A new amplified π-shape electrochemical aptasensor for ultrasensitive detection of aflatoxin B1

There is a prompt need for determination of aflatoxin B1 (AFB1) in food products to avoid distribution and consumption of contaminated food products. In this study, an accurate electrochemical sensing strategy was presented for detection of AFB1 based on aptamer (Apt)-complementary strands of aptamer (CSs) complex which forms a π-shape structure on the surface of electrode and exonuclease I (Exo I). The presence of π-shape structure as a double-layer physical barrier allowed detection of AFB1 with high sensitivity. In the absence of AFB1, the π-shape structure remained intact, so only a weak peak current was recorded. Upon the addition of AFB1, the π-shape structure was disassembled and a strong current was recorded following the addition of Exo I. Under optimal conditions, the electrochemical signals enhanced as AFB1 concentrations increased with a dynamic range of 7-500 pg/mL and a limit of detection (LOD) of 2 pg/mL. The developed aptasensor was also used to analyze AFB1 spiked human serum and grape juice samples and the recoveries were 95.4-108.1%.