DNA纳米结构介导的金属纳米粒子组装及其表面增强拉曼研究

发布时间：2018-04-29 17:49

本文选题：DNA折纸 + 自组装　；参考：《南京邮电大学》2017年硕士论文

【摘要】：由于金属纳米颗粒具有独特的光学性能,金属纳米颗粒的组装吸引了人们的广泛关注。不同化学成分,不同形状,不同尺寸的金属纳米结构被精确的组装形成具有等离子体共振效应(plasmonic resonance)的纳米结构。这些纳米结构表现出独特的圆二色性(CD),表面增强拉曼(SERS)以及紫外(UV-VIS)等光谱特征。这些具有等离子体共振效应的纳米结构能够被广泛的应用在能量收集和生物传感等方面。金属纳米结构组装体在以往的研究中,一般采用自上而下的刻蚀方法制备。然而该方法成本较高,而且难于制备诸如三维组装体等较为复杂的结构。以DNA为基础的自组装技术提供了一种自下而上的快速组装方法来构建高度协调的纳米结构。由于DNA纳米结构具有可寻址能力和纳米级分辨率等优势,可作为良好的模板用于组装金属纳米粒子。本文主要设计合成了独特的DNA纳米结构模板,利用简便、高效的方法将不同尺寸的纳米金球组装到模板的特定位点上,形成多种构型的金属纳米结构。通过对组装的金属纳米结构进行SERS研究,发现这些金属纳米组装体可以有效的增强拉曼分子的响应信号。基于上述内容,本论文的研究内容分为以下三个方面:1.如何降低DNA修饰的纳米金球与DNA折纸模板之间存在的电荷斥力是提高大尺寸纳米金球在DNA折纸模板上定位组装效率的关键。我们利用孔洞型DNA折纸作为模板组装30 nm金球,形成二聚体和四聚体的结构。其透射电子显微镜(TEM)结果表明,相比于正常DNA折纸模板,纳米金球在孔洞型DNA折纸模板上的组装效率大大提高。因金纳米组装体具有较强的表面等离子体效应,当拉曼活性分子共价吸附至其表面时,拉曼信号大幅度增强。2.DNA折纸纳米结构将一条长单链DNA和数百条短链混合,经过数小时的退火组装进而形成预设结构。我们设计了一种新型DNA纳米带结构,仅需要四条DNA链在常温下等比例混合二十分钟即可形成高产率的微米级DNA纳米带。该纳米带还可以作为模板一步法组装纳米金球,形成长的纳米金链。通过一步法组装不同尺寸纳米金球(直径10 nm,20 nm,30 nm)形成纳米金链,其高密度的金球线性排列产生众多的热点。这些具有plasmonic性质的纳米金链可用于增强拉曼分子的SERS信号。3.利用DNA纳米技术,设计了一种仅仅用5条DNA链进行自组装形成微米级的二维DNA纳米结构,并且用云母作为表面辅助组装成的二维DNA纳米结构平整有序。在二维DNA纳米结构中特定位点伸出捕获DNA链来组装纳米金球,形成高密度的二维金球阵列。这种方法能够广泛的应用在制造纳米尺寸的集成电路,并且形成的二维金属纳米结构在作为优良的SERS研究基底方面具有很大的潜力。
[Abstract]:Due to the unique optical properties of metal nanoparticles, the assembly of metal nanoparticles has attracted wide attention. Metal nanostructures with different chemical compositions, shapes and sizes were assembled precisely to form nanostructures with plasmon resonance effect. These nanostructures exhibit unique circular dichroism, surface-enhanced Raman spectroscopy (SERS) and UV-VIS-UV spectra. These nanostructures with plasmon resonance effect can be widely used in energy collection and biosensor. In previous studies, metal nanostructures were prepared by top-down etching. However, the cost of the method is high, and it is difficult to prepare complex structures such as three-dimensional assembly. Self-assembly technology based on DNA provides a bottom-up rapid assembly method to construct highly coordinated nanostructures. Because DNA nanostructures have the advantages of addressable ability and nanometer resolution, they can be used as templates to assemble metal nanoparticles. In this paper, a unique DNA nanostructure template was designed and synthesized, and various metal nanostructures were formed by assembling different sizes of gold nanospheres onto specific sites of the template by a simple and efficient method. Through the SERS study of the assembled metal nanostructures, it is found that these metal nanoassemblies can effectively enhance the response signals of Raman molecules. Based on the above contents, the research content of this paper is divided into the following three aspects: 1. How to reduce the charge repulsion between the DNA modified gold nanoparticles and the DNA origami template is the key to improve the efficiency of locating and assembling the large size gold nanoparticles on the DNA origami template. We use porous DNA origami as a template to assemble 30 nm gold spheres to form dimer and tetramer structures. The results of transmission electron microscopy (TEM) show that compared with the normal DNA origami template, the assembly efficiency of the nanocrystalline gold ball on the porous DNA origami template is greatly improved. Because gold nanoassemblies have strong surface plasma effect, when Raman active molecules are covalently adsorbed on their surface, Raman signals are greatly enhanced. 2. DNA origami nanostructures mix a long single-stranded DNA with hundreds of short chains. After several hours of annealing assembly, a preset structure is formed. We have designed a novel DNA nanobelts structure, which requires only four DNA chains to be mixed at room temperature in equal proportion for 20 minutes to form micron DNA nanobelts with high yield. The nanobelts can also be used as templates for one-step assembly of gold nanospheres to form long nanocrystalline gold chains. Nanocrystalline gold chains with different sizes (10 nm ~ 20 nm ~ 30 nm in diameter) were assembled by one step method, and the linear arrangement of high density gold spheres produced a lot of hot spots. These nanocrystalline gold chains with plasmonic properties can be used to enhance the SERS signal of Raman molecule. 3. 3. Using DNA nanotechnology, a two-dimensional DNA nanostructure with only five DNA chains was designed to form micron size DNA nanostructures, and the two-dimensional DNA nanostructures were formed by using mica as the surface assistant. In the two-dimensional DNA nanostructures, the special position points extend and capture the DNA chains to assemble the gold nanospheres and form a high-density two-dimensional gold-ball array. This method can be widely used in the fabrication of nanoscale integrated circuits, and the resulting two-dimensional metal nanostructures have great potential as excellent substrates for SERS research.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1

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