Polymerized ionic liquids-based hydrogels with intrinsic antibacterial activity: Modern weapons against antibiotic-resistant infections

In this study, the inherent antibacterial activity of 11 different polymerized ionic liquids (PILs)-based hydrogels as well as their corresponding monomers was examined in an extensive screening. The methicillin-resistant Staphylococcus aureus Xen 30 (MRSA Xen 30) and Pseudomonas aeruginosa Xen 5 (P. aeruginosa Xen 5) were chosen as test microorganisms. Both are typical representatives of gram-positive and gram-negative bacteria, respectively. Six of the 11 tested monomers were able to eradicate more than 80% of P. aeruginosa Xen 5 cells in suspension. Unfortunately, the anionic, neutral and zwitterionic representatives lost their function after polymerization. However, the cationic gels retained their antibacterial activity with nearly 100% eradication of selected microorganisms - even at the smallest amount tested. Bactericidal activity against gram-positive MRSA Xen 30 was high when the bacteria were treated with the imidazolium-based monomers. Five of the tested compounds showed rather limited bactericidal activity <50% killed bacteria. The weak antibacterial activities could be significantly increased by crosslinking them to three-dimensional networks. As a result, all the hydrogels possessed strong killing efficiencies of at least 68% and were able to maintain this activity even at low hydrogel volume fractions. These findings are very promising for the development of new antibacterial materials for medical applications, for example, stent coatings.

Automated summary

The study found that out of the 11 monomers tested, 6 showed strong bactericidal activity against P. aeruginosa Xen 5. However, anionic, neutral, and zwitterionic representatives lost their function after polymerization, while cationic gels retained nearly 100% antibacterial activity. Crosslinking them into three-dimensional networks significantly increased the weak antibacterial activities.