Effects of TiO2-containing phosphate glasses on solubility and in vitro biocompatibility

Phosphate-based glasses with different amounts of titanium dioxide (TiO(2) ), having the following molar composition 50P(2) O(5) -30CaO-9Na(2) O-3SiO(2) -3MgO-(5-x)K(2) O-xTiO(2) , (where x = 0, 2.5, 5 mol %), were synthesised and characterized in terms of solubility (according to ISO 10993-14), and in vitro biocompatibility using human MG-63 osteoblast cells. Dissolution tests were carried out in Tris-HCl (pH 7.4) to simulate the physiological pH and in citric acid (pH 3.0) to simulate an acidic environment. The weight loss decreased with increasing TiO(2) content, a process further enhanced in acidic medium. TiO(2) reduced the pH changes usually caused by the dissolution products released. Cellular tests showed that all the glasses studied (0-5 mol % TiO(2) ) and TiCl(4) , used to investigate the biocompatibility of titanium ions, did not produce cytotoxic effects on human MG-63 osteoblasts for up to 5 days in culture. On the basis of these results, we suggest that TiO(2) -containing phosphate glasses could be promising substrates for bone tissue engineering applications.