Nitrodopamine modified MnO2 NS-MoS2QDs hybrid nanocomposite for the extracellular and intracellular detection of glutathione†

We have developed a highly sensitive and reliable fluorescence resonance energy transfer (FRET) probe using nitro-dopamine (ND) and dopamine (DA) coated MnO₂ nanosheet (ND@MnO₂ NS and DA@MnO₂ NS) as an energy acceptor and MoS₂ quantum dots (QDs) as an energy donor. By employing surface-modified MnO₂ NS, we can effectively reduce the fluorescence intensity of MoS₂ QDs through FRET. It can reduce MnO₂ NS to Mn²⁺ and facilitate the fluorescence recovery of the MoS₂ QDs. This ND@MnO₂ NS@MoS₂ QD-based nanoprobe demonstrates excellent sensitivity to GSH, achieving an LOD of 22.7 nM in an aqueous medium while exhibiting minimal cytotoxicity and good biocompatibility. Moreover, our sensing platform shows high selectivity to GSH towards various common biomolecules and electrolytes. Confocal fluorescence imaging revealed that the nanoprobe can image GSH in A549 cells. Interestingly, the ND@MnO₂ NS nanoprobe demonstrates no cytotoxicity in living cancer cells, even at concentrations up to 100 μg mL⁻¹. Moreover, the easy fabrication and eco-friendliness of ND@MnO₂ NS make it a rapid and simple method for detecting GSH. We envision the developed nanoprobe as an incredible platform for real-time monitoring of GSH levels in both extracellular and intracellular mediums, proving valuable for biomedical research and clinical diagnostics.