Introduction to Turku BioImaging key technologies (see the Turku BioImaging Black Book for more information).

Electron Microscopy

Electron microscopy is a microscopic imaging technique using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of electrons with a specimen are used to provide information on fine structure. In Transmission Electron Microscopy (TEM), the reactions of electrons transmitted through an ultrathin (60 nm) section of a specimen are imaged. In Scanning Electron Microscopy (SEM), an electron beam falls at a non-vertical angle on a specimen and an image is derived from secondary or backscattered electrons emitted from the specimen surface after the impact of the primary beam. The use of electrons allows detailed imaging of structure, and localization and identification of molecules and elements to a resolution below 1 nanometer (10-9 m).

If detailed structural details at nanometer resolution are required, micro- and nano-structural imaging combined with molecular analysis is the method of choice, applicable to samples of tissue, cells, bacteria, viruses, nanoparticles, macromolecules, and other related materials. Samples must be fixed with an aldehyde, and dried either with ethanol or at the critical point of carbon dioxide (for SEM), and embedded in epoxy or another resin (for TEM) before being cut into thin sections.

Turku BioImaging includes The Laboratory of Electron Microscopy at the University of Turku, which offers full service, including consultation in the planning of experiments, sample processing, microscopic examination and recording of images, and reporting and interpretation of results.