Development of an Enzyme-Based Photoluminescent Porous Silicon Detector for Chemical Warfare Agents

Photoluminescent (PL) porous silicon (PSi) has been modified for the attachment of biomolecules. Silicon wafers were etched by HF in CH(3)CH(2)OH and current to yield N-type PSi surfaces. A linker was constructed using hydrosilation reactions to give a direct Si-C bond on the surface. The other end of linker was designed so traditional protein cross-linking chemistry could be used to attach biomolecules. Dansyl cadaverine and Biotin-Streptavidin were attached to verify the utility of, and substantiate spectroscopically, the linking system. Glucuronidase was immobilized on the surface utilizing the linking system. The enzyme retained activity monitored through the conversion of p-nitro-phenyl-beta-D-glucuronide to p-nitro-phenol. The photoluminescence of the surface was retained, but varied upon enzymatic production of the p-nitro-phenol. Alteromonas sp. JD6.5 (OPAA-2) was also immobilized on the surface and exhibited sufficient enzymatic activity to transform p-nitro-phenyl-soman to p-nitro-phenol. The change in the photoluminescence of the surface was correlated to enzymatic activity producing the p-nitro-phenol hydrolysis product.