Plasma-induced nanostructured metallic silver surfaces: study of bacteriophobic effect to avoid bacterial adhesion on medical devices

Abstract

Biofilm formation in medical devices represents one of the major problems for the healthcare system, especially those that occur on implantable silicone-based devices. To provide a general solution to avoid biofilm formation in the first stages of development, this work studied how nanostructured metallic silver coatings hinder bacteria-surface interaction by preventing bacteria adhesion. The three studied silver nanostructures ("Sharp blades", "Thick blades" and "Leaves") combined superhydrophobic behavior with a physical impediment of the coating nanostructure that produced a bacteriophobic effect avoiding the adhesion mechanism of different bacterial strains. These silver nanostructures are immobilized on stretchable substrates through a polymeric thin film of plasma-polymerized penta-fluorophenyl methacrylate. The control over the nanostructures and therefore its bacteriophobic-bactericidal effect depends on the plasma polymerization conditions of the polymer. The characterization of this bacteriophobic effect through FE-SEM microscopy, live/dead cell staining, and direct bacterial adhesion counts, provided a complete mapping of how bacteria interact with the surface in each scenario. Results revealed that the bacterial adhesion was reduced by up to six orders of magnitude in comparison with uncoated surfaces thereby constituting an effective strategy to avoid the formation of biofilm on medical materials.

Keywords: Bacteriophobic surfaces; Biofilm; Metallic silver; Nanostructure; Surface characterization.