Surface modifications and cell–materials interactions with anodized Ti

The objective of this study was to investigate in vitro cell–materials interactions using human osteoblast cells on anodized titanium. Titanium is a bioinert material and therefore becomes encapsulated after implantation into the living body by a fibrous tissue that isolates it from the surrounding tissues. In this work, a bioactive TiO2 layer was grown on commercially pure titanium substrate by an anodization process using different electrolyte solutions, namely H3PO4, HF and H2SO4. These electrolytes produced bioactive TiO2 films with a nonporous structure showing three distinctive surface morphologies. Human osteoblast cell growth behavior was studied with as-received and anodized surfaces using an osteoprecursor cell line (OPC 1) for 3, 5 and 11 days. When anodized surfaces were compared for cell–materials interaction, it was noticed that each of the surfaces has different surface properties, which led to variations in cell–materials interactions. Colonization of the cells was noticed with a distinctive cell-to-cell attachment in the HF anodized surface. Good cellular adherence with extracellular matrix extensions in between the cells was noticed for samples anodized with H3PO4 electrolyte. The TiO2 layer grown in H2SO4 electrolyte did not show significant cell growth on the surface, and some cell death was also noticed. Cell adhesions and differentiation were more pronounced with vinculin protein and alkaline phosphatase, respectively, on anodized surfaces. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium assays also showed an increase in living cell density and proliferation with anodized surfaces. It was clear that rough surface morphology, high surface energy and low values of contact angles were important factors for better cell materials interaction. A mineralization study was done in simulated body fluid with ion concentrations nearly identical to those of human blood plasma to further understand biomimetic apatite deposition behavior. Similar to cell–materials interaction, variations in mineral deposition behavior were also noticed for films grown with different electrolytes.