Fluorescent Detection of Organophosphorus Pesticides Using Carbon Dots Derived from Broccoli

The determination of organophosphorus pesticide (OPS) residues is of great significance to the evaluation and monitoring of food quality. In this study, nitrogen-, sulfur-, and silicon-co-doped carbon dots (CDs) were prepared from broccoli leaves and stems using a hydrothermal method and applied in fluorescent detection of organophosphorus pesticides. The prepared N-, S-, Si-doped CDs are water-dispersible and hydrophilic with good fluorescent properties. It was found that fluorescence of the prepared CDs could be selectively quenched by Fe3+ derived from Fe2+ oxidation by hydrogen peroxide. A linear relationship between the fluorescence of CDs and concentration of Fe3+ was established in a range of 0 − 200 µM, and its specific detection limit was 1.43 µM. CDs/Fe2+/acetylcholinesterase (AChE) fluorescent system was subsequently established to detect and quantify OPs residues in food samples based on the AChE inhibition strategy with a good linear range of 0.01 − 1.0 µM of O,O-dimethyl-O-2,2-dichlorovinyl phosphate (DDVP) concentration. A low detection limit of 8.0 nM was achieved. The hetero-atoms-doped CDs, which could be prepared from agro-wastes on a large scale, have great potential for the rapid real-time detection of OPs in authentic food samples with low detection values.