, 4 Chemical Engineering, MIT, Cambridge, Massachusetts, United States
We recently developed a strategy for achieving non-toxic endosomal escape of drug delivery nanoparticles by sequestering proton sponge polymers in the core of crosslinked polymer nanoparticles with a stable core-shell structure. These particles absorb protons near neutral pH, promoting osmotic swelling and rupture of endolysosomes following uptake by cells. In epithelial cells, fibroblasts, and dendritic cells (phagocytic cells of the immune system), core-shell particles were capable of transporting small molecule or protein cargos to the cytosol, including cargos as large as ~100 nm viral particles. Importantly, endosome disruption was readily achieved in > 95% of particle-loaded cells while maintaining cell viability > 90%, as assessed by measurements of cell metabolism or long-term cell growth assays. Changes in the charge and chemistry of the shell layer of the particles, incorporating nonionic hydrophilic moieties such as poly(ethylene glycol) or charged groups such as carboxylates or primary amines did not alter the endosome disruption capacity of the particles, thus enabling the surface properties to be tuned. Tailoring of the surface chemistry enabled facile, nontoxic delivery of small interfering RNA (siRNA) molecules for gene regulation in live cells.
5:30 PM - HH4.4
Polyelectrolyte Multilayer Drug Delivery of Antimicrobial Peptides.
Anita Shukla 1 , Robert Langer 1 , Paula Hammond 1 Show Abstract
1 Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Medical conditions are often exacerbated by the onset of infection caused by hospital dwelling bacteria such as Staphylococcus aureus. The overuse of antibiotics has led to a rise in antibiotic resistance of these bacteria. Novel therapeutics that effectively target a range of bacteria without contributing to a rise in antibiotic resistance are needed to tackle this problem. The effective delivery of antimicrobial peptides, an important component of the eukaryote innate immune system, is of interest due to their wide range of activity against gram positive and gram negative bacteria, as well as low onset of bacterial resistance. Our work focuses on using polyelectrolyte multilayer films (PEMs) for the delivery of these novel therapeutics targeting S. aureus infections. PEMs allow the incorporation of a broad spectrum of materials and highly tunable dosage. We have examined hydrolytically degradable layer-by-layer (LBL) constructed films for the delivery of an antimicrobial peptide, ponericin G1. This peptide exhibits a low S. aureus minimum inhibitory concentration, as well as low blood cell lysis. Poly(β-aminoesters), containing hydrolysable ester bonds, have been incorporated into PEMs in order to effectively deliver functional doses of ponericin G1 over the desired release time scales. Current results show this technique to be highly effective for ponericin delivery. Ponericin is released over several days, with a large initial release of drug from the film intended to immediately eliminate bacteria surrounding the film. This is followed by a more gradual release of ponericin to maintain a bacteria-free zone. The film released ponericin retains its activity against S. aureus. Various film architectures are being explored to achieve the most desirable release properties of ponericin G1, including co-release with basic fibroblast growth factor. Toxicity of released agents against NIH 3T3 Fibroblasts and Human Umbilical Vein Endothelial cells is also being studied.
5:45 PM - HH4.5
Nanostructured Ceramic Coatings for Drug Delivery.
