Gel-derived powders of CaO-P2O5-SiO2 system as a starting material to production of bioactive ceramics

Three types of glass-ceramic material of the CaO-P2O5-SiO2 system were obtained using the sol-gel method and applying calcium nitrate, tetraethoxysilicate and triethylphosphate as precursors of the respective oxides. The gels were heated to 700 degrees C and then sintered at 450 degrees C and 1000-1300 degrees C. It has been found that, after heating, these materials contain a glassy phase, hydroxyapatite and wollastonite; there were important differences in the phase compositions, as well as in the pore structure of these materials. The solubility of gel-derived materials in simulated body fluid (SBF) was investigated, and FTIR, SEM and EDAX examinations of the surface layer after contact with SBF were carried out. It has been found that crystallization of hydroxyapatite occurs on the surface of the materials obtained. This observation may be an indication of the bioactivity of the gel-derived materials in the CaO-P2O5-SiO2 system. A series of experiments was conducted on immune system cells of rat alveolar and peritoneal macrophages in order to confirm the biocompatibility of the obtained materials. It has been found that the chemical and phase composition of gel-derived materials has an influence on the macrophage stimulation.