Membrane affinity and antibacterial properties of cationic polyelectrolytes with different hydrophobicity.

The antibacterial behavior of cationic polyelectrolytes is studied using model membrane experiments and in vitro bacterial investigations. The molecular interaction with lipid films is evaluated by the degree of penetration of the polymers into Langmuir monolayers of neutral or negatively charged lipids. The polymer/lipid interaction results in structural changes of the penetrated lipid layer visualized using AFM. The polymers are found to be effective in inhibiting the proliferation of E. coli, B. subtilis and S. aureus. The influence of the chemical structure on the functional behavior is related to the conformational properties. An optimum structure is identified on the basis of antibacterial and hemolytic tests as well as membrane-destroying efficacy of the antimicrobial polymers.