A dual-modal biosensor coupling cooperative catalysis strategy for sensitive detection of AFB in agri-products.

Herein, the cooperative catalysis effect between nanocomposite (AgPd NPs/POD-M/PEI-rGO) and horseradish peroxidase (HRP) was applied for the fast and sensitive detection of aflatoxin B1 (AFB). Upon specific and competitive binding of HRP@DNA and AFB to cDNA, the working electrode presented different catalytic capacities for supporting electrolytes (TMB and HO). In the redox mechanism of TMB and HO, HRP and nanocomposite effectively catalyzed the oxidization of TMB to form the one-electron oxidation intermediate TMB+, and contributed the electrical signals and absorbance signals. Electrochemistry and colorimetric analyses were successfully realized for AFB detection with 0.2 pg/mL and 8 pg/mL of detection limits, respectively, which is much lower than that of traditional HPLC methods. Overall, this method had significant reliability and sensitivity, offering a promising potential for conveniently evaluating the quality of agri-products polluted with AFB. Moreover, this approach provides a new idea for fast and accurate detection of mycotoxin.