• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Synthesis, purification and assembly of gold and iron oxide nanoparticles.
【24h】

Synthesis, purification and assembly of gold and iron oxide nanoparticles.

机译：金和氧化铁纳米粒子的合成，纯化和组装。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The aims of the current research include developing new synthetic strategies to prepare structurally complex gold nanoparticles and new size sorting methods to separate nanoparticles of larger size, as well as studying the assembly of nanoparticles into novel hierarchical structures through both template-assisted and template-free strategies.;In the synthesis section of this dissertation (Chapters 2 & 3), a size controllable synthesis of dendritic gold nanoparticles through a seed-mediated process in ethanol is described. The effect of seeds size and shape as well as the carbon chain length of alkylamines on the formation of dendritic structure was investigated. The synthetic strategy developed is capable of forming dendritic structure on various substrates, like flat or rod-like gold particles. In another work, the shape evolution of gold nanoparticles in a seed-mediated growth as well as the kinetics of reduction of HAuCl4 in the presence of seeds was studied. The reduction of the gold precursor by sodium citrate could be greatly accelerated in the presence of seed nanoparticles. Along with the enhanced reaction kinetics, dramatic shape evolution of gold nanoparticles was observed by changing ratios of precursors.;In the purification section (Chapter 4), a novel method of separating nanoparticles of different sizes in a viscosity gradient was developed. The viscosity gradient was created with polyvinylpyrrolidone (PVP) aqueous solutions. Previously, such size separation was all achieved in the density gradient, while the hidden contribution of viscosity difference inside the density gradient was not well recognized. Through this work, it is clarified that the viscosity can contribute as importantly as density in the size sorting of nanoparticles through rate zonal centrifuge. It was also demonstrated both experimentally and mathematically that the viscosity gradient is more effective in separation of larger sized nanoparticles.;In the assembly section (Chapter 5, 6 & 7), nanoparticles were assembled into three different hierachical structures through both template-assisted and template-free approaches. In the template-assisted assembly, gold nanorods were aligned into ordered 1D linear pattern by using soft biological filamentous, namely bacteria flagella, as templates. Two different ways of assembling nanorods onto flagella were investigated. In another study, a highly commercialized polymer, polyvinylpyrrolidone (PVP), was discovered for the first time to be able to self-assemble into branched hollow fibers. Based on this discovery, two approaches (one through direct deposition of silica onto the PVP aggregate and the other through co-assembly of PVP covered gold nanoparticles with free PVP molecules) by which the self-assembly behavior of PVP could be exploited to template the formation of branched hollow inorganic fibers were demonstrated. In the template-free assembly, a general method for assembling nanoparticle into clusters (NPCs) in an oil-in-water emulsion system was investigated. Detailed studies on the mechanism of formation of NPCs structure, optimized conditions, scalable production and surface chemistry manipulation were carried out. Besides, comparison of the properties of individual and clustered iron oxide nanoparticles was conducted. It was discovered that due to their collective properties, NPCs are more responsive to an external magnetic field and can potentially serve as better contrast enhancement agents than individually dispersed magnetic NPs in Magnetic Resonance Imaging (MRI).
机译：当前研究的目的包括开发新的合成策略以制备结构复杂的金纳米颗粒，以及新的尺寸分选方法以分离较大尺寸的纳米颗粒，以及研究通过模板辅助和无模板将纳米颗粒组装成新颖的分层结构在本论文的合成部分（第2章和第3章）中，描述了通过种子介导的乙醇过程可控制尺寸的树枝状金纳米颗粒的合成。研究了种子尺寸和形状以及烷基胺碳链长度对树枝状结构形成的影响。开发的合成策略能够在各种基底上形成树枝状结构，例如扁平或棒状金颗粒。在另一项工作中，研究了金纳米颗粒在种子介导的生长中的形状演变以及在种子存在下HAuCl4还原的动力学。在存在种子纳米颗粒的情况下，柠檬酸钠对金前驱物的还原可以大大加速。随着反应动力学的增强，通过改变前驱体的比例观察到了金纳米颗粒的急剧形变。在纯化部分（第4章），开发了一种新的方法来分离粘度梯度不同大小的纳米颗粒。用聚乙烯吡咯烷酮（PVP）水溶液产生粘度梯度。以前，这样的尺寸分离都是在密度梯度中实现的，而在密度梯度内部的粘度差的隐藏作用还没有得到很好的认识。通过这项工作，澄清了粘度可以通过速率分区离心对纳米颗粒的尺寸分选产生与密度同样重要的贡献。在实验和数学上也证明了粘度梯度在分离较大尺寸的纳米颗粒时更有效。在组装部分（第5、6和7章）中，纳米颗粒通过模板辅助和纳米组装为三种不同的层次结构无模板的方法。在模板辅助的组装中，金纳米棒通过使用柔软的生物丝状细菌鞭毛作为模板排列成有序的一维线性图案。研究了将纳米棒组装到鞭毛上的两种不同方式。在另一项研究中，首次发现高度商业化的聚合物聚乙烯吡咯烷酮（PVP）能够自组装成支链中空纤维。基于这一发现，可以利用两种方法（一种是通过将二氧化硅直接沉积到PVP聚集体上，另一种是通过PVP覆盖的金纳米颗粒与游离PVP分子的共组装）来利用PVP的自组装行为来模板化。证实了支链空心无机纤维的形成。在无模板组装中，研究了在水包油乳液系统中将纳米颗粒组装为簇（NPC）的一般方法。对NPCs结构的形成机理，优化条件，可扩展生产和表面化学操作进行了详细研究。此外，比较了单个和簇状氧化铁纳米粒子的性能。已经发现，由于NPC具有集体特性，因此它们在磁共振成像（MRI）中比单独分散的磁性NP更能响应外部磁场，并且有可能成为更好的对比度增强剂。

著录项

  • 作者

    Qiu, Penghe.;

  • 作者单位

    The University of Oklahoma.;

  • 授予单位 The University of Oklahoma.;
  • 学科 Chemistry Inorganic.;Nanoscience.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 227 p.
  • 总页数 227
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号