Polymeric cryoproteetants in the preservation of biological ultrastructure

Abstract
The solid states formed by vitrified and frozen aqueous solutions of some hydrophilic polymers, able to act as biological cryoproteetants, have been studied by differential scanning calorimetry and freeze fracture electron microscopy. Glass transitions, devitrification, recrystallization and melting behaviour of aqueous solutions of polyvinylpyrrolidone, hydroxyethyl starch and dextran have been established. The vitrified polymer solutions exhibit a characteristic microspherical morphology which is not induced by the quench cooling process but is an inherent feature of the solutions themselves.