Polydopamine-coated HKUST MOFs-based strip lateral flow immunoassay for on-site ultrasensitive detection of aflatoxin B1 in foods

Owing to the high residue in foods and severe carcinogenic and teratogenic effects to human health of aflatoxin B1 (AFB1), it is vital to develop a reliable method for sensitive detection of AFB1. In this work, the polydopamine-coated Cu-based metal-organic framework (HKUST@PDA) as a signal amplification marker was introduced to develop a strip lateral flow immunoassay (SLFIA) for on-site detection of AFB1 in food samples. The HKUST@PDA was prepared by simple oxidative self-polymerization of dopamine on the surface of the HKUST. HKUST@PDA with excellent hydrophilicity and biocompatibility allowed rapid labeling of anti-AFB1 monoclonal antibodies (mAbs) by simple physical adsorption. Under optimal conditions, HKUST@PDA-mAbs probes-based SLFIA could realize the qualitative visualization and sensitive quantitative detection by using a portable test strip reader. The detection limit for AFB1 was as low as 0.01 ng/mL with a wide concentration range of 0.05–2 ng/mL. Practical application in Maize and Lotus seed samples indicated satisfactory recoveries of 80.3–104.6%. The effectiveness and accuracy of the new SLFIA method were verified with a validated UFLC-MS/MS technique. The preparation process of HKUST@PDA-mAbs-based SLFIA was easy to operate with significantly improved sensitivity and stability, and could be widely used in the rapid and accurate detection of mycotoxins and other toxic hazards in foods.