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Synthesis, characterization and functionalization of silicon nanoparticle based hybrid nanomaterials for photovoltaic and biological applications.

机译：用于光伏和生物应用的基于硅纳米粒子的杂化纳米材料的合成，表征和功能化。

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摘要

Silicon nanoparticles are attractive candidates for biological, photovoltaic and energy storage applications due to their size dependent optoelectronic properties. These include tunable light emission, high brightness, and stability against photo-bleaching relative to organic dyes (see Chapter 1). The preparation and characterization of silicon nanoparticle based hybrid nanomaterials and their relevance to photovoltaic and biological applications are described.;The surface-passivated silicon nanoparticles were produced in one step from the reactive high-energy ball milling (RHEBM) of silicon wafers with various organic ligands. The surface structure and optical properties of the passivated silicon nanoparticles were systematically characterized. Fast approaches for purifying and at the same time size separating the silicon nanoparticles using a gravity GPC column were developed. The hydrodynamic diameter and size distribution of these size-separated silicon nanoparticles were determined using GPC and Diffusion Ordered NMR Spectroscopy (DOSY) as fast, reliable alternative approaches to TEM.;Water soluble silicon nanoparticles were synthesized by grafting PEG polymers onto functionalized silicon nanoparticles with distal alkyne or azide moieties. The surface-functionalized silicon nanoparticles were produced from the reactive high-energy ball milling (RHEBM) of silicon wafers with a mixture of either 5-chloro-1-pentyne in 1-pentyne or 1,7 octadiyne in 1-hexyne to afford air and water stable chloroalkyl or alkynyl terminated nanoparticles, respectively. Nanoparticles with the &ohgr;-chloroalkyl substituents were easily converted to &ohgr;-azidoalkyl groups through the reaction of the silicon nanoparticles with sodium azide in DMF. The azido terminated nanoparticles were then grafted with monoalkynyl-PEG polymers using a copper catalyzed alkyne-azide cycloaddition (CuAAC) reaction to afford core-shell silicon nanoparticles with a covalently attached PEG shell. Covalently linked silicon nanoparticle clusters were synthesized via the CuAAC "click" reaction of functional silicon nanoparticles with &agr;,&ohgr;-functional PEG polymers of various lengths. Dynamic light scattering studies show that the flexible globular nanoparticle arrays undergo a solvent dependent change in volume (ethanol> dichloromethane> toluene) similar in behavior to hydrogel nanocomposites.;A novel light-harvesting complex and artificial photosynthetic material based on silicon nanoparticles was designed and synthesized. Silicon nanoparticles were used as nanoscaffolds for organizing the porphyrins to form light-harvesting complexes thereby enhancing the light absorption of the system. The energy transfer from silicon nanoparticles to porphyrin acceptors was investigated by both steady-state and time-resolved fluorescence spectroscopy. The energy transfer efficiency depended on the donor-acceptor ratio and the distance