Physical Chemistry - Al-Shamery

Probe preparation and additional devices

The Reichert Ultracut E allows semithin and ultrathin sectioning from resin-embedded biological material. Ultrathin sections with a thickness of approximately 60-70 nm are cut normally with the help of diamond knives and collected onto copper grids (3 mm in diameter).

The Leica EM Stain device is used for automatically post-staining of ultrathin sections with uranylacetate, followed by lead citrate. Higher contrast of biological material is normally achieved by staining with these “heavy metal” salts.

The Bal Tec Critical point dryer CPD030 is used for preparing biological material for scanning electron microscopy. Biological specimens, which have been fixed with glutardialdehyde and afterwards have been dehydrated in either ethanol or acetone, are transferred into liquid CO2. Raising pressure and temperature above the critical point of fluid CO2, it becomes gaseous and can be released. The entire procedure finally results in dehydrated and completely dried specimens which can be sputter-coated and then examined in a scanning electron microscope.

The Bal Tec Sputter Coater SCD 005 is used to coat a specimen with either a heavy metal (Au, Pt) or carbon (C). Within a vacuum chamber, Argon ions are created which drive out atoms from the cathode material (Au, Pt). These atoms finally will precipitate as fine coat of 5-20 nm thickness onto the specimen surfaces. Carbon coating is achieved by C-evaporation. Coated specimens will not become negatively charged by the incident electrons when examined within a scanning electron microscope.