A near-infrared fluorescent sensor based on the architecture of low-toxic AgS quantum dot and MnO nanosheet for sensing glutathione in human serum sample.

Near-infrared (NIR) emitting AgS quantum dots (QDs) are excellent fluorescent nanoprobes for bioassays with low toxicity. A novel fluorescent sensing platform which employing NIR fluorescent AgS QDs and MnO 2D nanosheets as NIR emitters and quenchers is designed for rapid and selective determination of glutathione (GSH). A facile and efficient approach was demonstrated for the synthesis of NIR fluorescent AgS QDs with the emission of 845 nm. Then the NIR fluorescent nanoprobe of AgS QDs-MnO nanosheets is obtained by adsorbing AgS QDs onto the surface of MnO nanosheets which have atomically thick two-dimensional structure and high specific surface area. And the NIR fluorescence of AgS QDs is quenched by the MnO nanosheets. The presence of GSH could reduce MnO to Mn that results in the restoration of NIR fluorescence for AgS QDs. The NIR fluorescent nanoprobe could be used for highly selective detection of GSH. Also a low detection limit of 60 μmol/L was obtained. Because NIR fluorescence of the AgS QDs can efficiently reduce the interferences from background scattering and autofluorescence. The NIR fluorescent nanoprobe was directly applied to monitor the GSH level in human serum sample with high accuracy and precision.