Leek-derived codoped carbon dots as efficient fluorescent probes for dichlorvos sensitive detection and cell multicolor imaging.

A biomass nitrogen and sulfur codoped carbon dots (NS-Cdots) was prepared by a simple and clean hydrothermal method using leek, and was employed as efficient fluorescent probes for sensitive detection of organophosphorus pesticides (OPs). The leek-derived NS-Cdots emitted blue fluorescence, but was quenched by H2O2. Due to acetylcholinesterase/choline oxidase-based cascade enzymatic reaction that produces H2O2 and the inhibition effect of OPs on acetylcholinesterase activity, a NS-Cdots-based fluorescence "off-on" method to detect OPs-dichlorvos (DDVP) was developed. More sensitivity and wider linear detection range were achieved from 1.0 × 10-9 to 1.0 × 10-3 M (limit of detection = 5.0 × 10-10 M). This developed method was applied to the detection of DDVP in Chinese cabbage successfully. The average recoveries were in the range of 96.0~104.0% with a relative standard deviation of less than 3.3%. In addition, the NS-Cdots fluorescent probes were also employed successfully in multicolor imaging of living cells, manifesting that the NS-Cdots fluorescent probes have great application potential in agricultural and biomedical fields. Graphical Abstract.