The Microscopy Unit has a broad range of both preparative techniques and transmission electron microscopes, each with unique capabilities, to meet the diverse needs of NIAID research scientists.
- Hitachi H-7500 TEM – operates up to 120 kV TEM used for routine imaging
- FEI/Tecnai 120 kV TEM – offers 3D tomographic imaging for specimens in thickness up to 250 nm.
- FEI/Titan Krios 300kV TEM – enables higher resolution for single particle or tilt series image collection for 3D tomographic renderings of room temperature or cryo specimens in thickness to 1 micron.
Associated Techniques and Technologies
- Negative staining
- Embedded and sectioned material
- Immune-labeled material
- Cryo-preserved material
- 3D tomography
Applications for negative staining include imaging whole mounts of viral suspensions, bacteria, macromolecules, isolated membrane, and cellular components. Small aliquots of the suspensions typically are applied to coated grids and excess fluid wicked away with filter paper. An electron dense stain is likewise applied and excess is wicked away, resulting in a thin layer of stain enabling better visualization of electron lucent structures.
Embedded and sectioned material
Specimens that are too thick for visualization by negative staining can be chemically fixed, embedded in resin, and then cut into thin slices using an ultramicrotome. These slices, or “sections,” can be picked up on grids for viewing in an electron microscope.