Yuan Chunling, Qin Xiu, Xu Yuanjin, Shi Rui, Cheng Shiqi, Wang Yilin
School of Chemistry and Chemical Engineering, Guangxi University, Guangxi Key Laboratory of Electrochemical Energy Materials, Nanning 530004, China.
School of Chemistry and Chemical Engineering, Guangxi University, Guangxi Key Laboratory of Electrochemical Energy Materials, Nanning 530004, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Jun 5;254:119678. doi: 10.1016/j.saa.2021.119678. Epub 2021 Mar 10.
Fluorescent carbon quantum dots (CQDs), which showed excitation-dependent emission characteristics, were prepared using a facile hydrothermal method. The structure and optical properties of CQDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, UV-Vis spectroscopy, and fluorescence spectroscopy. These CQDs also showed peroxidase-like activity and could catalyze the HO-mediated oxidation of o-phenylenediamine (OPD) to form 2,3-diaminophenazine (DAP) with an absorption peak at 420 nm. DAP exhibited an obvious fluorescence emission at 550 nm under the excitation of 360 nm. On the other hand, it decreased the fluorescence of CQDs at 450 nm via inner filter effect. The experimental results indicated that the HO concentration affected the color of DAP and the fluorescence intensity of CQDs and DAP. Thus, a colorimetric and ratiometric fluorescence dual-signal method was established for measuring the concentrations of HO and uric acid (UA). The effects of pH, incubation temperature, incubation time, and OPD concentration on the response were investigated. Under the conditions of pH 7.5, temperature 50 °C, incubation time 30 min, and OPD 1.5 mM, the absorbance and fluorescence intensity ratio responses were linearly dependent on UA concentration ranging from 5.0 μM to 100 μM. The limits of detection were 0.7 and 0.5 μM with a colorimetric method and ratiometric fluorescence method, respectively. More importantly, this dual responsive method has been applied to the determination of UA in urine samples with satisfactory results.
采用简便的水热法制备了具有激发依赖发射特性的荧光碳量子点（CQDs）。通过透射电子显微镜、X射线光电子能谱、傅里叶变换红外光谱、紫外可见光谱和荧光光谱对CQDs的结构和光学性质进行了表征。这些CQDs还表现出类过氧化物酶活性，可催化HO介导的邻苯二胺（OPD）氧化形成2,3 - 二氨基吩嗪（DAP），其在420 nm处有吸收峰。DAP在360 nm激发下于550 nm处表现出明显的荧光发射。另一方面，它通过内滤效应降低了CQDs在450 nm处的荧光。实验结果表明，HO浓度影响DAP的颜色以及CQDs和DAP的荧光强度。因此，建立了一种比色和比率荧光双信号法来测定HO和尿酸（UA）的浓度。研究了pH、孵育温度、孵育时间和OPD浓度对响应的影响。在pH 7.5、温度50 °C、孵育时间30 min和OPD 1.5 mM的条件下，吸光度和荧光强度比响应与5.0 μM至100 μM范围内的UA浓度呈线性相关。比色法和比率荧光法的检测限分别为0.7和0.5 μM。更重要的是，这种双响应方法已应用于尿液样品中UA的测定，结果令人满意。
