Ionic liquids are remarkable chemical compounds, which find applications in many areas of modern science. Because of their highly tunable nature and exceptional properties, ionic liquids have become essential players in the fields of synthesis and catalysis, extraction, electrochemistry, analytics, biotechnology, etc. Apart from physical and chemical features of ionic liquids, their high biological activity has been attracting significant attention from biochemists, ecologists, and medical scientists. This Review is dedicated to biological activities of ionic liquids, with a special emphasis on their potential employment in pharmaceutics and medicine. The accumulated data on the biological activity of ionic liquids, including their antimicrobial and cytotoxic properties, are discussed in view of possible applications in drug synthesis and drug delivery systems. Dedicated attention is given to a novel active pharmaceutical ingredient-ionic liquid (API-IL) concept, which suggests using traditional drugs in ...

Biological Activity of Ionic Liquids and Their Application in Pharmaceutics and Medicine.

Potential applications of enzymes immobilized on/in nano materials: A review

Different methods of preparing lipases for use in organic media are critically reviewed. Solid lipase preparations can be made by typical immobilisation methods such as adsorption, entrapment, covalent coupling or cross-linking. Immobilisation is especially attractive for lipases because, in addition to the normal benefits of enzyme immobilisation, it can also lead to a considerable increase in catalytic activity, probably caused by conformational changes in the lipase molecules. Activation can be achieved, for example, using hydrophobic support materials or surfactants during the immobilisation procedure. Surfactants can also be used to solubilise lipases in organic media via the formation of hydrophobic ion pairs, surfactant-coated lipase or reversed micelles. Lipase preparation methods are discussed with regard to potential lipase inactivation and activation effects, mass transfer limitations, lipase stability and other features important for applications. The practical applications of lipases in organic media reviewed include ester synthesis, modification of triacylglycerols and phospholipids, fatty acid enrichment, enantiomer resolution, biodiesel production and acylation of carbohydrates and bioactive compounds.

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Immobilisation and application of lipases in organic media.

There is no doubt that ionic liquids have become a major subject of study for modern chemistry. We have become used to ever more publications in the field each year, although there is some evidence that this is beginning to plateau at approximately 3500 papers each year. They have been the subject of several major reviews and books, dealing with different applications and aspects of their behaviours. In this article, I will show a little of how interest in ionic liquids grew and developed.

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Ionic liquids: a brief history

Lipase promiscuity and its biochemical applications

Up to date more than 70 lipases from the Bacillus and Geobacillus genera have been isolated, but for most of them only basic biochemical properties have been reported. In general, Bacillus lipases are easily produced and display high tolerance toward organic solvents, proving them useful in the synthesis of esters for food industry, cosmetics and biodiesel production. Many lipases preserve their activity at extreme temperatures and pH, and in the presence of surfactants, hydrogen peroxide, sodium hypochlorite, and therefore they can be applied in laundry formulations. Bacillus lipases display diverse selectivity to the chain length of the acid, and few enzymes show positional specificity. Several enzymes can be applied in the production of enantiopure compounds for the pharmaceutical industry due to their remarkable enantioselectivity. The immobilization experiments with Bacillus lipases, though a limited number, illustrate the vast possibilities for optimization of the properties of the biocatalysts for a particular application. The paper summarizes available experimental data on Bacillus and Geobacillus lipases and identifies areas for further research.

Catalytic properties and potential applications of Bacillus lipases

The influence of nonionic surfactants on the activity of a novel thermostable lipase from Bacillus stearothermophilus MC7 was investigated with a view to its potential for synthesis of structured lipids. A large number of modifiers within a broad concentration range were applied. The activity of the enzyme was measured at a relatively high reaction temperature. Highest degree of activation was observed when PEG6000 was applied (up to 2.3-fold increase). Modification essentially changed the performance of the lyophilised preparations—they keep up to 80% of the activity of the native enzyme in the presence of a detergent against 30% in its absence. The effect of sorbitan esters (spans) and polyoxyethylene derivatives of sorbitan esters (tweens) on lipase MC7 was estimated, their HLB value varying within the interval 2.1–16.7. Tweens were strong inhibitors at higher concentrations. For all spans, excepting span 60, an increase of enzyme activity with concentration was observed. All studied additives slow down the process of thermal denaturation. Lipase preparations preserve more than 60% of their activity after 30-min incubation at 75 °C in the presence of tween 60 or PEG4000.

Effect of nonionic detergents on the activity of a thermostable lipase from Bacillus stearothermophilus MC7

Immobilization of lipase from Candida rugosa on novel phosphorous-containing polyurethanes: Application in wax ester synthesis

Elucidation of the effect of some cholinium amino acid ionic liquids on the thermal and the conformational stability of insulin

Stabilization of the monomeric form of insulin (In) under condition of low pH has been a recent challenge. This research aims to reveal the effect of a series of 1-butyl-3-methylimidazolium-based ionic liquids (ILs) on the stability of In dissolved in highly acidic solution (pH 2.0). Differential scanning calorimetry was applied to assess the thermal stability of In in the presence of these ILs. In addition, we monitored the IL-induced changes in the In secondary structure using Fourier transformed infrared spectroscopy. The peak of In thermal denaturation was shifted to higher temperatures in the presence of the tested acetate, trifluoroacetate and dicyanamide salts. At the same time, chloride and thiocyanate ILs had no effect on the thermal stability of the insulin, while the tricyanomethanide salt slightly destabilized the protein. The change in the In conformation affected not only the position but also the sharpness and the shape of the transition peak. As a whole, those ILs which were able to preserve or enhance helical structure of In produced stabilizing effect and those which stimulated the formation of unordered and random-coiled structures deteriorated its thermal stability. No aggregation of In in the presence of the imidazolium-based ILs was observed under the tested acidic media.

Maya Guncheva

Papers

Catalytic properties and potential applications of Bacillus lipases

Effect of nonionic detergents on the activity of a thermostable lipase from Bacillus stearothermophilus MC7

Immobilization of lipase from Candida rugosa on novel phosphorous-containing polyurethanes: Application in wax ester synthesis

Elucidation of the effect of some cholinium amino acid ionic liquids on the thermal and the conformational stability of insulin

Thermal and conformational stability of insulin in the presence of imidazolium-based ionic liquids