The development, characterization, and application of a biomimetic method of enzyme immobilization

Abstract

This dissertation describes the characterization of layer-by-layer silica and titania coatings deposited using a protamine-induced method. It was found that silica coatings were thinner and more porous than titania coatings. These coatings were functionalized by immobilizing modified Glucose oxidase during the layer-by-layer buildup. The enzyme was found to retain higher activity in silica versus titania, with full retention of activity observed in one configuration. Immobilization in both materials resulted in enhanced thermal stability and proteolytic protection. The enzyme-functionalized coatings were then modified by the immobilization of silver nanoparticles to the exterior, and this biological/inorganic composite was tested for its antimicrobial activity against E. coli and S. aureus. Against E. coli the composite worked in a synergistic fashion, showing more potent antimicrobial activity when compared to either agent used alone. The enzyme modification method was then extended to Laccase, which was immobilized to carbon nanotubes and characterized as a biocathode. Modified laccase returned a nearly two-fold higher current density versus the native enzyme. Finally, synthetic peptides were tested for their ability to adsorb to silica and titanium-oxide surfaces and subsequently deposit titanium-oxide coatings, in an effort to better understand the structure-function relationships of mineralizing peptides.