Integration of antifouling and bactericidal moieties for optimizing the efficacy of antibacterial coatings

Hypothesis: Surface coatings that are either antifouling or bactericidal can reduce bacterial colonization, but either type has certain drawbacks. We hypothesize that by integrating an antifouling polymer, poly(sulfobetaine methacrylate) (pSBMA), and a bactericidal polymer, N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (HTCC), in one coating, these drawbacks can be overcome and the antibacterial efficacy can be greatly improved compared to an antifouling or bactericidal coating.

Experiments: A copolymer comprising chitosan and pSBMA in almost equal molar ratio was grafted onto an aminolyzed silicone surface via genipin-induced crosslinking reaction, and treated with glycidyltrimethylammonium chloride to endow the surface with quaternary ammonium groups. The antibacterial property and cytotoxicity of the resultant coating (HTCC-b-pSBMA) were tested. The possibility of incorporating heparin in the coating to improve blood compatibility was also investigated.

Findings: The HTCC-b-pSBMA coating reduced colonization by both planktonic bacteria from aqueous medium and aerosolized bacteria by approximately two orders of magnitude compared with the pristine surface. In comparison, surfaces coated with either the pSBMA or HTCC component are unable to achieve such efficacy. The heparin-loaded HTCC-b-pSBMA coating improved hemocompatibility without adversely affecting the antibacterial efficacy. No significant cytotoxicity of the coatings was observed with mammalian cells.