Glutaraldehyde

Template:Short description Template:Use dmy dates Template:Chembox Glutaraldehyde is an organic compound with the formula Template:Chem2. The molecule consists of a five carbon chain doubly terminated with formyl (CHO) groups. It is usually used as a solution in water, and such solutions exists as a collection of hydrates, cyclic derivatives, and condensation products, several of which interconvert. Because the molecule has two aldehyde functional groups, glutaraldehyde (and its hydrates) can crosslink substances with primary amine groups, through condensation. Crosslinking can rigidify and deactivate proteins and other molecules that are critical for normal biological function, such as DNA, and so glutaraldehyde solutions are effective biocides and fixatives. It is sold under the brandnames Cidex and Glutaral.<ref name="WHO-2009">Template:Cite book</ref><ref name="BMA-2015">Template:Cite book</ref><ref>Template:Cite book</ref><ref>Template:Cite book</ref> As a disinfectant, it is used to sterilize surgical instruments.<ref name="WHO-2009"/>

Uses

Biochemistry

Glutaraldehyde is used in biochemistry applications as an amine-reactive homobifunctional crosslinker and fixative.<ref name="Srinivasan-2002">Template:Cite journal</ref><ref>Template:Cite journal</ref> It kills cells quickly by crosslinking their proteins. It is usually employed alone or mixed with formaldehyde<ref name="Karnovsky-1965">Karnovsky, M.J. (1965). A formaldehyde-glutaraldehyde fixative of high osmolality for use in electron microscopy. Journal of Cell Biology 27: 137A–138A</ref> as the first of two fixative processes to stabilize specimens such as bacteria, plant material, and human cells. A second fixative procedure uses osmium tetroxide to crosslink and stabilize cell and organelle membrane lipids.

Another application for treatment of proteins with glutaraldehyde is the inactivation of bacterial toxins to generate toxoid vaccines, e.g., the pertussis (whooping cough) toxoid component in Tdap vaccines.

Material science

In material science glutaraldehyde application areas range from polymers to metals and biomaterials. Glutaraldehyde is commonly used as fixing agent before characterization of biomaterials for microscopy. Glutaraldehyde is a powerful crosslinking agent for many polymers containing primary amine groups.<ref>Template:Citation</ref><ref>Template:Citation</ref> Glutaraldehdye also can be used for an interlinking agent to improve the adhesion force between two polymeric coatings.<ref>Template:Citation</ref> Glutaraldehyde is also used to protect against corrosion of undersea pipes.<ref>Template:Cite conference</ref>

Medical

Clinical uses

Glutaraldehyde is used as a disinfectant and medication.<ref name="WHO-2009" /><ref name="BMA-2015"/><ref>Template:Cite book</ref> Usually applied as a solution, it is used to sterilize surgical instruments and other areas.<ref name="WHO-2009"/>

Dermatological uses

As a medication it is used to treat plantar warts.<ref name="BMA-2015"/> For this purpose, a 10% w/v solution is used. It dries the skin, facilitating physical removal of the wart.<ref>NHS Choices: Glutarol Template:Webarchive</ref>

Glutaraldehyde is also used in the treatment of hyperhidrosis under the control of dermatologists in people who have frequent sweating but do not respond to aluminum chloride. Glutaraldehyde solution is an effective agent to treat palmar and plantar hyperhidrosis as an alternative to tannic acid and formaldehyde.<ref>Template:Citation</ref>

Other uses

Aquaria

Glutaraldehyde diluted with water is often marketed as alternative to carbon dioxide gas injection for aquarium plants, but it lacks any characteristics that promote the growth of aquatic plants, and does not raise the Template:CO2 concentration of water it is added to Template:Citation needed. Aquarists also commonly use it in low concentrations as an algicide.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Safety

Side effects include skin irritation.<ref name="BMA-2015"/> If exposed to large amounts, nausea, headache, and shortness of breath may occur.<ref name="WHO-2009"/> Protective equipment is recommended when used, especially in high concentrations.<ref name="WHO-2009"/> Glutaraldehyde is effective against a range of microorganisms including spores.<ref name="WHO-2009"/><ref name="Fraise-2012"/> Glutaraldehyde is a dialdehyde.<ref>Template:Cite book</ref> It works by a number of mechanisms.<ref name="Fraise-2012">Template:Cite book</ref>

As a strong sterilant, glutaraldehyde is toxic and a strong irritant.<ref name="CCOHS">Canadian Centre for Occupational Health and Safety (CCOHS) (a federal government site) > OSH Answers > Diseases, Disorders & Injuries > Asthma Template:Webarchive Document last updated on 8 February 2005</ref> There is no strong evidence of carcinogenic activity,<ref name=NTP1999>Toxicology and Carcinogenesis Studies of Glutaraldehyde Template:Webarchive</ref> However, some occupations that work with this chemical have an increased risk of some cancers.<ref name=NTP1999/>

Production and reactions

Production

Glutaraldehyde is produced industrially by the catalytic oxidation of cyclopentene by hydrogen peroxide, which can be achieved in the presence of various tungstic acid-based heteropoly acid catalysts.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> This reaction essentially mimics ozonolysis. Alternatively it can be made by the Diels-Alder reaction of acrolein and vinyl ethers followed by hydrolysis.<ref name="Kohlpaintner-2008">Template:Ullmann</ref>

File:Glutaraldehyde synthesis (2).svg

Reactions

Like other dialdehydes, (e.g., glyoxal) and simple aldehydes (e.g., formaldehyde), glutaraldehyde hydrates in aqueous solution, forming gem-diols. These diols in turn equilibrate with cyclic hemiacetal.<ref>Template:Cite journal</ref><ref name="Kohlpaintner-2008" /><ref name="Srinivasan-2002"/> Monomeric glutaraldehyde polymerizes by aldol condensation and Michael reactions yielding alpha, beta-unsaturated poly-glutaraldehyde and related oligomers. This reaction occurs at alkaline pH values.<ref name="Migneault-2004">Template:Cite journal</ref>

File:GlutaldehydeHydrateEquilibria.png

A number of mechanisms have been invoked to explain the biocidal and fixative properties of glutaraldehyde.<ref name="Fraise-2012"/> Like many other aldehydes, it reacts with primary amines and thiol groups, which are common functional groups in proteins, nucleic acids and polymeric materials. Being bi-functional, glutaraldehyde is a crosslinker, which rigidifies macromolecular structures and shuts down their reactivity.<ref name="Uhr-2013">Template:Ullmann</ref>

File:Imine-synthesis.svg

Imine formation from a primary amines and the carbonyls of glutaraldehyde is the basis of its fixative and biocidal properties.

The aldehyde groups in glutaraldehyde are susceptible to formation of imines by reaction with the amines of lysine and nucleic acids. The derivatives from aldol condensation of pairs of glutaraldehyde also undergo imine formation.<ref name="Migneault-2004"/>

External links

• Glutaraldehyde: Sources of emissions AU National Pollutant Inventory
• Glutaraldehyde US National Institute for Occupational Safety and Health
• Glutaraldehyde NIST Standard Reference Data