Fluorescent Detection of Organophosphorus Pesticides Using Carbon Dots Derived from Broccoli

The determination of organophosphorus pesticide (OP_S) 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.