Propane jet-freezing: a valid ultra-rapid freezing method for the preservation of temperature dependent lipid phases

We have developed a temperature controlled specimen stage on the existing jet-freezing apparatus, in order to quench samples from elevated temperatures up to 330 K. We have shown that the phase transition both from the liquid-crystalline to solid phase for pure phosphatidylcholines and from hexagonal II to lamellar phase for phosphatidylethanolamine/4% egg phosphatidic acid is prevented. Moreover, cooling rates exceeding 10,000 K s-1 were recorded indicative of ultra-rapid freezing capacity. Cryoprotectants can be omitted, since phase separation due to ice crystal growth does not occur.