Sustainability concept in chemistry involves replacement of toxic chemical components with bio-compatible analogues in attempt to produce environmentally friendly materials and technologies.

Principles of Green chemistry and Sustainability concept have largely influenced research and development in chemical sciences. These principles include convenient degradability and minimised toxicity. It is a well-known fact that common chemicals are mainly based on toxic, bio-incompatible substances, which are dangerous for the environment.

On the contrary, natural components are biocompatible and have no toxic effects. Nowadays, chemists undertake numerous efforts to replace toxic substances with corresponding natural analogues, and fortunately, change of just one component sometimes does increase environmental compatibility and reduces harmful impact.

This approach has been used in attempt to create biocompatible ionic liquids. Ionic liquids, also called molten salts, liquid electrolytes, or ionic melts, are salts, which are liquid at temperatures below 100ºC. Spatial directionality and segregated nano-structuring found in ionic liquids provide them with unique properties, one of the most startling of which is the possibility of ‘fine-tuning’: each ionic liquid consists of cation and anion moieties, and by varying them, individually or together, certain properties of the IL can be changed.

Being non-volatile and non-flammable substances, ionic liquids were believed to become a replacement to traditional volatile and flammable organic solvents, and have found application in such various fields of modern chemistry and technology as organic synthesis, catalysis, electrochemistry, nuclear fuel processing, and others. Originally, ionic liquids were considered as ‘green’ chemicals; however, their biological potential has quickly become evident. Now it is established that ionic liquids may affect life at all levels, from single biomolecules to whole ecosystems.

The authors tested a series of common and amino acid-based ILs and showed that ionic liquids containing anions or cations based on the amino acids Glycine, Alanine, or Valine generally demonstrate cytotoxicity higher or comparable to that of conventional imidazolium-based ILs with inorganic or small organic anions. The authors observed increased toxicity for several ionic systems after incorporation of natural amino acid fragments.

A possible mechanism of action of such amino acid containing ionic liquids involves interactions with membrane transporter proteins employed by cells for amino acid intake. A harmless amino acid, being a part of ionic liquid, helps a biologically active/toxic moiety to enter the cell, where it causes apoptosis, or the programmed cell death. Although the original goal on making a non-toxic ionic liquid was not achieved, these findings suggest potential application of amino acid containing ionic liquids in biology and medicine for targeted drug delivery utilising tuneable properties of ionic liquids.