Our laboratory studies biological specimens at a range of scales and resolutions. We extend light-microscopical imaging of fluorescentically labelled samples with cellular and sub-cellular analysis, using the Serial Blockface Imaging in collaboration with the FMI. This is done with a FEI Quanta-200 scanning electron microscope that is combined with an in-microscope ultramicrotome to serially section the surface of a block, while iteratively imaging the remaining block face with the SEM. Once areas of interest are located, this instrument allows removing the room-temperature sample, which is then mounted into a conventional ultramicrotome, where thicker (e.g. 100 to 400 nm) sections are cut from the block. These sections are then analyzed by 3D electron tomography in the transmission electron microscopes. The FEI Titan can be used for this. Higher resolution of biological specimens can be achieved by cryo-electron tomography imaging, single particle cryo-electron microscopy, or electron crystallography imaging, for which the transmission electron microscopes of different acceleration voltages and beam qualities are available. Surface topographies of membraneous and other samples can also be recorded with atomic force microscopy instruments, which scan the high-resolution surface of biological specimens under buffer solution with a small cantilever, while recording the surface topography on a computer. Scanning transmission electron microscopy (STEM) is used to determine the masses and mass-distributions of biological particles, which are adsorbed to ultra-thin carbon films and freeze dried. We also employ STEM for structural analysis, as described below.
We employ various imaging methods with the purpose to bridge cellular and atomic imaging.