Oxazoline-Based Antimicrobial Oligomers: Synthesis by CROP Using Supercritical CO ₂

A method using supercritical CO ₂ to obtain biocompatible 2-oxazoline-based oligomers quaternized with different amines is described. The synthesized oligo(2-oxazoline)s display partial carbamic-acid insertion at one end. The syntheses of quaternary oligo(2-bisoxazoline)s and linear oligoethylenimine hydrochlorides are reported. Oligo(2-methyl-2-oxazoline) and oligo(2-bisoxazoline) quaternized with N,N-dimethyldodecylamine are the most efficient biocidal agents showing fast killing rates against Staphylococcus aureus and Escherichia coli. Linear oligoethylenimine hydrochloride shows the lowest MIC values but higher killing times against both bacteria. Based on the antimicrobial activity studies, a cooperative action of carbamic acid with the ammonium end group is proposed. Biocompatible and antimicrobial quaternary-ammonium oligo(2-oxazoline)s, oligo(2-bisoxazoline) and linear oligo(ethylenimine) hydrochloride are synthesized using a supercritical-fluid-assisted strategy. Detailed descriptions and evaluations of their antimicrobial properties, comprising MIC and killing time determination, and cytotoxic behavior against pathogenic bacteria and a fungus strains are reported.