One-pot preparation of nitrogen-doped carbon dots for sensitive and selective detection of Ag+ and glutathione

Herein, a novel nitrogen-doped carbon dots (N-CDs) nanosensor for detecting Ag + and glutathione (GSH) has been designed. Interestingly, Ag + could significantly improve the fluorescence (FL) intensity of the N-CDs we prepared, which is different from most other metal ions with FL quenching effects on N-CDs. The sensing mechanism can be attributed to the oxidation characteristics of Ag + and the formation of silver nanoparticles (AgNPs). In the reaction, the N-CDs acted as the reducing agent and stabilizer. Under the optimal conditions, the N-CDs could detect Ag + with a nice linear relationship of R 2  = 0.992 and the limit of detection was 0.091 μM. Furthermore, the FL of N-CDs solutions could return to nearly original intensity after introducing glutathione (GSH), which allowed the N-CDs to be applied for GSH detection sensitively and selectively. In addition, the N-CDs were also successfully applied to cellular multicolor imaging of Hela cells. The results reported here pave the way for N-CDs-based fluorescent “off-on-off” sensor in environment, bioassay and bioimaging.