A novel Z-scheme ZnIn2S4/WO3 photocatalyst based photoelectrochemical immunosensor for the sensitive detection of prostate specific antigen

A novel three-dimensional (3D) ZnIn2S4/WO3 (ZIS/WO3) photocatalyst is prepared via a simple hydrothermal method and used as photoanode material in constructing photoelectrochemical (PEC) immunosensor of prostate specific antigen (PSA). The photocatalyst presents high activity, and its photocurrent intensity is up to 23 and 7 times of WO3 and ZnIn2S4 (ZIS) respectively, under 430 nm light illumination. The improved PEC behavior is due to the sensitization and 3D structure of ZIS and the formation of Z-scheme heterojunction between ZIS and WO3, which greatly enhance light harvesting, promote the spatial separation of interfacial charges and prolong the lifetime of photogenerated electrons. At the same time, the high oxidation capacity of valence band holes of WO3 is retained. A label-free PEC immunosensor is fabricated by using the photocatalyst, and it shows good performance for PSA detection. The linear response range is 0.01-500 ng/mL, and the detection limit is low to 5 pg/mL. Moreover, the PEC immunosensor afforded high stability, specificity and reproducibility. Therefore, it possesses great application potential in biological/clinical analysis.