Influence of immobilized quaternary ammonium group surface density on antimicrobial efficacy and cytotoxicity

Abstract

Bacterial colonization of medical devices causes infections and is a significant problem in healthcare. The use of antibacterial coatings is considered as a potential solution to this problem and has attracted a great deal of attention. Using concentration density gradients of immobilized quaternary ammonium compounds it was demonstrated that a specific threshold of surface concentration is required to induce significant bacterial death. It was determined that this threshold was 4.18% NR₄⁺ bonded nitrogen with a surface potential of + 120.4 mV. Furthermore, it is shown for the first time that adhesion of constituents of the culture medium to the quaternary ammonium modified surface eliminated any cytotoxicity towards eukaryotic cells such as primary human fibroblasts. The implications of this type of surface fouling on the antimicrobial efficacy of surface coatings are also discussed.

Keywords:

• Density gradients
• quaternary ammonium
• antibacterial
• cytotoxicity
• biological fouling

Acknowledgements

The authors would like to thank the group of Professor Michael Roberts at the School of Pharmacy and Dr Louise Smith at the School of Engineering, University of South Australia, for help with the sourcing and collection of the fibroblasts.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

KV thanks the Australian Research Council for support through fellowship FT100100292.