Tyrosinase coupled with boron-doped carbon nanodots for fluorometric determination of dithiocarbamate fungicide ziram

Abstract Determination of dithiocarbamate fungicides using chromatography is not available for real-time and on-site residue analysis. Herein, a novel fluorescent assay for dithiocarbamate fungicides ziram based on the boron-doped carbon nanodots (B-CDs) and tyrosinase was established. The fluorescent B-CDs with maximum excitation and emission at 490 and 540 nm were synthesized by hydrothermal reaction. PCV can combine with the B-CDs, leading to a fluorescent quenching effect. Tyrosinase can catalyze the PCV oxidation, thus fluorescent intensity of the B-CDs recovers due to the consumption of PCV. While ziram can inhibit tyrosinase activity, resulting in less oxidation of PCV and more quenching effect of the B-CDs. Fluorescence was first employed to enzymatic ziram assay to improve sensitivity. This assay demonstrates a higher sensitivity for ziram (LOD: 0.46 μg L-1) compared to other optical assays and feasibility of determining ziram residue in environmental and food samples (Recovery: 73.9-92.6%, RSD: 2.53-6.57%).