Ratiometric electrochemical aptasensor for AFB1 detection in peanut and peanut products

Aflatoxin B1 (AFB1) is a potent natural toxin and carcinogen. Accurate and sensitive determination of AFB1 in food is of great interest. In this work, a ratiometric electrochemical aptasensor for the detection of AFB1 in peanut and its products was constructed. This aptasensor was fabricated by immobilizing Fc-labeled com-plementary DNA on Thi-rGO/CS/aptamer modified electrode surface through biorecognition between the ap-tamer and complementary DNAs. In the presence of AFB1, the aptamer preferred to form an aptamer-AFB1 complex, resulting in the separation of aptamer and complementary DNA. With the addition of more AFB1, the amount of Fc present on the electrode surface reduced and Thi as the reference signal remained approximately constant. Consequently, this ratiometric electrochemical aptasenor for AFB1 detection was achieved by using the current intensity ratio (IThi/IFc) as signal transducer. Under the optimal conditions, the proposed method exhibits a good linear relationship between IThi/IFc and the concentration of AFB1 ranging from 0.001 ng/mL to 1000 ng/ mL and a low detection limit of 0.33 pg/mL. The proposed ratiometric electrochemical aptasensor for AFB1 detection shows satisfactory selectivity, stability and reproducibility, and is successfully applied for the de-termination of AFB1 detection in peanuts, peanut butter, and peanut oil samples.