Monitoring of glutathione using ratiometric fluorescent sensor based on MnO2 nanosheets simultaneously tuning the fluorescence of Rhodamine 6G and thiamine hydrochloride

• A simple and low-cost ratiometric fluorescence sensor for GSH was successfully developed based on MnO 2 nanosheets, R6G and VB 1 . • The sensor showed a broad linear range of 1.0–300.0 μmol L −1 with a relatively low LOD of 0.52 μmol L −1 . • The method is applied in the detection of GSH in human serum with a satisfactory result. • The method is simple to operate and does not require sophisticated instruments. L-glutathione (GSH) which has reducibility and integrated detoxification plays an important role in maintaining normal immune system function. Its abnormal levels are relevant to some clinical diseases. In this work, a facile ratiometric fluorescence sensor for GSH was designed based on MnO 2 nanosheets, Thiamine hydrochloride (VB 1 ) and Rhodamine 6G (R6G). VB 1 could be oxidized into fluorescent ox-VB 1 due to the strong oxidizing property of MnO 2 , and MnO 2 nanosheets simultaneously could quench the fluorescence of R6G based on the inner filter effect (IFE). MnO 2 could react with GSH to form Mn 2+ , which caused its losing oxidizing property and quenching capacity. According to this principle, the concentration of ox-VB 1 diminished, resulting in its fluorescence intensity decreasing at 455 nm and the fluorescence of R6G recovering at 560 nm. Under optimal conditions, the VB 1 -MnO 2 -R6G detection system showed a wide linear range towards GSH in the range of 1.0–300.0 µmol L −1 with a low detection limit reaching 0.52 µmol L −1 . Furthermore, the method was also applied in the determination of GSH in human serum.