半胱胺功能化CdTe量子点开关型荧光传感体系的构建及应用

发布时间：2018-08-22 16:15

【摘要】：量子点(Quantum dots,QDs)是由II-VI族和III-V族元素组成的一种零维半导体纳米晶体,具有不同与常规荧光染料的优异荧光特性,基于量子点的荧光传感分析一直以来是研究的热点。开关型荧光传感是目标分子与荧光猝灭剂之间特殊的分子识别作用而建立起来的一种分析方法。对目标的检测具有高度的选择性和灵敏度,是高灵敏高选择荧光传感器构建的主要设计策略。量子点表面的功能化基团是影响量子点传感性能的重要因素,半胱胺(Cysteamine,CA)是一种巯基胺类化合物,巯基能与量子点的中心金属原子配位,氨基赋予量子点较好的水溶性、表面正电性等较多的分子功能。本论文就以半胱胺(CA)作为修饰剂和稳定剂,通过水热法,合成CA功能化的Cd Te量子点(CA-CdTeQDs),基于特殊的发光性能构建了三种开关型荧光传感器,并通过实际样品的检测,探讨了所构建荧光传感器的实际应用可能性,所获结果对于高灵敏高选择荧光传感器的构建提供了方法学的参考和依据。具体内容如:(1)基于CA-CdTeQDs-Au NPs的开关型荧光传感器测定谷胱甘肽(GSH)以半胱胺(CA)作为稳定剂和修饰剂,碲粉为Te源,Cd Cl2为Cd源,合成CA-CdTeQDs,以柠檬酸钠作为稳定剂和还原剂合成了带负电的纳米金(Au NPs)。由于Au NPs的紫外-可见吸收光谱与CA-CdTeQDs的荧光光谱有较大部分的重叠,发生内滤光效应使CA-CdTeQDs荧光猝灭。Au NPs与GSH强的配位作用,使Au NPs从量子点周围得到释放;且GSH在检测条件下的正电性,使负电的Au NPs团聚,Au NPs可见吸收光谱红移,IFT过程受阻,CA-CdTeQDs荧光恢复。基于上述原理构建了检测谷胱甘肽的分子开关型荧光传感器。在最优的实验条件下,CA-CdTeQDs的荧光恢复程度与GSH浓度在6.7-40×104 nmol/L范围内呈线性关系,检测限为3.3 nmol/L。相对于报道的方法,该方法有更高的灵敏度和选择性,10倍的半胱氨酸和高半胱氨酸不干扰测定,可应用于血清中GSH的检测,为生物GSH的检测提供了高灵敏度高选择提供了方法学的参考和依据。(2)基于CA-CdTeQDs-Cu~(2+)开关型荧光传感器测定高半胱氨酸(Hcy)Cu~(2+)与CA-CdTeQDs发生相互作用,量子点表面状态发生改变,CA-CdTeQDs荧光猝灭。Hcy与Cu~(2+)有较强的配位作用,与CA-CdTeQDs发生竞争结合,使得Cu~(2+)与CA-CdTeQDs相互作用解除,荧光恢复。基于以上原理,构建了检测Hcy的荧光传感体系。在优化的实验条件下,体系的荧光恢复程度与Hcy的浓度在0.05-10μmol/L范围内呈现线性关系,检测限为10 nmol/L。相比文献的检测方法,该方法具有更好的选择性和灵敏度,较好地解决了结构类似物和样品中共存物谷胱甘肽和半胱氨酸的干扰,可用于生物血样中高半胱氨酸的选择性检测。(3)基于CA-CdTe QDs-PSS-甲基紫精(Mv~(2+))开关型荧光传感器测定L-抗坏血酸(AA)带正电的CA-CdTeQDs作为电子供体,与带正电的电子受体甲基紫精(Mv~(2+)),在带负电的阴离子聚合物聚苯乙烯磺酸钠(PSS)的桥梁作用下,发生分子间的电子转移,CA-CdTeQDs荧光猝灭。AA具有强的还原性,可以将Mv~(2+)还原成非电子受体Mv+,CA-CdTeQDs与Mv+之间的电子转移解除,CACdTeQDs的荧光恢复。基于以上原理构建了检测L-抗坏血酸的开关型荧光传感体系。在优化的实验条件下,L-抗坏血酸的浓度为0.8-20μmol/L时与整个体系的恢复程度成正比,检测限是50 nmol/L。相比报道的方法,该体系不仅具有较高的检测灵敏度,而且也有较好的选择性,10倍的GSH,Hcy和半胱氨酸均不干扰测定,可应用于血清和细胞中AA的检测。
[Abstract]:Quantum dots (QDs) are zero-dimensional semiconductor nanocrystals composed of II-VI and III-V elements, which have different fluorescence characteristics from conventional fluorescent dyes. Fluorescence sensing based on QDs has been a hot research topic. Switched fluorescence sensing is a special molecule between target molecule and fluorescent quenching agent. An analytical method based on recognition is developed. Target detection with high selectivity and sensitivity is the main design strategy for the construction of highly sensitive and selective fluorescent sensors. In this paper, cysteamine (CA) was used as modifier and stabilizer to synthesize CA-functionalized Cd Te quantum dots (CA-CdTeQDs) by hydrothermal method. Three kinds of open-ended Cd Te quantum dots (CA-CdTeQDs) were constructed based on their special luminescent properties. The practical application possibility of the fluorescence sensor is discussed by the detection of real samples. The results provide a methodological reference and basis for the construction of high sensitive and high selective fluorescence sensor. Specific contents are as follows: (1) The determination of glutathione (GSH) based on the switched fluorescence sensor CA-CdTeQDs-Au NPs. CA-CdTeQDs were synthesized with cysteamine (CA) as stabilizer and modifier, tellurium powder as Te source and Cd Cl2 as Cd