Iron-copper nanozyme mimicking laccase for colorimetric determination of deoxynivalenol in feed

Due to the simplicity of their synthesis, robust stability, and adjustable enzymatic activities, nanozymes are particularly effective in inducing changes in substrate coloration, thus proving to be invaluable tools in colorimetric analysis. In this study, terephthalic acid was employed as an organic ligand to synthesize an iron-copper nanozyme with laccase activity using a one-pot hydrothermal method. Remarkably, the introduction of deoxynivalenol (DON) enhanced the laccase activity, significantly deepening the substrate's color. The absorbance displayed a strong correlation with DON concentrations ranging from 5 μM to 35 μM, following the linear equation Y = 0.03097x + 0.00883 with a correlation coefficient (R2) of 0.994, and the limit of detection (LOD) was found to be 0.59 μM. This developed colorimetric method was then applied to determination DON in wheat, wheat bran, and corn samples, exhibiting relative standard deviations (RSD) between 1.5 % and 2.8 %. The analytical results were consistent with those obtained using the standard high performance liquid chromatography (HPLC) method. Therefore, this rapid, sensitive, and cost-effective technique promises efficient determination of DON in feed samples.