A Highly Sensitive Electrochemical Immunosensor For Fumonisin B₁ Detection In Corn Using Single-walled Carbon Nanotubes/Chitosan

Fumonisins are naturally found as secondary metabolites of fusarium moniliforme, and frequently contaminate corn and corn products. Among them, fumonisin B1(FB1) is endowed with both acute and chronic aspects of toxicity and cause a broad variety of toxic effects in human and animals. Therefore, it is extremely demanded to develop a simple, sensitive, efficient and rapid method for the direct detection of FB1. In the present research, a sensitive electrochemical immunosensor was developed for detecting fumonisin B1(FB1) in corn using the single-walled carbon nanotubes/chitosan(SWNTs/CS). The FB1-BSA conjugate was firstly immobilized on a GCE covered with SWNTs/CS to obtain the electrochemical immunosensor. Second, FB1 antibody and FB1 standard solution were added onto the surface of the modified FB1-BSA electrochemical immunosensor to perform the competition assay. After the competition, the alkaline phosphatase(ALP) labeled anti-rabbit immunoglobulin G(IgG) secondary antibody(ALP-anti-antibody) was bound to the electrode surface. Lastly, electrochemical signal was produced through the catalytic hydrolysis between ALP and the substrate α-naphthyl phosphate(α-NP). This method could detect FB1 from 0.01 to 1000 ng mL-1 with a detection limit of 2 pg mL-1. This is well below the detection limit required from European Union legislation, 2-4 mg L-1. Moreover, good recovery(96.34-115.95%) was obtained for the detection of spiked corn samples, and the immunosensor was successfully applied to assay FB1 in naturally contaminated corn power. In consequence, the sensor with excellent sensitivity, specificity and reproducibility was achieved and it is market-oriented aiming to be adopted for fumonisin B1 detection in agricultural and food safety industry in the future.