Acid-induced bioactive titania surface.

Nano- and conventional-TiO(2) powders were deposited onto titanium alloy using atmospheric plasma spraying technology. As-sprayed titania coatings were treated by H(2)SO(4) and HCl solutions at room temperature for 24 h, and the bioactivity was evaluated by simulated body fluid tests. Measured X-ray diffraction patterns indicated that as-sprayed titania coatings obtained from both nano and conventional powders were composed of primary rutile as well as a small quantity of anatase and Ti(3)O(5). The surface of as-sprayed coatings prepared from the conventional powder was rougher than that from nanopowder. After immersion in simulated body fluid for 2 weeks, both acid-treated nano- and titania coatings have induced carbonate-containing hydroxyapatite to form on the surfaces. However, this phenomenon did not appear on the surface of as-sprayed nano- and conventional-titania coatings. The results obtained indicated that the bioactivity of plasma sprayed titania coatings was improved by the acid treatment and had nothing to do with phase composition and particle size of the original TiO(2) powders.