Signal-on fluorescent sensor based on GQDs-MnO2 composite for glutathione

摘要

Graphene quantum dots (GQDs) exhibit strong photoluminescence, biocompatibility, and low toxicity and can easily functionalize surfaces to improve the detection of biomolecules. As-prepared MnO2 nanosheets were applied in the fabrication of GQDs-MnO2 composite to develop a signal-on fluorescent platform for sensing glutathione (GSH). The fluorescence of the GQDs was quenched by MnO2 in the GQDs-MnO2 composite as a result of fluorescence resonance energy transfer within the composite. The fluorescence of GQDs was restored when GSH was introduced because GSH reduced the MnO2 nanosheets into Mn2+ and released GQDs. Under the optimized conditions, the concentration of GSH can be accurately detected with high sensitivity and specificity in Tris-HCl buffer and simulated serum. The proposed sensing strategy was successfully used to measure GSH in the range of 1-1000 mu M with a detection limit of 0.45 mu M. In addition, GSH in reduced glutathione injection and reduced glutathione tablets can be determined accurately using the proposed method. GQDs-MnO2 composite is thus a promising GSH fluorescence sensor for the analysis of complex systems and for quality control in the pharmaceutical industry.