【作者】 郭艳丽；

【导师】 阎宏涛；

【作者基本信息】 西北大学 ， 分析化学， 2007， 博士

【摘要】 金纳米微粒及其薄膜具有特殊的光学、电学性质及良好的催化活性和生物分子亲和能力，在非线性光学器件和微电子器件的研制、催化以及分析科学等方面具有十分重要的研究意义和广泛的应用前景。本论文进行了金纳米微粒的制备新方法以及光谱分析应用研究，全文包括六个部分。第一章对金纳米微粒的制备方法、金纳米微粒的组装及其应用，特别是在分析化学中的应用进行了较为详尽的综述，在此基础上提出了自己拟进行的研究方向。引用文献203篇。第二章利用糖胺聚糖—肝素作还原剂和稳定剂，以HAuCl₄为前驱体，在水溶液中制备了肝素稳定的金纳米微粒。采用紫外—可见光谱、共振散射光谱、透射电子显微镜以及电泳技术对制备的金纳米微粒进行了测定和表征，探讨了反应物浓度比对金纳米微粒制备的影响。研究结果表明，制备的金纳米微粒带有负电性；可以通过改变肝素和HAuCl₄的浓度比，有效的对金纳米微粒的粒径大小和形貌进行控制。建立的制备方法简单易行，是一种对环境友好的绿色制备方法。第三章采用静电自组装技术，在玻璃基片上成功地组装了金纳米微粒的单层和多层薄膜。以原子力显微镜、紫外—可见光谱和拉曼光谱等分析技术对薄膜的形貌和光学特性进行了测定与表征。结果表明，相对于金纳米微粒溶液的吸收峰而言，自组装金纳米微粒薄膜的吸收峰发生了展宽和红移，并随着组装层数的增加，红移明显增大。单层膜中金纳米微粒呈紧密堆积排列，局部区域有缺陷，二层膜为一种致密的、连续的颗粒膜，单层膜的粗糙度较二层膜的大。拉曼光谱分析结果表明，薄膜具有表面拉曼散射增强效应。该组装薄膜可应用于表面增强拉曼光谱的研究和化学传感器的制备等。第四章研究了不同粒径金纳米微粒与荧光素钠的相互作用，发现金纳米微粒对荧光素纳具有荧光猝灭效应，探讨了荧光猝灭的机理和金纳米微粒荧光猝灭的粒径效应。结果表明，荧光猝灭程度与金纳米微粒的粒径大小有关，随着金纳米微粒粒径的减小，荧光猝灭程度增大。不同粒径的金纳米微粒对荧光素钠的猝灭符合Stern-Volmer方程，荧光猝灭常数随着金纳米微粒粒径的减小而增大。金纳米微粒对荧光素钠的猝灭作用为动态猝灭过程，不同温度下的猝灭常数分别为1.5×10⁴ L/mol（25℃），1.7×10⁴L/mol（35℃），1.9×10⁴ L/mol（45℃）。第五章实验发现水溶液中金纳米微粒对NaBH₄还原亚甲基蓝的反应具有显著的催化作用。进行了金纳米微粒催化该反应体系的动力学研究，探讨了催化反应的机理，讨论了酸度、温度和不同类型的表面活性剂对该催化反应的影响。研究表明，金纳米微粒的催化作用是由于BH₄^-（给体）向亚甲基蓝（受体）进行电子转移时，金纳米微粒充当了电子转移的媒介参与了电子转移的过程。金的浓度在1.47×10^-7—2.36×10^-6mol/L之间时，催化反应初速率与金的浓度呈线性关系。阳离子和非离子表面活性剂的浓度低于临界胶束浓度时，催化反应初速率急剧增大；大于临界胶束浓度时，表面活性剂形成胶束，同催化剂竞争吸附反应物分子，使得催化反应初速率缓慢下降。阴离子表面活性剂与亚甲基蓝生成缔合物，阻碍了金纳米微粒催化NaBH₄还原亚甲基蓝的反应。第六章研究建立了一种以金纳米微粒为探针共振光散射（RLS）法测定维生素B₄的新方法。在弱酸性介质中（pH 4.2），金纳米微粒在635nm有一最大共振散射峰。加入微量维生素B₄后，金纳米微粒与维生素B₄通过静电引力结合，形成了粒径较大的聚集体，导致RLS强度显著增强。研究了体系的共振光散射光谱特征和反应适宜条件，探讨了共振光散射增强的机理。结果表明，维生素B₄浓度在0.1—5.0μg/mL时与散射强度（ΔI）呈线性关系，检测限（3σ）为12ng/mL，相对标准偏（RSD）为2.2％。该方法应用于片剂中维生素B₄的测定，结果满意。更多还原

