Cu2+ enhanced fluorescent Ag nanoclusters with tunable emission from red to yellow and the application for Ag+ sensing

In this work, the water-soluble fluorescent Ag nanoclusters (DPA@Ag NCs) were first prepared based on D-Penicillamine (DPA) as a stabilizer, however, the fluorescence quantum yield (QY) of DPA@Ag NCs was very low, then Cu2+ was employed to improve the fluorescence QY and the doped Ag nanoclusters with Cu2+ (DPA@Ag/Cu NCs) were obtained. The study showed that the QY increased fourfold and the emission of nanoclusters changed from red to yellow after addition of Cu2+. The reason for change of fluorescent properties was attributed to the change of self-assembly structures caused by adding Cu2+ into reaction system, leading to the aggregation-induced emission enhancement (AIEE) effect and enhancing the band gap (Eg) between the HOMO and LUMO in nanoclusters. Subsequently, a fluorescent Ag+ sensor with high sensitivity and selectivity was established based on the DPA@Ag/Cu NCs as probes in aqueous solution. Experiments showed that the Ag+ could significantly quench the fluorescence of DPA@Ag/Cu NCs under experimental conditions, and there was a good linear relationship between the fluorescent intensity quenching value and Ag+ concentration in the range of 0.05-800 mu M, and the limit of detection (LOD) was 0.03 mu M (3 sigma/k). Meanwhile, most of common ions had no effect on the experimental results under the same conditions. In addition, the sensor was successfully applied on the detection of Ag+ in real water samples, and the recovery rate was 80.3-99.0%. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A water-soluble fluorescent Ag nanoclusters (DPA@Ag NCs) were prepared using D-Penicillamine as a stabilizer, and the fluorescence quantum yield was enhanced fourfold by doping with Cu2+ to create DPA@Ag/Cu NCs. This enhancement was attributed to changes in the self-assembly structures of the nanoclusters induced by Cu2+. A highly sensitive and selective Ag+ sensor was developed based on these nanoclusters, with a linear relationship between fluorescence intensity quenching and Ag+ concentration in the range of 0.05-800 mu M, and a detection limit of 0.03 mu M.