Highly sensitive quantitative detection of glutathione based on a fluorescence-colorimetric dual signal recognition strategy

Glutathione (GSH) serves as a critical component in numerous physiological processes, functioning as a significant antioxidant. Therefore, the establishment of a precise method for the quantification of GSH is of paramount significance for disease diagnosis, clinical interventions, and various biomedical applications. In this study, a nanocomposite material (NSCQDs@MSN) is prepared by in situ synthesizing nitrogen-sulfur doped carbon quantum dots (NSCQDs) in mesoporous silica nanoparticle (MSN). By loading Cu2+ on the surface of NSCQDs@MSN, a novel dual-mode sensor (NSCQDs@MSN-Cu) is developed for fluorescence and colorimetric detection of GSH. On the one hand, based on the fluorescence quenching phenomenon caused by the electron or energy transfer process between Cu2+ and NSCQDs, a "Turn-On" fluorescence sensing model is successfully constructed for GSH detection; on the other hand, based on the principle that NSCQDs@MSN-Cu can catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) by hydrogen peroxide to produce blue oxTMB, a colorimetric sensing model is devised for the detection of GSH. This dual-mode sensor was successfully used for the detection of GSH in real samples, and the experimental results further verified the accuracy and practicality of the dual signal recognition strategy. Thus, this strategy not only introduces a novel research concept for the creation of multifunctional sensors but also holds significant promise for early disease diagnosis and biochemical research applications.