Cryogenic electron microscopy (Cryo-EM): a cutting-edge technology for nanometric analysis
A nanometric analysis method for biomolecules and advanced materials
Cryo -electron microscopy (Cryo-EM or Cryo-EM) is a high-resolution microscopy technique that allows the analysis of biological samples and complex materials at the nanoscale. By preserving structures in their native state through ultra-rapid cooling, this method eliminates the preparation artifacts often encountered in conventional electron microscopy. Used in biomedical research, biotechnology, the pharmaceutical industry, and nanotechnology, Cryo-EM is essential for the study of proteins, viruses, nanoparticles, and polymers.
What are the different types of cryo-electron microscopy?
Cryo-TEM (transmission electron microscopy) and cryo-SEM (scanning electron microscopy) are two advanced imaging techniques used for the analysis of samples in their native state, thanks to rapid vitrification which preserves their original structure.
- Cryo-TEM allows for the observation of internal structures at very high resolution by transmitting an electron beam through ultrathin sections of frozen samples. It is particularly well-suited to the study of cells, tissues, proteins, biomolecular complexes, or nanoparticles, and can be coupled with methods such as immunolabeling or 3D tomography.
- Cryo-SEM, on the other hand, is dedicated to surface analysis. It offers precise visualization of topography, interfaces, and interactions while avoiding any deformation due to desiccation. Used particularly for biological and organic materials, it allows observation of the morphological evolution of hydrated samples without the use of chemical fixatives. These techniques can also be combined with elemental microanalysis (EDS) for detailed chemical characterization.
How does cryogenic electron microscopy work?
Cryogenic electron microscopy relies on a combination of rapid cooling and transmission electron imaging. Its operation involves several steps:
- Sample vitrification : The sample is rapidly frozen in liquid ethane or liquid nitrogen. This process prevents the formation of ice crystals and maintains the structural integrity of the material.
- Electron beam or transmission electron observation : for both techniques (TEM and SEM), electrons are sent through the frozen sample, generating very high resolution images.
- Image acquisition and reconstruction : Advanced image processing software allows for 3D reconstructions and detailed analysis of nanometric structures.
Technical characteristics of cryogenic electron microscopy
- High-resolution imaging : Resolution close to the angstrom, ideal for the analysis of proteins and biological complexes.
- Cryogenic cooling : Optimal preservation of molecular structures and nanomaterials in their native state.
- Sample preservation : Absence of chemical fixation or dyes that could alter the sample.
- 3D reconstruction : Ability to model complex biological structures from images obtained from different angles.
For which matrices is cryogenic electron microscopy suitable?
This method is particularly effective for studying the following matrices:
Industrial applications of cryogenic electron microscopy
Cryogenic electron microscopy is an essential technology for many industrial sectors:
Léa Géréec
Technical and scientific expert
