Rajesh R. Naik Air Force Research Laboratory
Carole C. Perry Nottingham Trent University
Kiyotaka Shiba Japanese Foundation for Cancer Research
Rein Ulijn University of Manchester
T1: Bioinspired Materials
Tuesday PM, April 10, 2007
Room 2006 (Moscone West)
9:00 AM - T1.1
Biogenic Nanostructured Silica Formation in Diatoms: Proteins, Genes, and Structure.
Mark Hildebrand 1 Show Abstract
1 , Scripps Institution of Oceanography, UCSD, La Jolla, California, United States
Diatoms make cell walls containing three-dimensional nano- and micro- scale silica structures, with a complexity and organization exceeding that possible with current synthetic approaches. Diatom silica structure formation occurs dynamically inside an expandable and moldable membrane-bound intracellular compartment called the silica deposition vesicle, with control occurring at multiple levels. Understanding the molecular details of the process requires identifying structural intermediates and correlating their formation with genes and proteins involved. We have applied molecular, genomic, and microscopic approaches to examine diatom cell wall synthesis. During characterization of structural intermediates, we identified three scales and two distinct stages in structure formation, and observed a correlation between the formation process and optimization of the final structural property required. Using synchronized cultures, we used microarrays to screen all genes in the genome of Thalassiosira pseudonana for a characteristic expression pattern identified in other cell wall genes. One hundred and four genes were identified, and categorized according to cellular role or possible function. We are determining the intracellular localization of proteins encoded by these genes to evaluate their involvement in cell wall formation. Correlation of structure formation with the genes and proteins involved will be essential to understand how diatom genetic information is translated into active chemical moieties that ultimately control the formation of the solid material. These approaches, coupled with genetic manipulation tools, will enable elucidation and manipulation of the intracellular systems involved in biogenic nanostructured silica synthesis, facilitating applications of diatoms in materials science.
9:45 AM - T1.3
Lessons from Diatoms: Formation of nanopatterned functional ceramics under ambient conditions
Nils Kroger 1 2 , Nicole Poulsen 1 , Ken Sandhage 2 , Matt Dickerson 2 , Gul Ahmad 2 Show Abstract
1 Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States, 2 Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
The direct syntheses of functional organic-inorganic hybrid materials are severely restricted by the incompatible thermal and/or chemical conditions often required to form desired organic and ceramic phases. Recently, biomineral-forming organisms like diatoms (see figure) and sponges have been recognized as inspirational sources of new strategies for directly synthesizing such hybrid materials under environmentally benign conditions. Here we present novel in vitro and in vivo approaches to produce functional ceramics employing molecules from diatoms as well as using living diatoms themselves.The in vitro approach relies on diatom genes that encode proteins (termed silaffins) involved in biosilica formation. We have designed recombinant silaffins that are able to induce the rapid formation of silica and titania from aqueous precursor solutions. Recombinant silaffin rSilC enabled the synthesis of hierarchically nanopatterned rutile microparticles at ambient temperature and neutral pH. Due to its high refractive index, rutile is highly desirable material for photonic applications, yet previous rutile syntheses require extreme reaction conditions (600-800C, or strongly acidic, hydrothermal conditions). Using an in vivo approach we have developed a unique method for the silica immobilization of functional proteins. The bacterial enzyme hydroxylaminobenzene mutase (HabB) was expressed as a silaffin-fusion protein in the diatom Thalassiosira pseudonana, which resulted in targeted incorporation of the fusion protein into the T. pseudonana silica cell wall. The diatom silica bound HabB was enzymatically active, and remained functional as well as associated with the diatom silica during isolation.
10:00 AM - T1.4
Silicification Biomimetic Studies in Confined Media.
