Molecules and Cells

Korean Society for Molecular and Cellular Biology (한국분자세포생물학회)
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Copper Oxide Spike Grids for Enhanced Solution Transfer in Cryogenic Electron Microscopy

  • Dukwon Lee (Research Institute of Agriculture and Life Sciences, Center for Food and Bioconvergence, Department of Agricultural Biotechnology, Interdisciplinary Programs in Agricultural Genomics, College of Agriculture and Life Sciences (CALS), Seoul National University) ;
  • Hansol, Lee (School of Biological Sciences, Seoul National University) ;
  • Jinwook Lee (Research Institute of Agriculture and Life Sciences, Center for Food and Bioconvergence, Department of Agricultural Biotechnology, Interdisciplinary Programs in Agricultural Genomics, College of Agriculture and Life Sciences (CALS), Seoul National University) ;
  • Soung-Hun Roh (School of Biological Sciences, Seoul National University) ;
  • Nam-Chul Ha (Research Institute of Agriculture and Life Sciences, Center for Food and Bioconvergence, Department of Agricultural Biotechnology, Interdisciplinary Programs in Agricultural Genomics, College of Agriculture and Life Sciences (CALS), Seoul National University)
  • Received : 2023.04.11
  • Accepted : 2023.06.27
  • Published : 2023.09.30
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Abstract

The formation of uniform vitreous ice is a crucial step in the preparation of samples for cryogenic electron microscopy (cryo-EM). Despite the rapid technological progress in EM, controlling the thickness of vitreous ice on sample grids with reproducibility remains a major obstacle to obtaining high-quality data in cryo-EM imaging. The commonly employed classical blotting process faces the problem of excess water that cannot be absorbed by the filter paper, resulting in the formation of thick and heterogeneous ice. In this study, we propose a novel approach that combines the recently developed nanowire self-wicking technique with the classical blotting method to effectively control the thickness and homogeneity of vitrified ice. With simple procedures, we generated a copper oxide spike (COS) grid by inducing COSs on commercially available copper grids, which can effectively remove excess water during the blotting procedure without damaging the holey carbon membrane. The ice thickness could be controlled with good reproducibility compared to non-oxidized grids. Incorporated into other EM techniques, our new modification method is an effective option for obtaining high-quality data during cryo-EM imaging.

Keywords

Acknowledgement

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean Government (2019M3E5D606387122, 2020R1A5A1018081, 2021M3A9I4021220). Purified GroEL and MmCpn proteins were kindly provided by Mingyu Jung and Sojeong Kim from the Lab of Molecular Imaging, SNU.

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