between the nanoparticle and the porphyrin ring. The addition of C60 resulted in the formation of silicon nanoparticle-porphyrin-fullerene nanoclusters which led to charge separation upon irradiation of the porphyrin ring. The electron-transfer process between the porphyrin and fullerene was investigated by femto-second transient absorption spectroscopy.;Finally, the water soluble silicon nanoparticles were used as nanocarriers in photodynamic therapeutic application, in which can selectively deliver porphyrins into human embryonic kidney 293T (HEK293T) cells. In particular, the PEGylated alkynyl-porphyrins were conjugated onto the azido-terminated silicon nanoparticles via a CuAAC "click" reaction. The resultant PEGylated porphyrin grafted silicon nanoparticles have diameters around 13.5 +/- 3.8 nm. The cryo-TEM and conventional TEM analysis proved that the PEGylated porphyrin grafted silicon nanoparticle could form the micelle-like structures at higher concentration in water via self-assembly. The UV-Vis absorption analysis demonstrated that the silicon nanoparticle could reduce the porphyrin aggregation in water which can reduce the photophysical activity of porphyrin. In addition, the nanoparticle complex was capable of producing singlet oxygen when the porphyrin units were excited by light. The cell studies demonstrated that the silicon nanoparticle could deliver the porphyrin drugs into HEK293T cells and accumulate in the mitochondria where the porphyrin could serve as an efficient photosensitizer to kill the cells via mitochondrial apoptotic pathway.
机译：硅纳米颗粒由于其尺寸依赖性的光电特性而成为生物，光伏和能量存储应用的有吸引力的候选者。这些包括可调节的发光，高亮度以及相对于有机染料的光漂白稳定性（请参见第1章）。描述了基于硅纳米颗粒的杂化纳米材料的制备，表征及其与光伏和生物应用的相关性。表面钝化的硅纳米颗粒是由反应性高能球磨（RHEBM）的硅片与多种有机物一步制备得到的配体。系统地表征了钝化的硅纳米颗粒的表面结构和光学性质。开发了一种使用重力GPC色谱柱纯化和同时分离硅纳米颗粒的快速方法。使用GPC和扩散有序NMR光谱（DOSY）作为TEM的快速，可靠的替代方法来确定这些尺寸分离的硅纳米颗粒的流体动力学直径和尺寸分布。远端炔烃或叠氮基部分。表面功能化的硅纳米粒子是由硅晶片的反应性高能球磨（RHEBM）与1-氯炔中的5-氯-1-戊炔或1-己炔中的1,7辛二炔的混合物制得的，以提供空气和水稳定的氯烷基或炔基封端的纳米颗粒。通过在DMF中使硅纳米颗粒与叠氮化钠反应，具有-氯烷基取代基的纳米颗粒容易转化为-叠氮烷基。然后使用铜催化的炔-叠氮化物环加成（CuAAC）反应，将单叠氮基封端的纳米颗粒与单炔基PEG聚合物接枝，以提供具有共价连接的PEG壳的核壳硅纳米颗粒。共价连接的硅纳米颗粒簇是通过功能性硅纳米颗粒与各种长度的α，α-官能PEG聚合物的CuAAC“点击”反应合成的。动态光散射研究表明，柔性球状纳米颗粒阵列的行为与水凝胶纳米复合材料相似，具有溶剂依赖性的体积变化（乙醇>二氯甲烷>甲苯）.;设计了一种新型的基于硅纳米粒子的捕光复合物和人造光合材料合成的。硅纳米颗粒用作纳米支架，用于组织卟啉以形成光收集复合物，从而增强系统的光吸收。通过稳态和时间分辨荧光光谱研究了从硅纳米颗粒到卟啉受体的能量转移。能量转移效率取决于施主与受主的比率以及纳米粒子与卟啉环之间的距离。 C60的添加导致硅纳米颗粒-卟啉-富勒烯纳米簇的形成，这导致在卟啉环的照射下电荷分离。通过飞秒瞬态吸收光谱研究了卟啉与富勒烯之间的电子转移过程。最后，水溶性硅纳米粒子被用作光动力治疗应用中的纳米载体，可以选择性地将卟啉传递到人胚胎肾脏293T（HEK293T）中。 ） 细胞。特别地，通过CuAAC“点击”反应将PEG化的炔基-卟啉缀合到叠氮基封端的硅纳米颗粒上。所得的聚乙二醇化的卟啉接枝的硅纳米颗粒具有约13.5 +/- 3.8nm的直径。低温TEM和常规TEM分析证明，聚乙二醇化的卟啉接枝的硅纳米颗粒可以通过自组装在水中以较高的浓度形成胶束状结构。 UV-Vis吸收分析表明，硅纳米颗粒可以减少水中卟啉的聚集，从而降低卟啉的光物理活性。另外，当卟啉单元被光激发时，纳米粒子复合物能够产生单线态氧。细胞研究表明，硅纳米颗粒可以将卟啉药物传递到HEK293T细胞中并积聚在线粒体中，在那里，卟啉可以作为有效的光敏剂通过线粒体的凋亡途径杀死细胞。

著录项

  • 作者

    Xu, Zejing.;

  • 作者单位

    Tulane University School of Science and Engineering.;

  • 授予单位 Tulane University School of Science and Engineering.;
  • 学科 Chemistry Physical.;Engineering Materials Science.;Chemistry Organic.;Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 326 p.
  • 总页数 326
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 物理化学（理论化学）、化学物理学;
  • 关键词

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