微纳米结构SERS基底的制备及物性研究

发布时间：2018-02-26 13:34

  本文关键词： 表面增强拉曼散射(SERS) 氧化锌纳米梳阵列(ZnO-NC) 银纳米枝状晶(Ag dendrites) 单链DNA(ss-DNA) 金纳米颗粒 时域有限差分(FDTD)　出处：《北京化工大学》2016年硕士论文　论文类型：学位论文

【摘要】：拉曼散射是因为光入射到介质表面时,由于入射光与分子有互相作用,从而导致的入射光频率发生改变的一种散射现象,也叫拉曼效应。拉曼散射光谱技术可以提供很多有用的信息,例如,可以给出分子振动的固有频率,可以得知分子结构的对称性信息以及分子内部的作用力等等。由于拉曼光谱技术的一些特点,它常常被称之为分子的“指纹谱”。但是,在发展初期,拉曼光谱没有被广泛的认识和使用。主要是由于分子的拉曼散射过程非常弱,散射强度不够。这直接导致物质的拉曼信号在实际应用的时候达不到灵敏度的要求。因此,表面增强拉曼散射(Surface Enhanced Raman Scattering, SERS)技术的研究逐渐被人们关注和重视。SERS技术是一种高效的光谱检测技术。从根本上讨论的话,一方面,SERS光谱技术是由于电磁增强,另一方面是基底表面吸附分子与基底之间的电荷转移构成拉曼增强的另一部分活性点,也就是化学增强。这两者共同构成了拉曼光谱的增强原理。SERS增强效果用增强因子(Enhancement factor, EF)来表示,一般可以达到103-107。因此,SERS光谱技术具有非常高的灵敏度,成为定性以及定量检测物质的又一个有力途径。SERS光谱技术由于具备了无损检测、制样简单、快速检测等优点,同时克服了拉曼光谱信号强度低的问题,对于它的应用性探究得到了广泛的关注,被广泛应用于很多领域。目前,SERS光谱技术被广泛用于有毒残留物质的痕量检测、化学反应过程的实时监测以及对生物领域的一些分子的定量检测从而对整个生物反应过程进行调控等等。同时,微纳米技术的发展为多种形貌的,性能优良的SERS基底的制备提供了可能性。目前,主要的研究方向包括：SERS基底结构设计和制备,SERS基底的性能测试、性能优化以及增强机制的讨论,基底的功能化修饰、特异性结合及其应用等等。本论文以对某些特定性质的有毒有害物质分子的痕量检测、生物分子检测等为应用方向,设计、制备、表征了几种高“热点”密度的微纳米结构的SERS基底：硅基氧化锌纳米梳阵列修饰银纳米颗粒基底(ZnO-Nanocomb decorated with Ag nanoparticles, ZnO-NC decorated with AgNPs)、银纳米枝状晶包裹金膜基底(Ag@Au core-shell dendrites)以及金包银和壳结构枝状晶表面修饰单链DNA(single-stranded DNA, ss-DNA)的特异性基底。同时设计了DNA连接金纳米颗粒的二聚体结构,针对热点区域性质进行研究,从理论和实验的对比结果上来对热点区域的SERS性能变化进行探究。论文中,对几类基底的形貌结构、SERS特性、重复利用性能、时间稳定性、以及多种应用性能等方面进行了详细的测试表征和结果分析。本论文的具体研究内容如下：一、氧化锌纳米梳阵列修饰银纳米颗粒,纳米银枝状晶包裹金膜以及DNA连接金纳米颗粒的二聚体结构的多种基底的制备。以及针对不同的基底的应用对基底进行一些表面修饰。首先,制备不同的基底使用了不一样的实验方法。这些实验方法各有优劣。对于基底的选择,应该综合考虑从制备方法、基底结构、到SERS性能等多方面的因素。首先,氧化锌纳米梳阵列修饰银纳米颗粒基底涉及到多种实验方法,包括：水热腐蚀、化学气相沉积(chemical vapor deposition, CVD)和浸渍还原法,经过这一系列的制备过程才能得到最终要使用的基底,综合来看,该基底的制备实验方法较为复杂,消耗时间长。但是,得到的基底具有比较好的规则结构,拉曼测试信号的再现性好,增强性能好；为了简化实验过程,设计了纳米银枝状晶包裹金膜结构的SERS基底,阵列结构比较规则,制备过程只涉及到水热反应,同时,由于表面包覆了金膜,基底具备了较好的稳定性和生物兼容性；最后,为了从理论上解释“热点”区域的SERS性能变化,设计了DNA连接金纳米颗粒的二聚体结构,SERS信号分子修饰在热点区域不同位置有不同强度的拉曼信号出现,组成二聚体的金纳米颗粒的直径尺寸也对SERS信号强度有很大的影响,根据对实验结果的分析,结合有限时域差分软件(Finite Difference Time Domain, FDTD)方法,从理论和实验两方面互相验证结果的可靠性,探究了分子位置,颗粒尺寸等因素对热点区域信号强度的影响。二、多种SERS信号分子包括：罗丹明6G(Rhodamine 6G, R6G)、结晶紫(Crystal violet, CV)以及一些污染物质如镉离子(Cd2+)等作为测试物质,系统测试并且分析基底的SERS性能、时间稳定性、均匀性、重复利用性、生物兼容性以及待测物的定量关系曲线等。根据对表征结果的系统分析,确定基底的应用领域或者针对应用前景,对基底进行进一步的修饰或优化。三、SERS增强机制的研究。依据基底的微观结构特征,采用FDTD模拟的方法对几种不同结构的基底进行模拟,模拟出随时间变化基底表面的空间电磁场分布情况。从结果可见,电磁场增强的区域即“热点”(hot spots)是SERS信号来源的主要区域。为了更进一步的了解热点区域的不同位置SERS强度的变化,我们设计了DNA链连接两个金纳米颗粒这一最简单二聚体结构构筑热点区域。进一步了解热点区域的信号变化有利于我们下一步设计基底结构以及更加有效地了解间距、尺寸、信号分子的位置等因素对SERS信号的直接影响。
[Abstract]:Raman scattering is because light incident on the surface, due to the incident light and the molecules interact with each other, a scattering of incident light frequency as a result of the change, also called the Raman effect. Technology of Raman spectrum can provide useful information, for example, can give the natural frequency of molecular vibration, the molecular force the structure of information symmetry and molecular internal and so on. Because of some characteristics of Raman spectroscopy, it is often referred to as the molecular "fingerprint". However, in the early stages of development, no Raman spectroscopy to be recognized and widely used. Is mainly due to the Raman scattering process of molecules is very weak, the scattering intensity is not enough. This is a direct result of the Raman signal of material is not up to the requirements of the sensitivity of the