氮掺杂碳量子点的合成及作为荧光探针对Hg2+的检测

摘要

与传统量子点相比,碳量子点作为一种新型的荧光碳纳米材料,由于其良好的生物相容性、易于表面功能化、低毒性等优点受到了广泛关注。采用柠檬酸为碳源,氨水为氮源,热解法制备出水溶性好的氮掺杂碳量子点(NCDs)。透射电镜(TEM)观察NCDs的粒径在3 nm左右；X射线光电子能谱(XPS)和傅里叶红外光谱(FIIR)证明 NCDs的表面被羧基、氨基、羟基、羰基等官能团功能化,说明 NCDs 有很好的水溶性。研究还发现 Hg2+对 NCDs的荧光有良好的猝灭作用,可作为荧光探针检测水中 Hg2+含量。在 PBS缓冲液中(0.1 mol·L-1 pH 7.0),NCDs的荧光猝灭率(F/F0)与汞离子浓度在0.001~0.1μmol·L-1之间存在良好的线性关系,检出限为2.1 nmol·L-1。该方法灵敏度高、选择性好、方法简便,可应用于 Hg2+快速、灵敏的检测。%Compared with traditional quantum dots,carbon quantum dots (CQDs)have aroused tremendous research interest among scientists as new fluorescent carbon nanomaterials due to their unique properties (easy surface functionalization,good bio-compatibility,and low toxicity).The nitrogen-doped carbon quantum dots (NCDs)was synthesized with one-step hydrothermal treatment with citric acid as carbon source,and ammonia as nitrogen source.The obtained NCDs exhibited excellent water-solu-bility and high stability.High-resolution Transmission electron microscopy (HRTEM)image showed that the diameter of parti-cles was about 3nm.Fourier transform infrared (FIIR)and X-ray photoelectron spectroscopy (XPS)spectra analysis demonstra-ted that the NCDs are functionalized with hydroxyl,amino,carbonyl,and carboxylic acid groups,which indicated NCDs has better water-solubility.It was further demonstrated that such NCDs can serve as effective fluorescent sensing platform for Hg2+ ions detection with sensitivity and selectivity.In a PBS butter solution (0.1 mol·L-1 pH 7.0),the fluorescence quenching ratio (F/F0 )indicated linear responses with Hg2+ concentration ranging from 0.001 to 0.1 μmol·L-1 ,with the detection limit of 2.1 nmol·L-1 .The fluorescence technique was superior in terms of sensitivity,selectivity and simplicity.It was successfully applied to determination of Hg2+ in samples.