Thibaud Coradin 1 , Clementine Gautier 1 2 , Pascal Lopez 2 , Myriana Hemadi 1 , Jacques Livage 1 Show Abstract
1 Chimie de la Matiere Condensee, CNRS-UMR 7574, Université Paris VI, Paris France, 2 Diatom Signaling and Morphogenesis, CNRS-FRE 2910, Ecole Normale Supérieure, Paris France
10:15 AM - **T1.5
The Bioclastic and Shape-preserving Inorganic Conversion (BaSIC) Route to Chemically Tailored Three-Dimensional Nanostructured Microassemblies
Kenneth Sandhage 1 2 , Samuel Shian 1 2 , Michael Weatherspoon 1 2 , Zhihao Bao 1 2 , Phillip Graham 1 2 , David Lipke 1 2 , Eric Ernst 1 2 , Matthew Dickerson 1 2 , Shawn Allan 1 2 , Ye Cai 1 2 , Gul Ahmad 1 2 , Michael Haluska 1 2 , Robert Snyder 1 2 , Laura Sowards 3 , Rajesh Naik 3 Show Abstract
1 Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States, 2 Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia, United States, 3 Biotechnology Group, Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, United States
Appreciable worldwide R&D effort is underway to develop new fabrication routes to three-dimensional (3-D) nanostructured micro-assemblies for advanced devices. Such processes must be capable of: i) precise 3-D fabrication on a fine (down to nanometer) scale, and ii) mass production on a large scale. These often-conflicting requirements can be addressed with a hybrid fabrication paradigm that merges biological self-assembly with synthetic chemistry: Bioclastic and Shape-preserving Inorganic Conversion (BaSIC)*. Nature provides numerous examples of organisms that assemble biominerals into complex 3-D (bioclastic) microscale structures. For example, diatoms (unicellular planktonic algae) assemble intricate 3-D microshells (frustules) comprised of silica nanoparticles. Each of the tens of thousands of extant diatom species forms a microshell with a distinct shape and pattern of fine features. Sustained reproduction of a given diatom species can yield enormous numbers of identical frustules (e.g., 40 reproduction cycles can yield >1 trillion replicas!). Such massively parallel, genetically precise, and environmentally benign 3-D self-assembly is highly attractive for device manufacturing, and has no man-made analog. However, the natural silica-based chemistry of diatom frustules inhibits their use in a variety of devices. With BaSIC, these biogenic assemblies can be converted into a wide range of new functional chemistries (TiO2, F-doped TiO2, ZrO2, Cl-doped ZrO2, MgO, BaTiO3, Eu-doped BaTiO3, Zn2SiO4, Mn-doped Zn2SiO4, polymers, etc.), while preserving the 3-D frustule morphologies. Various chemical conversion approaches (gas/solid reaction, liquid/solid reaction, conformal coating, reaction and coating, coating and reaction) utilized in the BaSIC process to generate shape-preserved replicas will be described. Such shape-preserving chemical alteration has also been applied to nanostructured synthetic silica preforms. The optical and chemical properties of such chemically-altered nanostructured micro-assemblies will be discussed. Future advances in the genetic engineering of diatoms (to allow for tailoring of frustule shapes), coupled with shape-preserving chemical modifications via BaSIC, offer the exciting promise of 3-D Genetically Engineered Micro/nanodevices (3-D GEMs).*K. H. Sandhage, “Shaped Microcomponents via Reactive Conversion of Biologically-derived Microtemplates,” U.S. Patent No. 7,067,104, June 27, 2006.
