MRI: Acquisition of a High-Pressure Freezing System for Cryo-Electron Microscopy

MRI：获取用于冷冻电子显微镜的高压冷冻系统

• 批准号: 1428296
• 负责人: Matthew Libera
• 金额: $ 19.83万
• 依托单位: Stevens Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-15 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1428296&HistoricalAwards=false
• 关键词: MRI; Acquisition; Pressure; Freezing; System

Technical (Original) title: MRI: Acquisition of a High-Pressure Freezing System for Cryo-Electron MicroscopyLay Title: Rapid Freezing for Advanced Electron Microscopy of Wet Materials Nontechnical explanation: Using microscopes to see the structure of a material provides very important information that helps scientists and engineers understand how to make new materials with better properties. While many microscopes use light to form images, electron microscopes can reach much higher magnifications and resolve finer detail in a material's structure. However, unlike light microscopes, electron microscopes require a vacuum (the air inside the microscope must be removed )so that the electrons will not collide with gas molecules from the air. Vacuum isn't a problem when studying dry materials, but it is a big problem when studying wet materials, because water quickly evaporates in a vacuum. This research team is developing new materials that all contain water. These materials are being designed to help regrow human tissue, to make biomedical implants more resistant to infection, and to deliver drugs where and when they are needed within the human body. These new materials can be studied in an electron microscope if they are frozen and kept cold, because then the water is solid rather than liquid and it doesn't evaporate. However, the freezing has to be done in a special way, otherwise the material gets damaged just like a sealed bottle of milk will break if it freezes. So, this research project is using a new tool called a high-pressure freezer, which eliminates expansion of the liquid water when it freezes. Consequently, the team is able to study wet materials and gather information about structure at levels of detail that no one has previously achieved. Because this approach is so new and significant, the research team is working with an electron-microscope manufacturer to help share these developments with other microscope users. And, because this freezing tool can also be used to study everyday materials like cosmetics, food, plants, and insects, the research team is partnering with an all-girls school in New Jersey to use this new technology to help dozens of young women get exposed to some of the excitement associated with science and engineering. Technical Project Description: While the average morphology of many hydrated materials can often be determined by scattering (neutron, X-ray, light), these techniques can not match the ability of electron microscopes to collect site-specific, high-resolution, real-space, image data. The high vacuum required for both scanning (SEM) and transmission electron microscopy (TEM), however, precludes the direct observation of hydrated specimens, and this limitation is only partially mitigated by variable-pressure microscopes and environmental/liquid microscope stages. The long-standing solution has been to freeze the specimens and study them in the electron microscope under cryogenic conditions. Simply quenching specimens in a liquid cryogen is, however, no longer adequate for the imaging problems being addressed by this research team. This team is pursuing six externally funded inter-related projects centered on polymer and nanoparticle self-assembly, microfluidic 3-D tissue models, advanced scaffolds for tissue engineering, and hierarchical surface nano-patterning for infection control. These projects all involve advanced materials with high levels of hydration, which inhibits high-resolution morphological studies using conventional cryo-EM techniques. The goal of this project is thus to exploit the new technique of high-pressure freezing to prepare highly hydrated materials for advanced electron microscopy, both SEM and TEM, as well as for 3-D imaging using slice-and-view focused ion beam (FIB-SEM) microscopy. High-pressure freezing mitigates artifacts created by water crystallization and solute segregation during conventional freezing. Incorporating this state-of-the-art technology is enabling the research team to assess the detailed morphology of emerging materials and material systems in their native hydrated state at pioneering levels of image resolution.

技术（原始）标题：MRI：用于冷冻电子显微镜的高压冰冻系统的获取：用于湿材料的高级电子显微镜的快速冷冻，非技术解释：使用显微镜来查看材料的结构提供非常重要的信息，可帮助科学家和工程师了解如何使新材料与更好的物业建立新的材料。 尽管许多显微镜都使用光来形成图像，但电子显微镜可以达到更高的宏伟效果，并在材料结构中解决更精细的细节。 但是，与光显微镜不同，电子显微镜需要真空（必须去除显微镜内部的空气），以使电子不会与空气中的气体分子相撞。 研究干材料时的真空不是问题，但是在研究湿材料时，这是一个大问题，因为水很快在真空中蒸发。 该研究团队正在开发所有含有水的新材料。 这些材料旨在帮助再生人体组织，使生物医学植入物对感染更具耐药性，并在人体内需要何时和何时提供药物。如果将这些新材料冷冻并保持冷，可以在电子显微镜中研究，因为那时水是固体而不是液体，并且不会蒸发。 但是，冻结必须以特殊的方式进行，否则材料会损坏，就像密封的一瓶牛奶冻结的情况下会破裂。 因此，该研究项目正在使用一种称为高压冰柜的新工具，该工具在冻结时消除了液体水的膨胀。 因此，团队能够研究湿材料并收集有关以前没有人实现的细节水平的信息。 由于这种方法是如此新颖而重要，因此研究团队正在与电子微镜制造商合作，以帮助与其他显微镜用户分享这些发展。 而且，由于这种冻结工具也可以用于研究化妆品，食品，植物和昆虫等日常材料，因此研究团队正在与新泽西州的全女孩学校合作使用这项新技术来帮助数十名年轻女性与科学和工程有关的一些兴奋。 技术项目描述：虽然许多水合材料的平均形态通常可以通过散射（中子，X射线，光）来确定，但这些技术无法匹配电子显微镜收集特定地点，高分辨率，真实空间，图像数据的能力。 但是，扫描（SEM）和透射电子显微镜（TEM）所需的高真空无法直接观察水合样品，并且仅通过可变压力显微镜以及环境/液体显微镜阶段来部分缓解这种限制。 长期的解决方案是在低温条件下冻结样品并在电子显微镜中进行研究。 但是，仅仅在液体低温中淬灭标本就不再足以解决该研究团队所解决的成像问题。 该团队正在追求六个以聚合物和纳米颗粒自组装为中心的外部资助的相关项目，微流体3-D组织模型，用于组织工程的晚期支架以及用于感染控制的等级表面纳米体现。 这些项目都涉及具有高水平水合作用的高级材料，该材料使用常规的冷冻EM技术抑制了高分辨率的形态学研究。 因此，该项目的目的是利用高压冻结的新技术来为高级电子显微镜（SEM和TEM）以及使用切片和视图集中的离子束（FIB-SEM）显微镜制备高度水合的材料。 高压冻结会减轻传统冰冻过程中水结晶和溶质隔离产生的伪像。 结合这种最先进的技术正在使研究团队能够以图像分辨率的开创性水平评估其本地水合状态下新兴材料和材料系统的详细形态。