An enzyme linked aptamer photoelectrochemical biosensor for Tau-381 protein using AuNPs/MoSe

Alzheimer's disease is a worldwide health problem and it has attracted extensive attention. Tau protein is an important biomarker in the pathogenesis of Alzheimer's disease. Herein, we devise a in situ enzyme catalysis generating electron donor photoelectrochemical (PEC) biosensor for Tau-381 protein. Tau-381 protein aptamer is immobilized onto the surface of AuNPs/MoSe2 nanosheets modified electrode. In the presence of Tau-381 protein, an aptamer-protein duplex is formed. Meanwhile, the Tau-381 antibody and the protein G/AP (protein G labeled with alkaline phosphatase) are captured with the affinity interaction between Tau-381 protein and Tau-381 antibody, Tau-381 antibody and protein G/AP. The electron donor, ascorbic acid, is in situ produced by the catalyzing of ascorbic acid 2-phosphate in the PEC detection solution. As a result, low blank noise and strong photocurrent response are engendered. The photocurrent response is related to the concentration of Tau-381 protein. The detection range of Tau-381 protein is from 0.5 fM to 1.0 nM with detection limit of 0.3 fM. This in situ generating electron donor PEC biosensor can detect various targets by simply alternating antibody, antigen, or aptamer commercially. Thus, this work represents a simple and general sensing protocol.