Electrochemistry-glucosemeter-smartphone integrated multi-mode biosensor for accurate detection of aflatoxin B1

Background: Aflatoxin B1 (AFB1) is a widely distributed toxic contaminant in food and poses a serious threat to public health. Therefore, an accurate, simple, cost-effective and on-site assay method is needed for sensitive detection of AFB1. Aptamer shows great potential in the construction of biosensor due to its high specificity and affinity. Multimodal biosensor based on aptamer is highly suitable for the analysis of AFB1 under complex conditions. And the detection results in different modes can be verified with each other, which greatly improves the accuracy of AFB1 detection. Results: Herein, accurate detection of AFB1 was achieved through the development of a multi-mode biosensor integrating electrochemistry, glucosemeter and smartphone-based colorimetric quantification. StreptavidinCu3(PO4)2 hybrid nanoflowers (SA-Cu3(PO4)2 HNFs) were synthesised and then conjugated with biotinylated invertase as a signal probe. The electrochemical signal was achieved via intrinsic redox activity. Simultaneously, sucrose could be converted to glucose by the action of invertase, which can cause changes in the glucosemeter signal as well as in the colour of urine glucose test strips. The glucosemeter could complete the signal response in 7 s, and the urine glucose test strips could complete the colour development in 30 s. The detection range of AFB1 by this system in electrochemical mode is 0.001-100 ng/mL, and in glucosemeter mode and smartphone mode is 0.01-50 ng/mL. The limits of detection were 0.49 pg/mL in electrochemistry mode, 5.4 pg/mL in glucosemeter mode and 3.7 pg/mL in smartphone mode. Significance: The successful construction of this multi-mode biosensor demonstrates the advantages of multi- functional nanomaterials and mobile technology. Rapid and accurate detection of AFB1 is achieved through the integration of electrochemistry, glucosemeter and smartphone-based colorimetric quantification. And this biosensor provides a novel detection platform that combines sensitivity, accuracy, affordability and portability for rapid on-site food safety screening.