Development of manganese dioxide-based nanoprobes for fluorescence detection and imaging of glutathione

Tripeptide glutathione (GSH) is an abundant and ubiquitous metabolite in living organisms and plays critical roles in various cellular processes. In this work, we report the development of a new nanoprobe (MnO2–PEI–FITC) for GSH detection and imaging by exploiting the response mechanism of specific GSH-triggered reduction of manganese dioxide (MnO2) nanosheets. The MnO2–PEI–FITC nanoprobe was developed by coating negatively charged MnO2 nanosheets with a positively charged polyethylenimine (PEI) polymer, followed by coupling with fluorescein isothiocyanate (FITC) through a thiourea linkage. The MnO2–PEI–FITC nanoprobe showed weak fluorescence due to the quenching of FITC emission absorption by MnO2, while the emission of FITC at 518 nm was observed in the presence of GSH. The MnO2–PEI–FITC nanoprobe is featured with a rapid response to GSH (