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Metal Coating Techniques for Contrast Enhancement of Biological Macromolecular Complexes In HRSEM, STEM and TEM Image Modes

Published online by Cambridge University Press:  02 July 2020

RP. Apkarian
Affiliation:
Integrated Microscopy & Microanalytical Facility, Emory University, Atlanta, GA30322
T.A.T. Lee
Affiliation:
Department of Chemistry, Emory University, Atlanta, GA30322
V.P. Conticello
Affiliation:
Department of Chemistry, Emory University, Atlanta, GA30322
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Extract

Modern field emission SEMs fitted with in-lens or near-lens (W.D. = l-3mm.) stages and above-lens SE detectors are capable of imaging 1-5 nm features at high voltage (15-30kV) and 5-10 nm features at low voltage (l-5kV). Ultrathin fine-grain refractory metal coatings were shown to optimize higher-solution (HR) secondary electron imaging of light element specimens especially biological samples. Ambient temperature dried specimens and frozen-hydrated cryo-specimens coated with continuous 1nm-thick metal films and staged in-lens have revealed biologically significant features of molecular dimension in tandem HRSEM and scanning transmission (STEM) modes. Although positive and negative stains have proved useful for general contrast enhancement of TEM specimens these stains alter many of our new genetically synthesized block protein copolymers. Therefore we have turned to non-evaporated metal coatings for contrast enhancement of these specimens in the TEM.

Type
Electron Cryomicroscopy of Macromolecules
Copyright
Copyright © Microscopy Society of America

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