Ga incorporation into calcium silicate sol-gel bioactive glasses: Effect of Ga on glass structure and ion release behavior

SiO2-CaO-based sol-gel glasses are well known bioactive materials; however, there remains a concern about the rapid pH increase in their surroundings after implantation in the body due to the burst release of calcium ions (Ca2+) from the glasses. In this study, we incorporated gallium oxide, which is an intermediate oxide, into SiO2-CaO sol-gel glasses to evaluate its effect on the glass structure and ion release behavior. The release of Ca2+ from the glasses at the initial stage of immersion in a buffer solution was suppressed by the incorporation of Ga in a dose-dependent manner. Ga was found to be primarily in tetrahedral coordination in the glasses. Thus, Ga served as a network former in the silicate network, forming a tetrahedral coordination unit and a charge balanced by Ca2+ ions. The viability of fibroblast-like cells was significantly higher for Ga-incorporated glass compared to nonincorporated glass.