Supramolecular systems based on cationic imidazole-containing amphiphiles bearing hydroxyethyl fragment: Aggregation properties and functional activity

Abstract

In the framework of this report, investigation of aggregation behavior, solubilization activity and antimicrobial properties of novel cationic amphiphiles of 1-(2-hydroxyethyl)alkylimidazolium bromide homologous series were carried out. Using conductometry and fluorescence spectroscopy it was shown that introduction of hydroxyethyl fragment into headgroup resulted in 1.5–2-fold decrease of critical micelle concentration in comparison with unsubstituted analogues. The aggregate size of amphiphile bearing tetradecyl tail was close to conventional micelles (hydrodynamic diameter DH 2–4 nm). However, the formation of aggregates with DH ~ 100 nm was demonstrated for amphiphile with octadecyl chain. TEM images for the latter showed the presence of worm-like particles. Solubilization capacity of these amphiphiles was 1.5-fold higher than that without hydroxyethyl fragment and 2-fold higher than in the case of conventional ammonium surfactants with the same length of hydrophobic tail. The investigation of antimicrobial activity revealed that all amphiphiles exhibit more pronounced effect against some strains of microorganisms in comparison with reference drugs (norfloxacin and ketoconazole).