Vitrification
Encyclopedia
Vitrification is the transformation of a substance into a glass
. Usually, it is achieved by rapidly cooling a liquid through the glass transition
. Certain chemical reactions also result in glasses. An important application is the vitrification of an antifreeze-like liquid in cryopreservation
.
Vitrification is characteristic for amorphous materials or disordered systems and occurs when bonding between elementary particles (atoms, molecules, forming blocks) becomes higher than a certain threshold value. Thermal fluctuations break the bonds therefore the lower the temperature the higher the degree of connectivity. Because of that amorphous materials have a characteristic threshold temperature termed glass transition temperature (Tg): below Tg amorphous materials are glassy whereas above Tg they are molten.
In a wider sense, the embedding of material in a glassy matrix is also called vitrification. An important application is the vitrification of radioactive waste to obtain a stable compound that is suitable for ultimate disposal.
is cooled slowly it results in crystal sugar
(or rock candy
), but when cooled rapidly it can form syrupy cotton candy
(candyfloss).
Vitrification can also occur when starting with a liquid such as water, usually through very rapid cooling or the introduction of agents that suppress the formation of ice
crystals. This is in contrast to ordinary freezing
which results in ice crystal formation. Additives used in cryobiology
or produced naturally by organisms living in polar region
s are called cryoprotectant
s.
Arctic
frog
s and some other ectotherm
s naturally produce glycerol
or glucose
in their liver
s to reduce ice formation. When glucose is used as a cryoprotectant by arctic frogs, massive amounts of glucose are released at low temperature and a special form of insulin
allows for this extra glucose to enter the cells. When the frog rewarms during spring
, the extra glucose must be rapidly eliminated, but stored. Arctic insect
s also use sugars as cryoprotectants. Arctic fish use antifreeze protein
s, sometimes appended with sugars, as cryoprotectants.
glass
, used in windows and drinking containers, is created by the addition of sodium carbonate
and lime (calcium oxide
) to silicon dioxide
. Without these additives silicon dioxide will require very high temperature to obtain a melt and subsequently (with slow cooling) a glass.
Vitrification is a proven technique in the disposal and long-term storage of nuclear waste or other hazardous wastes. Waste is mixed with glass-forming chemicals in a melter to form molten glass that then solidifies in canisters, immobilizing the waste. The final waste form resembles obsidian
and is a non-leaching
, durable material that effectively traps the waste inside. The waste can be stored for relatively long periods in this form without concern for air
or groundwater
contamination
. Bulk vitrification uses electrode
s to melt soil and wastes where they lay buried. The hardened waste may then be disinterred with less danger of widespread contamination. According to the Pacific Northwest National Labs, "Vitrification locks dangerous materials into a stable glass form that will last for thousands of years."
Ethylene glycol
is used as automotive antifreeze
and propylene glycol
has been used to reduce ice crystals in ice cream
, making it smoother.
For years, glycerol
has been used in cryobiology
as a cryoprotectant for blood cells and bull sperm
, allowing storage at liquid nitrogen
temperatures. However, glycerol cannot be used to protect whole organs
from damage. Instead, many biotechnology companies are researching the development of other cryoprotectants more suitable for such uses. A successful discovery may eventually make possible the bulk cryogenic
storage (or "banking") of transplantable
human and xenobiotic
organs. A substantial step in that direction has already occurred. Twenty-First Century Medicine
has vitrified a rabbit
kidney
to -135ºC with their proprietary vitrification cocktail. Upon rewarming, the kidney was successfully transplanted into a rabbit, with complete functionality and viability, able to sustain the rabbit indefinitely as the sole functioning kidney.
In the context of cryonics
, especially in preservation of the human brain
, vitrification of tissue is thought to be necessary to prevent destruction of the tissue or information encoded in the brain. Currently, vitrification techniques have only been applied to brains (neurovitrification
) by Alcor
and to the upper body by the Cryonics Institute
, but research is in progress by both organizations to apply vitrification to the whole body.
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
. Usually, it is achieved by rapidly cooling a liquid through the glass transition
Glass transition
The liquid-glass transition is the reversible transition in amorphous materials from a hard and relatively brittle state into a molten or rubber-like state. An amorphous solid that exhibits a glass transition is called a glass...
. Certain chemical reactions also result in glasses. An important application is the vitrification of an antifreeze-like liquid in cryopreservation
Cryopreservation
Cryopreservation is a process where cells or whole tissues are preserved by cooling to low sub-zero temperatures, such as 77 K or −196 °C . At these low temperatures, any biological activity, including the biochemical reactions that would lead to cell death, is effectively stopped...
.
