Bioactive borate glass coatings for titanium alloys

Bioactive borate glass coatings have been developed for titanium and titanium alloys. Glasses from the Na2O–CaO–B2O3 system, modified by additions of SiO2, Al2O3, and P2O5, were characterized and compositions with thermal expansion matches to titanium were identified. Infrared and X-ray diffraction analyses indicate that a hydroxyapatite surface layer forms on the borate glasses after exposure to a simulated body fluid for 2 weeks at 37°C; similar layers form on 45S5 Bioglass® exposed to the same conditions. Assays with MC3T3-E1 pre-osteoblastic cells show the borate glasses exhibit in vitro biocompatibility similar to that of the 45S5 Bioglass®. An enameling technique was developed to form adherent borate glass coatings on Ti6Al4V alloy, with adhesive strengths of 36 ± 2 MPa on polished substrates. The results show these new borate glasses to be promising candidates for forming bioactive coatings on titanium substrates.