Biosensor Based on Cysteine Monolayer and Monoclonal Antibody for Specific Detection of Aflatoxin B₁in Rice

Abstract

An electrochemical immunosensor for detection of aflatoxin B 1 (AFB 1 ) in food samples was developed. The sensor is composed by cysteine monolayer immobilized on gold electrode surface with subsequent bind to monoclonal antibody (MAb-Cys-modified electrode). The AFB 1 detection was evaluated by cyclic voltammetry and impedance spectroscopy in the frequency range of 100 mHz-100 kHz. Samples of rice were spiked with AFB 1 to evaluate the sensitivity of the sensor. Impedance spectra could be fitted to a Randles equivalent circuit containing a constant phase element. Atomic force microscope (AFM) images showed MAb-AFB 1 complex immobilized across the electrode surface. The electron transfer resistance (R ct ) increase was attributed to a decrease in the charge permeability of the MAb-AFB 1 -Au surface to a redox probe . The surface coverage exhibited a linear relationship as function of toxin concentration and is found to be 0.75 at 30 µg mL −1 . The obtained sensor is a promising candidate for detection of AFB 1 in rice with sensitivity and specificity.

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