Vitrification is characteristic for amorphous materials or disordered systems and occurs when bonding between elementary particles (atoms, molecules, forming blocks) becomes higher than a certain threshold value. Thermal fluctuations break the bonds therefore the lower the temperature the higher the degree of connectivity. Because of that amorphous materials have a characteristic threshold temperature termed glass transition temperature (Tg): below Tg amorphous materials are glassy whereas above Tg they are molten.
In a wider sense, the embedding of material in a glassy matrix is also called vitrification. An important application is the vitrification of radioactive waste to obtain a stable compound that is suitable for ultimate disposal.
Examples
When sucroseSucrose
Sucrose is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its role in human nutrition. The molecule is a disaccharide composed of glucose and fructose with the molecular formula...
is cooled slowly it results in crystal sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
(or rock candy
Rock candy
Rock candy is a type of confectionery mineral composed of relatively large sugar crystals. This candy is formed by allowing a supersaturated solution of sugar and water to crystallize onto a surface suitable for crystal nucleation, such as a string or stick...
), but when cooled rapidly it can form syrupy cotton candy
Cotton candy
Cotton candy , candy floss or candyfloss or candy buttox , or fairy floss is a form of spun sugar. Since cotton candy is mostly air, a small initial quantity of sugar generates a tremendously greater final volume, causing servings to be physically large and voluminous...
(candyfloss).
Vitrification can also occur when starting with a liquid such as water, usually through very rapid cooling or the introduction of agents that suppress the formation of ice
Ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...
crystals. This is in contrast to ordinary freezing
Freezing
Freezing or solidification is a phase change in which a liquid turns into a solid when its temperature is lowered below its freezing point. The reverse process is melting....
which results in ice crystal formation. Additives used in cryobiology
Cryobiology
Cryobiology is the branch of biology that studies the effects of low temperatures on living things. The word cryobiology is derived from the Greek words "cryo" = cold, "bios" = life, and "logos" = science. In practice, cryobiology is the study of biological material or systems at temperatures below...
or produced naturally by organisms living in polar region
Polar region
Earth's polar regions are the areas of the globe surrounding the poles also known as frigid zones. The North Pole and South Pole being the centers, these regions are dominated by the polar ice caps, resting respectively on the Arctic Ocean and the continent of Antarctica...
s are called cryoprotectant
Cryoprotectant
A cryoprotectant is a substance that is used to protect biological tissue from freezing damage . 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 or polyols as...
s.
Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s and some other ectotherm
Ectotherm
An ectotherm, from the Greek εκτός "outside" and θερμός "hot", refers to organisms that control body temperature through external means. As a result, organisms are dependent on environmental heat sources and have relatively low metabolic rates. For example, many reptiles regulate their body...
s naturally produce glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...
or glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
in their liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
s to reduce ice formation. When glucose is used as a cryoprotectant by arctic frogs, massive amounts of glucose are released at low temperature and a special form of insulin
Insulin
Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....
allows for this extra glucose to enter the cells. When the frog rewarms during spring
Spring (season)
Spring is one of the four temperate seasons, the transition period between winter and summer. Spring and "springtime" refer to the season, and broadly to ideas of rebirth, renewal and regrowth. The specific definition of the exact timing of "spring" varies according to local climate, cultures and...
, the extra glucose must be rapidly eliminated, but stored. Arctic insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s also use sugars as cryoprotectants. Arctic fish use antifreeze protein
Antifreeze protein
Antifreeze proteins or ice structuring proteins refer to a class of polypeptides produced by certain vertebrates, plants, fungi and bacteria that permit their survival in subzero environments. AFPs bind to small ice crystals to inhibit growth and recrystallization of ice that would otherwise be...
s, sometimes appended with sugars, as cryoprotectants.
Applications
Ordinary soda-limeSoda-lime glass
Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of glass, used for windowpanes, and glass containers for beverages, food, and some commodity items...
glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
, used in windows and drinking containers, is created by the addition of sodium carbonate
Sodium carbonate
Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the...
and lime (calcium oxide
Calcium oxide
Calcium oxide , commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline crystalline solid at room temperature....
) to silicon dioxide
Silicon dioxide
The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with the chemical formula '. It has been known for its hardness since antiquity...
. Without these additives silicon dioxide will require very high temperature to obtain a melt and subsequently (with slow cooling) a glass.
Vitrification is a proven technique in the disposal and long-term storage of nuclear waste or other hazardous wastes. Waste is mixed with glass-forming chemicals in a melter to form molten glass that then solidifies in canisters, immobilizing the waste. The final waste form resembles obsidian
Obsidian
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock.It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth...
and is a non-leaching
Leaching
In general, leaching is the extraction of certain materials from a carrier into a liquid . Specifically, it may refer to:...
