锌掺杂碳量子点“关-开”型荧光探针检测果蔬中谷胱甘肽的研究

Determination of Glutathione in Fruits and Vegetables Based on an “Off-On” Type Fluorescent Probe with Zinc-doped Carbon Quantum Dots

以柠檬酸、乙二胺和乙酸锌为前体,采用一步水热法制备了一种稳定的、高荧光量子产率的水溶性锌掺杂碳量子点(Zn-CQDs)。通过透射电子显微镜(TEM)、X射线衍射(XRD)、傅立叶红外光谱(FTIR)、紫外-可见吸收光谱(UV-Vis)、荧光光谱对Zn-CQDs的结构和光学性能进行了表征。研究表明,Cu^(2+)对Zn-CQDs的荧光产生猝灭,体系的荧光信号处于"关闭"状态,还原型谷胱甘肽(GSH)的存在,使Zn-CQDs-Cu^(2+)体系的荧光得以恢复,体系的荧光信号处于"打开"状态。由此构建了"关-开"型荧光探针用于谷胱甘肽(GSH)的选择性、高灵敏检测。探究了反应p H值和反应时间对荧光恢复体系的影响,同时考察了果蔬中常见的有机小分子和离子对Zn-CQDs-Cu^(2+)体系荧光强度的影响,在最佳实验条件下,GSH浓度在0. 05～80μmol/L内与Zn-CQDs荧光恢复率呈线性关系,检出限达63 nmol/L。将该探针用于果蔬中GSH的检测,样品的加标回收率为98. 6%～101%,相对标准偏差为1. 8%～3. 1%,结果令人满意。

An“off-on”type fluorescent probe with zinc-doped carbon quantum dots(Zn-CQDs)was established for the selective and sensitive detection of glutathione(GSH).A stable and water-soluble Zn-CQDs with high fluorescence quantum yield were prepared by one-step hydrothermal method using citric acid,ethylenediamine and zinc acetate as precursors.The structures and optical properties of the Zn-CQDs were characterized by transmission electron microscopy(TEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),ultraviolet-visible absorption spectroscopy(UV-Vis)and fluorescence spectroscopy.Results showed that the fluorescence of Zn-CQDs was quenched by Cu^2+,the fluorescence signal of the system was in the“off”state,while the fluorescence of Zn-CQDs-Cu^2+system was recovered because of the presence of reduced glutathione(GSH),and the fluorescence signal of the system was in the“on”state.The effects of pH value and reaction time on the fluorescence recovery system were investigated.The effects of small organic molecules and ions in fruits and vegetables on the fluorescence intensity of Zn-CQDs-Cu^2+system were also investigated.Under the optimal conditions,the fluorescence recovery rate of Zn-CQDs was linearly correlated with the concentration of GSH in the range of 0.05-80μmol/L with the detection limit of 63 nmol/L.The probe was applied in the detection of GSH in fruits and vegetables with the recoveries of 98.6%-101%and the relative standard deviations(RSD)of 1.8%-3.1%,and the results were satisfactory.