Monitoring biothiols dynamics in living cells by ratiometric fluorescent gold carbon dots.

Changes in biothiols, including glutathione (GSH) and cysteine, are closely related to a variety of diseases and cellular functions. Real-time monitoring intracellular GSH and cysteine dynamics in living cells are important for understanding pathophysiological processes. In this study, a stable heterostructure of dual-emission fluorescent gold carbon dots (GCDs) consisting of carbon skeleton and gold nanoclusters was prepared, which emits strong blue fluorescence and weak yellow-orange fluorescence. The blue fluorescence of the as-prepared GCDs has no response to biothiols including GSH and cysteine, but a turn-on yellow-orange fluorescence would be appeared accompanied by the biothiols reacting with the GCDs. Ratiometric fluorescent bioimaging therefore may be established based on the unique GCDs to detect GSH and cysteine levels in living cells. Moreover, real time monitoring GSH and cysteine levels in various cell lines in living cells at different growth stages was realized. The concentration of GSH in cancer cells is higher than that of normal cells, however, the level of cysteine in normal cells is consistently higher than in cancer cells at different stages of cell growth. The fluorescent GCDs probe provides a promising tool for tracking on regulation of GSH and cysteine dynamics by physiological environments due to the capability for real-time quantitation of GSH and cysteine.