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

Abstract

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)₆^3−/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.