Copper nanoclusters (CuNCs) as a new type of probe for environmental contaminants are gaining increasing attention because of its low cost, superior water dispersibility, wide availability and excellent optical properties. Compared with the other probes such as quantum dots and organic dyes, CuNCs show much more potential in practical application for their excellent photostability, large Stokes shift, low toxicity and other preponderance, especially in the fields of biosensing and environmental monitoring. Recently, the template-assisted synthesis of metal nanoclusters (MNCs) has been widely studied. A variety of templates such as proteins, small thiol molecules, polymers, and DNA with different spatial configuration have been used for the preparation of MNCs so far. This review primarily described recent advances in CuNCs in terms of the synthesis of CuNCs from different templates, the methods to improve the fluorescence (FL) properties of CuNCs, as well as the basic detection mechanisms based on the FL properties or catalytic properties. Finally, to promote the practical application of CuNCs probes, the challenges and prospects of CuNCs multifunctional probes are also discussed.

With the increase of agricultural production, the utilization of biomass waste has become the focus of current research. In this study, Si-containing carbon dots (Si-CDs) were prepared from peanut shells by one-pot hydrothermal method. These Si-CDs exhibit peroxidase-like activity and can catalyze H 2 O 2 oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a chromogenic reaction, while cysteine (Cys) can reduce the oxidation product of TMB (ox-TMB) to discolor it. A method for the determination of Cys using Si-CDs as peroxidase was developed. In addition, the effect of environmental factors on the enzyme-like reaction was investigated. The experimental results showed that the best catalytic effect was achieved at pH = 2.5, reaction temperature of 60 °C, and reaction time of 55 min when the concentrations of TMB and H 2 O 2 were 5 mmol·L −1 and 2.75 mmol·L −1 , indicating that Si-CDs still have the potential for enzymatic activity in extreme environments. The decrease in absorbance of the system (ΔA) showed a good linear relationship with Cys in the range of 5–100 μmol·L −1 , and the limit of detection was 0.037 μmol·L −1 . This sensor was successfully used for the determination of edible Cys content.

Hydroquinone (H2Q) present in water is becoming a growing problem in both daily life and industry, with various harmful effects on human health. Therefore, the detection of H2Q is very important. The Carbon dot-based sensor is considered an effective method to detect H2Q. In this work, Pericarpium citri reticulatae carbon dots (P-CDs) were synthesized by a one-pot hydrothermal method for wide linear sensing of H2Q. An orthogonal test was used to expand the active site and fluorescence properties of P-CDs. Under optimal conditions, the P-CDs exhibit an extremely stable blue fluorescence and a quantum yield (QY) of up to 15.4%. In the range of 5-1000 mu M, compared with the currently reported carbon dot-based H2Q sensors, the fluorescence intensity (FL) of P-CDs shows good linearity with the variation of H2Q concentration and a higher linear range. Moreover, the sensor demonstrates a low detection limit of 0.058 mu M. The possible detection mechanism is based on the synergistic action of static quenching and IFE. This method has been successfully applied to the determination of H2Q in real samples, and the P-CDs-based sensor has the potential to detect H2Q in various complex scenes.