In Situ Modification of a Semiconductor Surface by an Enzymatic Process: A General Strategy for Photoelectrochemical Bioanalysis

Usually, the photoelectrochemical (PEC) bioanalysis necessitates ready photoactive materials as signal sources to convert the specific biological events into electrical signals. Herein, the first PEC bioanalysis without the necessity of ready visible-light-active species was demonstrated. We use an enzyme catalytic process to couple with the unique surface chemistry of semiconductive nanocrystalline, whereby its electronic properties could be modified spontaneously during the enzymatic reaction. Specifically, the enzymatic hydrolysis of ascorbic acid 2-phosphate by alkaline phosphatase is allowed to interact on the TiO2 nanoparticles (NPs) matrix. PEC tests reveal that the self-coordination of the biocatalyzed enediol-ligands onto the undercoordinated surface defect sites would in situ form a ligand-to-metal charge transfer (CT) complex, endowing the inert semiconductor with strong absorption bands in the visible region, and hence underlying a novel and general PEC bioanalysis strategy.