Cryo-Electron Microscopy (EM) Imaging

Cryo-electron microscopy (EM) imaging can also be referred to as Cryo-EM or electron cryomicroscopy. It is a type of transmission electro-microscopy (TEM), which involves passing a beam of electrons through an ultra-thin specimen, interacting with it as it passes through. An image can be developed from the electrons’ interaction, and when magnified and focused onto a screen or other imaging device, it permits far smaller microscopy than can be achieved with a light microscope. In Cryo-EM, the sample is studied at extremely low (cryogenic) temperatures. Liquid nitrogen or liquid helium is typically used to produce these low temperatures. The purpose of the freezing process is to reduce the effects of radiation damage on the structure of the sample when compared to other techniques. Additionally, there is no need to stain the sample or fix it in any way, as there is with techniques such as X-ray crystallography, allowing the very smallest of samples to be analysed in their natural state and in their own environment. The technique is especially of use in structural biology, the study of the molecular structure of biological macro molecules, especially viruses, cells, proteins and nucleic acids.