Effect of magnesia on the degradability and bioactivity of sol–gel derived SiO2–CaO–MgO–P2O5 system glasses

Mesoporous 58SiO2–(38 − x)CaO–xMgO–4P2O5 glasses (where x = 0, 5, 10 and 20 mol%) have been prepared by the sol–gel synthesis route. The effects of the substitution of MgO for CaO on glass degradation and bioactivity were studied in tris-(hydroxymethyl)-aminomethane and hydrochloric acid buffer solution (Tris–HCl) and simulated body fluid (SBF), respectively. It is observed that the synthesized glasses with various MgO contents possess the similar textural properties. The studies of in vitro degradability and bioactivity show that the rate of glass degradation gradually decreases with the increase of MgO and the formation of apatite layer on glass surface is retarded. The influences of the composition upon glass properties are explained in terms of their internal structures.