actual application of time. Therefore, the surface enhanced Raman scattering (Surface Enhanced Raman Scattering, SERS) technology The research has been gradually paid attention to.SERS technology is a kind of efficient spectrum detection technology. Discussed fundamentally, on the one hand, SERS spectroscopy is due to electromagnetic enhancement, on the other hand is the charge between the molecular adsorption substrate surface and the substrate transfer constitutes another part of active site of Raman enhancement is chemical. Enhanced. The two jointlyform enhancement enhancement factor.SERS enhancement effect principle of Raman spectrum (Enhancement factor, EF) that can reach 103-107. so SERS spectroscopy has very high sensitivity, a qualitative and quantitative detection of material and a powerful way of.SERS spectroscopy with a nondestructive detection system simple, rapid detection etc., and overcomes the problem of low signal intensity of Raman spectrum, to explore its application have attracted much attention and has been widely used In many fields. At present, SERS spectroscopy is widely used for the detection of toxic trace residues, quantitative detection of real-time monitoring of chemical reaction process and some molecules of biological field and the regulation of the biological process and so on. At the same time, the development of micro nanotechnology for various shapes, excellent performance for SERS substrate provides possibility. At present, the main research directions include: SERS basement structure design and preparation, performance test of SERS substrate, discuss the performance optimization and enhancement mechanism, functional modification of the substrate, the specific binding and application and so on. In this paper, some special properties of trace toxic and harmful substances in molecular detection. The detection of biological molecules such as application, design, preparation, SERS substrate micro nano structure characterization of high density "hot spots": Zinc Oxide silicon nano comb array Modified silver nanoparticles (ZnO-Nanocomb decorated with Ag nanoparticles, ZnO-NC decorated with AgNPs), nano silver dendrite wrapped gold substrate (Ag@Au core-shell dendrites) and silver wrapped in gold and shell dendrite surface modified single stranded DNA (single-stranded DNA ss-DNA) the specific substrate. Two dimeric structure is also designed the DNA connection of gold nanoparticles, to research the regional hot property, to explore from the comparison between theoretical and experimental results on variation of SERS performance in hot area. In this paper, the morphology structure of several kinds of substrate SERS characteristics, performance, repeated use of time stability, and a variety of application performance are analyzed and tested characterization and detailed results. The specific contents of this paper are as follows: first, Zinc Oxide nanocombs array modified silver nanoparticles, nano silver dendrite gold film and DNA Poly two connected with the preparation of gold nanoparticles of various substrate structure. And the application of different substrate on the substrate of surface modification. Firstly, the basal system used different experimental methods were not the same. These experimental methods have advantages and