荧光银纳米团簇的绿色合成及其性能研究

发布时间：2018-10-17 11:46

【摘要】：金属（如Au、Ag、Cu）纳米团簇是由几个至几十个原子组成的具有荧光性、水溶性的分子级聚集体。它因特有的量子尺寸效应、生物相容性好、光稳定性强、反聚合能力强、斯托克斯位移较大等特点，使其在生化传感器、新型催化剂、生物标记、环境检测等领域有着广泛的应用前景。但是目前对于金属纳米团簇的研究还存在一定的缺陷和不足。基于金属纳米团簇的高灵敏度和高选择性的分析方法有待提高，以及金属纳米团簇的高化学性能和在水溶液中不稳定等问题。因此，本论文主要以银纳米团簇为研究对象，建立了基于聚甲基丙烯酸（PMAA）模板的荧光银纳米团簇（AgNCs）在合成方法以及检测分析中存在的问题，并进行了相关性能的研究。主要研究内容如下：首先，成功合理地设计了以聚甲基丙烯酸（PMAA）为模板，采用日光照射法，一步合成了稳定性好、高发光性能的AgNCs。该方法快速、简单、易操作、对环境友好。同时，实验发现银纳米团簇作为一种荧光探针可以高选择性地和含巯基官能团的生物化合物（半胱氨酸）通过Ag-S共价键发生相互作用，导致银纳米团簇的聚集，形成没有荧光的银纳米颗粒，从而使PMAA-AgNCs的荧光被猝灭。PMAA-AgNCs的荧光强度随着生物巯基化合物（半胱氨酸）浓度的增大而降低，而其他常见氨基酸由于不含巯基官能团，并不能使银纳米团簇的荧光猝灭。银纳米团簇对半胱氨酸检测的线性范围为1~200nM,检出限为0.57nM。基于这一原理，建立了快速、简单、高灵敏和高选择性的检测生物巯基化合物的新方法。同时，研究了PMAA-AgNCs对革兰氏阴性细菌（大肠杆菌）的抑菌性能。结果表明所制备的PMAA-AgNCs对大肠杆菌的生长有明显的抑制作用。其次，基于此新方法合成的稳定性良好的银纳米团簇，提出一种新型的荧光“关-开”式信号增强传感策略,用于高选择性地定量检测药物美洛西林钠和L-抗坏血酸。在此，利用Hg2+作为荧光猝灭剂，当其与PMAA-AgNCs接触时会导致银纳米团簇的荧光发生猝灭，，而Hg2+又可以同药物与L-抗坏血酸进行特异性识别，通过配位作用和银纳米团簇表面负载的Hg2+发生络合反应生成一种络合产物，从而使PMAA-AgNCs的荧光信号得到“恢复”。PMAA-AgNCs的荧光“关开”现象，降低了方法的背景信号，提高了检测方法的灵敏性，也实现了高特异性识别。本方法快速、简单、灵敏度高、具有良好的检测线性关系，而且该研究为选择高灵敏度、高识别度的贵金属纳米团簇作为一种荧光探针用于生化检测开拓了新的思路。
[Abstract]:Metal (such as Au,Ag,Cu) nanoclusters are molecular aggregates with fluorescence and water solubility composed of several to dozens of atoms. Due to its unique quantum size effect, good biocompatibility, strong photostability, strong ability to reverse polymerization, and large Stokes shift, it is widely used in biochemical sensors, novel catalysts, biomarkers, and so on. Environmental detection and other fields have a wide range of application prospects. However, there are still some defects and shortcomings in the research of metal nanoclusters. Based on the high sensitivity and selectivity of metal nanoclusters, the high chemical properties and instability in aqueous solution of metal nanoclusters need to be improved. Therefore, in this thesis, silver nanoclusters were studied, and the problems in synthesis, detection and analysis of fluorescent silver nanoclusters based on polymethacrylate (PMAA) template were established, and the related properties were studied. The main research contents are as follows: firstly, AgNCs. with good stability and high luminescence performance was synthesized successfully and reasonably using polymethacrylate (PMAA) as template and sunlight irradiation method. The method is fast, simple, easy to operate and environmentally friendly. At the same time, it was found that silver nanoclusters, as a fluorescent probe, could interact with thiol functional compounds (cysteine) via Ag-S covalent bonds, which led to the aggregation of silver nanoclusters. The fluorescence intensity of PMAA-AgNCs decreases with the increase of the concentration of biological thiol compounds (cysteine), while other common amino acids are free of sulfhydryl functional groups. It can not quench the fluorescence of silver nanoclusters. The linear range for detection of cysteine in silver nanoclusters was 1 ~ 200 nm and the detection limit was 0.57 nm. Based on this principle, a rapid, simple, highly sensitive and highly selective method for the detection of biological thiol compounds has been established. At the same time, the inhibitory effect of PMAA-AgNCs on gram-negative bacteria (E. coli) was studied. The results showed that the PMAA-AgNCs could inhibit the growth of Escherichia coli. Secondly, based on the stable silver nanoclusters synthesized by the new method, a novel fluorescence "turn-on" signal enhancement sensing strategy is proposed for the quantitative detection of meloxicillin sodium and L-ascorbic acid. When Hg2 was used as a fluorescence quenching agent, the fluorescence of silver nanoclusters was quenched when it was in contact with PMAA-AgNCs, and Hg2 could be specifically identified with drugs and L-ascorbic acid. A complexation product is formed by the coordination reaction with Hg2 loaded on the surface of silver nanoclusters, which makes the fluorescence signal of PMAA-AgNCs "recover". The fluorescence of PMAA-AgNCs is "off" and the background signal of the method is reduced. The sensitivity of the detection method is improved, and the high specificity recognition is realized. The method is rapid, simple, sensitive, and has good linear relationship. Moreover, it opens up a new idea for the selection of noble metal nanoclusters with high sensitivity and recognition as a fluorescent probe for biochemical detection.
【学位授予单位】：淮北师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O614.122;TB383.1

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