10:45 AM - T1.6
The activity of Diatom inspired synthetic polyamines in Silicification
Carole Perry 1 , David Belton 1 , Vadim Annenkov 2 , Siddharth Patwardhan 1 , Elena Danilovtseva 2 Show Abstract
1 Biomedical and Natural Sciences, Nottingham Trent University, Nottingham United Kingdom, 2 , Limnological Institute of Siberian Branch of Russian Academy of Sciences, Irkutsk Russian Federation
In nature many organisms are able to capture and use monosilicic acid in the formation of highly functional and sometimes elaborate siliceous structures. Much effort has been invested in attempts to determine the underlying synthetic principles involved in this chemical manipulation, not least into investigations involving the unicellular algae diatoms. Within the frustule considerable levels of polyamines have been found either as post translational modifications on the side chain of lysine groups in the peptides known as silaffins or as isolated molecules. Silaffins and the polyamines are proposed to play a significant role in diatom biosilicification producing diverse nano-structured silica valves. The isolated polyamines influence the condensation of silica from condensing systems based on alkoxysilanes or sodium silicate precursors, producing dense silica spheres that are not produced under similar conditions in their absence. The presence of polyamines in nature is not an unusual occurrence with cellular compounds such as spermine, and spermidine, common and the formation of these much longer diatom polyamine species is likely to be a serendipitous extension of their biosynthetic process. The polyamines so far isolated from diatoms have been shown to be very species dependant with varying methylation levels of the amine functionality from primary to quaternary and it is thought that this species dependency ultimately determines the final structural form of the diatom thecae.Here we report on the novel stepwise synthesis of a group of linear methylated propylamines and their activity in silica formation in vitro. Measurements were conducted to determine kinetic effects, the solution state of the polyamines, the surface area and porosity of the siliceous products and the gross morphologies. Comparison is made with the naturally occurring polyamines and the influence of chain length and amine separation assessed both as amine solution species and in the nature of the siliceous materials produced. Their effects on the condensation of a model silicic acid system is reported in terms of kinetic changes through pH and amine concentration as well as characterisation of the novel bimodal (dense hollow microporous spherical and thin walled vesicular) silicas produced. The charge states of the amines during addition to the condensation process were found to affect their solution chemistry and to be critical to the nature of the materials produced, with these charge states being in turn highly affected by amine length. The influence of the level of primary, secondary and tertiary amine functionality has also been investigated. These results show that rates of proton transfer are important in terms of flux from amines to precursor. Finally we show how siliceous materials with tailored properties can be produced through control of pH, amine concentration, chain length and ionic strength.
11:00 AM - T1:Biomat
11:30 AM - T1.7
Alkylation is crucial to enhancement of silica condensation rate by diamines.
David Robinson 1 , Blake Simmons 1 , Judith Rognlien 1 Show Abstract
1 , Sandia National Laboratories, Livermore, California, United States
11:45 AM - T1.8
Formation of Porous Hydroxyapatite
Deepa Khushalani 1 Show Abstract
1 Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai India
Most biological materials with predominantly mechanical function have a hierarchical structure consisting of several different length scale levels (angstrom to millimeter) and incorporate a composite structure where an inorganic component is epitaxially linked to an organic component. In this way, tough materials are designed by nature based on a complex configuration where size and morphology of component and its intricate link to the other species present in the composite all play a pivotal role in creating an impressive 3D organization with multifaceted function. In bone for example, the organization is an elaborate design based on collagen fibrils reinforced with nanosized inorganic mineral particles (hydroxyapatite). These nanosized mineral platelets are able to sustain a large tensile stress whereas the protein layer between them sustain sheer stress. This is an excellent example of how morphology of the inorganic component plays a pivotal role in the function of the overall composite. To this aim, both soft-condensed matter and solid inorganic porous supports have been studied in formation of porous hydroxyapatite. The work carried out using (1) a novel micoremulsion involving reverse micelles of calcium bis(2-ethylhexyl)phosphate (Ca(DEHP)2) and (2) Porous membrane supports of alumina and polycarbonate will be detailed. Products such as nanoporous porous hydroxyapatite with intricate tubular morphology will be presented along with their characterization involving microscopy, diffraction, and their uses in bioactive studies will also be evaluated.
12:00 PM - T1.9
Directed Evolution of Hydroxyapatite-Associated Protein Using Phage Display
Seung-Wuk Lee 1 2 4 , Jing Hang Huh 3 2 , Eddie Wang 1 4 , Emily Perttu 1 4 , Yue Zhao 1 Show Abstract
1 Bioengineering , University of California, Berkeley, Berkeley, California, United States, 2 Physical Bioscience Division, Lawrence Berkeley National Lab, Berkeley, California, United States, 4 , UCSF and UCB Joint Graduate Group in Bioengineering, Berkeley, California, United States, 3 Chemical Biology, University of California, Berkeley, Berkeley, California, United States
The formation of natural bone is thought to occur by the templated mineralization of HA by the surrounding proteins, which include collagen and highly acidic phosphoproteins attached to the collagen scaffold. It has been proposed that the acidic groups serve as binding sites for calcium ions and align them in an orientation that matches the HA crystal lattice, but the biological mineralization process is not understood at the molecular level. Using directed evolution process (phage display), we identified specific binding peptides for single crystal hydroxyapatite in various pH ranges and study their interactions between HA binding peptides and crystal surfaces. Remarkably, the consensus HA binding peptides resulted in characteristic tripeptide repeat (Pro-X-Y) at pH 7.5 and (Ser-Ser-Asp) at pH 5. These sequences are similar to the major repeats of type I collagen and dentin phosphoproteins respectively. Using a panel of synthetic peptides, we defined the structural features required for binding and mineralizing activity of HA. We also incorporated these short HA-binding peptides to construct three-dimensional bone-like materials.
