Nanoscale Investigation of Protein-Surface Interactions

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The interactions and molecular structures of peptides and proteins at interfaces play an important role in a wide range of biomedical applications (implanted biomaterials, diagnostic arrays, cell cultures, tissue engineering constructs, etc.). Here we propose the development of a complementary suite of surface bioanalytical and computational tools to provide information at the nanoscale about the structures and interactions of peptides and proteins with surfaces. Initially model leucine/lysine (LK) peptides with well- defined a-helix and b-sheet secondary structures will be used to develop this tool set. The surfaces investigated will range from alkanethiol functionalized nanoparticles to nanostructured substrates. The experimental techniques used in these studies will include solid state NMR, static time-of-flight secondary ion mass spectrometry, sum frequency generation, near edge x-ray absorption fine structure, surface plasmon resonance and x-ray photoelectrdn spectroscopy. To realize the full power of these experimental techniques, complementary computational approaches will be developed to theoretically analyze the adsorption behavior of these same systems using molecular dynamics simulations. Together these experimental and computational methods will provide a comprehensive understanding at the nanoscale of the secondary structure, molecular orientation and side chain/surface interactions of surface bound peptides, and the role of interfacial water in the peptide/surface interactions and structures. Then, these methods will be extended to the nanoscale characterization of a more complex biomolecule, Protein G. The information provided by this new tool set will elucidate the design principles for attaching peptides and proteins on surfaces in well-defined structures at the nanoscale, enabling molecular-level control of protein adsorption and immobilization. This will have wide spread impact in biological applications since controlling the conformation, orientation, etc.of surface immobilized peptides and proteins at the nanoscale will directly effect bioactivity and biocompatibility of biomedical devices. The attachment of proteins and peptides to the surface of nanoparticles is a promising strategy for the early detection and treatment of cancer. Similarly, the attachment of proteins and peptides to biomedical devices holds the promise for improving the function of those devices. The tools developed in this proposal will provide understanding and information needed to optimally attach protein and peptides to surfaces.