A Study Of Electrochemical Immunosensor For Highly Sensitive Detection Of Aflatoxin Using Single-walled Cqrbon Nanotubes/Chitosan

Aflatoxins are naturally found as secondary metabolites of Aspergillusparasiticus and Aspergillus flavus, and frequently contaminate food andfeed. Aflatoxin B1(AFB1) is the most prevalent form, with a high pollutionlevel, and is deemed as signal of aflatoxin contamination in food detection.Additionally, AFB1is characterized by high stability, strong toxicity andcarcinogenicity. In the present research, an indirect competitiveelectrochemical immunosensor based on single-walled carbonnanotubes/chitosan was developed for sensitive determination of aflatoxinB1(AFB1).The sensing substrate was preared using a carbon electrodemodified with a self-assembled single-walled carbon nanotubes/chitosan.The immunosensor was based on an indirect competitive binding to a fixedamount of anti-AFB1between free AFB1and AFB1-bovine serum albumin,which conjugate immobilized on covalently functionalizednanotubes/chitosan laid on the glass carbon electrode. Then, the anti-mouse immunoglobulin G secondary antibody labeled with alkaline phosphatasewas bound to the electrode surface through reacting with primary antibody.Finally, alkaline phosphatase catalyzes the hydrolysis of the substrateα-naphthyl phosphate, which produced electrochemical signal. Comparedwith conventional methods, the established immunosensor was moresensitive and simple. Under optimal conditions, the electrochemicalimmunosensor could quantitatively detect AFB1from0.01to100ng mL-1with a detection limit of3.5pg mL-1. Moreover, the immunosensor wassuccessfully applied to assay AFB1in corn powder, which showed goodcorrelation with the results obtained fromHigh performance liquidchromatography (HPLC), the relative errors were in the rage from-4.4%to8.4%.