Bioimaging-guided discrimination of normal/cancer cells using Ag+-mediated red fluorescent carbon dots

Glutathione (GSH) serves as a significant cancer-related biomarker that plays a pivotal role in preserving intracellular homeostasis. However, the structural and functional similarities between GSH and other biothioles (cysteine and homocysteine), make it difficult to distinguish GSH from them. In this study, we have developed a novel fluorescent probe utilizing silver-mediated red emissive carbon dots (RCDs@Ag+) for the discrimination of cancer cells from normal cells through the bioimaging of glutathione (GSH). The fluorescence intensity of RCDs is quenched significantly upon the addition of Ag+ (50 µM) and is recovered 95 % with the identical concentration of added GSH, without such effect occurring in cysteine and homocysteine. The fluorescence lifetime of the RCDs was found to be approximately 7.022 ns and the quantum yield was determined to be approximately 9.24 %. Further, RCDs@Ag+ are suitable for selectively detecting intracellular GSH due to their excellent biocompatibility, and low toxicity in normal NIH3T3 and HeLa cells. Most significantly, RCDs@Ag+ may be used as an excellent approach to spot cancer cells overexpressing GSH.