氮掺杂碳点的开关型荧光传感器检测蔬菜中的生物硫醇

研究并建立一种开关型荧光传感器模型快速检测Hg2+和生物硫醇。以柠檬酸和尿素为前驱体,通过一锅水热法制备了氮掺杂碳点(N-CDs),并对其进行了表面形貌、紫外和荧光光谱以及表面基团表征的检测,以检测体系pH、Hg2+浓度、孵育时间(荧光猝灭和恢复时间)为单因素,优化检测生物硫醇的最佳条件,并在最优检测条件下建立相应的标准曲线。结果表明,N-CDs的最佳激发和发射峰分别是340和432 nm,量子产率(FLQY)为32.72%。优化得到谷胱甘肽(GSH)的最佳检测条件为pH=5.0,Hg2+浓度为200 μmol/L,460 s荧光猝灭和380 s荧光恢复,最佳检测半胱氨酸(Cys)条件为pH=5.6,Hg2+浓度为300 μmol/L,440 s荧光猝灭和400 s荧光恢复,在最优条件下该传感器对0~300 μmol/L的GSH和100~400 μmol/L的Cys具有线性响应,检测限(LOD)分别为2.56和3.46 μmol/L,加标回收率为80%~120%。以上结果表明该传感器对检测蔬菜中生物硫醇有较好的选择性和准确度,能为食品基质中生物硫醇的荧光快速检测提供一种新思路。

Detection of Biothiols in Vegetables by Switched Fluorescence Sensor with Nitrogen-Doped Carbon Dot

The study established a switchable fluorescent sensor for rapid detection of Hg^2+ and biothiols. Nitrogen-doped carbon dots(N-CDs)was prepared by citric acid and urea as processors through one-pot hydrothermal method. The surface morphology,ultraviolet/fluorescence spectra and surface group characterization were performed. The detection conditions of biothiols were optimized by using the pH of detection system,Hg^2+ concentration,and incubation time(fluorescence quenching and recovery time)as single factors and the corresponding standard curve was established under the optimal detection condition. The results showed that the optimal excitation and emission wavelength of N-CDs were 340 and 432 nm respectively,and the fluorescence quantum yield(FLQY)was 32.72%. The optimal detection conditions for glutathione(GSH)were pH=5.0,Hg^2+ concentration 200 μmol/L,fluorescence quenching of 460 s and fluorescence recovery of 380 s;for cysteine(Cys)were pH=5.6,Hg^2+ concentration 300 μmol/L,fluorescence quenching of 440 s and fluorescence recovery of 400 s. The sensor had a linear response to 0~300 μmol/L GSH and 100~400 μmol/L Cys,and the detection limit(LOD)was 2.56,3.46 μmol/L respectively under optimal conditions. The recoveries of this method in spiked samples were between 80% and 120%. These results indicated that the sensor showed good selectivity and accuracy for biothiols detection in vegetables,herein providing a new idea for the fast fluorescence detection of biothiols in food matrix.