Ce3+-induced Fluorescence Amplification of Copper Nanoclusters Based on Aggregation-induced Emission for Specific Sensing 2,6-pyridine Dicarboxylic Acid

A straightforward, cost-effective and biocompatible reduction approach was applied to fabricate soluble but non-luminous glutathione-stabilized copper nanocluster (GSH-CuNCs). Surprisingly, as high as 1 x 10(3) times fluorescence enhancement was acquired when Ce3+ was injected at an extremely low concentration of only 18 mu M. Ce3+ outperformed other rare-earth metal ions in terms of inducing fluorescence amplification of the non-luminous GSH-CuNCs. Furthermore, Ce3+ was employed as inducer for aggregation-induce emission (AIE) effect as well as reactant to coordinate with target of 2,6-pyridine dicarboxylic acid (DPA) due to the stronger coordination ability between Ce3+ and DPA than that of Ce3+ and GSH. As a result, the Ce3+/GSH-CuNCs ensemble was developed as a novel sensor to detect DPA in the on-off mode. When DPA was introduced into the sensor, Ce3+ failed to interact with GSH and detached from the surface of GSH-CuNCs, leading to fluorescence quenching. In addition, static quenching process and internal filtration effect (IFE) between Ce3+/GSH-CuNCs and DPA were also responsible for fluorescence quenching effect. A good linear relationship was obtained from 0.3 mu M to 18 mu M, with a limit of detection (LOD) of 0.19 mu M. The as-proposed probe displayed high specificity to DPA and provided a simple, fast rapid and cheap method for construction this type of ensemble sensors to detect other targets.

Automated summary

A soluble but non-luminous glutathione-stabilized copper nanocluster (GSH-CuNCs) was successfully fabricated using a straightforward, cost-effective and biocompatible reduction approach. When Ce3+ was injected at an extremely low concentration of only 18 μM, a remarkable fluorescence enhancement of up to 1 x 10(3) times was achieved. Ce3+ outperformed other rare-earth metal ions in inducing fluorescence amplification of the non-luminous GSH-CuNCs and was also employed as an inducer and reactant to construct a novel ensemble sensor for the detection of 2,6-pyridine dicarboxylic acid (DPA).