Biostable Gradient Coating Implants with Drug Release

In the interest of improving long-term stability, functionally graded hydroxyapatite/titanium (HA/Ti) layers consisting of an underlying Ti bond coat, an alternating HA/Ti layer, and an HA top-layer have been deposited onto Ti6Al4V substrates. In this work, the major consideration was to examine the corrosion resistance and bond strength of graded coatings after various postheat treatment temperatures ranging from 400 degrees C to 700 degrees C. Gentamicin loading onto the plasma-sprayed coating was used to improve its antibacterial activity. Our results indicate that an appropriate heat treatment resulted in recrystallization of amorphous calcium phosphate of the as-sprayed coatings. The enhancement in corrosion resistance took place after heat treatment. Gentamicin loading might provide effective release at early time points (up to 1 h). On the basis of these observations, we conclude that the heat treatment at 600 degrees C for I h in air, leading to increased crystallinity and fewer defects, as well as enhanced bond strength,. may be a suitable post-deposition treatment method to promote the characteristics of graded HA/Ti coatings that also serve as a drug carrier.