Enzyme-Mediated Mineralization of TiO2 Nanotubes Subjected to Different Heat Treatments

Abstract

Surface-modified titanium (Ti) and titanium alloys with physical topography and bioactive components mimicking those of bone tissues have attracted increasing interest as biomaterials for accelerating osseointegration. In this study, an enzyme-mediated mineralization system containing an organic phosphate is used to form a coating of calcium phosphate on titanium dioxide (TiO2) nanotubes heat-treated at different temperatures (350, 450, and 550 °C). Surface characterization using analytical techniques shows that this system can lead to the deposition of an amorphous calcium phosphate layer on the TiO2 nanotube (TNT) surface while preserving the original nanotopography. In this respect, the heat treatment of TNT plays an essential role in the formation of the calcium phosphate layer, with TNT annealed at 450 °C having the best mineralization results. The synergistic effect of the TNT topography and chemical cues of the calcium phosphate layer improves adhesion, proliferation, and differentiation of pre-osteoblasts in vitro when compared with surfaces with only one of these features. This hybrid coating can thus potentially enhance the osseointegration of titanium-based implants.