Synthesis routes for bioactive sol-gel glasses:: Alkoxides versus nitrates

The synthesis of a new bioactive glass with a composition in mol % of 76% SiO2, 23% CaO, and 1% P2O5 was achieved by the sol-gel method with the employment of two different pathways: via inorganic salts (76S) and via metal alkoxides (76SA). The in vitro bioactivity of both glasses was assessed by soaking them in simulated body fluid for different time periods, and the changes in the texture were analyzed. Comparison of glasses synthesized by the two pathways was also carried out. Although both show good bioactivity, glass synthesized via metal alkoxides leads to the formation of a more homogeneous apatite layer on its surface. In addition, this newly formed layer is thicker and more compact for 76SA, and the homogeneous nucleation of the apatite on the surface leads to a better bond between glass and the mentioned newly formed layer.