Summary: Biotechnology Provides a New Route to Semiconductors
Sumerel, Kisailus, Weaver and Morse, 2003
Harnessing the genes and proteins that control the nanofabrication of the intricate fiberglass
constructions made by sponges made it possible in our earlier MRL-supported research to
control the structures and optoelectronic properties of silicon-based polymers and materials.
Now, based on those results, a biotechnological approach to metal oxide semiconductor
nanofabrication is being developed.
Gene cloning and genetic engineering, in conjunction with materials synthesis and
characterization enabled us to identify the proteins, genes and molecular mechanisms governing
the synthesis of silica at neutral pH and low temperature. Recently we discovered that
"silicatein", the enzyme we found responsible for this synthesis, could be harnessed to produce
nanostructure-controlled titanium dioxide and other metal oxide semiconductors from solution
precursors at low temperature. This represent the first discovery of enzyme-catalyzed,
nanostructure-directed synthesis of semiconductors. Most remarkably, we found, the enzyme
directs the nanoscale assembly of these materials with some control over their atomic alignment.
The surface of the proteins filaments actually guides the assembly of the atoms of titanium and
oxygen! The result is a partial alignment of the nanocrystallites of the semiconductor on the
protein surface. We now are working to characterize, harness and further enhance this
Figure caption: Silicatein catalyzes and structurally directs the growth of titanium