Cryogenic Electron Microscopy and Tomography on Radiation Sensitive Crystalline Materials
Author: Weijiang Zhou
Publisher:
Published: 2022
Total Pages:
ISBN-13:
DOWNLOAD EBOOKCryogenic electron microscopy (Cryo-EM) has been one of the most exciting technology advancements in biological field in recent years. The idea of freezing samples in liquid nitrogen temperature provides a unique advantage to preserve and observe the object of interest in their native state. The improvements in both electron microscopy related hardware and data processing software enable the retrieval of structural information to atomic details. However, many technical features in electron microscope have not been fully explored for cryo-EM and many other sample systems other than biological specimens could utilize cryo-EM to accelerate their structural characterization research. This dissertation focuses on developing a new cryo-EM based experimental and data processing pipeline to further extend the applications of cryo-EM to broader research fields, where the samples of interest are normally not amenable to conventional electron microscopy methods. There are two common features across the specimens aforementioned: first, they are crystalline materials, meaning they are either single crystals or contain certain degree of periodic structures; second, they are sensitive to electron radiation, thus conventional transmission electron microscopy is not suitable to study such materials due to its high electron radiation damage. To investigate those specimens using cryo-EM, we developed several new methods: customized freezing protocol to preserve the samples from ambient environment; cryogenic focused ion beam milling to prepare electron transparent samples; continuous tilting electron diffraction to solve the atomic structure from single crystals; electron diffraction and high resolution low dose electron imaging to acquire the sub-nanometer structural information in both real-space and Fourier space; electron tomography and automated annotation to recover the morphology of non-biological samples in 3D. Those lead to many unprecedented findings in those representative specimens, which will be described in this dissertation. We anticipate those new technical developments will facilitate the usage of cryo-EM in structural biology, chemical biology, organic chemistry and material science in the near future.