source. Negatively charged gold nanoparticles (Au NPs) were synthesized with sodium citrate as stabilizer and reductant. The strong coordination between Au NPs and GSH results in the release of Au NPs from the surrounding quantum dots; the positive nature of GSH leads to the agglomeration of negatively charged Au NPs, the red shift of Au NPs visible absorption spectrum, the blockage of IFT process and the recovery of CA-CdTeQDs fluorescence. Based on the above principle, a molecular switched fluorescence sensor for detecting glutathione is constructed. Under the optimum experimental conditions, the fluorescence recovery of CA-CdTeQDs was linearly related to the concentration of GSH in the range of 6.7-40 *104 nmol/L, and the detection limit was 3.3 nmol/L. Compared with the reported method, this method has higher sensitivity and selectivity. Ten times of cysteine and homocysteine do not interfere with the determination of GSH in serum and can be applied to the detection of GSH in order to live. The detection of GSH provides a methodological reference and basis for high sensitivity and high selectivity. (2) The determination of homocysteine (Hcy) Cu ~ (2+) interacts with CA-CdTeQDs based on CA-CdTeQDs-Cu ~ (2+) switched fluorescence sensor, the surface state of quantum dots changes, and the fluorescence quenching of CA-CdTeQDs. Based on the above principle, a fluorescence sensing system for detecting Hcy was constructed. Under the optimized experimental conditions, the fluorescence recovery degree of the system showed a linear relationship with the concentration of Hcy in the range of 0.05-10 micromol/L, and the detection limit was 10 nmol/L. The method has better selectivity and sensitivity. It can solve the interference of glutathione and cysteine in structure analogue and sample. It can be used for selective detection of homocysteine in biological blood samples. (3) Determination of L-ascorbic acid (AA) by switched fluorescence sensor based on CA-CdTe QDs-PSS-methyl viologen (Mv~ (2+)) The fluorescence quenching of CA-CdTeQDs occurs when the positively charged CA-CdTeQDs and the positively charged electron acceptor methyl viologen (Mv~ (2+) are bridged by the negatively charged anionic polymer sodium polystyrene sulfonate (PSS). AA has strong reducibility and can reduce Mv~ (2+) to non-electron acceptors Mv+, CA-CdTeQDs. The fluorescence of CACdTeQDs was restored when the electron transfer between S and Mv+ was removed. A switched fluorescence sensor system for the detection of L-ascorbic acid was constructed based on the above principle. Under the optimized experimental conditions, the concentration of L-ascorbic acid was 0.8-20 micromol/L, which was proportional to the recovery degree of the whole system, and the detection limit was 50 nmol/L. It has not only high sensitivity but also good selectivity. Ten times of GSH, Hcy and cysteine do not interfere with the determination of AA in serum and cells.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.3;TP212

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