Intracellular Imaging of Glutathione with MnO2 Nanosheet@Ru(bpy)32+–UiO-66 Nanocomposites

Fluorescent detection of glutathione (GSH) in the living system has attracted much attention, but current fluorescent probes are usually exposed to the exterior environment, leading to photobleaching and premature leakage and subsequently limiting the sensitivity and photostability. Herein, luminescent metal–organic frameworks [Ru(bpy)32+ encapsulated in UiO-66] coated with manganese dioxide nanosheets [MnO2 NS@Ru(bpy)32+–UiO-66] were prepared by an in situ growth method and further explored to construct a GSH-switched fluorescent sensing platform. Because of the splendid fluorescence quenching ability, special probe leakage blocking role and distinguished recognition of the MnO2 NS, and the improved fluorescence of Ru(bpy)32+ by UiO-66, a low background, highly sensitive and selective detection of GSH with a low limit of detection as 0.28 μM was realized. At the same time, the preparation of MnO2 NS@Ru(bpy)32+–UiO-66 nanocomposites is simple and less toxic, and there was no notable loss of cell survivability after being exposed to MnO2 NS@Ru(bpy)32+–UiO-66 below the concentrations of 120 μg mL–1 for 24 h. Consequently, the results coming from this effort suggest that the new sensing platform will have a great potential in the detection of GSH in living cells.