Karin Dittmar 1 , Arnaud Tourvieille 1 2 , Laurent-Dominique Piveteau 2 , Heinrich Hofmann 1 Show Abstract
1 Laboratory of Powder Technology, Ecole Polytechnique Fédérale de Lausanne, Lausanne Switzerland, 2 , Debiotech SA, Lausanne Switzerland
Medical implants delivering drugs are often used to ensure efficient medication at body sites where systemic administration is insufficient. The combination of a drug delivery coating on a mechanically supporting substrate is a beneficial concept for implants exposed to loads, e.g. stents or orthopaedic implants. Many of the commercially available coated stent implants are designed to release a drug locally and with a predefined rate out of a polymer matrix. These polymers are biodegradable, bio-erodible or inert. In spite of their successful drug release capability, they have often failed in regards to biocompatibility, long-term chemical and mechanical stability. This project aims at creating a novel, structured, ceramic drug delivering coating for stent implants. The coating is produced on a substrate by a multi-step dip coating technique into a TiO2-nanoparticle and a template suspension. Following sintering burns out the template particles to create a thin ceramic coating with defined meso and macro pores. The porosity of the mesoporous structure is greater than 50 %, as could be determined by nitrogen sorption and mercury intrusion porosimetry. This porosity can be increased if the macro pores (diameter 1 to 5 um, created by the templates) are present in the coating. The mean pore diameters of the mesoporous structure are 40 and 200 nm and the layer features a specific surface area below 20 m2/g. Anatase/rutile crystalline phases were determined in the ceramic by thin film XRD. The porosity of the film and the biocompatibility of TiO2 make the coating an ideal candidate as a drug reservoir and drug eluting system to be coated on stents.In drug eluting stents, immunosuppressive or anti proliferative agents are applied to prevent restenosis. In this study, paclitaxel is loaded into the coating by a low- pressure solvent evaporation technique. The amount of drug embedded and its release in different media are quantified by high performance liquid chromatography. The load obtained until now ranges from 0.2 up to 1.2 µg/mm2 (geometric area of the coating). Release tests in ultra pure water have revealed a continuous liberation of paclitaxel up to 2 month. Since a prolonged drug release is favourable to prevent restenosis on a long-term period, studies are now done to optimize the load and release kinetics of the drug. Results will be presented.First results of an in-vitro biocompatibility test using bovine endothelial cells in direct contact with the coated substrate showed a good biocompatibility of the coating. A major challenge lies in the compromise between a thin mechanically stable coating and the drug loading levels needed for the clinical application. The detailed characterization of the coating’s mechanical properties is therefore being conducted. Fracture starting point, delamination starting point and maximum shear strength between the coating and the substrate have been measured and will be presented.
HH5: Poster Session: Functional Materials and Drug Delivery Systems
Tuesday AM, December 02, 2008
Exhibition Hall D (Hynes)
9:00 PM - HH5.1
Favorable Surface Adhesion Response of Electrodeposited Nano-hydroxyapatite on Ultrafine-grained (UFG)/nano-grained (NG) Austenitic Stainless Steel.
Sachin Mali 1 , Mahesh Somani 1 , L. Karjalainen 1 , Devesh Misra 1 , Sashank Nayak 1 Show Abstract
1 Center for Structural and Functional Materials, University of Louisiana at Lafayette, Lafayette, Louisiana, United States
We describe here the significance of ultrafine-grained (UFG)/nanograined (NG) structures in the electrodeposition of nano-hydroxyapatite and compare with conventional coarse-grained structures. The study demonstrates superior adhesion of electrodeposited nano-hydroxyapatite on UFG/NG structures in relation to coarse-grained austenitic stainless steel examined using nanosratching by a nanoindenter. It is proposed that hydrophilicity (contact angle) and grain structure are the underlying reasons for the difference in nanoscratching or adherent nature of nano-hydroxyapatite coatings on coarse-grained and UFG/NG austenitic stainless steel. An accompanying aspect that emerged from the primary objective is that the amorphous calcium phosphate is a precursor to the formation of nano-hydroxyapatite.
9:00 PM - HH5.10
Synthesis of Magnetic Porous Hollow Silica Nanostructures for Drug Delivery.
Hui Ma 1 , Mark DeCoster 2 , James McNamara 2 , Daniela Caruntu 1 , Jianfeng Chen 3 , Charles O'Connor 1 , Weilie Zhou 1 Show Abstract
1 AMRI/Chemistry, Advanced Materials Research Institute/UNO, New Orleans, Louisiana, United States, 2 Biomedical Engineering and Institute for Micromanufacturing , Louisiana Tech University, Ruston, Louisiana, United States, 3 Key Lab for Nanomaterials, Ministry of Educations,, Beijing University of Chemical Technology, Beijing China
Magnetic porous hollow silica nanostructures with advantages of high surface area, good bio-compatibility and magnetic targeting, are considered as novel drug carriers in nanomedcine applications. In this presentation, we report a synthesis of magnetic porous hollow silica nanospheres and nanotubes using sol-gel method. Pure CaCO3 nanoneedles were first fabricated in rotating packed bag (RPB). Then Fe3O4 nanoparticles (diameter less than 10 nm)/methanol dispersion was added to attach the CaCO3 nanoparticles and nanoneedles surface. Surfactant hexadecyltrimethylammonium bromide (CTAB) was used as a template to direct the formation of porous structure on the surface. Tetraethoxysilane (TEOS) was then applied to generate silica by basic hydrolysis. After removing CTAB by calcination and etching CaCO3 nanoparticels and nanoneedles away in diluted acetic acid, magnetic porous hollow silica nanospheres and nanotubes with Fe3O4 nanoparticles embedded in the silica shell are achieved. The mangnetic porous hollow silica nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray powder diffraction. SQUID measurement shows the nanostructures exhibit superparamagnetism property in room temperature, and ferromagnetism below the blocking temperatures. The drug loading/releasing tests using ibuprofen were studied and a slow release was observed. The toxicity test was also performed.