12:15 PM - **T1.10
Mollusk shell nacre- and prismatic sequence - directed crystal design.
John Evans 1 , Sebastiano Collino 1 , Jennifer Giocondi 2 , Christine Orme 2 , Il Kim 1 , Katya Delak 1 Show Abstract
1 , New York University, New York, New York, United States, 2 Biophysical and Interfacial Sciences, Lawrence Livermore National Laboratories, Livermore, California, United States
The biomineralization environment of the nacre and prismatic layers of the mollusk are undoubtedly complex, consisting of many proteins present at the same or at different times in the extracellular matrix, and it is likely that numerous polypeptides jointly manage the overall polymorph selection process. Similarly, it has been postulated that Mg (II) also participates in calcium carbonate mineralization, although the exact role of this metal ion is not yet defined. Up until now, our in vitro mineralization studies of individual nacre- and prismatic-specific polypeptides have omitted this important feature of complexity, i.e., the participation of different polypeptides and Mg (II) in the calcium carbonate formation and the polymorph selection process. Obviously, if Nature employs multiple agents to effect net control over crystal formation, then material science might also need to adopt similar approaches to “tailor” inorganic - based materials with specific properties. To address this issue, we have explored the combinatorial effects of nacre and prismatic polypeptide sequences and the presence of “catalytic” levels of Mg (II)(1:10 Mg : Ca) on in vitro crystal growth. We find that It appears that low levels of Mg (II) can affect the mineralization activity of certain calcium biomineralization sequences in selective ways. In particular, we observe either subtle effects on crystal morphology or surprising alterations that deviate from normal polypeptide activity patterns. Moreover, Mg (II) can “switch” the function of a set of peptides to mimic one another with regard to selective adsorption, pinning, or growth patterns in calcite dislocation hillocks. We believe that Mg (II) can catalytically alter the outcome of protein-mediated biomineralization. With regard to combinatorial mixtures of mollusk shell polypeptides, there is clearly a synergistic effect when specific biomineralization protein sequences are combined together within in vitro assays settings. At this point we do not know if the observed morphologies are due to individual, overlapping effects arising from each peptide component, or, due to effects brought about by the interaction of one peptide species with another. Moreover, we do not know if these synergistic effects are the result of peptide - mineral interactions and/or peptide-catalyzed ion cluster assembly or shuttling in solution. We are now beginning to explore these possibilities in more detail.
12:45 PM - T1.11
Adaptable CaCO3 Mineralization Templates Based on Bis-urea Surfactants: in-situ Synchrotron X-ray Measurements of Structure and Kinetics.
Elaine DiMasi 1 , Seo-Young Kwak 1 , Benoit Pichon 3 , Daniela Popescu 2 , Maarten Smulders 2 , Natalia Chebotareva 2 , Rint Sijbesma 2 , Nico Sommerdijk 3 4 Show Abstract
1 National Synchrotron Light Source Dept., Brookhaven National Laboratory, Upton, New York, United States, 3 Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven Netherlands, 2 Department of Chemistry and Chemical Engineering, Eindhoven University of Technology, Eindhoven Netherlands, 4 Soft Matter Cryo-TEM Research Unit, Eindhoven University of Technology, Eindhoven Netherlands
T2: Bioinspired Materials-II
Tuesday PM, April 10, 2007
Room 2006 (Moscone West)
2:30 PM - **T2.1
Bio-inspired material synthesis and nanoelectronic devices production by protein supramolecule.
