目标物诱导的量子点荧光淬灭及其应用
发布时间：2019-02-16 02:47
【摘要】：目前,量子点因具有优良的荧光性能而得到了广泛的关注,在无机离子检测、药物分析等领域应用广泛。本文合成了CdS量子点和碳点,并将其成功地应用于环境中污染物的检测。首先,实验发现,全氟辛酸(Perfluorooctanoic acid,PFOA)能选择性淬灭巯基丙酸修饰的CdS量子点荧光。其淬灭机理是PFOA的羧基和CdS量子点表面的羧基相结合后吸附至量子点表面,再通过PFOA的氟原子之间的相互作用(氟-氟亲和作用)使量子点团聚,导致其荧光发生淬灭。据此建立了检测PFOA的荧光新方法。在优化条件下,PFOA浓度在0.5~40μmol L-1范围内与体系的荧光淬灭效率(F/F0)之间存在良好的线性关系,检出限为0.3μmol L-1。采用此法对纺织品样品中PFOA的含量进行了测定,其加标回收率在95.0%~113.0%之间。其次,发现在pH为4.0的醋酸盐缓冲溶液中,Fe3+对以苯硼酸为前驱体合成的富含羟基的碳点的荧光有很明显的淬灭作用,而其它金属离子不能淬灭其荧光。研究表明,其淬灭过程包括动态和静态淬灭两种方式:Fe3+通过静电引力吸附到碳点表面,由于Fe3+是很强的电子接受体,吸附于碳点表面的Fe3+可接受碳点受光激发产生的光生电子而被还原为Fe2+,与此同时Fe3+又可与碳点表面的羟基结合使碳点团聚,这两种作用均导致碳点的荧光淬灭。据此建立了选择性测定铁的荧光方法。Fe3+浓度在1.0~250?mol L-1范围内与体系的荧光淬灭效率(ln[F0/F])有良好的线性关系,检出限为0.4?mol L-1。本法用于奶粉中铁含量的测定,结果令人满意。此外,根据Fe3+可大幅度淬灭碳点的荧光,而Fe2+不能淬灭碳点的荧光之特性,利用Feton反应,使用H2O2将Fe2+氧化为Fe3+,建立了一种基于Fe3+淬灭碳点荧光而间接测定H2O2的新方法。该方法的线性范围为0.7~500?mol L-1,检出限为0.2?mol L-1。采用此方法测定了一次性筷子中H2O2的残留量,结果与钛盐比色法的测定结果相符合。另外,还发现EDTA能淬灭碳点-Fe2+混合体系的荧光,据此建立了一种测定EDTA的新方法。该方法的线性范围为1.0~150?mol L-1,检出限为0.4?mol L-1。采用此法测定了自来水和湖水中EDTA的含量,其回收率在95.2%~106.5%之间。
[Abstract]:At present, quantum dots (QDs) have been widely used in inorganic ion detection, drug analysis and other fields because of their excellent fluorescence properties. CdS quantum dots and carbon dots have been synthesized and successfully applied to the detection of pollutants in the environment. Firstly, it was found that perfluorooctanoic acid (Perfluorooctanoic acid,PFOA) can selectively quench the fluorescence of CdS quantum dots modified by mercaptopropionic acid. The mechanism of quenching is that the carboxyl group of PFOA and the carboxyl group on the surface of CdS quantum dot are adsorbed to the surface of quantum dot, and then the fluorine atom interaction (fluorine-fluorine affinity) of PFOA makes the quantum dot agglomerate, resulting in the fluorescence quenching of the quantum dot. A new fluorescence method for the detection of PFOA was established. Under the optimum conditions, there is a good linear relationship between the concentration of PFOA in the range of 0.5 渭 mol L-1 and the fluorescence quenching efficiency (F/F0) of the system, and the detection limit is 0.3 渭 mol L-1. The content of PFOA in textile samples was determined by this method. The recoveries of PFOA in textile samples were between 95.0% and 113.0%. Secondly, it was found that in the acetate buffer solution with pH 4.0, Fe3 had obvious quenching effect on the hydroxyl rich carbon point synthesized from phenylboric acid, but other metal ions could not quench the fluorescence. The results show that the quenching process consists of dynamic and static quenching: Fe3 is adsorbed to the surface of carbon point by electrostatic gravitation, because Fe3 is a very strong electron acceptor. The Fe3 adsorbed on the surface of the carbon point can be reduced to Fe2 by photoinduced electrons generated by the carbon point. At the same time, the Fe3 can combine with the hydroxyl group on the surface of the carbon point to make the carbon point agglomerate. Both of these actions lead to the fluorescence quenching of the carbon point. A fluorescence method for the selective determination of iron was established. The fluorescence quenching efficiency (ln [F _ 0 / F]) of the system was linear in the range of 1.0~250?mol L ~ (-1) for Fe3, and the detection limit was 0.4?mol L ~ (-1). The method has been applied to the determination of iron in milk powder with satisfactory results. In addition, according to the characteristic that Fe3 can greatly quench the fluorescence of carbon point, but Fe2 can not quench the fluorescence of carbon point, using Feton reaction, Fe2 is oxidized to Fe3 by H2O2, and a new method for indirect determination of H2O2 based on Fe3 quenching carbon point fluorescence is established. The linear range of the method is 0.7~500?mol L -1 and the detection limit is 0.2?mol L -1. The residue of H2O2 in disposable chopsticks was determined by this method. The results were in agreement with the results of titanium salt colorimetry. In addition, it was found that EDTA can quench the fluorescence of the mixture of carbon point and Fe2, and a new method for the determination of EDTA was established. The linear range of the method is 1.0~150?mol L -1 and the detection limit is 0.4?mol L -1. This method was used to determine the content of EDTA in tap water and lake water. The recovery was between 95.2% and 106.5%.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O657.3;X830.2
