CuNCs modified with dual-ligand to achieve fluorescence visualization detection of Tin (IV)

In this study, polyvinylpyrrolidone (PVP) supported and cysteine (Cys) modified copper nanoclusters (Cys-PVP-CuNCs) with high fluorescence intensity have been synthesized and used to establish a simple and sensitive assay for the determination of trace Sn4+. The presence of Sn4+ can lead to fluorescence quenching based on the aggregation of PVP-CuNCs caused by the coordination of Sn4+ and oxygen atoms. For Cys-PVP-CuNCs, the ligand Cys can transfer electrons to the metal center of the cluster, resulting in strong fluorescence enhancement of CuNCs and intensification of fluorescence quenching after interaction with Sn4+, which is conducive to more sensitive visual detection. The proposed assay allows for the detection of Sn4+ in a linear range from 5 mu g L-1 to 100 mu g L-1, with a detection limit as low as 4.5 mu g L-1 at a signal-to-noise ratio of 3. Moreover, under UV light, the obvious fluorescent color change can be observed by naked eyes at Sn4+ concentration ranging from as low as 5 mu g L-1 to 200 mu g L-1. Benefiting from the high sensitivity of this assay, satisfactory test results have been obtained when using only 10 mg of canned food samples with rapid digestion. The proposed Cys-PVP-CuNCs fluorescent probe shows excellent stability, simple operation, good selectivity, and high sensitivity, and thus it is expected to be used in the real-time field detection of Sn4+.

Automated summary

Synthesized Cys-PVP-CuNCs were utilized for a sensitive detection of trace Sn4+, showing a linear range for detection, low detection limit, and noticeable fluorescent color change visible to the naked eye. The proposed fluorescent probe exhibits high sensitivity, stability, simplicity, selectivity, and is expected to be used for real-time field detection of Sn4+.