Abstract: Mg is a modifier of Si--O network in sol-gel bioactive glasses, and Zinc is an essential trace element in human body
and has a stimulatory effect on bone formation. In this work, a CaO-SiO₂-P₂O₅ bioactive glass (58S) used as the based glass, Mg doped glass
(58S0.5M) and Zn doped glass (58S0.5Z) were prepared by the sol-gel technique , and the phase composition and the mechanical
strength of the glass cuboids were evaluated. In addition, the in vitro bioactivity of the glasses was tested by immersion in simulated body fluid
(SBF). The results indicated that 58S0.5M and 58S0.5Z were all amorphous even calcined at 800℃, and the incorporation of Mg and Zn improved
bending strength due to the higher bond energy of Mg--O and Zn--O as compared to Ca--O. The in vitro study showed that all glasses could induce hydroxyapatite
(HA) formation, but 58S0.5M and 58S0.5Z revealed a slower deposition of HA at the early stage of the immersion. After prolonged soaking, a thick layer of
HA was formed on all glasses, which suggested that Mg and Zn inhibited the HA nucleation at the early stage, but did not affect the deposition of HA in long
term soaking in SBF.

Key words: bioactive glass, sol-gel, magnesium, zinc