9:00 PM - HH5.11
Novel Superparamagnetic Iron Oxide Nanoparticles for a Multifunctional Nanomedicine Platform.
Oleh Taratula 1 3 , Ronak Savla 1 3 , Ipsit Pandya 1 , Andrew Wang 2 , Tamara Minko 3 4 , Huixin He 1 4 Show Abstract
1 Chemistry, Rutgers, the State University of New Jersey, Newark, New Jersey, United States, 3 Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, Piscataway, New Jersey, United States, 2 , Ocean NanoTech, Fayetteville, Arizona, United States, 4 , Cancer Institute of New Jersey, New Brunswick, New Jersey, United States
9:00 PM - HH5.12
Single File Diffusion of Protein Drugs through Cylindrical Nanochannel.
Seung Yun Yang 1 , Jeong-A Yang 2 , Sei Kwang Hahn 2 , Jin Kon Kim 1 Show Abstract
1 Environmental Science & Engineering and Chemical Engineering, POSTECH, Pohang Korea (the Republic of), 2 Material Science & Engineering, POSTECH, Pohang Korea (the Republic of)
Development of drug delivery with the controlled and long-term release has been considered as one of the most promising biomedical applications. A wide range of materials and devices developed based on osmotically controlled diffusion and swelling-controlled delivery have been reported. Although the existing methods showed long-term stability and constant release, several adverse problems, such as burst of a drug, might be anticipated under some chemical environments. Here, we achieve the single file diffusion of protein drugs by using the nanoporous membrane with cylindrical nanochannels. Nanoporous membrane consists of separation layer prepared by polystyrene-block-poly(methyl methacrylate) copolymer and conventional microfiltration membrane for the supporting membrane. We found that the rate of protein drug release throughout the nanoporous membrane becomes constant irrespective of the concentration of the drug. Since the pore size in the nanoporous membrane is easily controlled to match the size of drugs, it could be widely used for drug delivery of various proteins.
9:00 PM - HH5.13
Bioinspired Design of Polymer Films for Controlled Release of Self-assembling Colloidal Aggregate Containing Sirolimus.
Hyung Il Kim 1 4 , Madoka Takai 2 4 , Tomohiro Konno 2 4 , Ryosuke Matsuno 2 4 , Jeong-Sun Seo 3 , Kazuhiko Ishihara 1 2 4 Show Abstract
1 Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo Japan, 4 Center for NanoBio Integration (CNBI), The University of Tokyo, Tokyo Japan, 2 Department of Materials Engineering, School of Engineering, The University of Tokyo, Tokyo Japan, 3 Ilchun Genomic Medicine Institute, MRC and Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul Korea (the Republic of)
Extensive clinical studies have reported better outcomes with sirolimus-eluting stents (SES) than with paclitaxel-eluting stents. However, there are few published reports on the in vitro studies of sirolimus release in spite of poor control over the release from the current SES. The discrepancy between the clinical need and the poorly published in vitro data is probably due to instability of sirolimus in buffer. An attractive approach to stabilize bioactive agents is to develop a self-assembling colloidal aggregate of amphiphilic molecules. It was widely believed that only block copolymers could form reasonably controlled micelles before French and Canadian group published several reports about the colloidal stability of the integral membrane proteins/ amphiphilic random copolymers complex in buffer; the size dispersity was well controlled. Earlier than their contribution to the field of polymer therapeutics, we originally reported that PMB30W, a water-soluble amphiphilic poly(2-methacryloyloxyethyl phosphorylcholine-random-n-butyl methacrylate), self-assembled into reasonably controlled colloidal aggregate and maintained hydrophobic drugs inside the micelles stably.