Carbon quantum dots "on-off-on" fluorescent nanoprobes for sensitive detection of Ag(I) and D-penicillamine

Ag(I) as the second pollutant, is seriously hazardous to human health, while D-penicillamine (D -PA) as an antidote to heavy metal poisoning, is also hazardous to human health by lowering human platelets when used in excess. Based on this, we designed a one-step hydrothermal method for the preparation of carbon quantum dots (CQDs) from o -phenylenediamine and sulfamide, which emits bright yellow fluorescence with a fluorescence quantum yield of 22.85 %, a Stoke shift of 151 nm and excellent stability. The bright yellow fluorescence of the CQDs was successfully applied to detect Ag(I) and D -PA in an aqueous environment, and the results were satisfactory. The presence of Ag(I) can form a non -fluorescent complex with the CQDs to cause a static quench, resulting in a fluorescence quenching. The D -PA has an excellent ligand ability with Ag(I) and is preferred over Ag(I). D -PA has excellent coordination ability with Ag(I) and binds preferentially to Ag(I), allowing the quench fluorescence of CQDs to be restored by adding D -PA. In addition, the sensor showed good selectivity and sensitivity for both Ag(I) and D -PA, with detection limits of 0.11 mu M and 0.15 mu M, respectively. This sensor method has potential applications in environmental monitoring and water quality detection and provides a significant reference value for research and practice in related fields.