A sandwich-type photoelectrochemical immunosensor based on ReS2 nanosheets for high-performance determination of carcinoembryonic antigen

Photoelectrochemical (PEC) sensing system has received much more attention as a powerful strategy for detecting trace substances. Herein, a sandwich-type PEC immunosensor constructed by two-dimension rhenium disulfite nanosheets (2D-ReS2) was developed for high-performance detection of carcinoembryonic antigen (CEA). 2D-ReS2 was facilely exfoliated from bulk crystals by ultrasonication in a mixture of 1,3-di-(3-mercaptopropyl)-imidazolium bromide (DMimBr) ionic liquid and alcohol. Then, ReS2 nanosheets were modified onto a glassy carbon electrode surface to construct an interface for fabricating a sandwich-type PEC immunosensing platform which has been accomplished by successive immobilizing anti-CEA antibody (Ab1), binding CEA and capturing the alkaline phosphatase labeled CEA antibody (ALP-Ab2). The introduced alkaline phosphatase can efficiently catalyze vitamin C magnesium phosphate to afford ascorbic acid (AA). Ascorbic acid can serve as an electron donor to capture holes photogenerated from ReS2 nanosheets to produce photocurrent signal for CEA detection. The PEC immunosensor shows superior stability, selectivity, sensitivity, and accuracy for CEA determination. An extremely low detection limit of 0.468 pg mL(-1) with a broad linear range of 0.0005 similar to 10.0 ng mL(-1) can be obtained for CEA determination. The PEC immunosensor can be applied for determining CEA in human serum samples with good selectivity and accuracy, demonstrating promising potential in biomedical analysis.