disadvantages. For substrate selection, should be considered from the preparation method the basement structure, factors to SERS, performance and other aspects. First of all, Zinc Oxide nanocombs relates to arrays of silver nanoparticles modified substrate to a variety of experimental methods, including hydrothermal corrosion, chemical vapor deposition (chemical vapor, deposition, CVD) and impregnation method, after a series of preparation process to get the substrate. To use the comprehensive view, experiment method of preparing the substrate is complex, long time consumption. However, the rule base has a good structure, Raman test signal reproducibility, performance enhancement Good; in order to simplify the experimental process, the design of SERS base nano silver dendrite inclusion gold membrane structure, array structure comparison rules, preparation process involves the hydrothermal reaction, at the same time, because the surface coating gold film, substrate with good biological compatibility and stability; finally, in order to explain the changes of SERS performance hot spots "in theory, two dimeric structure design of the DNA connection of gold nanoparticles, SERS signal molecule modification in hot regions at different locations with different intensity of Raman signal, consisting of two poly gold nanoparticles of the diameter size has great effect on the signal intensity of SERS, according to the analysis of the experiment the results, combined with the finite difference time domain software (Finite Difference Time Domain, FDTD) method, the reliability from two aspects of theory and experiment results verify each other, to explore the molecular position, particle size and other factors on heat Effect of signal intensity. Two, a variety of SERS signal molecules including: Luo Danming 6G (Rhodamine 6G R6G), crystal violet (Crystal violet, CV) as well as some pollutants such as cadmium ion (Cd2+) as test material, system testing and performance analysis of SERS, the time base stability, uniformity, reuse of biological compatibility and analyte quantitative curves. According to systematic analysis on the characterization results, determine the application base or for application for further modification or optimization of substrate. Three, research on SERS enhancement mechanism. Based on the microstructure characteristics of the substrate, using the FDTD simulation method for several the basement of different structure simulation, simulate the spatial distribution of electromagnetic field changes with time the surface of the substrate. From the results it can be seen that the electromagnetic enhancement region that is the "hot spot" (hot spots) is a SERS signal source The main area. In order to further understand the change of different positions of SERS intensity of regional hot spots, we design a DNA chain connecting two gold nanoparticles the simplest two dimer structure hotspots. To further understand the signal changes of regional hot spots is conducive to our next design of basement structure and more effective understanding of space the size, location and other factors directly affect the signal molecules of SERS signal.

【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O657.37
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本文编号：1538236