Effect of mechanical and chemical process variation on antibacterial activity of polydopamine coating.

Low bacterial load and adhered biofilms are challenges to current tests and prophylactic measures, and can result in healthcare-associated infections (HAIs). It has been shown that the risk of HAIs can be reduced when antibacterial coatings are applied to the surface of medical devices. This study aims to optimize the antibacterial efficacy of polydopamine coating as a potential material for the prevention of HAIs.

Polydopamine coatings were characterized after varying the coating process. Modifications included the concentration of dopamine monomers, the sample position (horizontal vs vertical), the stirring speed (0 – 90 RPM) and the reaction time (0.5 – 24 h). The results were monitored via UV-visible, wettability and atomic force microscopy. The dopamine cytotoxicity was evaluated on the L929 cell line, in accordance with the ISO 10993-5 standard, and the antibacterial properties of polydopamine coatings were assessed using ISO 22196 standardization against Staphylococcus aureus and Escherichia coli.

Surface wettability, and therefore bacterial adhesion, are affected by the thickness and roughness of the polydopamine coating, playing a role in its antibacterial activity. Thicker and rough coatings had a better antibacterial effect against S. aureus (1.6 ± 0.4 log reduction), but not against E. coli (0.05 log reduction). The viability of L929 cells was ≥ 94 % in the presence of the polydopamine coating.

These results demonstrate that polydopamine is a promising non-toxic material for antibacterial coatings on medical devices. However, further tests are required to enhance its antibacterial properties.