Bi2S3/BiOCl heterojunction-based photoelectrochemical aptasensor for ultrasensitive assay of fumonisin B1 via signal amplification with in situ grown Ag2S quantum dots.

Fumonisin B1 (FB1) is a mycotoxin mainly found in corn, peanuts, and wheat crops, which affects human health. Based on bismuth sulfide/bismuth oxychloride (Bi2S3/BiOCl) composite material, silver sulfide (Ag2S) was grown in situ as a quantum dot sensitization signal, and a photoelectrochemical (PEC) aptasensor was designed by layer upon layer modification to detect FB1. Bi2S3/BiOCl has a wide range of visible light absorption, stable chemical properties, and a simple synthesis method. In the construction process, L-ascorbic acid (AA) is selected to provide electrons and inhibit photogenerated electron-hole (e-/h+) recombination. Under the optimal experimental conditions, the detection range of the fabricated PEC aptasensor was 0.001 ~ 100 ng/mL, and the detection limit was 0.016 pg/mL. The prepared PEC aptasensor has high sensitivity, stability, and reproducibility. The combination of aptamer and PEC sensor provides a novel method for the application of PEC sensor in mycotoxin detection.