Graded metal carbon protein binding films prepared by hybrid cathodic arc — Glow discharge plasma assisted chemical vapor deposition

•Graded composite layers containing metal and plasma polymer components were deposited.•Strong adhesion between the metal surface and the deposited layers was achieved.•Strong adhesion of protein molecules to the surface of the graded layer was confirmed.

Graded composite layers containing metal and plasma polymer components were deposited using a cathodic arc in conjunction with plasma immersion ion implantation. Using a bias potential throughout, pure metal was deposited initially using the cathodic arc alone and then acetylene was added to the process to increase the fraction of the plasma polymerized carbon film. To test adhesion, the substrate and film were strongly deformed by folding the substrate inward and outward with a small radius of curvature. Strong adhesion between the metal surface and the deposited layers was achieved by the use of the graded layers as inferred from the SEM observations of the deformation region. Strong adhesion of biologically active protein molecules to the surface of the graded layer was confirmed by detergent washing and colorimetric enzyme activity assays. These characteristics suggest that the coatings may be suitable for cardiovascular stent applications.