Ichiro Yamashita 1 2 3 Show Abstract
1 Material Science, NAIST, Ikoma Japan, 2 ATRL, Matsushita Electric Ind. Co., Ltd, Kyoto Japan, 3 CREST, Japan Science and Technology Agency, Kawaguchi Japan
We proposed a new process for fabricating functional nano-structure on a solid surface using protein supramolecules, which is named “Bio Nano Process” (BNP). We employed a cage-shaped protein, apoferritin as a spatially restricted chemical reaction chamber and biomineralized several kinds of nanoparticles (NP) in the apoferritin cavity. Among them are compound semiconductor NPs, CdSe, ZnSe, CdS. To synthesize these compound semiconductor NPs in the cavity, we designed the slow chemical synthesis system (SCRY) and the two step synthesis process (TSSP). Cd and Zn ions were stabilized by ammonia water and slow sown the chemical reaction speed outside apoferritin (SCRY). Se or S ions are added in the final step to let Cd or Z cation enter the cavity first (TSSP). The combination of the SCRY and TSSP works well and NPs can be synthesized with high efficiency. Making use of protein-protein and protein-solid surface interaction, a monolayer of 2D crystal of them can be made on the silicon wafer in self-assembly manner. Since the protein shell is vulnerable, heat-treatment or UV/ozone-treatment of the array produced a two-dimensional inorganic NP array on the silicon surface. The result demonstrated that inorganic nano-structure can be made by the combination of biomineralizaion, self-assembly and vulnerability of the protein. The inorganic nano-structure obtained by this process can be applied in a various field. We used the inorganic array, iron, cobalt and Indium oxide NP array for the fabrication of the floating nanodots memory. The fabricated floating gate memory functioned well and had the nice endurance and retention time. We also proposed another process using the obtained iron-oxide NP array as the nanometric etching mask. This was realized by the neutral beam etching and 7nm diameter Si nano crystalline columns with high aspect ratio were fabricated. Another effort to make a large biotemplate for single electron transistor (SET) produced a ball and spike type protein supramolecules which has a central cage-shaped protein and protruding spikes. This bio-template will be used to produce a SET by combining the biomineralization technique. These experimental results demonstrated that the BNP can fabricate the inorganic nanostructure using protein supramolecules and the BNP opens up a biological path to nanoelectronic devices.
3:00 PM - T2.2
Biomimetic Synthesis of Silica Nanoparticles
Tracy Davis 1 , Mark Snyder 1 , Michael Tsapatsis 1 Show Abstract
1 CEMS, University of MN, Minneapolis, Minnesota, United States
It is well recognized (1-5) that silica nanoparticles will form upon hydrolysis of tetraethylorthosilicate (TEOS) in basic solutions in the presence of tetrapropylammonium (TPA) and other alkylammonium cations upon exceeding the solubility limit of silica. We recently showed (6) that such silica nanoparticles, formed in the presence of TPA, participate in the growth of zeolites through an oriented aggregation mechanism. Prospects exist for formation and directed assembly of novel materials based upon the identification of such silica nanoparticles. In addition to the highly basic TPA-based pathways, biomimetic silica formation has also received significant attention (7-13). Such work has been driven, at least in part, by the goal to reveal the mechanisms by which hierarchical biosilica structures form and their extension to complex materials synthesis. While possible analogies between peptide mediated biosilica formation and alkylammonium cation templated zeolite crystallization have been acknowledged, the existence of nanoparticles in basic amino acid or peptide sols, similar to those in TPA silica sols, has not yet been reported.Here, we describe a method for room temperature synthesis of silica nanoparticles ranging in size from 4.5 nm to 8 nm in diameter in lysine-silica sols. The particles are characterized by cryogenic transmission electron microscopy and small angle X-ray scattering. Adjustment of silica and lysine concentrations within the sols enables fine control of the size and number density of the nanoparticles. While peptide-mediated biosilica formation is not a new concept in and of itself, the nanoparticles identified here serve as the smallest silica aggregates identified in these systems. Their existence and benign synthesis suggests that they may be of use as intermediate, high-purity reagents not only for films and gels, but also for novel, complex and biocompatible silica-based materials and nanocomposites. References 1. C.-H. Cheng, D. F. Shantz, J. Phys. Chem. B 109, 7266 (2005).2. J. Fedeyko, J. Rimer, R. Lobo, D. Vlachos, J. Phys. Chem. B 108, 12271 (2004).3. J. Fedeyko, D. Vlachos, R. Lobo, Langmuir 21, 5197 (2005).4. B. Schoeman, O. Regev, Zeolites 17, 447 (1996).5. S. Yang, A. Navrotsky, D. Wesolowski, J. Pople, Chem. Mater. 16, 210 (2004).6. T. M. Davis et al., Nat. Mater. 5, 400 (May, 2006).7. D. Belton, G. Paine, S. V. Patwardhan, C. C. Perry, J. Mater. Chem. 14, 2231 (2004).8. J. N. Cha, G. D. Stucky, D. E. Morse, T. J. Deming, Nature 403, 289 (2000).9. N. Kroger, R. Deutzmann, M. Sumper, Science 286, 1129 (1999).10. N. Kroger, S. Lorenz, E. Brunner, M. Sumper, Science 298, 584 (2002).11. M. Sumper, N. Kroger, J. Mater. Chem. 14, 2059 (2004).12. T. Yokoi et al., JACS 128, 13664 (2006).13. T. M. Davis, M. A. Snyder, J. E. Krohn, M. Tsapatsis, Chem. Mater. (2006, accepted).
