Detection of Aflatoxin B1 and ochratoxin a with a dual-function photoelectrochemical aptamer sensor based on BiOBr/Bi/BiOI hetero and Ag2S-sensitized signal amplification

Aflatoxin B 1 (AFB 1 ) and ochratoxin A (OTA) are highly toxic mycotoxins prevalent in food and feed, posing severe threats to human and animal health. This work presents an innovative photoelectrochemical aptamer sensor for the detection of AFB 1 and OTA, leveraging a ternary BiOBr/Bi/BiOI heterojunction and Ag 2 S quantum dot-mediated signal amplification. The BiOBr/Bi/BiOI composite was synthesized via a one-step hydrothermal reduction using l -ascorbic acid (AA), exhibiting a high specific surface area to enhance biorecognition efficiency. In situ-assembled Ag 2 S quantum dots amplified photocurrent responses, while a single aptamer probe enabled specific dual-target recognition. Under optimized conditions, the sensor achieved exceptional sensitivity: linear ranges of 0.001–100 ng·mL −1 for both mycotoxins, with detection limits of 4.34 fg·mL −1 (AFB 1 ) and 13.54 fg·mL −1 (OTA). Validation in complex food matrices confirmed high accuracy and robustness. This platform not only provides a reliable method for mycotoxin monitoring but also establishes a versatile design paradigm for multiplexed detection of food contaminants.