RE: [Histonet] ionic liquids as preservation mediums

From:"Tony Henwood"

There are some articles on the use of ionic liquids as a replacement for formalin eg

Pernaka et al (2005) Acta Histochemica 107(2):149-156

In summary:

Pernaka et al (2005) from Poland have advocated the use of ionic fluids as replacements for formalin.

Ionic liquids (ILs) are a novel class of compounds, and are called solvents of the 21st century. They are molten organic salts, typically comprised of bulky cations and weakly coordinated anions. Some of the better studied ILs contain a heterocyclic cation based on a substituted imidazole or pyridine. They have advantageous chemical and physical properties, such as a negligible vapour pressure, low melting temperature (<100 C), a broad liquid range, thermal, chemical and electrochemical stability, favourable solvation behaviour (many organic, organometallic and inorganic compounds can be dissolved in ILs) and have a large electrochemical window. They are also highly polar yet non-coordinating, non-flammable, easy to handle in a variety of standard experimental procedures and they are recyclable. This non-volatile nature means that ILs have been recognized as 'green' solvent alternatives to volatile organic solvents, and it decreases the risk of exposure and loss of solvent by evaporation. Careful selection of cation-anion pairs allows control of several chemical and physical properties of ILs. Moreover, it is possible to fine-tune their miscibility with water by changing the characteristics of side chains in the cation or the type of anion. In recent years, the number of possible cation and anion combinations has increased significantly. Pernaka et al (2005) have categorized ILs, into room temperature ionic liquids (RTILs), protic ILs, task-specific ionic liquids (TSILs) and chiral ILs (Pernaka et al 2005).

They found that 1-methyl-3-octyloxymethylimidazolium tetrafluoroborate (IL-[(C8H17OCH2)MIM][BF4]) exhibited tissue fixation properties similar to those of formalin and can be applied in both histological and immunohistochemical techniques. Tissue material fixed with [(C8H17OCH2)MIM][BF4] manifested a more intense staining than those fixed with formalin. With respect to the pattern, distribution and intensity of immunohistochemical staining, it was comparable in tissue material fixed with formalin or [(C8H17OCH2)MIM][BF4]. The time of fixation in formalin or IL had no effect on morphology. 

Their study confirmed the suitability of 1-methyl-3-octyloxymethylimidazolium 
tetrafluoroborate as fixative in histopathological procedures, eliminating the necessity of using formalin.


Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC)
Laboratory Manager & Senior Scientist
The Children's Hospital at Westmead,
Locked Bag 4001, Westmead, 2145, AUSTRALIA.
Tel: 612 9845 3306
Fax: 612 9845 3318

-----Original Message-----
From: [] On Behalf Of Laura Hunt
Sent: Wednesday, 20 February 2008 6:35 AM
Subject: [Histonet] ionic liquids as preservation mediums

Hello Histonetters:

I have another unusual question.  I have a friend in chemistry who has  
made a bunch of ionic liquids and is looking for potential  
applications. For example,  as a preservation medium for tissues,  
instead of formalin.  Anybody know if this is worth pursuing?  If so,  
would anyone be interested in a collaboration with him?
1. Made out of tartaric acid
2. Non-toxic
3. Cheaply made on a benchtop



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