Silica-Polypeptide Composite Particles

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TECHNICAL SUMMARY: Silica core-polypeptide shell composite particles will be synthesized with various core sizes, shell thicknesses and surface densities. This will permit the controlled investigation of thermal coil-to-helix transitions in a single organic solvent. Related transitions are known to destabilize cell membranes when influenza virus particles attack. It is hypothesized that when synthetic particles are mixed with other polymers, a conformational transition may be able to act as a phase stability switch to produce responsive materials. The nature of such phases will be explored by mixing rodlike polypeptides with the core-shell particles. The literature on mixtures of naturally occurring rods and spherical latex particles suggests that new, entropically driven phases may result; however, the size and functionality of the constituent rods and spheres has not been continuously variable as it will be in the proposed work. The core-shell particles can be prepared with a magnetic component, providing another means to initiate or destabilize new phases. NON-TECHNICAL SUMMARY: Particles having a glass-like core and a protein-like surface can be configured to capture, purify or deliver pharmaceuticals. Magnetic inclusions permit the particles to be manipulated simply, enhancing these functions. The particles form liquid crystals with light-diffracting properties that are of interest in the production of inexpensive blue lasers, which are essential for high-density data storage. A key factor here is increasing the uniformity of the crystal structure, which may be accomplished by a combination of magnetic and structural transitions. The particles can be used to emulate bio-mineralization, the process by which some sea animals make elegant nanostructures. This bio-inspired project stands near the confluence of fundamental and applied science, which is fertile ground for training young researchers. It poses challenging problems in synthesis, characterization and structure determination. The program will assist faculty and students at target colleges and universities with their research whenever possible; as a result, student interns will return to an interested local science coach who will be able to integrate the gains of an intense summer experience over at least one academic year of further research and coursework.