基于银纳米复合体系表面等离激元耦合增强荧光的研究

发布时间：2018-03-03 09:30

本文选题：银纳米复合材料　切入点：表面等离激元　出处：《广东工业大学》2017年博士论文　论文类型：学位论文

【摘要】：纳米金属体系中的耦合效应及其诱导的光电物理现象引起研究者的广泛关注。基于表面等离激元复合结构及其增强的荧光效应是其中一个重要的研究方向。本论文以银纳米复合材料体系为单元,提出并设计了两种复合结构:Fe3O4@Ag核壳结构(LSP-LSP),银纳米粒子-银纳米线复合结构(LSP-SPP)。采用紫外-可见分光光度计,拉曼光谱以及FDTD计算模拟,分别研究了核壳结构的尺寸,粒间距对局域表面等离激元特性的影响。重点利用荧光光谱,研究了两种复合结构对探针分子荧光增强的影响,并分析其物理机理。本论文在生物分子的荧光成像以及RB分子的检测方面具有一定的意义。主要研究内容如下:运用化学还原法,成功制备了分散性较好的Fe3O4纳米粒子以及Ag纳米粒子,通过表面修饰成功制备了 Fe3O4@Ag核壳结构纳米颗粒。另外,利用PVP作为表面修饰剂,通过媒介作用将银纳米粒子与银纳米线有机结合,成功制备了银纳米粒子-银纳米线复合结构。根据复合结构的特点,对于Fe3O4@Ag核壳结构,通过纳米粒子表面密度的调控,研究LSP及其耦合的表面等离激元特性;研究手段主要包括:紫外-可见分光光度计测试Fe3O4@Ag核壳结构的吸收光谱;拉曼光谱表征复合结构的场增强特性,FDTD计算Fe3O4@Ag核壳结构的电磁场分布,结果表明,对于相邻的Fe3O4@Ag核壳结构,当平均距离小于19 nm,形成了表面等离激元耦合,等离激元共振吸收峰红移,随着核壳结构平均距离减小,表面等离激元耦合程度增大,表面电磁场增强;对于银纳米粒子-银纳米线复合结构,通过银纳米粒子在银纳米线表面的沉积以及复合结构表面形貌的蚀刻,研究LSP-SPP耦合的表面等离激元特性。研究手段主要包括:紫外-可见分光光度计测试银纳米粒子-银纳米线复合结构的吸收光谱;拉曼光谱表征耦合结构的场增强特性,FDTD计算银纳米粒子-银纳米线复合结构的电磁场分布。结果表明,银纳米粒子-银纳米线形成复合结构后,表面形成更多的“热点”以及LSP-SPP耦合有效增强表面电磁场,表面等离激元共振吸收增大,对探针分子的拉曼光谱具有显著增强效应。实验研究了这两种复合结构表面等离激元耦合增强探针分子的荧光辐射。对于Fe3O4@Ag核壳结构,主要运用荧光光谱仪与荧光显微镜分析不同尺寸的核壳结构对探针分子荧光辐射的影响,然后研究Fe3O4@Ag核壳结构的LSP-LSP耦合效应对探针分子荧光增强的影响,结果表明,Fe3O4@Ag核壳结构的LSP-LSP耦合可有效增强探针分子的荧光辐射,随着耦合程度增大,荧光辐射增强越大,对RB分子以及PpIX分子分别具有5.4倍和15.8倍的增强效果;然后通过引入PVA介电层调控探针分子与核壳结构的平均间距,进一步探究LSP-LSP耦合表面增强荧光的机理,结果表明,荧光增强与荧光猝灭存在竞争关系,探针分子与核壳结构的平均间距是影响荧光增强的一个重要因素。对于LSP-SPP复合结构,主要运用荧光光谱仪与荧光显微镜分析银纳米粒子在银纳米线表面的沉积对探针分子荧光辐射的影响,然后利用酸刻蚀剂对合结构刻蚀,研究银纳米粒子-银纳米线复合结构表面形貌对荧光辐射增强的影响,结果表明,LSP-LSP耦合可有效增强探针分子的荧光辐射,并且复合结构表面的“热点”越多,电磁场增强效应越大,对RB分子以及PpIX分子分别具有9.6倍和10.6倍的增强效果。最后引入PVA介电层,进一步探究LSP-SPP耦合增强荧光的机理。基于表面等离激元耦合增强荧光的光学效应,设计并优化复合结构应用于生物医学上的荧光成像以及RB分子检测的初步探究。其中Fe3O4@Ag核壳结构应用于RB分子环境污染物的检测,结果表明最低可检测出RB分子的浓度为5×10-8mol/L;银纳米粒子-银纳米线复合结构应用于原卟啉(PpIX)分子的荧光成像,结果表明LSP-SPP耦合可有效增强原卟啉(PpIX)分子的荧光信号,降低其光漂白性。
[Abstract]:The physical phenomenon of photoelectric coupling effect of nano metal system and its induced caused extensive attention of researchers. The effect of surface plasmon polaritons fluorescence enhancement based on composite structure and is one of the important research direction. In this paper, system of silver nano composites as a unit, proposed and designed two kinds of composite structure: Fe3O4@Ag the core-shell structure (LSP-LSP), silver nanoparticles and silver nanowires composite structure (LSP-SPP) by UV VIS spectrophotometer, Raman spectroscopy and FDTD simulation, the core-shell structure size were studied, effects of particle spacing on the localized surface plasmon characteristics. Using fluorescence spectroscopy, research the effects of two kinds of composite structure on the fluorescence enhancement, and analysis of its physical mechanism. This paper has some significance in the detection of fluorescence imaging of biological molecules and RB molecules. The main research contents Are as follows: using chemical reduction method, successfully prepared better dispersion of Fe3O4 nanoparticles and Ag nanoparticles were successfully prepared by surface modification of Fe3O4@Ag nanoparticles with core-shell structure. In addition, the use of PVP as a surface modifying agent, through the media will be the role of silver nanoparticles and silver nano organic combination of nanowires were successfully prepared silver nanoparticles silver nanowires composite structure. According to the characteristics of the composite structure, the Fe3O4@Ag core-shell structure nanoparticles by regulating the surface density, LSP and the research on coupled surface plasmon properties; research methods mainly include: the absorption spectrum of UV VIS spectrophotometer to test the Fe3O4@Ag core-shell structure; field enhancement properties of Raman Spectra Characterization of the composite structure and calculation of electromagnetic field distribution, Fe3O4@Ag core-shell structure FDTD the results show that for the Fe3O4@Ag core-shell structure adjacent to, when the average distance is less than 19 nm, the formation of Surface plasmon coupled plasmon resonance absorption peak redshifts