Type-I heterojunction destruction by In situ formation of Bi₂S₃ for split-type photoelectrochemical aptasensor

Development of new strategies in photoelectrochemical (PEC) sensors is an important way to realize sensitive detection of biomolecule. In this study, mesoporous silica nanospheres (MSNs)-assisted split-type PEC aptasensor with in situ generation of Bi₂S₃ was proposed to achieve reliable detection of prostate-specific antigen (PSA). To be more specific, this bioresponsive release system will release large amounts of Na₂S by the reaction between PSA and aptamer that capped Na₂S-loading MSNs. Next, the Na₂S reacts with Bi to yield BiOI/BiOBr/Bi₂S₃ composite, which leads to an alteration in the electron-hole transfer pathway of the photoelectric material and a decrease in the response. As the PSA concentration increases, more Na₂S can be released and lower photocurrent is obtained. The linear range under the optimal experimental conditions is 10 pg·mL^-1-1 μg⋅mL^-1, and the detection limit is 1.23 pg⋅mL^-1, which has satisfactory stability and anti-interference.