该文以柠檬酸、L-半胱氨酸(L-Cys)和邻苯二胺(OPD)为前体通过一步水热法分别合成了蓝光碳点(B-CDs)与黄光碳点(Y-CDs),将两者杂化形成双碳点(d-CDs),并基于该d-CDs构建了快速检测环境水样中Ag+的可视化比率荧光传感器.采用透射电子显微镜、红外光谱、X射线光电子能谱、紫外吸收光谱、荧光光谱对d-CDs的结构和光学性能进行表征.考察了pH值、反应温度、孵育时间等因素对传感器检测效果的影响并进行了优化.d-CDs呈球形,分散性好且分布均匀,平均粒径为2.14 nm,含有巯基和芳香环结构,并存在大量的羟基和羧基基团.Ag+能与d-CDs表面的官能团发生官能团配位形成d-CDs/Ag+复合物,并可通过光致能量转移(PET)猝灭d-CDs的蓝色荧光.另外Ag+能够与d-CDs含有的巯基结合产生絮凝物.随着蓝色荧光的减弱,体系呈现出黄色荧光增强的现象.该传感器在Ag+浓度0~40 μmol/L范围内呈良好的线性响应,相关系数(r2)为0.996 7,检出限(LOD)为1.26 μmol/L,加标回收率为98.2%~105%,相对标准偏差(RSD)为0.49%~3.8%.该方法具有快速、简便、灵敏度和可靠性高的优势,并可实现环境水样中Ag+的可视化半定量检测.
In this work,blue carbon dots(B-CDs)and yellow carbon dots(Y-CDs)were synthe-sized through a hydrothermal method using citric acid,L-cysteine(L-Cys)and o-phenylenediamine(OPD)as precursors respectively,then hybridized dual carbon dots to form a visual ratiometric fluo-rescent sensor(d-CDs)for the rapid detection of Ag+ in environmental water samples.The structural and optical properties of d-CDs were characterized using transmission electron microscope(TEM),Fourier transform infrared(FTIR),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),ultraviolet absorption spectroscopy and fluorescence spectroscopy.The effects of pH,reac-tion temperature and incubation time of the sensor were investigated and optimized.The d-CDs are spherical with an average particle size of 2.14 nm,which were well dispersed and uniformly distrib-uted in the solution.The d-CDs contain mercapto and aromatic ring structures and a large number of hydroxyl and carboxyl groups,which can induce d-CDs/Ag+ complexes in the presence of Ag+ and quenched the blue fluorescence of d-CDs by photoinduced energy transfer(PET).As the blue fluores-cence decreases,yellow fluorescence significant increases in the ratiometric fluorescent system.The sensor showed good linear response in the range of Ag+ concentration 0-40 μmol/L with the r2 of 0.996 7 and the limit of detection(LOD)of 1.26 μmol/L.The spiked recoveries were 98.2%-105%with the rel-ative standard deviations of 0.49%-3.8%in practical test.The method is rapid,simple,sensitive and reliable,and can realize the visual semi-quantitative detection of Ag+ in environmental water samples.