freeze fracturing

Freeze fracturing is a technique to cut and expose the inner face of a biological specimen such as cells and tissues.  This technique freezes the specimen with liquid nitrogen, etc., and then fractures the specimen under vacuum by giving an impact on the frozen specimen using a knife.  After the specimen is fractured, a replica of a fractured surface is made for TEM observation.  To observe the fractured surface with a TEM, either of two replication techniques is applied.  One is freeze replication to make a replica of the fractured surface without any processing.  Another is freeze etching by which ice on the fractured surface is sublimated, followed by making a replica of the exposed inner structure without ice. 
A replica is usually made under vacuum by depositing platinum or platinum palladium onto the specimen and then by depositing carbon onto the already deposited surface.  The specimen is immersed and dissolved in an alkali reagent.  Only the replica is mounted on a mesh (grid) for TEM observation.

Related Term(s)