Impact of transition metal ions on the structure and bioactivity of alkali-free bioactive glasses

Transition metal ions are essential micronutrients for all living organisms and play an important role in bone metabolism. In the present study, we investigated the impact of transition metal ions (Cu, Co, Mn, Fe) on the structure and bioactivity of bioactive glasses. The emphasis was laid on understanding their influence on the chemical dissolution behavior of glasses and its impact on their vitro bioactivity, osteoblast proliferation and oxidative stress levels. The structure of glasses was studied by using molecular EXAFS in combination with Raman spectroscopy. The apatite-forming ability of glasses has been investigated by X-ray diffraction, infrared spectroscopy after immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1 and 7 days. A significant effect on the bioactivity was observed with addition of transition metal ions. The cellular responses were observed in vitro on glass powders using human osteosarcoma MG63 cell line. The dose-dependent cytoprotective effect of glasses with respect to the concentration of transition metal ions (Cu, Co, Mn, Fe) released from the glasses is also discussed.