Ionic liquid based cellulose acetate composites: an approach for controlling infection caused by microorganisms

The use of ionic liquids (ILs) as agents to address infections caused by pathogenic microorganisms has been increasingly investigated in the last decades. This work reports on the development of advanced materials incorporating ILs such as choline dihydrogen phosphate ([Ch][DHP]), choline bis(trifluoromethylsulfonyl)imide ([Ch][TFSI]) and choline acetate [Ch][Acetate], combined with the biodegradable natural polymer cellulose acetate (CA) for the development novel IL/polymer composite materials for controlling the spread of infections. The incorporation of the ILs on cellulosic polymer matrix do not change its structural properties, since the absorption bands and XRD patterns maintain the prevalence of the pristine CA matrix structure. Incorporating ILs into composites, on the other hand, has an influence on both morphology and mechanical properties. IL [Ch][Acetate] forms a porous structure and increases roughness, while IL [Ch][TFSI] preserves the structure, and [Ch][DHP] results in agglomerates within the polymer composite. The incorporation of the different ILs lead to a reduction of the Young's modulus, showing an increase of the composite elasticity. The antimicrobial activity and mode of action of the ILs with varying anions but using the same cation against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were evaluated and it was observed that the [Ch][TFSI] IL leads to the most significant antibacterial effects against E. coli and S. aureus. Further, cytotoxicity assays revealed that most CA/IL-based materials did not induce toxicity in mammalian cells. Altogether, the properties of the developed composites make them suitable for hygienic surfaces, food packaging or medical device applications, among others.