Self-Assembly, Antimicrobial Properties and Biodegradability of Ester-Functionalized Choline-Based Surface-Active...

Choline-based ionic liquids (ILs) have gained attention as antimicrobial and antibiofilm agents due to their biocompatibility and tuneable antimicrobial properties. However, a significant drawback of amphiphilic choline-based ILs is their decreasing biodegradability as the alkyl chain length increases. To address this issue and enhance the ecotoxicological profile of these compounds, a labile ester functionality was incorporated into the alkyl side chain. This strategic modification aims to improve biodegradation rates while maintaining the desirable antimicrobial properties of the ILs. A series of ester-functionalized choline-based ionic liquids (CnECholBr) with alkyl chains containing from 10 to 14 carbon atoms were synthesized, and their self-aggregation behaviour in aqueous solutions was studied. Their antimicrobial properties were then tested against clinically significant bacteria and yeasts, as well as their effectiveness in eliminating MRSA and C. albicans biofilms. Furthermore, the ecotoxicological properties of these compounds were investigated by assessing their aerobic biodegradability and aquatic toxicity using luminescent bacteria. The results indicated that CnECholBr exhibit higher surface activity and biodegradation rates than non-functionalized choline-based ILs. Conversely, their antimicrobial and antibiofilm activity was found to be lower to that of non-functionalized choline-based ILs. Among the compounds evaluated, the C₁₂ECholBr was identified as the most effective antimicrobial and antibiofilm agent.