[3,4] In this study, we hypothesized that PMB30W protect hydrolysis of sirolimus because the hydrophobic groups of PMB30W interact with the hydrophobic surface of sirolimus while phosphorylcholine groups of PMB30W provide a hydrophilic corona and thereby maintain the colloidal stability in aqueous medium. For the controlled release of sirolimus with good efficiency of drug loading, the novel domain-controlled release from poly(L-lactide-random-caprolactone-random-glycolide) (PLCG)/ PMB30W/ sirolimus films was designed. We controlled the release of sirolimus in vitro two compartment systems by tuning the size (by nano-range) of domains composed of PMB30W and sirolimus inside the PLCG/ PMB30W/ sirolimus blends. Three different formulations of films were designed; fast release (FR), moderate release (MR), slow release (SR) prepared by acetone/EtOH, acetone/MeOH, electrospinning in acetone/MeOH, respectively. The blend composition was fixed by 90/10/1 (PLCG/ PMB30W/ sirolimus, weight ratio). The size of domains composed of PMB30W and sirolimus was the main factor for determining the release velocity of sirolimus from the PLCG/ PMB30W/ sirolimus films; the release of sirolimus decreased while the size of the domains reduced. Electrospun nanofibers showed the remarkable structural stability in PBS and thereby became SR. Sirolimus was released by diffusion controlled manners; a degradation product of sirolimus released by degradation controlled. Compared to PLCG/ sirolimus films, all PLCG/ PMB30W/ sirolimus films reduced a degradation product of sirolimus significantly.References1. Serruys PW et al. N Engl J Med 354, 483, 2006.2. Diab C et al. Biochim Biophys Acta 1768, 2737, 2007. 3. Ishihara K et al. Polym J 31, 1231, 1999.4. Konno T et al. J Biomed Mater Res A 65, 210, 2003.
9:00 PM - HH5.14
Effect of Polymer Adsorption on Crystallization of Small Organic Molecules.
Hyemin Choi 1 , Jonghwi Lee 1 Show Abstract
1 Department of Chemical Engineering and Materials Science, Chung-Ang University, Seoul Korea (the Republic of)
The crystallization process of drugs is an important unit operation in the pharmaceutical industry. The controlled preparation of crystallites of a defined size can determine the kinetic aspects of solubility (drug release), crystal superstructures, and mechanical/flow properties. As the nucleation and growth processes in the crystallization of low molecular weight organic materials are sensitive to various parameters, crystallization can be controlled by addition of cosolvents, low molecular additives, heterogeneous surfaces, and sometimes functional polymers. Crystalline structures are often constructed by assembly and/or transformation from smaller units. It has been found that the morphology of polar organic crystals could be changed by the addition of oppositely charged polymeric additives, which can physically adsorb onto the surface of the smaller crystal units. To understand the role of polymer adsorption, the crystallization of atorvastatin calcium (a cholesterol-lowering statin drug) was performed in methanol/water (1:9(v/v)) mixture using 96-well plates. Polyethyleneimine(PEI), chitosan, bio-synthesized elastin like polymers [(GVGVP GVGVP GEGVP GVGVP GVGVP GVGVP)35(GVGVP) (PVII), and (GVGVP GVGFP GEGFP GVGVP GVGFP GFGFP)35(GVGVP) (PXIII)], poly(acrylic) acid(PAA) and polyethylene glycol(PEG) were used as polymeric additives. Crystal structure and particle morphology were analyzed by SEM, DSC and XRD. It is well known that many polymers in solution can induce colloidal aggregation by enthalpic changes (surface binding and interparticle bridging) as well as nonadsorption entropic mechanisms (depletion flocculation). This process is the molecular basis for polymer-directed crystallization. In addition, strong attractive interactions can prevent further crystal growth and change the shape and size of primary clusters. SEM showed distinctly different particle morphology in the cases of elastin like polymers: Overall, spherical particles were observed, but they consisted of smaller primary crystallites. Crystallization temperature also affected the size of crystals: The higher the temperature, the larger the crystal size resulted. Differences in particle sizes and pathway of crystal growth were obtained by using different kinds of polymers. There were significant differences in DSC melting points. This polymer-directed crystallization resulted in the formation of mesocrystals, artificially stabilized by polymeric additives. Interesting morphological features were observed in the mesocrystal cases. (G=glycine, V=valine, P=proline, I=isoleucine, F= phenyalanine and E=glutamic acid).
