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

There is a prompt need for determination of aflatoxin B (AFB) 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 AFB 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 AFB with high sensitivity. In the absence of AFB, the π-shape structure remained intact, so only a weak peak current was recorded. Upon the addition of AFB, 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 AFB concentrations increased with a dynamic range of 7-500pg/mL and a limit of detection (LOD) of 2pg/mL. The developed aptasensor was also used to analyze AFB spiked human serum and grape juice samples and the recoveries were 95.4-108.1%.