A photoelectrochemical aptasensor based on p-n heterojunction CdS-Cu2O nanorod arrays with enhanced photocurrent for the detection of prostate-specific antigen.

A sensitive photoelectrochemical (PEC) aptasensor was constructed for prostate-specific antigen (PSA) detection using an enhanced photocurrent response strategy. The p-n heterostructure CdS-Cu2O nanorod arrays were prepared on Ti mesh (CdS-Cu2O NAs/TM) by a simple hydrothermal method and successive ionic-layer adsorption reactions. Compared with the original CdS/TM, the synergistic effect of p-n type CdS-Cu2O NAs/TM and the internal electric field realizes the effective separation of photoinduced electron-hole pairs and improves the PEC performance. In order to construct the aptasensor, an amino-modified aptamer was immobilized on CdS-Cu2O NAs/TM to serve as a recognition unit for PSA. After the introduction of PSA, PSA was specifically captured by the aptamer on the PEC aptasensor, which can be oxidized by photogenerated holes to prevent electron-hole recombination and increase photocurrent. Under optimal conditions, the constructed PEC aptasensor has a linear range of 0.1-100 ng·mL-1 and a detection limit as low as 0.026 ng·mL-1. The results of aptasensor detection of human serum indicate that it has broad application prospects in biosensors and photoelectrochemical analysis.