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For initial inquiries whether TEM is suitable for your research and development needs, please contact one of the associated scientific staff members, or check out our recent research highlights.

The TEM Core Facility can support your materials or life science research with dedicated TEM measurements and associated sample preparation. Each instrument has an operator that can assist you with your measurement requests. For users that prefer more frequent, independent, access, we can provide advanced training so that you can use the instrument yourself.

For TEM measurements, we charge an hourly fee, for sample preparation, we charge a fee per (batch of) sample(s). Please contact prof. Moreels for more details.

Life Science Sample preparation, the basic protocol

Specimen preparation is an essential part of transmission electron microscopy and involves multiple steps.

Fixation: The purpose of fixation is to keep the ultrastructure of the cells or tissues as close as possible to its original state. To achieve this, primary fixation with aldehydes is first required, to crosslink protein molecules with nearby molecules, followed by secondary fixation with osmium tetroxide, to increase contrast.

Dehydration: This is the process by which the water content in the specimen is replaced with an organic solvent. Ethanol, acetone and isopropanol are the frequently used solvents in this method.

Infiltration and embedding: During the infiltration, epoxy or acrylic resin is used to penetrate the cell and occupy the space. Once the infiltration with resin is finished, polymerization follows at 62°C. This process makes the sample hard enough to withstand the pressure of sectioning.

Cutting: Ultrathin sections of 50 ‐ 70 nm thickness are made with the ultramicrotome and are collected on copper grids.

Staining: Staining in biological specimens is usually done twice – before dehydration (“en-bloc”) and after sectioning. In this process, heavy metals like uranium and/or lead are used to increase the contrast between different structures in the specimen.

Modifications of the basic protocol: Can be applied to achieve many different goals, immunogold labeling for example, i.e. the in-situ localization of specific tissue molecules using antibody and colloidal gold marker systems.

Negative staining: Viruses and bacteria can be studied without this extensive sample preparation, but after negative staining. For this technique, uranyl acetate is applied to the grids to which a drop of suspension was first applied and dried.

Please contact Liesbeth Couck or Myriam Claeys if you have specific questions about sample preparation.