Light-addressable electrochemical immunoassay for multiplexed detection of antigen

Abstract

Multi-channel evaluation on a single sensor interface is highly valuable but full of challenge. Herein, a universal light-addressable electrochemical immunoassay based on silicon photoelectrodes was proposed for spatially-resolved detection of prostate-specific antigen (PSA) as a model target. To stabilize and functionalize silicon substrate, a simple and robust antifouling coating was prepared by cross-linking bovine serum albumin (BSA) matrix with glutaraldehyde (GA). For the PSA detection, an electrochemical sandwich-type immunosensor was performed on the basis of BSA@GA functionalized silicon, in which horse radish peroxidase (HRP) was used to catalyze the reaction of H2O2 and hydroquinone (HQ), resulting in in situ generation of benzoquinone (BQ). The light-induced local reduction photocurrent of BQ was then recorded as the sensor response by irradiating the target spot of photoelectrode respectively with a moveable light pointer. The results demonstrated the feasibility of localized measurements of enzymatic reactions. Coupling with light-addressable electrochemistry (LAE) and enzyme-linked immunosorbent assay (ELISA) protocol, multiplexed PSA detection could be achieved on a single sensor chip with good sensitivity and specificity. This proof-of-concept study provides a promising platform for high-throughput and accurate immunoanalysis in diagnostic or biodefense applications.