Telechelic, Antimicrobial Hydrophilic Polycations with Two Modes of Action

Telechelic antimicrobial poly(2-oxazoline)s with quaternary ammonium (quat) end groups are shown to be potent antimicrobial polymers against Gram-positive bacterial strains. In this study, the activity against the Gram-negative bacterium Escherichia coli is additionally implemented by hydrolyzing the poly(2-methyl-2-oxazoline) with two quart end groups to poly(ethylene imine) (PEI). The resulting telechelic polycations are active against Staphylococcus aureus and E. coli. The contribution of the PEI backbone is determined by measuring the antimicrobial activity in the presence of calcium ions. The influence of PEI on the overall activity strongly depends on the molecular weight and increases with higher mass. The PEI dominates the activity against E. coli at lower masses than against S. aureus. The quart end groups require an alkyl substituent of dodecyl or longer to dominate the antimicrobial activity. Additionally, PEI and quart end groups act synergistically.