【作者】 刘春；

【导师】 黄承志；

【作者基本信息】 西南大学 ， 分析化学， 2010， 博士

【摘要】 本文以金纳米粒子为研究对象,探讨了金纳米粒子的特殊光学性质,并基于其局域表面等离子体共振散射和吸收性质,将金纳米粒子用于生化分析,建立了一系列分析方法。研究论文的主要内容概括如下：1.采用文献报道的方法,制备了表面修饰乙二胺端基的环糊精衍生物。由于Au-N原子之间的亲和力,修饰上的氨基可被用来捕获游离的金离子。在外加还原剂的情况下,其空腔结构可使生成的金纳米粒子主要以与空腔直径大小相当的金纳米簇形式存在。实验发现,采用不同还原能力的还原剂,可以得到不同荧光发射波长的金纳米簇溶液。用强还原剂硼氢化钠制得的金簇主要是Au7形式,用温和的还原剂抗坏血酸制得的金簇溶液包含三种发射波长,其中又以470 nm的发射为最强。所得到的金纳米簇的荧光量子产率可达5.2%。本文还探讨了反应时间、模板浓度、还原剂用量和不同制备方法对金纳米簇荧光强度的影响。这一研究将增大金纳米簇在分析测定和荧光共振能量转移方面的潜在应用。2.根据荧光染料在金纳米粒子表面的能量转移,建立了测定氨基酸及水溶液中铅离子的灵敏方法。研究表明,通过静电作用吸附在柠檬酸根包被的金纳米粒子表面的阳离子荧光染料如罗丹明B分子在受光激发时,发生从荧光染料到金属纳米微粒的能量转移,导致荧光染料的荧光猝灭。但当体系中存在半胱氨酸时,由于半胱氨酸与金纳米粒子之间具有更强的共价作用,导致罗丹明B分子远离金纳米粒子表面,降低了能量转移效率,使得罗丹明B的荧光得到恢复。恢复的荧光强度与0.025-4.5μmol/L半胱氨酸呈很好的线性关系,检测限为8.0 nmol/L(3σ),而其它十九种基本氨基酸的响应非常微弱。运用同样的原理,采用铅离子诱导TBA产生构象转变来控制荧光染料与金纳米粒子之间的距离,从而控制二者之间能量转移的效率。使得这个与铅离子浓度相关的构象转变过程可以用通过荧光强度的变化来监测。以此建立起线性响应范围在12.5-100 nmol/L,检测限达10 nmol/L(3σ)的水溶液中铅离子的灵敏检测方法。3.局域表面等离子体共振光散射(LSPR-LS)和动态光散射(DLS)技术是两种监测粒子聚集过程的有力手段。随着纳米技术的发展,两者都广泛应用于高灵敏的定量分析中。本文采用汞离子诱导金纳米粒子聚集为模式体系,对两种光散射技术进行了对比研究。研究发现,柠檬酸盐稳定的AuNPs由于在汞离子存在下的螯合过程而发生聚集,导致LSPR-LS信号的剧烈增强和平均水合直径的增大。加强的LSPR-LS强度(ΔI)与汞离子浓度在0.4-2.5μmol/L范围内成很好的线性关系,其线性回归方程为ΔI=125.7+569.5c,相关系数0.992(n=6),检测限达(3σ)94.3nmol/L。然而,用DLS检测到的平均水合直径的增加只在汞离子浓度大于1.0μmol/L时才有响应,并以相关系数为0.994遵循d=-6.16+45.9c关系式。在此条件下,LSPR-LS信号由于具有高灵敏度和高选择性,被进一步用于湖水样中汞含量分析。4.通过没食子酸(Gallic acid, GA)在弱碱性条件下对四氯金酸进行还原,制得表面包被没食子酸的球形金纳米粒子溶胶,其粒径均匀,平均粒径在15 nm左右。并对其形成机理进行了探讨。由于没食子酸的刚性结构,该金纳米粒子能对铅离子选择性配位。在铅离子浓度处于0.2-1.0μmol/L之间时,由体系聚集程度的增加而导致其局域表面等离子体共振光散射信号的增强与铅离子浓度存在良好的线性关系。并据此建立一个基于金纳米粒子局域表面等离子体共振光散射的水环境中铅离子检测方法。此研究对于拓展LSPR散射在普通生化分析方面具有一定的意义。总之,本文建立了一系列基于金纳米粒子的局域表面等离子体共振特性的分析方法,并探索了几个原子的金纳米粒子的合成及其荧光性质研究。这将拓宽金纳米粒子在光分析化学中的应用。更多还原

