Thin-film nanocomposites of diamond-like carbon and titanium oxide; Osteoblast adhesion and surface properties

Abstract

Thin films of a novel, nanocomposite material consisting of diamond-like carbon and polycrystalline/amorphous TiO x (DLC-TiO x , x ≤ 2) were prepared using pulsed direct-current plasma enhanced chemical vapour deposition (PECVD). Results from Raman spectroscopy indicate that the DLC and TiO x deposit primarily as segregated phases. Amorphous TiO 2 is found to be present on the surface region of the film and there is evidence for the presence of crystalline TiO in the bulk of the film. The hydrophilicity of the DLC-TiO x films increased with increasing titanium content. Culture studies with human osteoblasts revealed that the differences in three-day cell adhesion properties (count, morphology and area) between DLC and DLC-TiO x films containing up to 13 at.% Ti were not statistically significant. However, the cell count was significantly greater for the films containing 3 at.% of Ti in comparison to those containing 13 at.% of Ti. A post-plasma treatment with Ar/O 2 was used to reduce the water contact angle, θ, by nearly 40° on the DLC-TiO x films containing 3 at.% of Ti. A cell culture study found that the osteoblast count and morphology after three days on these more hydrophilic films did not differ significantly from those of the original DLC-TiO x films. We compare these results with those for SiO x -incorporated DLC films and evaluate the long-term osteoblast-like cell viability and proliferation on modified DLC surfaces with water contact angles ranging from 22° to 95°.