The goal of our research is to combine porous silicon and enzymes in order to build hybrid platforms for extremely selective chemical sensing applications. For this, a new synthetic route to covalently anchor bio-molecules on photo-luminescent porous silicon (PL PSi) while preserving the optical properties of the matrix was developed. The hydride terminated porous silicon surface was covalently functionalized with t-butyloxycarbonyl protected amine by light-assisted hydrosysilation. Protein cross-linker chemistry was then used to extend the linker and immobilize various enzymes. The glu-coronidase enzyme/p-nitro-phenyl-beta-glucoronide substrate test system provided a proof of concept for an enzyme-based porous silicon detector. The enzymatic activity and the luminescence of the porous silicon platform were both retained after the functionali-zation procedure and, charge transfer between the products of the enzymatic breakdown and the silicon quantum dots was demonstrated. The organophosphorous hydrolase enzyme OPAA was then immobilized and tested on p-nitrophenyl-soman, a surrogate substrate for soman. The production of the hydrolysis product, p-nitrophenol, correlated with the reversible luminescence quenching of the porous silicon matrix demonstrating the relevance of the enzyme-based platform for detection applications. This detection scheme, although indirect, takes advantage of the extreme specificity of enzymes. The approach is general and can be implemented for a series of target molecules.
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