Fabrication of a Versatile Aptasensing Chip for Aflatoxin B1 in Photothermal and Electrochemical Dual Modes

Abstract

The dual-mode sensing strategy not only has the inherent characteristics of each response mode but also can mutually verify the detection results obtained by different modes, which will effectively improve the accuracy and reliability of detection. The electrochemical-photothermal dual mode not only has two mode signals, but also has the advantages of fast response, high sensitivity, good selectivity, low cost, and simple operation. Efficient integration and accurate detection of pathogenic bacteria to achieve early warning of food safety is one of the most valuable antifouling methods. Here, we report an integrated design strategy to establish a photothermal and electrochemical dual modes for sensitive detection of aflatoxin B1 (AFB1). The aptasensor was fabricated by loading the Au@Fe3O4 onto the indium tin oxides (ITO) conductive glass modified AuNPs nano-layer (ITO/AuNPs) surface through DNA hybridization between aptamer and cDNA. After adding AFB1, aptamer tends to form aptamer-AFB1 complex, resulting in part of Au@Fe3O4 falling off the ITO/AuNPs surface and entering the reaction solution. 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2 system produces color change under the catalysis of Au@Fe3O4 and realizes the conversion of light and heat under the excitation of near-infrared light. Photothermal signal analysis is realized with the help of thermometer. In addition, combined with electrochemical impedance spectroscopy analysis with ITO/AuNPs electrode, a dual channel method is provided for AFB1 detection. Under the optimal conditions, the developed aptasensor realized sensitive and specific detection of AFB1 from 10 pg mL−1 to 300 ng mL−1 with low detection limit of 5 pg mL−1 in photothermal mode. Importantly, this work provided a promising prospect for the application of photothermal effect coupled with electrochemical aptasensor in food safety.