Integration detection of mercury(ii) and GSH with a fluorescent "on-off-on" switch sensor based on nitrogen, sulfur co-doped carbon dots.

Using aurine and citric acid as precursors, we have synthesized stable blue-fluorescent nitrogen and sulfur co-doped carbon dots (NS-CDs), with a high quantum yield of up to 68.94% via a thermal lysis method. The fluorescent NS-CDs were employed as a sensitive sensor for the integration detection of Hg 2+ and glutathione (GSH). This was attributed to Hg 2+ effectively quenching the fluorescence of the NS-CDs by static quenching, and then GSH was able to recover the fluorescence owing to the stronger binding between Hg 2+ and the sulfhydryl of GSH. Based on the "on-off-on" tactic, the detection limits of Hg 2+ ions and GSH were 50 nM and 67 nM respectively. The fluorescence sensor was successfully applied to detect Hg 2+ ions and GSH in actual samples (tap water and fetal bovine serum). Furthermore, we have proved that the sensor had good reversibility. Overall, our NS-CDs can serve as effective sensors for environmental and biological analysis in the future.