Development of Vanadium Carbide-Based Immunochromatographic Assay for T-2 Toxin Detection in Maize Samples

The purpose of this study was to construct a vanadium carbide-based immunochromatographic assay for the sensitive detection of T-2 toxin in maize. Vanadium carbide nanosheets (VCNSs) were synthesized by ultrasonic-assisted liquid phase exfoliation, and conjugated with T-2 monoclonal antibody (T-2-mAb) as a signal probe. Based on the competition principle, the T-2 toxin in samples competed with the T-2 antigen on the test (T) line for binding to the black VCNSs-mAb probe. As a result, the T-line value was inversely proportional to T-2 toxin concentration. The best experimental conditions and the standard curve were established based on color development in the T-line of the blank test strip (signal value > 800, detected using an MD-600 reader) and the inhibition rate of 0.5 and 1.5 ng/mL T-2 toxin. The results showed that the linear range of the proposed method was between 0.14 and 0.78 ng/mL, the visual detection limit was 0.25 ng/mL, the cut-off value was 1.5 ng/mL, and the half maximal inhibitory concentration (IC50) was 0.344 ng/mL. The sensitivity was 6.6 times higher than that of the traditional colloidal gold test strip. In addition, the assay did not cross-react with five other common mycotoxins. Moreover, the recoveries for real maize samples ranged from 92.8% to 117.2% with coefficients of variation (CV) of less than 9.13%, and the detection limit of 5.06 μg/kg. In summary, this method is characterized by simple operation, rapid sensitivity and low cost, which enables on-site rapid detection of T-2 toxin in cereals.