| AVS 61st International Symposium & Exhibition | |
| Biomaterial Interfaces | Wednesday Sessions |
| Session BI+AS-WeM |
| Session: | Nonlinear Optical & Vibrational Spectroscopy |
| Presenter: | Tobias Weidner, Max-Planck-Institute for Polymer Research, Germany |
| Authors: | H. Lutz, Max-Planck-Institute for Polymer Research, Germany J.E. Baio, Oregon State University V. Jaeger, University of Washington A. Roehrig, University of Washington G. Drobny, University of Washington J. Pfaendtner, University of Washington T. Weidner, Max-Planck-Institute for Polymer Research, Germany |
| Correspondent: | Click to Email |
Specialized mineral proteins control the growth of biogenic hard tissue. Using specific recognition motifs, proteins bind and release mineral facets and grow the intricate mineral morphologies found in Nature. Particularly fascinating examples of biomineralization are the high fidelity silica nanostructures in the shells of diatoms. Within the unicellular algae Cylindrotheca fusiformis, proteins called silaffin play a crucial role in the molecular biomineralization machinery. In order to harness the concepts used by Nature to efficiently fabricate mineral nanostructures we aim to understand the underlying protein–silica interactions. We found that artificial peptides consisting of lysine and leucine (LK peptides) can mimic silaffin’s capability of forming various biosilica nanostructures. These peptides were designed to adopt helical or beta-sheet structures due to their hydrophobic periodicities and represent simple model systems to study the effect of protein folding on mineralization. Using surface sensitive sum frequency generation (SFG) vibrational spectroscopy we have studied the interactions of LK peptides with biosilica surfaces and within biosilica composites. We monitored how different LK peptides fold at the silica- water interface and we found that interfacial folding is crucial for the silica morphology: spheres, rods and flakes were produced by LKs – depending on their surface folding. Side chains also actively participate in the mineralization process. We probed the side chain structure of LKs in contact with silicic acid solution and observed increased ordering of charged lysine side chains during the formation of biosilica, indicating their involvement in silica nucleation. Combined with cryo-TEM measurements and MD simulations of different stages of nanoparticle nucleation the SFG studies provide important details of peptide-driven silica formation.