To support our growing work on characterization of polymer, liquid crystal, and protein assemblies, we established a CryoTEM laboratory within the Materials Science Center. Sample preparation includes vitrification capability and cryoultramicrotomy of soft polymer and cellular specimens. The existing LEO 912 EFTEM has been upgraded to CyroTEM capability, with plans to acquire a new 300KVTEM fully outfitted for EM tomography. Cryogenic transmission electron microscopy (CryoTEM) is a useful method for directly obtaining real-space images of native surfactant nanostructures in aqueous solutions. This powerful technique requires that aqueous solutions of surfactants be cryogenically fixed as thin films (~100-300 nm thick) on TEM sample grids that can be imaged at -196 °C using the cryogenic sample holder associated with the existing LEO 912 EFTEM in the Materials Science Center (MSC) core facility. Thermal fixation of the samples requires rapid vitrification of the aqueous solution in liquid ethane to prevent water crystallization that will destroy the self-assembled surfactant aggregates and preclude imaging due to strong interactions of electrons with crystalline ice domains. The figures illustrate the upgraded LEO TEM, and sample preparation equipment.
|LEFT: Existing LEO 912: expanded capability for Cyro-sample work
CENTER: Leica EM UC7 Ultramicrotome: provides easy preparation of semi- and ultrathin sections.
RIGHT: FEI Vitrobot: vitrification of aqueous suspensions on grids; fully automated for reproducibility