Cryo-EM Imaging

Low temperature cryo-electron microscopy for aqueous systems analysis.

The high-vacuum conditions occurring in electron microscopes and their associated preparation instruments had precluded the study of wet materials. The process of drying water-containing samples invariably creates artefacts and often destroys features of interest. The emergence of variable-vacuum microscopes allows only partial hydration of such samples. New instrumentation available at Intertek MSG uses low temperatures to overcome these problems. allowing the lab to image "wet" samples with little or no loss or distortion of material.

Images like this picture of raw potato cells are generated on Intertek's high-resolution field-emission SEM with the aid of the Gatan Alto-2500 cryo-system. This allows Intertek to cool small samples rapidly, and to maintain them at low temperatures during their subsequent fracture and etching, sputter-coating, transfer to the microscope and imaging.

The key to success in studying aqueous systems lies in rapidity of cooling in order to avoid ice crystal formation. This can be acheived using a Gatan Cryoplunge device, which fires a small sample into condensed cryogen at -180°C.

The Cryoplunge incorporates a controlled blotting system, allowing preparation of rapidly-frozen thin-film suspensions of samples such as liposomes, viruses and macromolecules for cryo-TEM examination.

Other in-house methods of cryo-preparation include low-temperature sectioning of materials on the Reichert Ultracut/FC4 system. In addition to generating ultra-thin and semi-thin sections for the cryo-TEM, the Reichert unit provides cryo-planed flat surfaces for subsequent back scatter imaging, or etching and secondary electron imaging in the SEM. This growing suite of low-temperature methods enables Intertek scientists to apply a broad range of imaging and analytical techniques to materials.

Contact us to see how Intertek can help your organization with Cryo-EM Imaging.