Abstract Herein, we have investigated a highly specific and very sensitive quantification of L-Cysteine (Cys) in human urine samples using highly fluorescent glutathione decorated copper nanoclusters (GSH-CuNCs) as a fluorescence probe. GSH-CuNCs exhibits emission peak at 613 nm with an excitation wavelength of 380 nm. Emission intensity of GSH-CuNCs was reduced after the addition of Cys. We expected that the quenching of emission intensity is due to the metal-thiol interaction between the GSH-CuNCs surface and thiol group contains the Cys analyte. Cys stimulated Cu-thiol interactions were verified by FT-IR and natural bond orbital (NBO) theory. The good linearity was achieved in the range from 3.00 × 10−8 to 42.00 × 10−8 mol dm−3 and the lowest limit of detection (LOD) was calculated as 8.63 × 10−9 mol dm−3 (S/N = 3). The effect of various potential coexistence substances such as other amino acids, metal ions and some biological relevant chemicals to GSH-CuNCs has also been investigated. Furthermore, it was found that even 10-fold higher concentrations of other thiol containing amino acids did not interfering the detection of Cys. In addition, the proposed strategies were successfully applied for the quantification of Cys in human urine samples and live cell imaging.

中文翻译：

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谷胱甘肽功能化铜纳米团簇作为半胱氨酸特异性生物传感的荧光平台及其在细胞成像中的应用

摘要 在此，我们使用高荧光谷胱甘肽修饰的铜纳米团簇 (GSH-CuNCs) 作为荧光探针，研究了人类尿液样品中 L-半胱氨酸 (Cys) 的高度特异性和非常灵敏的定量。GSH-CuNCs 在 613 nm 处显示发射峰，激发波长为 380 nm。添加 Cys 后 GSH-CuNCs 的发射强度降低。我们预计发射强度的猝灭是由于 GSH-CuNCs 表面和包含 Cys 分析物的硫醇基团之间的金属-硫醇相互作用。Cys 刺激的 Cu-硫醇相互作用通过 FT-IR 和自然键轨道 (NBO) 理论得到验证。在 3.00 × 10-8 至 42.00 × 10-8 mol dm-3 范围内实现了良好的线性，最低检测限 (LOD) 计算为 8.63 × 10-9 mol dm-3 (S/N = 3）。还研究了各种潜在共存物质，如其他氨基酸、金属离子和一些生物相关化学物质对 GSH-CuNCs 的影响。此外，发现即使是 10 倍高浓度的其他含硫醇氨基酸也不会干扰 Cys 的检测。此外，所提出的策略已成功应用于人体尿液样本中 Cys 的定量和活细胞成像。