9:00 PM - HH5.15
Formulation Of A Hierarchically Designed Peptide Nucleic Acid Based DNA Delivery Construct.
Peter Millili 1 , Daniel Yin 3 , Haihong Fan 3 , Ulhas Naik 2 , Millicent Sullivan 3 Show Abstract
1 Chemical Engineering, University of Delaware, Newark, Delaware, United States, 3 Pharmaceutical Sciences, Merck & Co., West Point, Pennsylvania, United States, 2 Biological Sciences, University of Delaware, Newark, Delaware, United States
9:00 PM - HH5.16
IR Spectroscopy and DSC Studies of Binary Combinations of cis-6-Octadecenoic Acid and Octadecanoic Acid – Relevance to Stratum Corneum Permeation.
David Moore 3 , Eilidh Bedford 1 2 , Donald Koelmel 3 , Donna Laura 3 Show Abstract
3 , ISP, Wayne, New Jersey, United States, 1 Performance Products, Cabot Corporation, Billerica, Massachusetts, United States, 2 , Unilever, Port Sunlight United Kingdom
Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) studies are reported for combinations of cis-6-octadecenoic acid (also termed petroselinic acid, PSA) and octadecanoic acid (also termed stearic acid, SA) across a wide range of binary mole ratio combinations. The data are then used to plot the phase diagram which is found to be montotectic with the PSA reducing the melting temperature of SA at all compositions. The relevance of these experiments to stratum corneum (SC) biophysical behavior, particularly the influence and potential mechanisms of PSA on dermal permeation, are discussed. The phase behavior of this simple binary model system indicates a potential mechanism by which cis-6-octadecenoic acid can act as penetration enhancer in skin, given that discrete fatty acid domains may exist in the SC. This lipid model suggests that cis-6-octadecenoic acid forms a fluid lipid phase in the SC (at skin physiological temperatures ~32-34 °C) that will include some amount of fluidized SC fatty acids. Cis-6-octadecenoic acid clearly disrupts the crystalline orthorhombic domains of octadecanoic acid resulting in smaller domains and a reduced melting temperature. This separate cis-6-octadecenoic acid-stratum corneum fatty acid fluid phase could provide a pathway in the SC through which lipophilic molecules permeate the skin barrier.
9:00 PM - HH5.17
Antisense Oligonucleotides Delivery to the Antigen Presenting Cells by using Schizophyllan.
Shinichi Mochizuki 1 , Jusaku Minari 1 , Mika Kasuga 1 , Yoshiyuki Adachi 2 , Kazuo Sakurai 1 Show Abstract
1 , The University of Kitakyushu, Fukuoka Japan, 2 , Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo Japan
Antisense oligonucleotides (AS ODNs) have a great advantage as therapeutic agents. AS ODNs are designed to bind to RNA through the Watson-Crick hybridization. In general, their size ranges from 12 to 25 nucleotides in length and their gene silencing mechanism includes cleavage of the targeted RNA with endogenous cellular nuclease, such as RNase H. Several phosphorothioate ODNs are in the late phase clinical trials as the first generation in antisense regent. However, in vivo, there are a number of obstacles to overcome, such as rapid excretion via kidney, degradation in serum, uptake by phagocytes of the reticuloendothelial system, and inefficient endocytosis by target cells. A variety of supramolecular nanocarriers including liposomes, cationic polymer complexes, and various polymeric nanoparticles have been used to deliver AS ODNs. We have studied schizophyllan (SPG) as an AS ODNs carrier. SPG, an extracellular polysaccharide produced by the fungus, is consists of β-(1→3) –D-glucan and one β-(1→6)-D-glycosyl side chain that links to the main chain at every three glucose residues. We have revealed that SPG can form a complex with polynucleotides. In 2001, Gordon et al. identified dectin-1 as a major receptor involved in the recognition of β-glucans. Dectin-1 is predominantly expressed on antigen presenting cells such as macrophages and dendritic cells. Therefore it is thought that AS ODNs complexed with SPG are specifically incorporated into the antigen presenting cells. We prepared HEK293 cells transfected with mouse dectin-1 cDNA in order to examine its ability to uptake of SPG. The extent of expression of dectin-1 was confirmed