Incorporation of ZnIn2S4 semiconductors with S-vacancy engineered MoS2 nanosheets to develop sensitive photoelectrochemical aptasensor for aflatoxin B1 detection

Aflatoxin B1 (AFB1) has been categorized as group I potent carcinogen to human. Therefore, sensitive detection of AFB1 is of great significance for food safety. Here, a sensitive photoelectrochemical (PEC) aptasensor for AFB1 detection has been developed based on the incorporation of ZnIn2S4 semiconductors with S-vacancy engineered MoS2 (V-MoS2) nanosheets. V-MoS2 nanosheets were obtained by a mild H2O2-mediated chemical etching strategy with varying etching time. ZnIn2S4/V-MoS2 nanocomposites were prepared by a solvothermal method using V-MoS2 as one of the starting materials. Research demonstrated that the incorporation of ZnIn2S4 semiconductors with V-MoS2 could produce ZnIn2S4/V-MoS2 nanocomposites having a broader light absorption range and narrower energy bandgap, which help to generate a larger and highly stable PEC responses. The photocurrent intensity was 3.2 and 5.6 times greater than ZnIn2S4/MoS2 and ZnIn2S4, respectively. Based on the top performing ZnIn2S4/V-MoS2 nanocomposites and the specific aptamer, a PEC aptasensor was successfully constructed for AFB1 detection with a wide linear range of 0.05-50 ng/mL and a low detection limit of 17 pg/mL (S/N=3). The significance of this work lied not only in representing substantive progress in food safety monitoring, but also in promoting the design of more efficient ZnIn2S4 or V-MoS2-related heterostructures for PEC sensors.