Synthesis and Characterization of Surface-Active Ionic Liquids Used in the Disruption of Escherichia Coli Cells

Graphical Abstract

Ionic liquids as cell disruption agents: Twelve surface-active ionic liquids (SAILs) were synthesized and characterized in terms of their aggregation behavior, thermal properties and ecotoxicity. Additionally, due to their high surface activity, these ionic componds proved to be capable of promoting cell disruption of Escherichia coli and release of green fluorescent protein (GFP), produced intracellularly.

Abstract

Twelve surface-active ionic liquids (SAILs) and surface-active derivatives, based on imidazolium, ammonium, and phosphonium cations and containing one, or more, long alkyl chains in the cation and/or the anion, were synthetized and characterized. The aggregation behavior of these SAILs in water, as well as their adsorption at solution/air interface, were studied by assessing surface tension and conductivity. The CMC values obtained (0.03–6.0 mM) show a high propensity of these compounds to self-aggregate in aqueous media. Their thermal properties were also characterized, namely the melting point and decomposition temperature by using DSC and TGA, respectively. Furthermore, the toxicity of these SAILs was evaluated using the marine bacteria Aliivibrio fischeri (Gram-negative). According to the EC₅₀ values obtained (0.3–2.7 mg L⁻¹), the surface-active compounds tested should be considered “toxic” or “highly toxic”. Their ability to induce cell disruption of Escherichia coli cells (also Gram-negative), releasing the intracellular green fluorescent protein (GFP) produced, was investigated. The results clearly evidence the capability of these SAILs to act as cell disruption agents.