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

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.

Surfing the Third Wave of Ionic Liquids: A Brief Review on the Role of Surface‐Active Ionic Liquids in Drug Development and Delivery

“…The authors further established bacterial membrane disruption as the likely mode of antimicrobial action of the SAILs, based on SAIL-induced release of intracellular green fluorescent protein (GFP) from a GFPexpressing Escherichia coli bacterial strain. [41] [42,43] While, on the one hand, the above work underlines the need to be cautious regarding the potential ecotoxicity of bioactive SAILs, on the other it opens new avenues toward development of novel SAILs of therapeutic interest, which may combine activity against microbial pathogens with "selfvehiculation and delivery" ability. In turn, the intrinsic cytotoxicity exhibited by some SAILs may be worthy of future exploration for therapeutic applications, namely, against cancer.…”

“…The SAILs, which exhibited high thermal stability and self‐aggregation propensity, were significantly toxic against the marine Gram‐negative microorganism Aliivibrio fischeri . The authors further established bacterial membrane disruption as the likely mode of antimicrobial action of the SAILs, based on SAIL‐induced release of intracellular green fluorescent protein (GFP) from a GFP‐expressing Escherichia coli bacterial strain [41] …”

Present and Future Perspectives for Biocides and Antifouling Products for Stone-Built Cultural Heritage: Ionic Liquids as a Challenging Alternative

“…Due to their structural analogies with conventional amphiphilic quaternary ammonium (QACs) species, SAILs have an intense antimicrobial activity [64][65][66]. Their bioactivity is mainly correlated to their lipophilicity/hydrophobic behavior, with the cation playing the main role in that it is responsible for the primary electrostatic interactions with cell walls [67,68], while the role of the anion is not fully established [69].…”

Extraction and purification of violacein from Yarrowia lipolytica cells using aqueous solutions of surfactants

“…Various studies have shown that surfactants can disrupt the cell membrane when strong hydrophobic interactions are present. The spontaneous insertion of the surfactant alkyl chain in the lipid bilayer causes swelling of the cell membrane, leading to lipid bilayer disintegration.…”

“…12,13 Aqueous solutions of surfactants have some advantages over other solvents since they require using lower concentrations, leading to cheaper and more sustainable processes. 14 Various studies 15,16 have shown that surfactants can disrupt the cell membrane when strong hydrophobic interactions are present. The spontaneous insertion of the surfactant alkyl chain in the lipid bilayer causes swelling of the cell membrane, leading to lipid bilayer disintegration.…”