A competitive-type photoelectrochemical immunosensor for aflatoxin B1 detection based on flower-like WO3 as matrix and Ag2S-enhanced BiVO4 for signal amplification

A competitive photoelectrochemical (PEC) immunosensor was successfully utilized for quantitative detection of aflatoxin B1 (AFB1). The flower-like tungsten oxide (WO3) hierarchical architectures with large specific surface areas and porous nanostructure was prepared as a matrix material for immobilizing of BSA-AFB1. The Ag ions-modified bismuth vanadate nano-polyhedron (BiVO4@Ag+) was utilized as labels for immobilization anti-AFB1 through affinity specific binding. The Ag2S was prepared in-situ growth by immediately deposition the S2− onto the BiVO4@Ag+. The high photocurrent intensity was generated by the obtained BiVO4@Ag2S under visible-light irradiation. Moreover, excellent sensitivity was achieved by using the WO3 as the matrix and BiVO4@Ag2S as labels to enhance photocurrent response and improve the photocurrent conversion efficiency. Under optimal conditions, the competitive PEC immunosensor showed wide linear range from 1.0 pg mL−1 to 120 ng mL−1 with limit detection of 0.28 pg mL−1 for AFB1. The biosensor was performed with good reproducibility, acceptable stability, and high specificity, which indicated potential application in the detection of other toxic small molecules.