Bimetallic Nanozyme-Assisted Immunoassay for the Detection\nof Acetamiprid in Vegetables

The ability of conventional enzyme-linked\nimmunosorbent assays\nto satisfy the increasing demand for advanced immunoassays is limited\nby their reliance on natural enzymes, low sensitivity, and narrow\ndetection range. The development of nanozyme-assisted immunoassays\nis a viable approach to overcoming these constraints. Here, we report\na one-step bimetallic nanozyme-assisted indirect competitive immunoassay\nto detect the pesticide acetamiprid in vegetables. Litchi-like bimetallic\ngold and platinum (Au@Pt) nanozymes with high catalytic properties\nand excellent biocompatibility were synthesized for this assay. The\nAu@Pt nanozymes were simple and inexpensive to prepare, exhibited\nstability and adjustable catalytic activity, and were directly conjugated\nwith antibodies as signal probes, without the use of horseradish peroxidase-conjugated\nAffinipure goat antimouse IgG (IgG-HRP). Acetamiprid was shown to\ncompete with the antigen to bind the Au@Pt probes. Subsequently, Au@Pt\nprobes, which exhibited peroxidase-like activity, were used to catalyze\nthe oxidation of colorless 3,3′,5,5′-tetramethylbenzidine,\ndemonstrating the easy detection of acetamiprid through colorimetric\nsignal monitoring. The linear range, sensitivity, relative standard\ndeviation range, and limit of detection of the immunoassay were 1.85–327.19\nμg/L, 25.58 μg/L, 0.46–10.35%, and 0.78 μg/L,\nrespectively, satisfying the detection requirements. In conclusion,\nthe method exhibited high sensitivity, reproducibility, and a wide\nlinear range for the detection of acetamiprid, while eliminating the\nneed for IgG and simplifying the experimental procedure. This new\nindirect competitive immunoassay has great potential value for on-site\nsensitive detection of acetamiprid in vegetables.