WS₂ quantum dots-MnO₂ nanosheet system for use in ratiometric fluorometric/scattered light detection of glutathione

Based on WS₂ quantum dots (QDs) as fluorescent signals and MnO₂ nanosheets as second-order scattering (SOS) signals, a combination of fluorescence and scattered light was used to construct a ratio sensing platform for glutathione (GSH) detection. When MnO₂ nanosheets are added to WS₂ QDs, the fluorescence of WS₂ QDs is quenched by MnO₂ nanosheets through IFE. Large-sized MnO₂ nanosheets increase the SOS of the system and gradually approach the fluorescence. After adding GSH to WS₂ QDs-MnO₂, the MnO₂ nanosheets were decomposed into Mn²⁺. The disappearance of the characteristic absorption peak of the MnO₂ nanosheets suppressed the IFE to WS₂ QDs, resulting in the fluorescence recovery of WS₂ QDs. The reduction in size of MnO₂ nanosheets after decomposition results in a decrease in the SOS of the system. Therefore, the ratio detection of GSH is obtained through the fluorescence and SOS dual signal response. Under optimal experimental conditions, the value of F₄₀₆/S₆₄₈ is linearly related to the GSH concentration in the range 0 to 60 μM, and the limit of detection (LOD) of GSH is 0.12 μM. In addition, the system is also used for the determination of GSH in real water samples and human serum, with good analytical results. Graphical abstract Schematic principle of fluorescence/scattered light system based on WS₂ QDs-MnO₂ for GSH ratiometric detection.