Kriomikroskoopia

Kriomikroskoopia, or cryo-microscopy, is a set of imaging techniques that operate at cryogenic temperatures to observe specimens in a vitreous, near-native state. The most widely used form is cryo-electron microscopy (cryo-EM), together with cryo-electron tomography (cryo-ET). Cryo-microscopy relies on rapidly vitrifying aqueous samples by plunge-freezing into liquid ethane cooled by liquid nitrogen, creating vitreous ice and avoiding crystalline ice artifacts.

In cryo-EM, specimens are imaged with an electron beam at cryogenic temperatures. Advances such as direct electron detectors and sophisticated computational reconstruction enable high-resolution structures from individual particles. Cryo-ET collects tilt series to reconstruct three-dimensional volumes, providing contextual, in situ views of macromolecules within cells or at the periphery of cellular environments. There is also cryo-fluorescence microscopy (cryo-FM) used for correlative light and electron microscopy (cryo-CLEM), enabling precise localization in cells before electron imaging.

History and impact: The development of cryo-EM and related methods advanced significantly in the late 20th and early 21st centuries. Jacques Dubochet, Joachim Frank, and Richard Henderson were awarded the Nobel Prize in Chemistry in 2017 for their contributions to the development of cryo-EM.

Applications: Kriomikroskoopia is central to structural biology and virology, enabling studies of large protein complexes, ribosomes, viral particles, and membrane proteins that are difficult to study by other methods. It also supports imaging in cellular contexts and materials science research.

Advantages and challenges: Cryo-microscopy preserves samples in a near-native state and reduces radiation damage per image, enabling high-resolution insights. Challenges include the technical complexity of vitrification, the need for specialized equipment, and intensive data processing requirements. Ongoing developments—detectors, phase plates, and automation—continue to broaden its capabilities.