Imaging biological samples by integrated differential phase contrast (iDPC) STEM technique

Xujing Li; Ivan Lazić; Xiaojun Huang; Maarten Wirix; Li Wang; Yuchen Deng; Tongxin Niu; Dongchang Wu; Lingbo Yu; Fei Sun

doi:10.1016/j.jsb.2022.107837

Imaging biological samples by integrated differential phase contrast (iDPC) STEM technique

J Struct Biol. 2022 Mar;214(1):107837. doi: 10.1016/j.jsb.2022.107837. Epub 2022 Jan 31.

Authors

Xujing Li¹, Ivan Lazić², Xiaojun Huang¹, Maarten Wirix³, Li Wang¹, Yuchen Deng³, Tongxin Niu¹, Dongchang Wu³, Lingbo Yu³, Fei Sun⁴

Affiliations

¹ Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
² Thermo Fisher Scientific, Materials and Structural Analysis, Eindhoven, The Netherlands. Electronic address: ivan.lazic@thermofisher.com.
³ Thermo Fisher Scientific, Materials and Structural Analysis, Eindhoven, The Netherlands.
⁴ Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing, China; Physical Science Laboratory, Huairou National Comprehensive Science Center, No. 5 Yanqi East Second Street, Beijing 101400, China; Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, Guangdong 510005, China. Electronic address: feisun@ibp.ac.cn.

PMID: 35104612
DOI: 10.1016/j.jsb.2022.107837

Abstract

Scanning transmission electron microscopy (STEM) is a powerful imaging technique and has been widely used in current material science research. The attempts of applying STEM (annual dark field (ADF)-STEM or annular bright field (ABF)-STEM) into biological research have been going on for decades while applications have still been limited because of the existing bottlenecks in dose efficiency and non-linearity in contrast. Recently, integrated differential phase contrast (iDPC) STEM technique emerged and achieved a linear phase contrast imaging condition, while resolving signals of light elements next to heavy ones even at low electron dose. This enables successful investigation of beam sensitive materials. Here, we investigate iDPC-STEM advantages in biology, in particular, chemically fixed and resin embedded biological tissues. By comparing results to the conventional TEM, we have found that iDPC-STEM not only shows better contrast but also resolves more structural details at molecular level, including conditions of extremely low dose and minimal heavy-atom staining. We also compare iDPC-STEM with ABF-STEM and found that contrast of iDPC-STEM is even further improved, moderately in lower frequency domains while highly with preserving high frequency biological structural details. For thick sample sections, iDPC-STEM is particularly advantageous. It avoids contrast inversion canceling effects, and by adjusting the depth of focus, fully preserves the contrast of structural details along with the sample. In addition, using depth-sectioning, iDPC-STEM enables resolving in-depth structural variation. Our results suggest that iDPC-STEM have the place and advantages within the future biological research.

Keywords: Biological sample; Contrast; Integrated differential phase contrast; Scanning transmission electron microscopy; Thick section.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Electrons*
Microscopy, Electron, Scanning Transmission / methods
Microscopy, Phase-Contrast