ASU’s Titan Krios is a dedicated cryogenic transmission electron microscope for soft matter and organic assemblies such as those found in cellular life and other macromolecular assemblies.
It possesses a highly stable cryogenic environment suitable for automated and semi-automated data acquisition. Typical imaging modalities include 2D electron crystallography, single particle imaging, and tomographic imaging. This Krios has a point resolution limit of 1.8 Angstroms, a Cs of 2.7 mm with a 11 mm pole gap for high tilt imaging. This Krios is also equipped with FEI Volta phase plate technology that provides a π/2 phase shift in the incident beam to improve contrast at near Scherzer of weak phase objects embedded in vitreous ice.
- Autoloader with 12 sample positions
- X-FEG emission source
- Volta Phase plates
- K2 Summit direct electron detector
- CetaM high speed hybrid CMOS camera for electron diffraction data collection
- STEM imaging and HADDF detector
- Constant current lenses and stable parallel beam illumination
- Serial EM, EPU, S/TEM tomography software for automated data collection
Techniques: Cryogenic TEM
Organic materials preserved in vitreous ice by rapid freezing methods provides the nearest to native preservation of biological and water miscible molecules. In conjunction with tomographic or single particle reconstruction methods, molecular and atomic resolution models of macromolecular complexes can be obtained. The facility also houses preparatory equipment for plunge freezing, sample screening, and grid preparation. Available in house are carbon evaporators, glow dischargers, grid preparation materials, and a manual and automated (Vitrobot) plunge freezers. Liquid nitrogen storage for short-term holding is also available.
Consultation is required prior to starting a project within the facility. Samples submitted for cryoTEM imaging on the Titan Krios need to be accompanied with appropriate documentation establishing the sample is suitable for imaging. This is either a set of cryoTEM images establishing monodispersed particles in appropriate ice thickness and/or an initial structure derived from either negative stain TEM or lower resolution cryoTEM studies. Samples prepared in house will be screened by negative stain to demonstrate suitability for single particle imaging prior to cryogenic preparation by plunge freezing.
Shipping in a dry shipper is best, but appropriate packaging of the grid boxes must be performed to avoid frost deposition and support layer disruption during transport.
Associate Research Scientist