Investigation of the influence of SrO addition on the bioactivity of CaO[sbnd]Na2O-P2O5-B2O3 glass system

Abstract

In this work, the role of strontium oxide in the bioactive glasses calcium-sodium-borate was studied to evaluate the bioactivity of the system and the rate of the ion release in Simulated Body Fluid (SBF). Five samples were prepared, with concentration of strontium oxide (SrO) from 0 to 20 wt%, in order to understand how SrO change the glass structure and the ionic leaching process in SBF. Results of density and molar volume, XRD, FTIR, weight loss, pH and cytotoxicity assay were presented and discussed as a function of SrO. The measured pH values of SBF, presented lower values for samples with greater amounts of SrO, suggesting that the increase of SrO in the glasses can reduce the release of the ions in SBF. The fraction of tetracoordinate boron, N4, calculated by FTIR results, increases with the addition of SrO, which shows an increase in the glass connectivity and a decrease of the chemical reactivity. The FTIR spectra and X-ray diffraction results, after immersion in SBF, confirmed the materials bioactivity with the formation of carbonated hydroxyapatite or crystalline calcium phosphate. The samples did not show in vitro cytotoxicity against osteoblast cell line. Also, we highlight that 10SrO sample has induced proliferation of osteoblast-like cells in vitro to all concentrations of glass. These results show that SrO doped calcium-sodium-borate glasses are materials with high rate of bioactivity, low cytotoxicity and reduced dissolution rate of the glasses in an aqueous medium, besides induce cells proliferation and bone tissue growth and their biocompatibility with living tissues.