These steps involve chemical or plasma treatment of the grid, sample deposition and vitrification. Grid preparation describes the steps needed to make a sample suitable for analysis in the microscope.

Sample optimization involves specimen purification while maintaining the optimum biochemical state of the sample. Sample preparation in single-particle analysis has two main components: sample optimization and grid preparation. While these technical upgrades have made cryo-EM more accessible to structural biologists, sample preparation has emerged as the main impediment in the workflow, leading scientists and engineers to target this hurdle 14. Hardware improvements, primarily aimed at narrowing the energy spread of incident electrons, have brought the achievable resolution to below 1.3 Å 12, 13. Furthermore, data processing has become more robust and user friendly 10, with automated pipelines being developed to streamline data acquisition and processing 11. Software packages allow continuous unsupervised collection of high-quality data over days. Cryo-electron microscopes have become more amenable to automation through features such as the autoloader, constant-power lenses, mechanical stages with decreased drift and aberration-free image shifting. The new cameras are able to operate in single-electron counting mode and acquire movies to compensate for movement during imaging 9. One of the key driving forces has been the introduction of a new generation of cameras with direct electron detection and increased frame rates 8. The rise in popularity of cryo-EM as a breakthrough structural biology technique comes as a result of a number of technical advancements, often referred to as the ‘resolution revolution’ (ref. Pharmaceutical organizations have already shown a growing interest in the technique to analyze ligand binding, perform conformational studies and carry out drug testing 6.

Understanding the process of virus binding to specific receptors on human cells will aid the fabrication of targeted vaccines, drugs and diagnostics 4, 5. Cryo-EM was also instrumental in resolving the structure of the SARS-CoV-2 spike protein, which helps the virus gain entry to human cells, at a resolution of 3.5 Å 3. For example, resolving the structures of tau filaments 1 and amyloid fibrils 2 has provided insights into the mechanism of Alzheimer’s disease, the most common neurodegenerative disorder. The detailed structural models obtained from these reconstructions grant insight into the function of macromolecules and their role in biological processes.

In this technique, electron microscopy images of biomolecules embedded in vitreous, glass-like ice are combined to generate three-dimensional (3D) reconstructions. Cryo-EM is providing macromolecular structures with up to atomic resolution at an unprecedented rate.

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