A cryoprotectant is a substance that is used to protect biological tissue from freezing damage (damage due to ice formation). Arctic and Antarctic insects, fish, amphibians and reptiles create cryoprotectants (antifreeze compounds and antifreeze proteins) in their bodies to minimize freezing damage during cold winter periods. Insects most often use sugars or polyols as cryoprotectants. Arctic frogs use glucose, but Arctic salamanders create glycerol in their livers for use as cryoprotectant. Cryoprotectants operate simply by increasing the solute concentration in cells. However, in order to be biologically viable they must (1) easily penetrate cells, and (2) not be toxic to the cell.[1]

Conventional cryoprotectants are glycols (alcohols containing at least two hydroxyl groups), such as ethylene glycol[citation needed], 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, i.e. 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 cryoprotectants 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 are 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 do not pose any toxicity concerns. For example, many (raw) frozen chicken products contain a "solution" of water, sucrose, and sodium phosphates.

Common cryoprotectants

See also


  • Most information adapted from; the site is no longer active.

Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Cryoprotectant — A chemical component of a freezing solution used in cryopreservation (the process of cooling and storing cells, tissues, or organs at very low temperatures to maintain viability). The purpose of the cryoprotectant is to help protect what is being …   Medical dictionary

  • cryoprotectant — noun or adjective see cryoprotective …   New Collegiate Dictionary

  • cryoprotectant — chemicals such as sucrose and sorbitol that can be added to fish muscle before freezing to prevent adverse chemical reactions. Usually added to surimi (q.v.) before it is made into blocks and frozen …   Dictionary of ichthyology

  • cryoprotectant — Substance that is used to protect from the effects of freezing, largely by preventing large ice crystals from forming. The two commonly used for freezing cells are DMSO or glycerol …   Dictionary of molecular biology

  • cryoprotectant — cry·o·pro·tec·tant (krī ō prə tĕkʹtənt) n. A substance, such as glycerol, used to protect cells or tissues from damage during freezing.   cry o·pro·tecʹtant adj. cry o·pro·tecʹtive adj. * * * …   Universalium

  • cryoprotectant — noun Any substance (typically a polyhydric alcohol) that prevents cell damage on freezing …   Wiktionary

  • cryoprotectant — noun Physiology a substance that prevents the freezing of tissues, or prevents damage to cells during freezing …   English new terms dictionary

  • cryoprotectant — cryo·protectant …   English syllables

  • cryoprotectant — Compound preventing cell damage during successive freezing and thawing processes. Cryoprotectants are agents with high water solubility and low toxicity. Two types commonly used: permeating (glycerol and DMSO) and non permeating (sugars, dextran …   Glossary of Biotechnology

  • cryoprotectant — noun or adjective see cryoprotective …   Useful english dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”