A ratiometric fluorescent sensing system for the selective and ultrasensitive detection of pesticide residues via the synergetic effects of copper nanoclusters and carbon quantum dots

Agricultural products, such as foodstuffs and herbal medicines, may be contaminated by pesticides. Therefore, developing sensitive methods for pesticide detection are urgently needed for the assurance of food safety. In this study, a ratiometric fluorescent sensing system based on blue-emitted nitrogen-doped carbon quantum dots (N-CQDs) and red-emitted copper nanoclusters (CuNCs) complex was fabricated for pesticide detection. The selective detection of thiram and paraquat, two typical widely used pesticides, can be easily realized by changing the solvent environment. The detection limit can be reached as low as 7.49 nM and 3.03 nM, respectively. A good linear correlation was found over the concentration range from 10 to 500 nM for thiram and 5 to 100 nM for paraquat. More interestingly, fast and visual detection of thiram and paraquat can be achieved via smartphone-based colorimetric analysis, which has provided an effective implementation for on-site monitoring of the levels of pesticide residues in food.