How do you freeze biological material with liquid nitrogen and what are the critical technique differences between vitrification and slow freezing?
The technique used to freeze biological material with liquid nitrogen determines survival outcome as much as the equipment itself. In vitrification, the embryo or oocyte is loaded onto a carrier – typically a CBS High Security straw or open carrier device – after equilibration in a two-step cryoprotectant solution, then plunged directly into liquid nitrogen at -195.8°C. The cooling rate exceeds 10,000°C per minute, converting the intracellular and extracellular solution to a glass-like amorphous solid without ice crystal formation. The entire process from loading to submersion takes under 60 seconds and demands precise timing.
In controlled rate slow freezing, the sample is cooled at a programmed rate – typically 1 to 2°C per minute – using a controlled rate freezer that injects liquid nitrogen vapour into the freezing chamber in calculated pulses. The slower cooling rate allows partial dehydration of the cell to occur during the process, reducing the intracellular water available to form ice crystals. Both techniques require appropriate vitrification consumables or controlled rate freezing equipment, followed by transfer into liquid nitrogen storage vessels where samples remain below -130°C indefinitely. Cryolab supplies both technique pathways with full protocol support. Contact us to discuss consumable and equipment requirements for your laboratory’s cryopreservation protocols.
