After the development of antimicrobial agents, bacterial infections have become a minor problem in industrial societies. However, the rise of immune and multi resistant bacterial strains demands new and more effective biocides. Polymer-based antimicrobial agents are a promising alternative to low molecular antimicrobial agents. Telechelic poly(2-oxazoline)s with quaternary ammonium end groups have shown very good antimicrobial activities against Gram-positive bacterial strains, but lack in activity against Gram-negative strains. We could combine the characteristics of biocidal telechelic polymers and antimicrobial hydrophilic polycationic polymers in one macromolecule by partially hydrolyzing the backbone of a telechelic biocidal poly(2-oxazoline) to poly(ethylene imine) (PEI). The resulting polymers are active against Gram-positive Staphylococcus aureus as well as Gram-negative Escherichia coli. The contribution of the polycationic PEI backbone was determined by measuring the antimicrobial activity in the presence of calcium ions, which deactivates this polymer. While the presence of calcium ions deactivates PEIs with octyl and decyl quaternary end groups against E. coli similarly to linear PEI, this effect is less pronounced for PEIs with longer alkyl chain end groups. This indicates that both, the polycationic backbone and the end groups act synergistically. Similar results were found for S. aureus. Furthermore, variation of the length of the polymer backbone revealed, that the antimicrobial activity of telechelic PEIs with lower molecular weights is dominated by the quaternary end groups, while the polycationic backbone dominates the mode of action for PEIs with at least 80 repeating units.

Antimicrobial telechelic partially hydrolyzed poly(2-oxazoline)s with two modes of action

2019 Spring National Meeting

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