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Improving the sensitivity of immunochromatographic assays (ICAs) lies in the signal strength and probe activity of the labeled tracers, and the color properties and structure of the labeled tracers are key factors affecting the biological activity. In this study, cerium vanadate (CeVO4) of different sizes and shapes (230, 1058, and 710 nm) was synthesized to investigate its impact on the performance of ICA for T-2 detection. The prepared CeVO4possessed outstanding stability, a large specific surface area, superior biocompatibility, and high compatibility with T-2 mAb (affinity constant was 3.14 × 108M–1). As labeling probes for competitive ICA, the results showed that 1058 nm of CeVO4as labels exhibited the best detection performance, with a limit of detection (LOD) of 0.079 ng/mL, which was substantially 19-fold less than the average of gold nanoparticle ICA. Additionally, CeVO4–ICA was effectively used to detect T-2 toxin, and the recovery rate for spiking corn and oatmeal samples was determined to be 81.27–115.44% (relative standard deviation <9.16%). The above information demonstrates the efficiency and applicability of CeVO4–ICA as a technique for quick and thorough identification of T-2 toxin residues in food.

Nanozymes have drawn much attention as an enzyme mimetic with low cost and stability in enhancing analytical performance. Herein, a peroxidase-mimicking nanozyme-improved enzyme-linked immunosorbent assay (ELISA) was developed employing the bimetallic PdRu nanozyme to replace the natural enzymes as a catalytic carrier for the sensing of Escherichia coliO157:H7 (E. coliO157:H7). The PdRu nanozyme displayed ultrahigh catalytic activity, possessing a catalytic rate that was 5-fold higher than horseradish peroxidase (HRP). In addition, PdRu exhibited great biological affinity with antibody (affinity constant was about 6.75 × 1012M) and high stability. All those advantages ensure the successful establishment and the construction of a novel colorimetric biosensor for E. coliO157:H7 detection. PdRu-based ELISA not only achieved an ultrasensitive detection sensitivity (8.7 × 102CFU/mL) by approximately 288-fold as compared to the traditional HRP-based ELISA and also possessed satisfactory specificity and reproducibility (relative standard deviation (RSD) < 10%). Furthermore, the feasibility of PdRu-ELISA was further evaluated by detecting E. coliO157:H7 in actual samples with satisfactory recoveries, indicating its potential for applications in bioassays and clinical diagnostics.