Technologies
Transmission Electron Microscopy (TEM)
Passes an electron beam through an ultra-thin specimen to image internal ultrastructure with atomic-level resolution.
Description
This training activity provides theoretical and practical instruction in staining and contrast enhancement procedures for biological samples prepared for transmission electron microscopy.
Biological materials are mainly composed of light elements and therefore generally show low intrinsic contrast under the electron beam. Contrast enhancement procedures increase electron scattering and improve the visualization of membranes, organelles, macromolecular complexes and other cellular structures.
The training covers:
Correct handling of TEM grids
Selection of appropriate grid supports and coatings
Preparation and filtration of staining solutions
Positive staining of ultrathin sections
Use of heavy-metal contrast agents
Sequential contrasting procedures
Control of staining time and solution conditions
Washing and drying of grids
Prevention of precipitates and contamination
Evaluation of staining quality
Identification of common contrasting artefacts
Safe handling and disposal of hazardous reagents
Participants are introduced to commonly used contrast-enhancement procedures involving uranyl-based stains and lead salts, as well as alternative contrasting reagents when required by laboratory protocols or safety regulations.
Particular attention is paid to avoiding contamination from carbon dioxide, dust particles, stain precipitates and inadequate washing, all of which can interfere with image quality and ultrastructural interpretation.
At the end of the activity, participants will be able to prepare and contrast TEM grids correctly, optimize staining conditions and assess whether the contrast obtained is appropriate for electron microscopy analysis.