A pipette-smartphone portable on-site detection system for aflatoxin B1 detection in bread and peanut based on "Four-in-one" sea-urchin-like composite catalyst

The development of a low-cost, high-sensitivity, portable bioassay for detecting the highly toxic and thermally stable aflatoxin B1 (AFB1) is of significant importance to food safety and human health. A pipette–smartphone integrated biosensor based on a super “four-in-one” DNA sea-urchin-like composite catalyst (FSCC) was constructed for the efficient analysis of AFB1. Detection is possible via a self-made poly(methyl methacrylate) pipette, combined with a smartphone to further increase the biosensor’s portability. The combination of the two greatly simplifies experimental operations, reduces testing costs, and can minimize matrix interferences through sample pre-treatment operations. And the smartphone-APP signal readout strategy can avoid the need for a reading instrument, making it more suitable for field testing. The FSCC was developed by fully utilizing the properties of a Fe-Zr-metal–organic framework (Fe-Zr-MOF), which exhibits high catalytic activity and enables the encapsulation of abundant horseradish peroxidase in its pores, the in-situ reduction and enrichment of Pt nanoparticles on its surface, and the coordination of biotinylated DNA to achieve a high adsorption capacity of streptavidin-horseradish peroxidase. This ensured detection sensitivity, with a limit of detection = 1.57 pg/mL. The developed biosensor displays notable application potential, especially in resource-poor areas due to the advantages of low costs, simple operation, ultra-high sensitivity, portability, etc.