Ultrasensitive Lateral Flow Immunoassay for Aflatoxin B1 Detection via Magnetic Enrichment-Catalytic Signal Amplification

Aflatoxin B1 (AFB1) is one of the most toxic fungal secondary metabolites. High-sensitivity and rapid detection of AFB1 is crucial for safeguarding consumer health, reducing post-harvest food losses, and promoting agricultural trade. Here, we developed a magnetic enrichment–catalytic lateral flow immunochromatographic assay (E-C-LFIA) for quantitative AFB1 detection. The approach couples immunomagnetic capture and enrichment with carboxylated magnetite (Fe3O4) nanozyme probes and post-assay peroxidase-like catalysis of the H2O2–TMB system to enhance colorimetric readout. Compared with conventional LFIA performed without magnetic enrichment or catalytic amplification, E-C-LFIA achieved a visual detection limit of 0.05 μg/L for AFB1, corresponding to a 20-fold improvement in sensitivity. The quantitative limit of detection (LOD, 3σ) was 0.023 μg/L, representing a 14.8-fold improvement in sensitivity. The method was demonstrated for AFB1 screening in representative cereal- and nut-based matrices (rice, corn and peanut). Overall, E-C-LFIA provides a sensitive, rapid, and equipment-light option for on-site AFB1 screening and offers a transferrable strategy for other small-molecule contaminants.