金属—上转换复合纳米结构的制备及性能研究

发布时间：2018-02-27 16:39

本文关键词： 金属纳米材料稀土上转换纳米颗粒表面等离子共振效应表面改性多功能集成　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：在生物标记领域,近红外光激发的稀土上转换纳米发光材料与有机染料分子和量子点相比表现出极大的优势。不仅具有独特的上转换发光性能和温度传感功能,而且化学稳定性强、量子产率高、毒性低,同时可避免生物组织背景荧光的影响。但目前效率最高的上转换纳米发光材料——六方相NaYF4:Yb3+, Er3+的量子效率也仅为0.3%(粒径30nm,激发功率为150Wcm-2)。这很大程度上限制了上转换发光材料在生物医学领域的推广应用。金属纳米材料表面自由电荷在外加电磁场激发下可产生特殊的表面等离子共振效应,显著增强其周围局域电磁场,并使处于电磁场内的荧光分子光谱强度显著增强。此外,表面等离子共振还可引发光热转换效应,用于生物医学领域的光热治疗。因此,结合金属纳米材料和上转换纳米材料的特性,制备金属-上转换复合纳米结构,不仅可增强上转换纳米材料的发光效率,而且可实现上转换发光、温度传感及光热治疗的多功能集成。金纳米棒由于其表面等离子共振具有各向异性,产生的共振吸收光谱分裂为横向模式和纵向模式两个吸收峰,分别与NaYF4:Yb3+, Er3+上转换纳米颗粒的发射光谱和激发光谱产生光谱重叠,可从增加上转换辐射跃迁几率以及提高激发效率两个方面同时增强光谱。因此,本论文选用金纳米棒与NaYF4:Yb3+, Er3+上转换纳米颗粒制备复合结构,并对其多功能集成效果进行探索。主要工作包括：1.采用晶种法制备金纳米棒,根据TEM、UV-vis表征结果,对比十六烷基苄基二甲基氯化铵(BDAC)和5-溴代水杨酸两种添加剂对金纳米棒生长的辅助效果,发现5-溴代水杨酸可显著提高金纳米棒的形貌均匀性及棒状颗粒的产率,并制备得到长径比为2.8～6.0,共振吸收峰为600-1000nm的金纳米棒。成功采用胱胺分子修饰金纳米棒使其表面带氨基,发现胱胺分子修饰并不影响金纳米棒的表面等离子共振效应及其在水中分散性,且有利于生物应用及复合结构的制备。2.采用热分解法制备NaYF4:Yb3+, Er3+上转换纳米颗,并通过调节掺杂离子Gd3+的浓度、反应溶剂比例及稀土醋酸盐前驱体的比例调控上转换纳米颗粒的尺寸。TEM、XRD及荧光光谱表征结果证明,所合成上转换纳米颗粒具有良好的结晶度及上转换发光性能。分别以表面配体氧化法及表面配体交换法改性NaYF4:Yb3+, Er3+上转换纳米颗粒,使其表面带羧基以实现水溶性和生物相容性。TEM、FTIR及荧光光谱等表征结果表明,表面配体交换法的表面改性效果较好。3.探索金棒-上转换复合纳米结构的制备方法并研究其多功能集成。TEM结果表明静电吸附法的复合效果优于缩合反应法,且980nm共振吸收的金纳米棒与～11nm的NaYF4:Yb3+, Er3+,Gd3+上转换纳米颗粒匹配良好,可形成单分散的复合结构。此复合结构兼具上转换发光、温度传感及光热转换多种功能,可在光热治疗的同时实现实时成像和温度监控。但上转换发光产生了无辐射猝灭,可能是由共振能量转移造成的。
[Abstract]:In the field of biomarkers, near infrared photoluminescence of rare earth upconversion luminescence materials compared with organic dyes and quantum dots show great advantages. Not only has the conversion luminescence properties and temperature sensing unique features, and the chemical stability, high quantum yield, low toxicity, and can avoid the influence of tissue background fluorescence. But at present the highest efficiency of upconversion luminescence materials, six phase NaYF4:Yb3+, the quantum efficiency of Er3+ is only 0.3% (particle size 30nm, excitation power is 150Wcm-2). This greatly limits the popularization and application of upconversion luminescence materials in the biomedical field. Metal nano materials surface charge in the surface can produce additional free the plasma resonance effect of special electromagnetic excitation, significantly enhance the surrounding local field, and that is in the fluorescence spectrum intensity in this electromagnetic field is significantly enhanced. Also, surface plasmon resonance can cause photothermal conversion, for photothermal therapy in the biomedical field. Therefore, combined with the characteristics of metal nano materials and upconversion nano materials, preparation of metal upconversion nano composite structure, can not only enhance the upconversion luminous efficiency of nano materials, but also can realize the upconversion luminescence, multi function temperature sensing and photothermal therapy integration. Due to the surface plasmon resonance of gold nanorods is anisotropic, the resonance absorption spectrum is split into horizontal mode and vertical mode two peaks, respectively, and NaYF4:Yb3+, Er3+ emission spectra and excitation spectra of the converted nano particles generated from spectral overlap, increase conversion and radiative transition probability to improve the efficiency and enhance the two aspects of excitation spectrum. Therefore, this paper selected gold nanorods and NaYF4:Yb3+ nanoparticles were prepared by composite conversion Er3+ Structure, and the integrated effect of exploration. The main work includes: 1. the crystal preparation of gold nanorods, prepared according to TEM, the characterization of UV-vis, compared to sixteen of two alkyl benzyl dimethyl ammonium chloride (BDAC) and 5- bromo salicylic acid two kinds of additives on the growth of the auxiliary effect of gold nanorods, found 5- bromide salicylic acid can be morphology of gold nanorods and uniformity of rod like particles yield increased significantly, and the prepared slenderness ratio is 2.8 ~ 6, the resonance absorption peak of 600-1000nm gold nanorods. Using cysteamine modified gold nanorods on the surface of molecules with amino groups, found that cysteamine molecule modification does not affect the surface plasmon resonance of gold nanorods and its dispersion in water, and is conducive to biological applications and the composite structure of.2. was prepared by thermal decomposition of NaYF4:Yb3+ prepared, Er3+ upconversion nanoparticles, and by adjusting the concentration of doped ions of Gd3+, anti The sizes of.TEM solvent and the ratio of rare earth acetate precursor on the regulation of the ratio of conversion of nanoparticles, XRD and fluorescence spectroscopy results show that the synthesis of upconversion nanoparticles with crystallinity and upconversion luminescence of good performance. By surface ligand oxidation and surface ligand exchange method of modified NaYF4:Yb3+, Er3+ upconversion nanoparticles the surface of particles with carboxyl to achieve water solubility and biological compatibility of.TEM, FTIR and fluorescence spectra. The results show that the surface ligand exchange surface modification method is better to explore gold rod on the conversion of.3. composite nano structure and preparation method of the multifunctional integrated.TEM results show that the composite effect is better than condensation reaction method electrostatic adsorption method, and the 980nm resonance absorption of gold nanorods with ~ 11nm NaYF4:Yb3+, Er3+, Gd3+ upconversion nanoparticles are well matched, can form a composite structure of dispersed structure. The composite structure has many functions such as upconversion luminescence, temperature sensing and photothermal conversion. It can realize real-time imaging and temperature monitoring while photothermal therapy. However, upconversion luminescence has produced no radiation quenching, which may be caused by resonance energy transfer.

【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;TQ422

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