Bioactivity of metallic biomaterials with anatase layers deposited in acidic titanium tetrafluoride solution.

A simple and versatile treatment was developed to provide various metallic biomaterials such as Ti, NiTi, Ta and SUS 316L stainless steel with in vitro bioactivity or ability to deposit carbonate-incorporated apatite in a simulated body fluid (Kokubo solution). A well-crystallized anatase layer deposited on the metallic biomaterials surfaces after soaking them at 60 degrees C for 24 h in an aqueous solution of titanium tetrafluoride (40 mM) whose pH was adjusted to 1.9 with HCl. The as-coated anatase layers did not deposit apatite. When heated at 300 degrees C they were so bioactive as to deposit apatite within 5 day(s) in the Kokubo solution. The trace amount of fluorine weakly bound in the as-coated anatase layers was suggested to be one of the factors that suppressed the bioactivity.