高效液相色谱法应用于金纳米粒子形成机理的研究

Nowadays synthesis of gold nanoclusters (Au NCs) focuses on the precise control of size, shape and surface chemistry. However, there are still size range to a certain extent of Au NCs although the reaction conditions are controlled quite accurately and carefully. The complexity of the synthesized Au NCs is so great that separation approachs have been used to achieve numerous single size Au NCs. In order to obtain monodisperse Au NCs, improving synthesis technology or developing new method is also very important, which imply that the study of the growth mechanism of Au NCs is extremely significative. In this work, high performance liquid chromatography (HPLC) is employed to separate Au NCs protected by monolayer ligand, which synthesized by different methods. The Au NCs fractions will be fully characterized by UV-vis absorption spectroscopy, fluorescence spectroscopy, high resolution transmission electron microscopy, thermogravimetric analysis, and mass spectroscopy. The number of Au atoms and ligand is identified. And the information about the size and photometric characteristics of Au NCs can be also obtained. The proposed HPLC methodology will be applied to investigate the synthesis of AuNCs in real time. And various polydisperse Au NCs synthesized from different experimental conditions such as the type of reductant, the speed of reductant addition, ratio of Au and ligand, reaction time and reaction temperature are studied by HPLC. The distribution variation of the size and number of Au atoms/ligand along with the different experimental conditions is analyzed in order to study the growth mechanism of Au NCs in detail. The study about the growth mechanism of Au NCs could facilitate the development of controllable techonology for the size and shape of Au NCs. The Au NCs could be more effectively applied to materials, biology, medicine and toxicology field based on this work. By means of the proposed HPLC methodology, a lot of monodisperse but different size Au NCs could be achieved simultaneously. They can meet the demand of precision component and miniature catalyst in which exact structure of Au NCs are required.

精确控制尺寸和形貌是制备高性能金纳米粒子（Au NCs）的关键，通过控制反应条件制备的Au NCs仍存在一定的尺寸分布问题，为进一步改进制备技术或开发新技术，Au NCs生长机理的研究非常重要。分离技术的应用可得多种单一尺寸的金纳米粒子，本项目采用HPLC技术将不同方法制备的Au NCs产物进行分离，结合多种表征手段对分离得Au NCs进行分析测试，并采用HPLC方法对金纳米粒子的制备过程进行实时监测，研究不同反应条件对Au NCs尺寸、金原子/配体数目分布的影响，全面研究不同尺寸的Au NCs随反应条件的变化，较详细、准确地揭示Au NCs的微观生长机理，促进Au NCs可控制备的发展，使Au NCs更有效地应用于材料、生物、医学及毒理学等领域。通过HPLC分离还可同时得不同尺寸、含有不同金原子/配体数的Au NCs，满足对微观结构有较高要求的精密器件、微型催化等的需要。

金纳米粒子是最稳定的贵金属纳米粒子之一，其物化性质与其尺寸、形态直接相关，精确控制颗粒尺寸和形貌是制备高性能金纳米粒子的关键，也是材料性能研究与器件研制的前提。本项目以自身具有还原性的化合物为配体制备了7种新型的金纳米粒子，以HPLC为主要研究手段对Au NCs的反应过程进行了实时监测，分离反应产物并收集馏分采用紫外-可见光谱、荧光光谱、高分辨透射电子显微镜、热重分析、质谱等方法对收集的所有HPLC馏分进行了分析表征，分析各个馏分的组成成分，得到了其详尽的光谱、尺寸信息。通过考察AuNCs的尺寸及所含的金原子/配体数随反应条件的改变，研究了AuNCs的生长动力学，得到了AuNCs清晰、详细的形成机理。组氨酸保护的金纳米粒子由Au10(His)9, [Au11(His)9]−, Au11(His)10, Au12(His)9, Au12(His)11, Au12(His)12, Au13(His)9, Au13(His)11, Au14(His)13组成，且组氨酸与金原子数目的比值越小，在反应过程中越不稳定，易分解，反应采用的前驱体中配体比例越高，越有利于组氨酸与金原子数目的比值小的金纳米粒子的生成。DMF-AuNCs由 [Au10(DMF)9]+, Au8(DMF)7, Au12(DMF)8, Au12(DMF)10, Au13(DMF)9组成，DMF-AuNCs在HPLC中粒径小的金纳米粒子先流出，Au10+, Au8, 和 Au12 纳米粒子随着反应时间会逐渐生长，而Au13(DMF)9 先生长后随着DMF溶剂的减少而发生聚集变为较大粒径的AuNCs。NAC-AuNCs主要由Au27NAC32组成，巯基将Au(III)还原为Au(I)，随之Au(I)和-SH结合生成Au(I)−SH或Au(I)-COOH/Cl，NAC选择性地将Au(I)-COOH/Cl还原为Au(0)原子，Au(0) 原子被Au(I)-NAC隔离，形成以Au(0)原子为核，以复合物Au(I)-NAC为壳的稳定金纳米粒子。另外本项目将金纳米粒子应用于金属离子汞离子、镁离子、及生物小分子半胱氨酸、尿酸、硫化氢的高灵敏高选择性检测，并应用于活细胞成像中，为金纳米粒子在生态环境、生物医学等领域中的应用奠定了基础。