A competitive, reusable, reliable and sensitive immunosensor based on electrochemical quartz crystal microbalance (EQCM) was developed for the detection of aflatoxin B1 (AFB1). The sensing platform was developed using a primary monoclonal anti-aflatoxin antibody (anti AFB1) covalently immobilized on a monolayer of 4-amino thiophenol self assembled on a gold coated quartz crystal electrode (anti AFB1/4-ATP/Au). The reusability was achieved by a sandwiched system using secondary rabbit-immunoglobulin antibodies (r-IgGs) tagged with core shell of gold coated iron oxide nanoparticles (r-IgG-Au-Fe3O4), which can be used to regenerate the bioelectrode. A competitive mode was employed, between free and coated AFB1 for fixed concentration of nanoparticle conjugate (r-IgG-Au-Fe3O4). After the competitive interaction, immunoelectrode was washed with phosphate saline buffer (PBS) at pH 7.4 and examined by electrochemical quartz crystal microbalance-cyclic voltammetry (EQCM-CV). Under the optimized conditions, the fabricated immunosensor can be used to detect AFB1 quantitatively with a linear range of 0.05 to 5ngmL-1. For reliability, the fabricated immuno sensor was tested using cereal samples spiked with different concentrations of AFB1. In addition, this immuno electrode displays good reproducibility, and storage stability. The above immunosensor was regenerated with negligible loss in activity through removal of the r-IgG-Au-Fe3O4 conjugate using a strong magnet. It is shown that theAFB1/BSA/aAFB1/4-ATP/Au immuno sensor is a new approach for developing sensitive reliable and reusable electrochemical piezoelectric immunosensors.
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