Borosilicate sol–gel bioactive glasses and the effect of borate content on structure-property relationships

Abstract

Borate-doped silicate glasses with chemical compositions of (70 − x)SiO2–xB2O3–30CaO (x = 0, 5, 15, and 25, in mol%) were synthesized using the sol–gel method, intended to be used in tissue regeneration. The effects of borate content on the glass surface morphology, chemical structure, ion dissolution behavior, and fibroblast compatibility were investigated. 11B magic angle spinning-solid state nuclear magnetic resonance and Fourier transform infrared spectra demonstrated that borate, in the glasses, possessed both three- and four-coordinated structures. From nitrogen sorption, the specific surface area of the glasses decreased with increased borate content and calcination temperature, from 600 °C to 700 °C. In the case of glasses undergoing calcination at 700 °C, silicate and calcium ion released in a Tris–HCl buffer solution (pH = 7.4) at the early stage of the immersion test decreased as borate content increased. The decrease in surface area caused by stabilizing at 700 °C due to the effect of increasing borate concentration controlled the ion dissolution behavior of the glasses. The proliferation ability of fibroblasts cultured with the dissolution products of the glasses were improved as borate content increased in the glass composition.