Development of manganese dioxide-based fluorescent nanoprobe for glutathione detection and imaging

Tripeptide glutathione (GSH) is an abundant and ubiquitous metabolite in living organisms that plays critical roles in various cellular bioprocesses. In this work, we report the development of a new nanoprobe (MnO₂-PEI-FITC) for GSH detection and imaging through exploiting the response mechanism of specific GSH-triggered reduction of manganese dioxide (MnO₂) nanosheet. The MnO₂-PEI-FITC nanoprobe was developed by coating negatively charged MnO₂ nanosheet with 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 by MnO₂’s absorption, while FITC’s emission at 518 nm was observed in the presence of GSH. The MnO₂-PEI-FITC nanoprobe featured rapid response to GSH (< 12 min), high sensitivity (detection limit, 164 nM) and selectivity. Application of this nanoprobe for GSH imaging in in fresh yeast cells and onion inner-layer epidermal tissues were then successfully demonstrated. This work thus provides a new nanoprobe for GSH detection and imaging in biological samples.