Glutathione (GSH)-switched fluorescent assays have appealed much attention due to rapid signal changes of fluorescent probes. However, exposure to exterior environment of fluorescent probe causes photobleaching and premature leakage, leading to low sensitivity and poor photostability. Herein, luminescent SiO₂ nanoparticles encapsulated with Ru(bpy)₃²⁺ (Ru@SiO₂) were designed and synthesized as fluorescent probe to construct a GSH-switched fluorescent assay. The encapsulation of Ru(bpy)₃²⁺ in the SiO₂ nanoparticles could effectively prevent the leakage of Ru(bpy)₃²⁺ molecules, improving the photostability of probe. The fluorescence of Ru@SiO₂ nanoparticles was quenched by coating MnO₂ nanoparticles on Ru@SiO₂ surface (Ru@SiO₂@MnO₂ nanocomposites) through an in situ growth approach, which reduced background of the assay. The MnO₂ nanoparticles not only further inhibited the leakage of Ru(bpy)₃²⁺ molecules, but also could serve as a recognition unit of GSH. In the presence of GSH, the MnO₂ nanoparticles on the surface of Ru@SiO₂ nanoparticles were reduced to Mn²⁺, resulting the fluorescence recovery of Ru@SiO₂ nanoparticles. Thus, a signal-on fluorescent strategy was constructed for GSH detection. The assay displayed good analytical performance for GSH detection with a low detection limit of 16.2 nM due to excellent fluorescence quenching ability of MnO₂ nanoparticles and special role of Ru@SiO₂ nanoparticles to block probe leakage. The proposed assay was also applied to measure GSH levels in human serum samples. This work paves a new way to detect GSH with high sensitivity.

由于荧光探针的快速信号变化，谷胱甘肽 (GSH) 转换的荧光测定法引起了很多关注。然而，荧光探针暴露于外部环境会导致光漂白和过早泄漏，导致灵敏度低和光稳定性差。在此，设计并合成了包裹有Ru(bpy) ₃ ²⁺ (Ru@SiO ₂ ) 的发光SiO ₂纳米粒子作为荧光探针，以构建GSH 开关荧光检测。_{将Ru(bpy) 3} ²⁺包裹在SiO ₂纳米颗粒中可以有效防止Ru(bpy) ₃ ²⁺分子的泄漏，提高探针的光稳定性。Ru@SiO的荧光通过原位生长方法在Ru@SiO ₂表面（Ru@SiO ₂ @MnO ₂纳米复合材料）上涂覆MnO _{2纳米颗粒，从而使2纳米颗粒淬火，这降低了测定的背景。}MnO ₂纳米粒子不仅进一步抑制了Ru(bpy) ₃ ²⁺分子的泄漏，而且可以作为GSH的识别单元。在GSH存在下， Ru@SiO ₂纳米粒子表面的MnO ₂纳米粒子被还原为Mn ²⁺，导致Ru@SiO _{2的荧光恢复}纳米粒子。因此，构建了用于 GSH 检测的信号开启荧光策略。由于MnO _{2纳米粒子具有优异的荧光猝灭能力和Ru@SiO 2}纳米粒子对阻止探针泄漏的特殊作用，该测定显示出良好的GSH检测分析性能，检测限低至16.2 nM。所提出的测定法也用于测量人血清样品中的 GSH 水平。这项工作为高灵敏度检测 GSH 开辟了一条新途径。