, durable material that effectively traps the waste inside. The waste can be stored for relatively long periods in this form without concern for air
Air pollution
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....
or groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
contamination
Radioactive contamination
Radioactive contamination, also called radiological contamination, is radioactive substances on surfaces, or within solids, liquids or gases , where their presence is unintended or undesirable, or the process giving rise to their presence in such places...
. Bulk vitrification uses electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
s to melt soil and wastes where they lay buried. The hardened waste may then be disinterred with less danger of widespread contamination. According to the Pacific Northwest National Labs, "Vitrification locks dangerous materials into a stable glass form that will last for thousands of years."
Ethylene glycol
Ethylene glycol
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...
is used as automotive antifreeze
Antifreeze
Antifreeze is a freeze preventive used in internal combustion engines and other heat transfer applications, such as HVAC chillers and solar water heaters....
and propylene glycol
Propylene glycol
Propylene glycol, also called 1,2-propanediol or propane-1,2-diol, is an organic compound with formula C3H8O2 or HO-CH2-CHOH-CH3...
has been used to reduce ice crystals in ice cream
Ice cream
Ice cream is a frozen dessert usually made from dairy products, such as milk and cream, and often combined with fruits or other ingredients and flavours. Most varieties contain sugar, although some are made with other sweeteners...
, making it smoother.
For years, glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...
has been used in cryobiology
Cryobiology
Cryobiology is the branch of biology that studies the effects of low temperatures on living things. The word cryobiology is derived from the Greek words "cryo" = cold, "bios" = life, and "logos" = science. In practice, cryobiology is the study of biological material or systems at temperatures below...
as a cryoprotectant for blood cells and bull sperm
Artificial insemination
Artificial insemination, or AI, is the process by which sperm is placed into the reproductive tract of a female for the purpose of impregnating the female by using means other than sexual intercourse or natural insemination...
, allowing storage at liquid nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
temperatures. However, glycerol cannot be used to protect whole organs
Organ (anatomy)
In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...
from damage. Instead, many biotechnology companies are researching the development of other cryoprotectants more suitable for such uses. A successful discovery may eventually make possible the bulk cryogenic
Cryogenics
In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. A person who studies elements under extremely cold temperature is called a cryogenicist. Rather than the relative temperature scales of Celsius and Fahrenheit,...
storage (or "banking") of transplantable
Organ transplant
Organ transplantation is the moving of an organ from one body to another or from a donor site on the patient's own body, for the purpose of replacing the recipient's damaged or absent organ. The emerging field of regenerative medicine is allowing scientists and engineers to create organs to be...
human and xenobiotic
Xenobiotic
A xenobiotic is a chemical which is found in an organism but which is not normally produced or expected to be present in it. It can also cover substances which are present in much higher concentrations than are usual...
organs. A substantial step in that direction has already occurred. Twenty-First Century Medicine
Twenty-First Century Medicine
21st Century Medicine is a California cryobiological research company which has as its primary focus the development of perfusates and protocols for viable long-term cryopreservation of human organs, tissues and cells at cryogenic temperatures through the use of vitrification. Dr. Gregory M...
has vitrified a rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
to -135ºC with their proprietary vitrification cocktail. Upon rewarming, the kidney was successfully transplanted into a rabbit, with complete functionality and viability, able to sustain the rabbit indefinitely as the sole functioning kidney.
In the context of cryonics
Cryonics
Cryonics is the low-temperature preservation of humans and animals who can no longer be sustained by contemporary medicine, with the hope that healing and resuscitation may be possible in the future. Cryopreservation of people or large animals is not reversible with current technology...
, especially in preservation of the human brain
Human brain
The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...
, vitrification of tissue is thought to be necessary to prevent destruction of the tissue or information encoded in the brain. Currently, vitrification techniques have only been applied to brains (neurovitrification
Neurovitrification
Neurovitrification is the term that refers to vitrification of only the human brain , usually with the intention of neuropreservation. The term is used in cryonics....
) by Alcor
Alcor Life Extension Foundation
The Alcor Life Extension Foundation, most often referred to as Alcor, is a Scottsdale, Arizona, USA-based nonprofit company that researches, advocates for and performs cryonics, the preservation of humans in liquid nitrogen after legal death, with hopes of restoring them to full health when new...
and to the upper body by the Cryonics Institute
Cryonics Institute
The Cryonics Institute is a member-owned-and-operated not-for-profit corporation which provides cryonics services. It is located in Clinton Township, Michigan....
, but research is in progress by both organizations to apply vitrification to the whole body.