Structural effects of amino acid-based ionic liquids on thermophysical properties, and antibacterial and cytotoxic activity

Abstract

Mono- and dicationic amino acid-based (l-Glycine, l-Lysine, l-Arginine) ionic liquids (AAILs) were synthesized and evaluated in respecting to thermal stability, kinetic of decomposition, phase change profile, density, solubility, heat capacity, thermal storage density, antimicrobial activity and cytotoxicity. The presence of amino acid-based anion reduced the thermal stability of mono and dicationic AAILs and additional cationic head increased their thermal stability and heat capacity. AAILs with the highest number of carbon chains have the lowest glass transition temperature (Tg). The AAILs with the bulkier anion has greater thermal stability than the one with the smaller anion, which indicate that the decomposition depends on the anion reactivity and, therefore, mobility. In turn, the density of the dicationic AAILs was lower than the monocationic ones. Monocationic AAILs were more active against bacteria strains than dicationic AAILs, however all AAILs were cytotoxic at all concentrations tested. Thus, results showed that the amino AAILs synthesized may represent a potent strategy for uses requiring antimicrobial activity but biocompatibility is not a requisite.