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Cressington Quick Freeze/Deep Etch
The Cressington CFE-60 is an advanced Quick Freeze-Deep Etch (QFDE) apparatus. Specimens are quickly frozen by either impact freezing (Leica MM80) or high-pressure freezing (Leica EM-PACT2) immobilizing cell components instantly. The frozen specimen is transferred to the CFE-60 then placed under vacuum. The specimen can then be fractured with a cooled knife. The fracture surface is irregular and occurs along lines of weakness (e.g., plasma membrane). By raising the temperature of the specimen under vacuum, surface ice is removed leaving biological material standing in relief. A thin layer of carbon is evaporated onto the surface making a carbon replica; this replica is shadowed with platinum or another metal. Organic material is removed by treating with a bleach solution, leaving a replica. This carbon-metal replica is put on a grid and examined by a transmission electron microscope.
The CFE-60 is often used to study membranes and reveal the pattern of integral membrane proteins. In addition to freeze-fracture, the CFE-60 will also perform rotary and uni-directional shadowing with Pt, Pt/C or W/Ta. A 1200W automatic power unit gives reproducible multi-shot W/Ta shadowing. |
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