Fluorescent Sensors Based on Cu-Doped Carbon Quantum Dots for the Detection of Rutin

In this paper, Cu-doped carbon quantum dots (Cu-CQDs) were prepared by carrying out thermolysis of Na2[Cu(EDTA)] and hydroxylamine hydrochloride at 300 ºC for 2 h. The as-prepared Cu-CQDs were characterized by UV-Vis, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The Cu-CQDs exhibited good fluorescence property, high stability, excitation-dependent emission behavior and a quantum yield of 9.8%. More significantly, the synthesized Cu-CQDs were developed for sensing rutin (RT) based on the fluorescence quenching of the prepared Cu-CQDs. A good linear relationship between the fluorescence quenching of Cu-CQDs and different concentrations of RT was obtained in the range of 0.1-15 µg mL-1 with a correlation coefficient of 0.9959. The detection limit was as low as 0.05 µg mL-1 (signal-to-noise ratio, S/N = 3). The possible mechanism of fluorescence quenching was explored, which was proved to be inner filter effect. Importantly, the proposed method was successfully applied in the detection of RT tablet samples and with satisfactory results, showing the practical applications.

本研究以乙二胺四乙酸铜二钠（Na₂[Cu(EDTA)]）和盐酸羟胺为原料，于300 ℃下热解2 h，成功制备得到铜掺杂碳量子点（Cu-doped carbon quantum dots, Cu-CQDs）。所制备的Cu-CQDs通过紫外-可见（UV-Vis）光谱、傅里叶变换红外（Fourier transform infrared, FTIR）光谱、透射电子显微镜（transmission electron microscopy, TEM）、X射线光电子能谱（X-ray photoelectron spectroscopy, XPS）以及X射线衍射（X-ray diffraction, XRD）完成了系统表征。该Cu-CQDs展现出优异的荧光性能、较高的稳定性、激发依赖型发射特性，量子产率可达9.8%。尤为重要的是，基于所制备Cu-CQDs的荧光猝灭效应，本研究将合成的Cu-CQDs开发用于芦丁（rutin, RT）的传感检测。在0.1~15 µg·mL⁻¹的浓度区间内，Cu-CQDs的荧光猝灭强度与芦丁的不同浓度呈现出良好的线性关系，相关系数高达0.9959；检出限低至0.05 µg·mL⁻¹（信噪比S/N=3）。本研究探讨了该荧光猝灭的潜在作用机制，证实其为内滤效应（inner filter effect）。重要的是，所提出的检测方法已成功应用于芦丁片剂样品的检测，所得结果令人满意，展现出良好的实际应用价值。