Cryoholders

A cryoholder is a specialized tool used in cryo-electron microscopy (cryo-EM) to securely hold a sample that is frozen in a thin layer of vitreous ice. These holders are essential for maintaining the extremely low temperatures required for cryo-EM imaging, typically below -150 degrees Celsius. The primary function of a cryoholder is to provide a stable and reproducible environment for the biological or material sample while it is transferred from a freezing device to the electron microscope and then imaged.

Cryoholders are typically made of materials that conduct heat well, such as copper or aluminum, to facilitate rapid cooling and maintain a stable low temperature. They are designed with specific features to ensure the sample remains frozen throughout the process, preventing ice crystal formation which would degrade image quality. These features often include a vacuum-sealed shaft to insulate the sample from ambient temperature and moisture.

The sample itself is usually applied to a small grid which is then inserted into a receptacle at the tip of the cryoholder. The design of the receptacle is critical for securely gripping the grid without damaging the delicate frozen sample. Various types of cryoholders exist, differing in their length, diameter, and specific cooling mechanisms, to accommodate different microscope models and experimental needs. The correct use and handling of cryoholders are paramount for obtaining high-resolution data in cryo-EM.