标题： 液相快速电子断层扫描揭示了胶体组装体的真实三维结构 显示英文标题

标题： Liquid phase fast electron tomography unravels the true 3D structure of colloidal assemblies

摘要： 电子断层扫描已成为研究纳米材料三维（3D）结构的常用工具，包括胶体纳米颗粒组装体。 然而，电子显微镜通常在高真空条件下进行。 因此，对于通过（湿法）胶体化学方法获得的组装体，需要进行预处理样品制备，包括溶剂蒸发和沉积在固体TEM支撑膜上。 由于这一过程，实际纳米颗粒组织会受到持续的变化。 因此，我们在此提出在原始胶体液相环境中对纳米颗粒组装体进行电子断层扫描的应用。 为了解决液体中电子断层扫描相关的挑战，我们设计了一种方法，该方法结合了商业液体-TEM细胞中的快速数据采集，以及专用的对齐和重建工作流程。 我们展示了该方法在两种不同系统中的应用，这些系统说明了根据保护配体的性质，传统断层扫描与液体断层扫描之间的差异。 由聚合物壳包裹的聚苯乙烯封端金纳米颗粒组装体的三维重建显示，在液体介质中进行的实验相比干燥样品呈现出更松散和更扭曲的构型。 另一方面，水溶液中自组装金纳米棒的表面间距离的定量分析与之前报道的纳米棒周围配体层的尺寸一致，而在类似但干燥的组装体中，它们的接触更为紧密。 因此，本研究强调了开发能够保持胶体纳米结构原生环境的高分辨率表征工具的重要性。 显示英文摘要

摘要： Electron tomography has become a commonly used tool to investigate the three-dimensional (3D) structure of nanomaterials, including colloidal nanoparticle assemblies. However, electron microscopy is typically carried out under high vacuum conditions. Therefore, pre-treatment sample preparation is needed for assemblies obtained by (wet) colloid chemistry methods, including solvent evaporation and deposition on a solid TEM support. As a result of this procedure, changes are consistently imposed on the actual nanoparticle organization. Therefore, we propose herein the application of electron tomography of nanoparticle assemblies while in their original colloidal liquid environment. To address the challenges related to electron tomography in liquid, we devised a method that combines fast data acquisition in a commercial liquid-TEM cell, with a dedicated alignment and reconstruction workflow. We present the application of this method to two different systems, which exemplify the difference between conventional and liquid tomography, depending on the nature of the protecting ligands. 3D reconstructions of assemblies comprising polystyrene-capped Au nanoparticles encapsulated in polymeric shells revealed less compact and more distorted configurations for experiments performed in a liquid medium compared to their dried counterparts. On the other hand, quantitative analysis of the surface-to-surface distance of self-assembled Au nanorods in water agrees with previously reported dimensions of the ligand layers surrounding the nanorods, which are in much closer contact when in similar but dried assemblies. This study, therefore, emphasizes the importance of developing high-resolution characterization tools that preserve the native environment of colloidal nanostructures.