A highly sensitive upconverting phosphors-based off–on probe for the detection of glutathione

At present, glutathione (GSH) is a very important biomarker in vivo. However, the sensitive and selective assay for the detection of GSH in biological matrix still keeps challenging due to the high complexity of samples. Lanthanide-doped upconverting phosphors (UCPs) which exhibit unique near-infrared (NIR) excitation nature are able to overcome interferences from complex samples. In this study, a novel probe based on the linkage of UCPs and dopamine-quinone through hydrogen bonding and electrostatic interaction has been designed for rapid, economic, sensitive and selective detection of GSH in aqueous solution and human blood serum. Here, dopamine-quinone served as an efficient quencher for upconverting fluorescence, while GSH as a strong reducing agent chemically reduced the dopamine-quinone turning on the fluorescence. The fluorescence recovery was found to be proportional to GSH concentration within the range from 1 to 75 μM. The detection limit of this sensor was 0.29 μM, which was quite competitive for GSH detection. The simple, sensitive and selective fluorescence method took full advantages of UCPs properties of low interferences and broadened the application scope of UCPs in complex biological detection.