Osteoblast responses to novel titanium-based surfaces produced by plasma- and ion beam technologies

Abstract

Plasma and ion beam technologies have been proven to be effective approaches for modification of surface properties of different materials. In the present work, structure, phase composition, hydrophilicity and microhardness of titanium oxynitride TiN_xO_y, and pure and phosphorus ions implanted TiO₂ coatings produced by metal plasma immersion ion implantation and deposition were investigated. The mixed, highly amorphous TiN_0.4O_1.6 surface has maximal hydrophilicity and microhardness. P implantation in a TiO₂ layer consisting mainly of rutile phase leads to disorder in the crystal lattice, slight amorphisation, and increasing hydrophilicity as well as microhardness of the surface. To evaluate the correlation between the structure of the layers and their cytocompatibility, the influence of the surfaces on the behavior of osteoblast-like SaOS-2 cells was studied in vitro. The cells were cultured on the three Ti-based coatings, both on the bare surfaces as well as on the surfaces biomineralised from simulated body fluid. No statistically significant differences were observed for cell adhesion to all bare Ti-based surfaces. Cell proliferation and osteogenic differentiation were surface sensitive and showed an opposite effect: osteogenic differentiation, indicated by an increase of alkaline phosphatase (ALP) activity, on the P-implanted TiO₂ and TiN_xO_y surfaces was reduced whereas the proliferation increased in comparison to TiO₂. Attachment and proliferation of cells were significantly lower on biomineralised surfaces.