How it Works: Cryo-Electron Microscopy

Electron microscopes function on the basic principle that electron wavelengths are shorter than photons’, and thus generally are able to pick up more detail. Photons are the basic particles of light and everything we see around us is the result of these particles reflecting off of objects and into our eyes. However some objects are smaller than the wavelength of photons, so they don’t really interact and our eyes just can’t see them.

 

But never fear: because their wavelength is so minute, electrons can interact with tiny objects. So by using electron rather than light microscopes, we can delve even deeper into cellular and molecular structures – about 5,000 times deeper to be precise. Cryo-electron microscopy, or cryo-EM, is exactly what it sounds like: using this method under really cold conditions, at -200 °C using liquid nitrogen. This amazing technique can help us to uncover even more about the minute, hidden elements in matter, leading to advancements in medicine, bio-engineering, and our fundamental understanding of the world around us.

 

 

Electrons are the tiny charged particles that make up the outside of atoms, and they’re able to help us see minute components of matter like cells, microorganisms, molecules, and the up-close structure of materials.

 

Electron microscopes work by generating a beam of electrons. Electromagnetic lenses are used to focus the beam, which is then fired at a sample. The electrons then interact with nano-scale components, allowing us to investigate and visualise samples in astonishing detail.

 

There are different varieties of electron microscopy, and cryo-EM is a relatively new field. Regular electron microscopy requires samples to be prepared in complex ways – techniques include coating samples in substances that protect them from radiation, sectioning them into tiny slices, or dehydrating them to prevent the interaction between electrons and water molecules.

 

But with cryo-EM, samples don’t require this sort of preparation – they can simply be frozen and then studied in their normal state. This means that scientists can see biological elements as a whole and in an active state. Furthermore, rather than studying individual components of a sample and piecing a wider picture together, cryo-EM enables scientists to look at big, complex biological systems.

 

Cryo-EM isn’t perfect. It produces lower resolution images than some other techniques, like X-ray crystallography. But the real strength of cryo-EM lies in its versatility. The technique allows scientists to study objects that – because of their size, complexity, or sheer awkwardness – would be virtually impossible to scrutinise with other techniques. It’s quick and flexible; and when used in tandem with other techniques, cryo-EM is a supremely powerful tool.