Ultrasensitive colorimetric immunoassay for aflatoxin B1 detection in lotus seed powder based on enhanced catalysis of Au@Pt with in situ deposition of PtNPs

The enzyme-linked immunosorbent assay (ELISA) is a powerful and high-throughput method for detecting aflatoxin B₁ (AFB₁) in food. However, the susceptibility of native enzymes to environmental factors limits their potential applications. This study introduces the combined use of precious metal nanozymes as alternative catalysts to improve the performance of traditional ELISA. Au@Pt can be linked to antibodies to construct recognition probes, onto which platinum nanoparticles (PtNPs) are ingeniously deposited in situ to amplify the detection signal, thereby increasing the sensitivity. The proposed PtNP-enhanced Au@Pt-ELISA exhibited excellent resistance against matrix interference for AFB₁ detection in lotus seed powder and achieved a detection limit of 1.6 pg/mL (0.32 μg/kg), which was approximately six times lower than that of traditional ELISA. Furthermore, the results of the proposed approach were strongly correlated with LC-MS/MS analysis results for real samples (<i>r</i> = 0.9888, <i>n</i> = 13). This study offers a new strategy for AFB₁ monitoring in a complex matrix.