Multifunctional Eu-doped carbon dots nanoprobe for highly sensitive and selective determination of glutathione in biological fluid and cell imaging

Glutathione (GSH) holds a vital role in biological systems, serving diverse cellular functions. Selective determination of GSH over cysteine (Cys) and homocysteine (Hcy) stays challenging due to the shared functional groups among these biothiols. In this study, a versatile Eu-doped carbon dots (Eu-CDs) nanoprobe has been developed for the exceptionally sensitive and selective detection of GSH in biological fluids. The synthesized Eu-CDs exhibited high solubility in water, stability to salt and pH variations, and consistent fluorescence emission, boasting a quantum yield of 40.67 %. Following the optimization of detection parameters, a robust linear relationship for GSH was established in the concentration range of 0.0–50 μM, with a detection limit of 0.03 μM. The viability of the technique in actual samples was evaluated by successfully measuring the GSH in urine and human serum samples with a range recovery from 90.6 % to 98.5 %. Furthermore, Eu-CDs proved to be exceptionally suitable for imaging Hela cells owing to their low cytotoxicity and remarkable biocompatibility. As a result, the developed fluorescent biosensor demonstrated significant potential for widespread application in clinical diagnostic analyses.