by RT-PCR and flow cytometry. To test whether the dectin-1 transfectant could uptake SPG, the dectin-1 transfectant was incubated with various concentration of fluorescein-labeled SPG, and the uptake was analyzed by flow cytometry. The dectin-1 transfectant showed the increased fluorescent intensity with a higher concentration of fluorescein-labeled SPG. However control HEK293 cells did not show the increased uptake of fluorescein-labeled SPG. This suggests that fluorescein-labeled SPG was specifically recognized by dectin-1 on the transfectant. The formation of complex between SPG and AS ODNs having poly (dA)30 was carried out with the established method and the complexation was confirmed by gel electrophoresis. After gel electrophoresis, AS ODNs reacted with SPG did not migrate at all, which indicated that AS ODNs were formed a complex with SPG. These data suggest that SPG is a useful biomaterial for delivering AS ODNs to the antigen presenting cells.
9:00 PM - HH5.18
Design, Synthesis, and Biological Functionality of a Modular Drug Delivery Platform.
Douglas Mullen 1 3 , Daniel McNerny 2 3 , Xue-min Cheng 3 , Alina Kotlyar 3 , Ankur Desai 3 , Istvan Majoros 3 , James Baker 3 , Mark Banaszak Holl 1 3 4 Show Abstract
1 Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, Michigan, United States, 3 Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan, Ann Arbor, Michigan, United States, 2 Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, United States, 4 Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States
Poly(amidoamine) (PAMAM) dendrimers have shown great promise as targeted drug delivery platforms. Studies have demonstrated that PAMAM dendrimers functionalized with targeting moieties, drug molecules, and imaging dyes efficiently induce cytotoxicity in cancer cells without causing collateral damage to healthy cells. There remain several obstacles preventing large scale utilization of multi-functionalized dendrimers including multiple time-intensive synthesis steps, decreased solubility, and an increased PDI of the final product. Thus, a new approach to synthesize a modular drug delivery platform using mono-functionalized dendrimers is being pursued. This approach utilizes the specificity of the 1,3 dipolar cycloaddition reaction between azide and alkyne moieties to create multi-functionalized dendrimer platforms that have the same clinical properties as single multi-functional dendrimers while requiring fewer synthesis steps, achieving an increased carrying capacity, and minimizing PDI. Additionally, this approach has the added capability of creating different drug-target combinations in one combinatorial step, rather than requiring the complete synthesis for each desired combination.
9:00 PM - HH5.19
Layer-by-Layer Assembly of Block Copolymer Micelles for Applications in Drug Delivery from Surfaces.
Byeong-Su Kim 1 , Paula Hammond 1 Show Abstract
1 Chemical Engineering, MIT, Cambridge, Massachusetts, United States
Layer-by-layer (LbL) assembly has been widely used as a versatile method for fabricating multilayer thin films with controlled structure and composition. Due to its facile, inexpensive, and environmentally friendly nature, LbL assembled multilayer thin films find their applications ranging from materials to biology. LbL assembly is typically based on sequential adsorption of materials with complementary functional groups employing electrostatic interaction, hydrogen bond, and coordination bond, which limits the incorporation of small, hydrophobic drugs into multilayer film. There is, therefore, widespread interest in finding ways to integrate therapeutic reagent into LbL film.Here, we describe the incorporation of amphiphilic block copolymer micelle as a nanometer-sized vehicle for hydrophobic drugs within the LbL multilayer films. In particular, we chose block copolymers containing biodegradable poly(ε-caprolactone) as a core block for controlled release, including poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL), and poly(2-vinyl-N-ethylpyridinium bromide)-block-poly(ε-caprolactone) (P2VEP-b-PCL). We demonstrate the construction of polymer micelle containing films through different ass