with core-shell structure average distance decreases, surface plasmon polariton coupling degree increases, the surface field enhancement; for silver nanoparticles and silver nanowires composite structure, nano surface deposition and etching nanowires composite structure surface morphology in silver through silver nanoparticles study of LSP-SPP, the coupling of surface plasmon properties. Main research methods include: UV VIS spectrophotometer test - absorption spectra of silver nanoparticles and silver nanometer composite structure nanowires; field enhancement properties of Raman spectra of coupled structure, calculation of electromagnetic field distribution of silver nanoparticles silver nanowires composite structure. The results showed that FDTD silver nanoparticles, silver nanowires to form a composite structure, formed on the surface of more "hot spots" and LSP-SPP coupling effectively enhance the surface electromagnetic field, surface plasmon resonance absorption In the Raman spectra of the probe molecule has the remarkable enhancement effect. Experimental study of the two kinds of composite structure of surface plasmon coupled fluorescence enhancement of radiation probe molecules. The Fe3O4@Ag core-shell structure, mainly by the analysis of influence of core-shell structure of different size of the fluorescence radiation fluorescence spectrometer and fluorescence microscopy, influence LSP-LSP and Fe3O4@Ag study on the coupling effect of core-shell structure on the fluorescence enhancement results show that LSP-LSP coupling Fe3O4@Ag core-shell structure can effectively enhance the fluorescence of the probe molecules with the coupling degree increases, the greater the enhancement of fluorescence emission, respectively with enhanced effect of 5.4 times and 15.8 times of RB molecules and PpIX molecules; and by introducing the PVA average distance of dielectric layer control probe with core-shell structure, to further explore the mechanism of fluorescence enhancement of LSP-LSP coupling surface. The results show that, There is competition with the fluorescence enhancement of fluorescence quenching, the average distance between probe molecules with core-shell structure is an important factor affecting the fluorescence enhancement. The LSP-SPP composite structure, mainly using fluorescence spectroscopy and fluorescence microscope analysis of silver nanoparticles precipitation effect product radiation on fluorescent probe molecules on the surface of silver nanowires, and then use the acid etching agent the structure of etching, silver nanoparticles of silver nanowires composite structure surface morphology on the fluorescence radiation enhancement effect, the results show that the LSP-LSP coupling can effectively enhance the fluorescence of the probe molecules and the surface of the composite structure more "hot spots", the electromagnetic enhancement effect is greater, respectively, can enhance the effect of 9.6 times and 10.6 times. The RB molecules and PpIX molecules. The PVA dielectric layer, to further explore the mechanism of fluorescence enhancement of LSP-SPP coupled surface plasmon enhancement based on coupling The optical effect of fluorescence detection, a preliminary inquiry design and optimization of composite structure is applied to the biomedical imaging and fluorescence molecular RB. Detection of Fe3O4@Ag core-shell structure is applied to the RB molecule of environmental pollutants which results show that the minimum detectable concentration of RB molecule is 5 * 10-8mol/L; silver nanoparticles and silver nanowires composite structure is applied to protoporphyrin (PpIX) molecular fluorescence imaging, the results show that LSP-SPP can effectively enhance the coupling of protoporphyrin (PpIX) fluorescence signal molecules, reduce the photobleaching.

【学位授予单位】：广东工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O657.3

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