From Nature to Engineering: Biotechnology, Biomimetics and Bio-Inspiration Opens Novel Routes to Metal Oxide Semiconductors

Featuring David Kisailus, Ph.D.
Assistant Professor, Chemical and Environmental Engineering
Bourns College of Engineering
UC Riverside

Host: Professor Martha Mecartney, Chemical Engineering and Materials Science, UC Irvine

Location:  ICS 174
Refreshments to follow

Abstract:
Working with silica needles produced by marine sponges, we discovered that the proteins named “silicateins” catalyze and structurally direct the hydrolysis and polycondensation of silica, titania, gallia and zinc oxide from alkoxide precursors at neutral pH and low temperature. The silicateins are true enzymes, closely related to a well-known family of hydrolases. These are the first reported examples of enzyme-catalyzed, nanostructure-directed synthesis of these materials – and the first such syntheses at low temperature and neutral pH. Interaction with the template-like protein surface is capable of stabilizing polymorphs of these materials that otherwise are not normally observed at low temperatures. A preferential alignment of the resulting nanocrystallites of gallia to the protein was recognized, suggesting an epitaxial-like relationship similar to that of GaN on sapphire systems. Biomimicry is currently being used to catalyze and template the growth of various metal oxides. We are incorporating analogs of the critical amino acid residues found in silicatein’s catalytic active site, anchoring these functional groups (via self-assembled monolayers on gold) adjacent to one another to facilitate catalytic activity by the same mechanism exhibited by the enzyme. Results have shown that biomimetics of the active site in silicatein are capable of producing silica and metal oxides from alkoxide precursors at neutral pH.

About the Speaker:
David Kisailus joined the Department of Chemical and Environmental Engineering at the University of California, Riverside in 2007. He has investigated the synthesis and self-assembly of nanoscaled materials from bio-inspired and bio-mimetic platforms. His recent research at HRL Laboratories included conceiving synthetic strategies for the Hydrogen Fuel Cell Program. Prior to HRL, Professor Kisailus was a post-doctoral researcher at UC Santa Barbara, where he investigated biological pathways to novel materials and extended this to bio-mimetic and inspired systems. He received his Ph.D. from the Department of Materials at the University of California, Santa Barbara in 2002, where he developed novel solution routes to epitaxial thin films and nanocrystals of GaN. He received his M.S. degree from the Department of Materials Science and Engineering from the University of Florida in 2000, where he synthesized ceramic colloids and investigated densification behavior of glass-ceramic composites.