Methods

Single particle analysis

For single particle analysis, purified proteins and other biological macromolecules are frozen in a thin layer of vitreous ice and imaged in a transmission electron microscope (TEM). Through computational averaging of many identical particles and combining different orientations, it is  possible to obtain 3D structures at near-atomic resolution.

Cryo-Electron Tomography

3D models of whole cells are obtained by rotating frozen cells in the electron beam, taking 2D projection images at angles ranging from +60° to -60°. This opens a window for observing cellular processes at sub-nanometer resolution. Through sub-tomogram averaging and/or fitting single particle structures into the cellular models, proteins can be observed in their native context.     

cryo-TEM screening & imaging

The 12-sample autoloader and user-friendly software of the Krios G4 TEM allows for fast and efficient screening of samples, which is always the first step in identifying suitable candidates for single particle analysis and cryo-ET. But cryo-EM imaging can be used for more than structural biology: Various types of nanoparticles, which are used as delivery vehicles for mRNA vaccines and other drugs, are routinely imaged using cryo-EM. The cryo-fixation and and sidestepping of artificial staining provides more detailed images than traditional methods such as negative staining and room temperature TEM.