Novel solution- and paper-based sensors based on label-free fluorescent carbon dots for the selective detection of pyrimethanil

[Display omitted] •Sensitive: carbon dots were sensitive to pyrimethanil (PMT) yielding LOD of 14 nM.•Selective: carbon dots were selective to PMT against several interferences.•Accurate: concentrations of PMT in real samples were accurately determined.•Reusable: paper-based sensor produced excellent results even after 8-time uses.•Fast: the sensor gave the detection results within 30 s. Novel sensors based on fluorescent carbon dots were developed for a rapid, selective, and sensitive detection of pyrimethanil, a fungicide widely used in many agricultural crops. The carbon dots were synthesized from maleic anhydride and triethylenetetramine via a facile one-pot pyrolysis. A quenched fluorescence intensity of carbon dots in the presence of pyrimethanil occurred via inner filter effect and strong π-π interaction. The carbon dots were sensitive to pyrimethanil across a linear range from 0.5 to 75 µM with a low detection limit of 14 nM. The sensing results could be generated in 30 s. The fluorescent carbon dots showed excellent stability and selectivity to pyrimethanil in the presence of interferences, including fungicides and metal ions. They were also successfully employed for pyrimethanil detection in apples, cucumbers, and drinking water, yielding 98.6–107.1% recovery. The practical, portable, and reusable paper-based sensor was also developed. The cytotoxicity of carbon dots was tested to demonstrate that they are sufficiently safe to use. The novel pyrimethanil sensor based on fluorescent carbon dots developed in this work can be used as a high-performance sensor and a rapid tool for quality control in food, agricultural, and environmental monitoring.