【Abstract】 Owing to the special optical and electrical properties, good catalytic activity and favorable biocompatibility, gold nanoparticle and its thin films have extensive application prospects in fabricating nonlinear optical and microelectronic devices, catalyzing, analytical science and etc. The new preparation method and applications in spectral analysis of gold nanoparticles were studied in this dissertation.The dissertation includes six parts:Chapter 1: The preparation, assembly, and analytical applications of gold nanoparticles were reviewed in detail.Chapter 2: A facile method for the preparation of gold nanoparticles in aqueous solution was developed by using glycosaminoglycan-heparin as reducing agent and HAuCl₄ as precursor. The properties of gold nanoparticles were characterized by UV-vis spectroscopy, resonance light scattering spectroscopy （RLS）, transmission electron microscopy （TEM） and electrophoresis technology. The effects of reactant concentration ratio for the preparation of gold nanoparticles were investigated. The results showed that the gold nanoparticles carried negative charges in the aqueous solution and the size and shape of the gold nanoparticles could be controlled by changing the concentration ratio of the heparin and the HAuCl₄. Preparing gold nanoparticles in this way had environment-friendly characteristics, and it was a green preparation method.Chapter 3: The monolayer and multilayers of gold nanoparticles were constructed on the glass by electrostatic self-assembly method. The morphology and optical properties of thin films were characterized by AFM, UV-Vis spectroscopy and Raman spectroscopy. Plasmon absorbance peak of gold nanoparticles thin films were broad and red-shift compared with the gold nanoparticles in aqueous solution. As the layer increased, this feature strengthened and the peak shifted to longer wavelength. AFM images showed a close-packed array of gold nanoparticles in monolayer with small region defects. The 2-layers showed that the interparticle distance was very small to form a compact, continuous film on the glass slide. The roughness of gold nanoparticles monolayer was bigger than the 2-layers’s. The measurements of the Raman spectrum of crystal violet indicated that the gold nanoparticles self-assembly thin film has the high SERS activity. Therefore, it can be used for the study of SERS and fabricating chemical sensors.Chapter 4: The Spectroscopic characteristic of interaction between fluorescein sodium and gold nanoparticles with different sizes was investigated via UV-vis and fluorescence spectrophotometry. It was found that gold nanoparticles quench the fluorescence of fluorescein sodium in water. The quenching mechanism and size-dependence quenching effect were discussed. The results showed that the degree of quenching was concerned with the size of gold nanoparticles. The smaller gold nanoparticles were efficient quenchers than the larger ones due to larger surface areas. It showed that the gold nanoparticles quenching of fluorescein sodium follows Stern-Volmer relation for plots of F₀/F against gold nanoparticles concentration. In additation, the results showed that the quenching of fluorescein sodium by gold nanoparticles was a dynamic quenching, and the quenching constants respectively were 1.5×10⁴ L/mol （25℃） , 1.7×10⁴ L/mol （35℃） and 1.9×10⁴ L/mol （45℃） .Chapter 5: It was found that the gold nanoparticles have strong catalysis for the redox reaction between methylene blue and NaBH₄. The catalytic reaction kinetics was studied and the catalytic reaction mechanism was investigated. The effects of reaction temperature, solution acidity and different kinds of surfactants were discussed. It was indicated the gold nanoparticles provided a substrate via which electron transfer can easily occur between the reactants. The rate of catalytic reaction increased linearly with the concentration of catalyst for the reaction system catalyzed by the gold nanoparticles in the range of 1.47×10^-7—2.36×10^-6 mol/L. A change of the initial rates was observed in cationic and nonionic surfactants above and below the critical micelle concentration. Anionic surfactants restrained the catalytic reaction due to the association reaction of surfactants with methylene blue.Chapter 6: A sensitive method for detecting Vitamin B₄ was proposed by resonance light scattering （RLS） spectroscopy with gold nanoparticles as probe. In a weak acid medium （pH4.2）, the resonance light scattering spectrum of gold nanoparticles had a maximum peak at 635 nm and the RLS intensity was enhanced by trace amount of Vitamin B₄ due to forming aggregate with bigger diameters between gold nanoparticles and Vitamin B₄. The RLS spectral characteristics of gold nanoparticles-Vitamin B₄ system and the optimum conditions of the reaction were investigated. The mechanism for the enhancement of RLS was also discussed. The results showed that the enhancement of the RLS signal （△I） was proportional to the concentration of Vitamin B₄ in the range of 0.1—5.0μg/mL. The corresponding detection limit （3σ） was 12ng/mL, and the RSD was 2.2 %. The method was applied to the determination of Vitamin B₄ in tablets with satisfactory results.更多还原