3:15 PM - T2.3
Structure and Orientation of an Amelogenin on Hydroxyapatite
Wendy Shaw 1 , Susan Kreuger 2 , Ursula Perez-Salas 3 , Kim Ferris 1 , Barbara Tarasevich 1 Show Abstract
1 , Pacific Northwest National Labs, Richland, Washington, United States, 2 , NIST, Gaithersburg, Maryland, United States, 3 , Argonne National Lab, Argonne, Illinois, United States
Amelogenin consists of 90% of the protein present during the formation of the unusually long and highly ordered enamel crystals and is found to be critical in proper enamel development. Here we investigated an amelogenin, LRAP, to understand its structure and amino acids important in interacting with HAP. There is indirect evidence of a specific interaction between the C-terminus of amelogenin and the crystal lattice exists, but only recently have direct measurements been made to indicate how the protein is interacting with the inorganic crystal. Solid state NMR and neutron reflectivity are complementary techniques which can provide insight into the protein-crystal interface, under biologically relevant conditions. Using solid state NMR and NR, experimental data will be presented that demonstrate that the C-terminus of LRAP is close enough to the surface of HAP to influence the resulting crystal structure. The structure of the protein in the region has also been investigated. The experimental results are combined to develop a model of the LRAP-HAP interface, providing significant molecular level insight into enamel formation. This work was funded by the NIDCR institute of NIH. PNNL is operated by Battelle Memorial Institute for the U.S. Department of Energy.
3:30 PM - **T2.4
Reversibly Actuated Nanostructures
Joanna Aizenberg 1 , Tom Krupenkin 1 , Alexander Sidorenko 1 Show Abstract
1 , Lucent Technologies/Bell Laboratories, Murray Hill, New Jersey, United States
An important feature of biological/natural systems is their response to external stimuli with the subsequent change in structure or function. The ability to “engineer” adaptiveness into the next generation devices is becoming a key requirement and challenge in materials science and engineering. Here we describe new hybrid nano/micro-structures that mimic biological cilia. These structures are designed to reversibly change and dynamically control the surface geometry, rougness and interfacial chemistry. We demonstrate the application of these novel architectures as actuators that offer fast reversible formation of complex micropatterns.
4:00 PM - T2.5
Bio-Inspired Routes to Functional Metal Oxides
David Wright 1 , Sarah Sewell 1 , Leila Deravi 1 Show Abstract
1 Chemistry, Vanderbilt University, Nashville, Tennessee, United States
Unicellular plankton known as diatoms are able to produce ornate nanostructures of silica at ambient conditions. In contrast, current materials approaches require extremes of temperature and pH. Diatoms are able to biomineralize the silica using species specific peptides known as silaffins that possess lysine residues heavily post-translationally modified with polyamines. Herein, we report the use of amine-terminated dendrimers as mimetic templates for silica condensation. Further, the unique host-guest capabilities of the dendrimer may be used to create novel functional silica nanospheres with applications in supported heterogeneous catalysis, biocatalysts, and as biological probes. Additionally, these materials may be readily processed to create functional biomimetic surfaces.
