The Coordination Chemistry of Nanocrystal Surfaces: Understanding the Role of Val

纳米晶体表面的配位化学：了解 Val 的作用

• 批准号: 7999072
• 负责人: Brandi Michelle Cossairt
• 金额: $ 4.56万
• 依托单位: COLUMBIA UNIV NEW YORK MORNINGSIDE
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-09 至 2012-07-08
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7999072
• 关键词: Address; Binding; Biological; Biology; Biotin; Cells; Charge; Chelating Agents; Chemistry; Drug Delivery Systems; Equilibrium; Extinction (Psychology); Face; Fluorescence; Fluorescent Probes; Goals; High Pressure Liquid Chromatography; Human; Investigation; Kinetics; Label; Lead; Life; Ligand Binding; Ligands; Magic; Measurement; Methods; Modeling; Molecular; NMR Spectroscopy; Nanotechnology; Optics; Organism; Photobleaching; Property; Research; Research Personnel; Role; Semiconductors; Solubility; Structure; Surface; Technology; Thermodynamics; Water; aqueous; chromophore; design; electrical property; improved; nanocrystal; nanomaterials; nanoscale; nanoscience; public health relevance; quantum; stem; stoichiometry

DESCRIPTION (provided by applicant): Semiconductor nanocrystals present numerous technological opportunities that stem from their tunable optical and electrical properties. Their extraordinary extinction coefficients, fluorescence quantum yields, and stability toward photobleaching have lead many researchers to investigate nanocrystals as fluorescent probes in biology. Among the many challenges facing these endeavors, tailoring nanocrystal surfaces to the desired application by ligand exchange has been persistently problematic. For example, attempts to interface nanocrystals with biological molecules have struggled to synthesize sufficiently luminescent nanocrystals with compact ligand shells that are easily conjugated to biomolecules and stable to aqueous conditions. The importance of ligand exchange to emergent nanocrystal technologies underscores the need for an improved description of nanocrystal surface chemistry in general. By focusing on this subject we hope to build a molecular description of nanocrystals, and to improve models of their coordination chemistry, surface structure and reactivity. Ultimately, these fundamental studies will lead us to integrate these extraordinary chromophores in sensing applications. Current descriptions of semiconductor nanocrystal surfaces do not adequately distinguish between dative ligand interactions (L-type binding) and ligands that balance their charge with nonstoichiometric crystals (X-type binding). To address this problem we propose to study the relationship between nanocrystal stoichiometry and the exchange of both X- and L-type surface ligands using multi-nuclear magnetic resonance spectroscopy. We aim to determine the thermodynamic binding constants of ligands and to study the mechanisms and kinetics of their exchange. The use of magic-sized clusters with a well defined structure will further allow us to obtain details about specific aspects of ligand exchange at crystal edges, faces, and vertices. Building upon these studies, we aim to systematically design anchoring chelators (L,X-type ligands) to bind water solubilizing groups irreversibly to the nanocrystal surface. Using HPLC methods the stability of biotin-conjugated nanocrystals will then be assessed. We will also determine, using traditional UV-Vis and photoluminescnece measurements, how these new ligands effect the optical properties of the nanocrystals under investigation. Clarifying the importance of X-type ligands to nanocrystal surface chemistry and its relationship to stoichiometry can have a dramatic influence on all avenues of nanocrystal research. Furthermore, by investigating X-type ligand exchange we stand to gain powerful methods to precisely tailor nanocrystal surfaces. Our studies on new water solubilization methods will lead to biologically relevant nanocrystals with improved size, stability, and solubility properties. These directions are a promising step for nanoscience, on both a fundamental and a technological level. PUBLIC HEALTH RELEVANCE: Nanotechnology has provided a means by which humans can interface with matter at a scale that was previously unobtainable. Living organisms are built of cells that are typically micrometers across and are filled with machinery on the nanometer scale, and thus, nanotechnology has great potential to interrogate and manipulate biology at the cellular level. This proposal aims to better understand the fundamental properties of nanomaterials that govern their structure and function with the ultimate goal of improving the fabrication of nanocrystals for use as biological probes, cellular labels, and drug delivery agents.

描述（由申请人提供）：半导体纳米晶体因其可调的光学和电学特性而带来了众多技术机会。纳米晶体具有优异的消光系数、荧光量子产率和光漂白稳定性，这使得许多研究人员将其作为生物学中的荧光探针进行研究。在这些努力所面临的许多挑战中，通过配体交换来定制表面以用于所需的应用一直存在问题。例如，尝试将纳米晶体与生物分子界面连接已经努力合成具有紧凑配体壳的足够发光的纳米晶体，所述配体壳容易与生物分子缀合并且对水性条件稳定。配体交换的重要性，以紧急的表面处理技术强调需要改进的表面化学的描述一般。通过对这一问题的研究，我们希望建立一个纳米晶体的分子描述，并改进其配位化学，表面结构和反应性的模型。最终，这些基础研究将引导我们将这些非凡的发色团整合到传感应用中。 目前对半导体晶体表面的描述不能充分区分配位配体相互作用（L型结合）和配体与非化学计量晶体（X型结合）的电荷平衡。为了解决这个问题，我们建议使用多核磁共振光谱研究X-和L-型表面配体的交换与化学计量之间的关系。我们的目标是确定配体的热力学结合常数，并研究其交换的机制和动力学。使用具有明确结构的魔法大小的簇将进一步使我们能够获得有关晶体边缘，表面和顶点处配体交换的特定方面的细节。在这些研究的基础上，我们的目标是系统地设计锚定螯合剂（L，X型配体）结合水增溶基团不可逆的表面。然后使用HPLC方法评估生物素缀合的纳米晶体的稳定性。我们还将确定，使用传统的紫外-可见和photoluminescnece测量，这些新的配体如何影响的光学性质的纳米晶体的调查。 阐明X型配体对表面化学的重要性及其与化学计量的关系可以对表面化学研究的所有途径产生巨大影响。此外，通过研究X型配体交换，我们将获得精确定制纳米晶体表面的强大方法。我们对新的水增溶方法的研究将导致具有改进的尺寸、稳定性和溶解性的生物相关纳米晶体。这些方向是纳米科学在基础和技术层面上迈出的有希望的一步。 公共卫生相关性：纳米技术提供了一种手段，通过这种手段，人类可以在以前无法获得的规模上与物质接触。活的生物体是由通常为微米的细胞组成的，并且充满了纳米尺度的机械，因此，纳米技术具有在细胞水平上询问和操纵生物学的巨大潜力。该提案旨在更好地了解纳米材料的基本特性，这些特性决定了它们的结构和功能，最终目标是改善纳米晶体的制造，以用作生物探针，细胞标记和药物递送剂。