Bioinspired phosphorylcholine containing polymer films with silver nanoparticles combining antifouling and antibacterial properties

Abstract

The antibacterial (bioactive) and antifouling (biopassive) properties of stable, uniform, high surface coverage films of poly(hydroxyethyl methacrylate-co-2-methacryloyloxyethyl phosphorylcholine) (p(HEMA-co-MPC)) with embedded, non-leaching silver nanoparticles (AgNPs) are reported. Based on the experimental findings, a mechanism of action of AgNPs in antibacterial activity in combination with antifouling characteristics is discussed. Long-term antifouling studies of E. coli determine little to no adhesion on p(HEMA-co-MPC)/Ag films at 2.5 × 10⁶ CFU mL⁻¹ for 7 d, measured using live/dead staining assays. Agar diffusion tests indicate that there is no leaching of Ag from the films and SEM and EDX analyses of the films before and after incubation with E. coli show no attachment of E. coli and no visible change in film morphology or AgNP dispersal. Antibacterial studies are investigated using E. coli K-12 as a model bacterial strain and are tested in static (CFUs) and dynamic contact assays. Antibacterial efficacy of the films containing extremely low AgNP concentration (3.8 ng cm⁻²) is shown with growth suppression of E. coli in culture medium for 4 h at 1.35 × 10⁵ CFU mL⁻¹ and killing greater than 99% of E. coli in only 1 h of exposure to concentrations up to 1 × 10⁵ CFU mL⁻¹. These hybrid films may propose an exciting direction to long-term antibacterial and antifouling films in clinical applications.