Bacterial adhesion on silicon-doped diamond-like carbon films

In this paper the surface properties of silicon-doped diamond-like carbon films with various Si contents on 316 stainless steel substrate by a magnetron sputtering technique were investigated. X-ray photoelectron spectroscopy was applied to determine the surface chemical composition of the films. Atomic force microscopy was used for the determination of surface roughness and topography. The sp² contents in the films were determined with Auger electron spectroscopy, which were 67.1%, 34.2% and 25.0% for silicon contents 1%, 2% and 3.8%. The sp³/sp² ratio increases with increasing the silicon contents in the films. Contact angles of three test liquids on the films were obtained with a Dataphysics OCA-20 contact angle analyzer. Surface free energies of the films and their dispersive and polar components were calculated using van Oss acid–base approach. Staphylococcus aureus was used for bacterial adhesion test. The experimental results showed that bacterial adhesion decreased with increasing the silicon content or with increasing sp³/sp² ratio in the films.