11-Mercaptoundecanoic acid capped gold nanoclusters with unusual aggregation-enhanced emission for selective fluorometric hydrogen sulfide determination.

In present study, we discovered unusual solvent-mediated aggregation-enhanced emission (AEE) character of 11-mercaptoundecanoic acid capped gold nanoclusters (MUA-Au NCs). When aggregated in aqueous media, the MUA-Au NCs showed strong emission, which was weakened by adding ethanol. Interestingly, the suppressed emission was selectively enhanced in the presence of hydrogen sulfide (HS) because HS was absorbed onto Au NCs through the strong sulfur-gold bonding affinity. The hydrolyzed HS, namely, HS, made the Au NCs negatively charged, which aggregated again due to decreased solubility. The HS-mediated fluorescence enhancement can be further amplified by introducing a hydrophilic thiolate (glutathione, GSH) onto the surface of Au NCs (GSH/MUA-Au NCs), which enabled sensitive determination of HS. Under the optimized condition, a detection limit of 35 nM was achieved. The determination was not interfered by other anions such as F, Cl, Br, I, OAc, N, NO, HCO, SCN, SO, and SO. This excellent sensing performance allowed practical application of the GSH/MUA-Au NC-based sensing platform to accurate determination of HS in human serum samples. Graphical abstractUnusual aggregation-enhanced emission character of 11-mercaptoundecanoic acid capped gold nanoclusters is discovered and has been applied for fluorometric hydrogen sulfide detection.