Everything about Cryoprotectant totally explained
A
cryoprotectant is a substance that's used to protect
biological tissue from
freezing damage (damage due to
ice formation).
Arctic and
Antarctic insects,
fish,
amphibians and
reptiles create cryoprotectants in their bodies to minimize freezing damage during cold winter periods. Insects most often use
sugars as cryoprotectants. Arctic
frogs use
glucose, but Arctic
salamanders create
glycerol in their
livers for use as cryoprotectant.
Conventional cryoprotectants are glycols (
alcohols containing at least two
hydroxyl groups), such as
ethylene glycol,
propylene glycol and
glycerol.
Ethylene glycol is commonly used as automobile
antifreeze and
propylene glycol has been used to reduce ice formation in
ice cream.
Dimethyl sulfoxide (DMSO) is also regarded as a conventional cryoprotectant. Glycerol and DMSO have been used for decades by
cryobiologists to reduce ice formation in
sperm and
embryos that are cold-preserved in
liquid nitrogen.
Mixtures of cryoprotectants have less
toxicity and are more effective than single-agent cryoprotectants. A mixture of
formamide with DMSO, propylene glycol and a
colloid was for many years the most effective of all artificially created cryoprotectants. Cryoprotectant mixtures have been used for
vitrification, for example solidification without any crystal ice formation.
Vitrification has important application in preserving embryos,
biological tissues and
organs for
transplant.
Vitrification is also used in
cryonics in an effort to eliminate freezing damage.
Some cryoprotectants function by lowering a solution's or a material's
Glass transition temperature. In this way, the cryprotectants prevent actual freezing, and the solution maintains some flexibility in a glassy phase. Many cryoprotectants also function by forming hydrogen bonds with biological molecules as water molecules are displaced. Hydrogen bonding in aqueous solutions is important for proper protein and DNA function. Thus, as the cryoprotectant replaces the water molecules, the biological material retains its native physiological structure (and function), although they're no longer immersed in an aqueous environment. This preservation strategy is most often observed in
anhydrobiosis.
Cryoprotectants are also used to preserve foods. These compounds are typically sugars that are inexpensive and don't pose any toxicity concerns. For example, many (raw) frozen chicken products contain a "solution" comprised of water, sucrose, and sodium phosphates.
Common Cryoprotectants
Further Information
Get more info on 'Cryoprotectant'.
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