【Abstract】 In this thesis, gold nanoparticles (Au-NPs), which have unique optical properties, have been investigated. Thus, new analytical methods based on the LSPR absorption and scattering properties of Au-NPs have been established. The mainly points are as follows:1. An ethylenediamine terminated (3-cyclodextrin derivate was synthesized according to the literature. Because of the affinity of Au-N atom, the amino group can capture the dissociative gold ions. By using additional reductant, we can obtain the gold nanoclusters whose size was relative to the size of the cavity ofβ-cyclodextrin. Different reducing capability of the reductant would make the fluorescence emission of the acquisition solution be different. For example, the gold nanocluster was dominated in Au7 by employing sodium borohydride which has a strong reducing ability, the obtained solution which was reduced by ascorbic acid, a mild reducing agent, contained three kinds of emission wavelength, and the emission intensity of 470 nm is the strongest. The quantum yield of the obtained gold nanocluster solution is 5.2%. The influence of reaction time, the concentration of template and various reductant were investigated. This research will enhance the potential application of gold nanoclusters in biochemical analysis and fluorescence resonance energy transfer.2. According to the energy transfer between fluorescent dye and gold nanoparticle surface, sensitive detections of amino acid and aqueous lead were developed. The research shows, when the fluorescent dye, such as Rhodamine B, which was absorbed on the surface of citrate stabilized gold nanoparticles through the electrostatic interaction was excitated by the light, the fluorescence of the Rhodamine B gets quenched because of the occurrence of surface energy transfer from the fluorophore of Rhodamine B to the gold nanoparticles. However, with the addition of cysteine, the strong covalent combination between the mercapto group of cysteine and gold nanoparticles drives Rhodamine B molecular apart from the gold nanoparticles surface, which reduce the energy transfer efficiency and result in a significantly increase of fluorescence of the solution. It was found that the fluorescence gets increased linearly with the concentration of cysteine ranging from 0.025μmol/L to 4.5μmol/L. This phenomenon allows sensitive detection of cysteine with a limit of detection of 8.0 nmol/L (3σ). Other 19 kinds of natural amino acids have a weak influence on the surface energy transfer. According to the same principle, the efficiency of surface energy transfer can be controlled through the conformation transition of thrombin-binding aptamer (TBA) induced by lead ion, which changed the distance between gold nanoparticles and the dye molecule. This make the lead ion-dependent conformation transition process can be monitored based on the change of the fluorescent intensity. The sensitive detection of lead ion with a limit of detection of 10 nmol/L (3σ) and linear range from 12.5 nmol/L to 100nmol/L was provided.3. Both localized surface plasmon resonance light scattering (LSPR-LS) and dynamic light scattering (DLS) techniques are powerful tool to monitor the aggregation of particles. With the development of nanosciences, both of them have been widely used for quantitative purposes with high sensitivity. In this contribution, we make a comparison of the two light scattering techniques by employing gold nanoparticles (AuNPs) aggregation induced by mercuric ions. It was found that citrate-stabilized AuNPs get aggregated in aqueous medium in the presence of mercuric ions through a chelation process, resulting in greatly enhanced LSPR-LS signals and increased hydrodynamic diameter. The enhanced LSPR-LS intensity (ΔI) is proportional to the concentration of mercuric ions in the range of 0.4-2.5μmol/L following the linear regression equation ofΔI=125.7+569.5c with the correlation coefficient of 0.992 (n=6) and the limit of determination (3σ) about 94.3 nmol/L However, the increased hydrodynamic diameter can be identified by the DLS signals only with a concentration of Hg2+ beyond 1.0μmol/L, and a linear relationship between the average hydrodynamic diameters of the resulted aggregates and the concentration of Hg2+ can be expressed as d=-6.16+45.9c with correlation coefficient of 0.994. In such case, LSPR-LS signals were further applied to the selective determination of mercuric ions in lake water samples with high sensitivity and simple operation.4. We synthesized gallic acid-capped gold nanoparticles (GA-AuNPs) by reducing chloroauric acid trihydrate using gallic acid in the alkalescent condition. The average diameter of the synthesized GA-AuNPs is about 15 nm and size distribution is narrow. Because of the rigid structure of gallic acid molecule, it can selectively bind lead ions. The enhanced LSPR-LS intensity (ΔI) caused by the increase of aggregation is proportional to the concentration of lead ions in the range of 0.2-1.0μmol/L. A LSPR light scattering method for detecting aqueous lead ions based on gold nanoparticles was developed. This research promoted the application of LSPR light scattering to common biochemical analysis.In conclusion, a series novel analytical methods based on localized surface plasmon resonance properties of gold nanoparticles were established in this thesis. A few-atoms gold nanoparticle was synthesized and its fluorescene property was also investigated. This will improve the the application of AuNPs in optical analytical chemistry.更多还原