An “off-on” fluorescent probe for selective detection of glutathione based on 11-mercaptoundecanoic acid capped gold nanoclusters

Glutathione (GSH) is an important biothiol and participates in various physiological processes. Therefore, development of highly sensitive and selective fluorescent probes for detecting GSH is of great significance for drug analysis and disease diagnosis. Herein, 11-mercaptoundecanoic acid (11-MUA) capped gold nanoclusters (AuNCs@11-MUA) combining with copper ions (Cu2+) were applied to construct an "off-on" fluorescent probe for GSH detection. In this strategy, the coordination of Cu2+ with AuNCs@11-MUA leads to the fluorescence quenching of AuNCs@11-MUA, and the fluorescence signal of the system is in the “off” state. Due to the stronger binding ability between GSH and Cu2+, the addition of GSH forces Cu2+ detach from AuNCs@11-MUA, resulting in fluorescence recovery of AuNCs@11-MUA, and the fluorescence signal of the system is in the “on” state. The fluorescence recovery is linearly proportional to the concentration of GSH in the range of 0.05–5 μM. The detection limit is 33.3 nM. The proposed sensor can be used for the accurate detection of GSH in commercial drugs and cell lysate, indicating the potential applicability of the nanoprobe.