4:15 PM - T2.6
An In Vitro Model System for Elucidating the Crystallochemical Mechanisms of Biomineralization.
Laurie Gower 1 Show Abstract
1 Materials Science & Engineering, University of Florida, Gainesville, Florida, United States
Biologically formed hard tissues, often referred to as biominerals, are hierarchical composite structures formed of mineral and organic matrix. The organic matrix, being composed of proteins and/or polysaccharides, often consists of an insoluble phase (such as collagen in bone, or chitin in mollusk shells), as well small quantities of water soluble acidic (i.e., polyanionic) proteins. The acidic macromolecules associated with biominerals have long been thought to regulate the formation of the biomineral crystals, as well as influence the final properties of the bioceramic composite if they become occluded within the mineral phase. Our in vitro studies have led us to propose that these acidic proteins may serve as process-directing agents, in which we have shown that mimetic polypeptides (e.g. polyaspartate) can induce liquid-liquid phase separation in the crystallizing medium, which transforms the traditional crystallization process into an amorphous precursor process. An important contribution of the polyanionic macromolecules is the level of hydration water that is integrated with the sequestered ions to generate the amorphous precursor, because this imparts fluidity to the precursor phase, which has important consequences with respect to molding and shaping crystals since the crystals retain the shape of the precursor phase once it has solidified and crystallized. By manipulating the precursor phase, non-equilibrium crystal morphologies can be generated which mimic many biomineral features, such as the deposition of thin mineral tablets and films, “extrusion” of crystal fibers, patterning and templating of thin mineral films, “molding” 3-D mineral structures, and intrafibrillar mineralization of collagen to mimic the interpenetrating nanostructure of bone. In light of recent studies that have shown a transient amorphous phase is present in many biominerals, there is a strong likelihood that this process plays a fundamental role in the morphogenesis of calcific biominerals. With respect to biomimetic engineering, we have been examining the crystallochemical mechanism involved in this polymer-induced liquid-precursor (PILP) process, to determine if there are general concepts related to this non-specific process which can ultimately be adapted to a variety of inorganic crystallization systems.
4:30 PM - T2.7
Artificial proteins having mineralization motifs
Kiyotaka Shiba 1 Show Abstract
1 , Cancer Institute, Tokyo Japan
The presence of peptide motifs that are related to biomineralization provides the synthetic biologist with the opportunity to fabricate novel proteins affecting mineralization processes. Here I describe our method that enables one to combine multiple peptide motifs to create functional proteins. With this method, we prepared a protein library from natural biomineralization motifs as well as artificial motifs (created by a peptide phage system). Characterization of the created proteins will be introduced.
4:45 PM - **T2.8
Viruses – dynamic, responsive nanostructures with materials applications
Trevor Douglas 1 2 , Mark Young 2 Show Abstract
1 Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States, 2 Center for BioInspired Nanomaterials, Montana State University, Bozeman, Montana, United States
Viruses have emerged as platforms for synthetic manipulation with a range of applications from materials to medicine. The use of viruses as synthetic templates utilizes the inherent properties that viruses have evolved. The essential nature of all viruses is to infect a host cell, replicate, package its nucleic acid, and exit the cell. In the process, viruses have evolved to move through a broad range of chemical environments. In their journey, viruses demonstrate a remarkable plasticity in their metastable structure and dynamics including coordinated assembly/disassembly and site-specific delivery of cargo molecules. These properties of viruses parallel the ideal properties of many synthetic materials. An appreciation of these properties has resulted in a paradigm shift from the study of viruses as disease causing agents to highly useful molecular assemblies, which can be chemically and genetically manipulated. This allows for synthetic manipulation to impart new function to protein cage architectures combining the best of evolution and truly intelligent design. Characterized viruses represent only a fraction of the predicted viral diversity present in the biosphere making this an exciting time for virology and their applications in materials science.
5:15 PM - T2.9
Interfaces Involving Biomolecules and Inorganic Materials: a Solid State NMR Approach.
