Regular articleDisposable amperometric immunosensor for simple and sensitive determination of aflatoxin B1 in wheat

- The microelectrodes fabricated in batch by MEMS are economic and disposable.
- The preparation of immunosensor is simple, controllable and non-toxic.
- Fast response and high sensitivity towards AFB1 is obtained by the immunosensor.

A disposable and label-free electrochemical immunosensor was developed for aflatoxin B1 (AFB1) determination in wheat based on immobilization of anti-AFB1 antibodies on the chitosan-gold nanoparticles (chitosan-AuNPs) modified gold microelectrode. The chitosan-AuNPs nanocomposite formed by one-step electrodeposition using chronoamperometry not only exhibited improved conductivity but also offered porous three-dimensional morphology, plentiful amine groups and good biocompatibility for antibody immobilization via covalent binding. To evaluate the effect of electrodeposition conditions on the surface structure and amperometric response of the chitosan-AuNPs modified microelectrode, both scanning electron microscope (SEM), cyclic voltammetry (CV) and energy dispersive spectroscopy (EDS) were studied under the different parameters of deposition potential and time. The morphology and electrochemical characterizations of the immunosensor were also investigated by atomic force microscopy (AFM) and CV. The developed immunosensor demonstrated good linearity between highly sensitive current response and AFB1 concentration in two ranges of 0.2-2 ng mL−1 and 2-30 ng mL−1, with a detection limit of 0.12 ng mL−1 (S/N = 3). For assay of AFB1 in wheat matrix, the linear range from 1.6 to 32 ng mL−1 was obtained considering the extraction of the sample.