Liquid-phase 3D electron microscopy for materials science and biology

电子显微镜传统上与真空中薄的固体样品的研究有关。在过去的十年中，一些研究小组率先开发了液体样品纳米分辨率的系统。液相电子显微镜（LPEM）的广泛适用性引发了人们的兴趣，因为它为解决材料科学，化学，生物学和其他领域的重大挑战开辟了令人兴奋的可能性，并为操作研究开辟了道路。无论应用领域如何，通常需要液体中样品的三维（3D）表示来理解其结构。目前用于深入了解生物学和材料科学独特样品纳米级3D结构的主要方法是倾斜系列透射电子显微镜。特别是，扫描透射电子显微镜（STEM）是非常适合厚标本，如液体样品的研究。该提案的目标是建立液体3D STEM作为新的显微镜模式，为材料科学和生物学中液体样品的纳米级表征提供独特的方式。与最先进的3D电子显微镜相比，液体3D STEM具有更强的功能，因为它提供了一种在液体中研究标本的方法。该项目得益于两个领先的原位电子显微镜中心的协同作用，里昂的INSA专注于材料科学，萨尔布吕肯（德国）的INM专注于生物物理学研究。该技术将通过收集两个小组的互补专门知识来共同开发。每个小组都将使用Liquid 3D STEM来研究一个已经有多年经验的系统。通过结合努力和专业知识，我们希望能够克服实验过程中遇到的主要困难（对电子束的敏感性，低对比度，大厚度）。建立这种技术将为材料科学和生物学样品的纳米级表征开辟一条新途径。该项目包括4个工作包（WP）。其中两个专门用于仪器：理论和计算方面（WP 1），以及优化显微镜设置的液体3D STEM的实施（WP 2）。另外两个WP涉及新建立的技术应用于材料科学（乳胶悬浮液中表面活性剂分布的测定，WP 3）和生物样品（纳米颗粒细胞间命运的研究，WP 4）。

Electron microscopy has traditionally been associated with the study of thin, solid samples in vacuum. In the last decade, a few groups pioneered systems achieving nanometer resolution for liquid specimens. The broad applicability of liquid phase electron microscopy (LPEM) has driven a wave of interest as it has opened exciting possibilities for solving grand challenges in materials science, chemistry, biology, and other fields, and has opened the route for operando studies. Whatever the application field, a three-dimensional (3D) representation of the sample in liquid is often required for understanding its structure. The primary method currently used for obtaining insight into the 3D structure at the nanometer scale of unique samples from biology and materials science is tilt-series transmission electron microscopy. In particular, scanning transmission electron microscopy (STEM) is well-adapted to the study of thick specimens such as liquid samples. The goal of this proposal is to establish Liquid 3D STEM as new microscopy modality, presenting an unique way for nanoscale characterization of samples in liquid from both materials science and biology. Liquid 3D STEM has enhanced capabilities compared to state-of-the-art 3D electron microscopy because it provides a means to study specimens in liquid. The project benefits from the synergy of two leading centers for in situ electron microscopy, INSA in Lyon, with a focus on materials science, and INM in Saarbrücken (Germany), with research focused towards biophysics. The technique will be jointly developed by gathering the complementary expertise of both groups. Each group will use Liquid 3D STEM to study a system with which it has already several years of experience. By combining efforts and expertise, we expect to be able to overcome the main difficulties encountered during the experiments (sensitivity to the electron beam, low contrast, large thickness). Establishing this technique would open up a novel way for nanoscale characterization of samples from materials science and biology. The project consists of 4 work packages (WPs). Two of them are dedicated to instrumentation: theoretical and computational aspects (WP1), and implementation of Liquid 3D STEM with optimized microscope settings (WP2). The two other WPs involve the application of the newly-established technique to materials science (determination of the surfactant distribution in latex suspensions, WP3), and to biological samples (study of nanoparticle intercellular fate, WP4).