Christian Bonhomme 1 , Cristina Coelho 1 , Thierry Azais 1 , Geoffrey Hartmeyer 1 , Florence Babonneau 1 , Akiyoshi Osaka 4 , Satoshi Hayakawa 4 , Bruno Alonso 2 , Michel Wong Chi Man 3 , Guilhem Arrachart 3 Show Abstract
1 , universite P et M Curie, Paris France, 4 , Okayama university, Okayama Japan, 2 , CRMHT CNRS, Orléans France, 3 , ENSCM, Montpellier France
The structural characterization of biological/inorganic interfaces is one of the most fascinating spectroscopic challenge in the frame of bio-inspired materials. Recent developments in high resolution solid state NMR offers new perspectives in terms of chemical bonding and spatial connectivities between the organic and inorganic components of a given material. 1H nuclei are a key structural probe, as protons are present at all interfaces and "tailor" them by establishing complex hydrogen bonded networks. We will present the latest 1H NMR experiments, including 1D (single quantum -SQ-, ultra fast MAS at very high fied) and 2D (double quantum, DQ) experiments, illuminating the structural features of ureidopyrimidinone silica based materials [1-2]. The DQ experiments allow to establish unambiguous connectivities between pairs of protons, allowing the precise description of H-bonded networks in the crystalline precursors, as well as in the corresponding structured materials. The 1H high resolution solid state NMR approach has been extented to the study of bio-inspired materials, involving SiO2 pillars and adenine/thymine complementary bases .Solid state NMR offers original approaches, based on the various interactions involved, such as the heteronuclear dipolar coupling (involving unlike spins) and J-coupling (establishing chemical bond connectivities). These new opportunities will be illustrated by the study of silicophosphate gels, which are excellent candidates for biocompatible materials. New NMR techniques have been implemented for that purpose, including original MAS-J-techniques . The study of substituted HAP materials will be also presented, including new insights obtained by 1H/13C/31P triple resonance dipolar-mediated experiments . J. J. E. Moreau, M. Wong Chi Man et al. Angew. Chem., 43, 203, 2004. G. Arrachart, PhD thesis, december 2005, University of Montpellier, France. (a) C. Coelho, C. Bonhomme et al. J. Sol-Gel Sc. Technol., 40, 181, 2006. (b) C. Lejeune, C. Bonhomme et al. Solid State NMR, 27, 242, 2005. (c) C. Coelho, C. Bonhomme et al. J. Magn. Reson., 179, 114, 2006.  (a) E. Fujii, A. Osaka, S. Hayakawa, F. Babonneau, C. Bonhomme et al. Acta Biomaterialia, 2, 69, 2006. (b) S. Hayakawa, A. Osaka, F. Babonneau, C. Bonhomme et al. Key Engin. Mater., 309, 503, 2006. (c) S. Hayakawa, A. Osaka, F. Babonneau, C. Bonhomme et al. J. Am. Ceram. Soc, accepted for publication.
5:30 PM - **T2.10
Geckel: Nanostructured Wet/Dry Adhesive Inspired by Gecko and Mussel.
Phillip Messersmith 1 2 , Haeshin Lee 1 Show Abstract
1 Biomedical Engineering, Northwestern University, Evanston, Illinois, United States, 2 Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States
Living organisms have evolved a variety of elegant strategies for adhering to surfaces, and several of these have inspired materials scientists in their quest for new high performance synthetic adhesives. Two classic models for bioadhesion include the gecko and the mussel. The gecko adheres to surfaces on a temporary basis through the use of specialized foot-hairs called setae, which are subdivided into terminal nano-sized contact pads (spatulae). Gecko adhesion is strong yet reversible, allowing the gecko to cling to vertical and even inverted surfaces. However, the gecko adhesive strategy works poorly under wet or high humidity conditions. In this talk we report dramatic enhancement of the wet performance of gecko mimetic adhesives through the use of mussel adhesive protein mimetic polymers. In contrast to geckos, mussels thrive under wet conditions through secretion of specialized adhesive proteins that mediate attachment to wet surfaces. The design, synthesis and characterization of a nanostructured temporary adhesive material that exploits both gecko and mussel adhesive strategies will be described. The hybrid ‘geckel’ adhesive adheres well to surfaces under both dry and wet conditions and can be removed and reattached over 1000 times with little decrease in performance. The ‘geckel’ adhesive should prove useful in medical, consumer, military and other applications where temporary adhesion under wet or dry/wet environments.