QUANTIFOIL® with Circular Holes
QUANTIFOIL® Holey Carbon Film supports with circular holes are frequently used for cryo-electron microscopy (cryo-EM) of biological samples. The circular holes allow improved particle distribution and reduced background scatter due to the formation of thin, even layers of vitrified ice that support the molecules of interest.
The optimum base grid mesh and QUANTIFOIL® Holey Carbon Film support geometry and hole size for a particular project depends on many variables, and researchers will want to try several combinations. Some general guidelines when selecting the ideal film geometry for your experiment include:
- Higher magnifications require smaller holes, as the presence of some support film in the image it will aid focusing. The power spectrum of the amorphous carbon is much stronger than that of ice, which allows Thon rings to be more easily seen. As a rough guide:
- Use 1.2 μm holes and smaller (R 1.2/1.3 and R 0.6/1) at x 50,000 or higher magnification. These magnifications are normally used for high-resolution data collection for biological specimens.
- Approx. 2 μm holes (eg R 2/1 or R 2/2) for x 30,000 and x 40,000
- 5 μm or larger (eg R 3.5/1) at x 20,000
- A larger sample size will require larger hole sizes. For example:
- Proteins and protein complexes at high-resolution: R 1.2/1.3 or R 0.6/1
- Viruses and tomography: R 2/1, R 2/2, R 2/4
- Whole cells, especially for CLEM and tomography: R 2/2, R 2/4 and R 3.5/1
- To increase data collection speed using beam-image shift, choose a larger hole size (R 2/1 or R 2/2), to allow multiple shots in the same hole before shifting the stage and re-focusing.
- A MixBox of 30 grids in popular sizes (QUANTIFOIL® R 1.2/1.3, R 2/1, R 3.5/1, S 7/2 and Multi A) on Copper 300 mesh base grids is available to help select the optimum foil.
Additional Ultrathin Carbon Layer
Improve data quality by adding an ultrathin continuous carbon layer to any QUANTIFOIL® holey carbon film support. Read more.
|QUANTIFOIL® geometry||Hole size (μm)*||Spacing (µm)*||Periodicity (µm)*|