A label-free electrochemical impedance immunosensor for the sensitive detection of aflatoxin B1

Because of the potential health impact of aflatoxin B1 (AFB1), it is essential to monitor the level of this mycotoxin in a variety of foods and agricultural products. In this paper, a novel immunosensor for the rapid detection of AFB1 based on label-free electrochemical impedance spectroscopy (EIS) monitoring was achieved. The immunosensor was fabricated by stepwise immobilization of 1,6-hexanedithiol, colloidal Au, and aflatoxin B1–bovine serum albumin conjugate (AFB1–BSA) on a gold electrode via self-assembling technique. The interfacial properties of the modified electrodes were evaluated using the Fe(CN)63−/4− redox couple as a probe via cyclic voltammetry (CV) and EIS. An equivalent circuit model with a constant phase element was used to interpret the obtained impedance spectra. The impedance via the specific immuno-interaction at the sensor surface was utilized to detect AFB1 in samples. Under the optimized conditions, the impedance increment was linearly related to the AFB1 concentration in the range of 0.08 to 100 ng mL−1 with a detection limit of 0.05 ng mL−1 (S/N = 3) and a correlation coefficient of 0.9919.

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