CdSe半导体纳米晶体在检测水溶液pH值的应用

发布时间：2018-05-21 14:56

本文选题：量子点 + pH检测　；参考：《上海应用技术大学》2017年硕士论文

【摘要】：在化学、生物医学、环境等各种领域,监控氢离子(H+)浓度是非常重要的,发展一种快速检测pH值的方法是非常有意义的。在荧光分析领域,凭借着成熟、简便的合成方法和独特的发光性质,半导体纳米晶作为替代有机荧光基团的替代者己经崭露头角。本论文在调研文献的基础上,设计并合成了两种基于CdSe/ZnS量子点的pH荧光探针,对其性能和检测机理进行了研究,主要研究内容包括以下两个部分:第一部分以发射峰为610 nm的CdSe/ZnS核壳量子点为荧光团,对巯基苯胺(pATP)作为氢离子敏感的功能配体,通过在量子点表面进行配体交换制得一种荧光恢复型pH荧光探针(pATP-QDs),并利用各种手段进行表征,如紫外吸收光谱、傅里叶变换红外光谱、荧光光谱、荧光寿命等。由于pATP是一个空穴受体,pATP-QDs表现出弱荧光。作为有机碱,pATP很容易接受H+被质子化,质子化后的结构(pATP-H+)改变pATP原有的最高占有分子轨道(HOMO)的能级,从而抑制了量子点的空穴转移过程,量子点的荧光恢复。荧光"off-on"模式、高的量子产率、pATP-H+稳定性让pATP-QDs表现出了良好的pH检测性能。在优化条件下,荧光响应和pH值(pH 3.2～6.0)之间具有好的线性关系。此外,pATP-QDs对H+表现出了高的选择性表现出了高的选择性并成功的应用到实际水样的pH检测。第二部分是以发射峰为581 nm的CdSe/ZnS核壳量子点为荧光团,用对巯基苯酚(HOPhSH)进行表面配体交换过程后去质子化得到pH探针(-OPhS-QDs)。-OPhS-QDs能够作为一种选择性的荧光"on-off"的荧光探针用于水溶液中pH的检测。-OPhS-QDs在近中性溶液中表现出强荧光。根据路易斯酸碱理论,量子点表面的酚盐(-OPhS)对H+敏感,-OPhS-QDs在一定的酸性溶液中能够与H+反应生成HOPhS-QDs。而HOPhS是高效的空穴受体,结果使得量子点的荧光淬灭。在优化条件下,在pH 3.0～5.2范围,荧光响应和pH值之间具有好的线性关系。此外,-OPhS-QDs对H+表现出了高的选择性并成功的应用到实样的pH检测。
[Abstract]:In chemistry, biomedicine, environment and other fields, it is very important to monitor the concentration of hydrogen ion (H), so it is very important to develop a rapid method to detect pH value. In the field of fluorescence analysis, semiconductor nanocrystals have emerged as substitutes for organic fluorescent groups due to their mature, simple synthesis methods and unique luminescent properties. In this paper, two kinds of pH fluorescence probes based on CdSe/ZnS quantum dots are designed and synthesized, and their properties and detection mechanism are studied. The main research contents include the following two parts: in the first part, the CdSe/ZnS core-shell quantum dots with emission peak of 610nm were used as fluorescence groups, and p-mercaptoaniline pATP was used as the hydrogen-ion-sensitive functional ligand. A fluorescence recovery pH fluorescence probe pATP-QDsN was prepared by ligand exchange on the surface of quantum dots, and characterized by various methods, such as UV absorption spectrum, Fourier transform infrared spectroscopy, fluorescence lifetime and so on. Because pATP is a hole receptor, pATP-QDs exhibit weak fluorescence. As an organic base, it is easy to accept the protonation of H, and the protonated structure (pATP-H) changes the energy level of the original highest occupied molecular orbital of pATP, which inhibits the hole transfer process of quantum dots and the fluorescence recovery of quantum dots. Fluorescence "off-on" mode, high quantum yield and pATP-H stability make pATP-QDs have good pH detection performance. Under the optimized conditions, there was a good linear relationship between the fluorescence response and pH value (pH 3.2 ~ 6.0). In addition, pATP-QDs showed high selectivity to H and were successfully applied to the pH detection of real water samples. In the second part, CdSe/ZnS core-shell quantum dots with emission peak of 581nm are used as fluorescence groups. The pH probe (-OPhS-QDsN. -OPhS-QDs) can be used as a selective fluorescent "on-off" fluorescence probe to detect pH in aqueous solution. OPhS-QDs show strong fluorescence in near-neutral solution. According to Lewis acid-base theory, the phenolic salts on the surface of quantum dots can react with H to form HOPhS-QDs in a certain acid solution. HOPhS is an efficient hole receptor, resulting in fluorescence quenching of quantum dots. Under the optimized conditions, there is a good linear relationship between the fluorescence response and pH value in the range of pH 3.0 ~ 5.2. In addition, OPhS-QDs showed high selectivity to H and were successfully applied to the pH detection of real samples.
【学位授予单位】：上海应用技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.3;TB383.1

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