Visual detection of mercury ions and glutathione is of great significance to public health and environmental issues. Herein, we developed a fluorescent sensor (l-Cys/CuNCs@ESM) based on the eggshell membrane (ESM) and red-emitting copper nanoclusters (CuNCs) by the in situ strategy via l-cysteine (l-Cys) as the reducing and protective agent for mercury ions and glutathione sensing visually. The as-prepared fluorescent product had good stability, portability, large Stokes shift (250 nm), and long fluorescence lifetime (7.3 μs). Notably, the l-Cys/CuNCs@ESM exhibited a specific fluorescence quenching response toward Hg2+. Moreover, the interaction between glutathione (GSH) and Hg2+ could subsequently recover the fluorescence effectively. Inspired by this “on-off-on” switch, the l-Cys/CuNCs@ESM was applied as the dual-sensing system for visual detection of mercury ions and glutathione integrating with the portable smartphone. The limit of detection (LOD) of Hg2+ is 1.1 μM for visualization and 0.52 μM for the fluorescence spectrometer. The corresponding LODs of GSH are 2.8 and 0.59 μM, respectively. This platform presents significant sensitivity, specificity, and stability, offering a promising potential for real-time/on-site sensing.

Dopamine (DA) is an important neurotransmitter in the brain of mammals. There is a critical need for fast and sensitive determination approaches to monitor these potential diseases due to various...

Copper nanoclusters (CuNCs) with bright blue-emitting fluorescence have been synthesized via a simple one-pot process using 2-mercapto-1-methylimidazole (MMI) as a stabilizer. The as-prepared MMI-CuNCs exhibited a high quantum yield of 19.2%, a long luminescence lifetime of 10.57 μs, and excellent photostability. Significantly, the fluorescence intensities of MMI-CuNCs were effectively quenched with addition of Ag+ ions, and the MMI-stabilized CuNCs were developed as a sensitive fluorescent nanoprobe for the label-free determination of silver ions for the first time. The fluorescence sensor provided a fast linear response toward Ag+ in the range of 0.025–50 μM, with a detection limit of 6.7 nM. The fluorescence quenching mechanism was ascribed to an agglomeration-induced effect and static quenching. A fluorescence sensing platform was successfully applied for Ag+ detection in human serum samples with good accuracy and high reproducibility, signifying the practical applicability of the assay. Additionally, MMI-CuNCs displayed good solid-state blue emission and are suitable for security ink applications. The MMI-CuNCs were utilized as a color conversion layer to construct blue- and white-light-emitting diodes (LEDs) with excellent white light properties by a facile combination of MMI-CuNCs and UV LED chips. This result facilitates multiple functions of MMI-CuNCs in the application of label-free sensors, anticounterfeiting, and optical devices.

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Recently, copper nanoclusters (CuNCs) have attracted great research interest for their low synthesis cost, wide application, and easy functionalization. Until now, CuNCs have been developed and applied in multi-fields such as sensing, catalysis, light-emitting diode manufacturing, and cell imaging. Furthermore, the application of heavy metal ions (HMIs) detection is also regarded as a major part of fluorescence sensing and the necessity of detecting the makeup of HMIs (Ag+, Te3+, Co2+, Se6+, Hg2+, Mn2+, etc.) in organisms and the environment. This has promoted the development of CuNCs in fluorescence sensing. This paper reviews the research progress of CuNCs detection in HMIs, which can be divided into four parts. The synthesis and characterization of CuNCs are first described. Then, the synthesis methods making the types of CuNCs more varied are also summarized. Furthermore, mechanisms of fluorescence changes induced by HMIs are explained. After that, the relevant reports of CuNCs in several typical HMI detection are further listed. In addition, combined with the above content, the challenges and prospects of CuNCs in HMIs detection are also proposed.