Amphiphilic Ionic Liquid-Induced Membrane Permeabilization: Binding Is Not Enough

Abstract

The interaction of amphiphilic ionic liquids containing an 1-alkyl-3-methylimidazolium cation ([C₁₂MIM]⁺), which shows acute cytotoxicity towards marine and bacterial life, with zwitterionic POPC and anionic POPG membranes was investigated. Biophysical parameters of this interaction were quantified using fluorescence spectroscopy, ITC, and solution NMR measurements. [C₁₂MIM]⁺ inserts into the membrane and induces vesicle leakage at relatively low concentration (12MIM]⁺ is suspected to play a key role for membrane leakage. Furthermore, solid-state NMR spectroscopy was employed to determine the location of [C₁₂MIM]⁺ in lipid membranes and its impact on the structure and dynamics of the bilayer. The study provides a molecular understanding of the membrane permeabilizing effect of the [C₁₂MIM]⁺ mediated by its detergent-like structure.