[Abstract]:At present, quantum dots (QDs) have been widely used in inorganic ion detection, drug analysis and other fields because of their excellent fluorescence properties. CdS quantum dots and carbon dots have been synthesized and successfully applied to the detection of pollutants in the environment. Firstly, it was found that perfluorooctanoic acid (Perfluorooctanoic acid,PFOA) can selectively quench the fluorescence of CdS quantum dots modified by mercaptopropionic acid. The mechanism of quenching is that the carboxyl group of PFOA and the carboxyl group on the surface of CdS quantum dot are adsorbed to the surface of quantum dot, and then the fluorine atom interaction (fluorine-fluorine affinity) of PFOA makes the quantum dot agglomerate, resulting in the fluorescence quenching of the quantum dot. A new fluorescence method for the detection of PFOA was established. Under the optimum conditions, there is a good linear relationship between the concentration of PFOA in the range of 0.5 渭 mol L-1 and the fluorescence quenching efficiency (F/F0) of the system, and the detection limit is 0.3 渭 mol L-1. The content of PFOA in textile samples was determined by this method. The recoveries of PFOA in textile samples were between 95.0% and 113.0%. Secondly, it was found that in the acetate buffer solution with pH 4.0, Fe3 had obvious quenching effect on the hydroxyl rich carbon point synthesized from phenylboric acid, but other metal ions could not quench the fluorescence. The results show that the quenching process consists of dynamic and static quenching: Fe3 is adsorbed to the surface of carbon point by electrostatic gravitation, because Fe3 is a very strong electron acceptor. The Fe3 adsorbed on the surface of the carbon point can be reduced to Fe2 by photoinduced electrons generated by the carbon point. At the same time, the Fe3 can combine with the hydroxyl group on the surface of the carbon point to make the carbon point agglomerate. Both of these actions lead to the fluorescence quenching of the carbon point. A fluorescence method for the selective determination of iron was established. The fluorescence quenching efficiency (ln [F _ 0 / F]) of the system was linear in the range of 1.0~250?mol L ~ (-1) for Fe3, and the detection limit was 0.4?mol L ~ (-1). The method has been applied to the determination of iron in milk powder with satisfactory results. In addition, according to the characteristic that Fe3 can greatly quench the fluorescence of carbon point, but Fe2 can not quench the fluorescence of carbon point, using Feton reaction, Fe2 is oxidized to Fe3 by H2O2, and a new method for indirect determination of H2O2 based on Fe3 quenching carbon point fluorescence is established. The linear range of the method is 0.7~500?mol L -1 and the detection limit is 0.2?mol L -1. The residue of H2O2 in disposable chopsticks was determined by this method. The results were in agreement with the results of titanium salt colorimetry. In addition, it was found that EDTA can quench the fluorescence of the mixture of carbon point and Fe2, and a new method for the determination of EDTA was established. The linear range of the method is 1.0~150?mol L -1 and the detection limit is 0.4?mol L -1. This method was used to determine the content of EDTA in tap water and lake water. The recovery was between 95.2% and 106.5%.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O657.3;X830.2
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