Synthesis of CaO-SiO2-P2O5 mesoporous bioactive glasses with high P2O5 content by evaporation induced self assembly process

Mesoporous bioactive glasses (MBGs) of the CaO-SiO2-P2O5 system containing relatively high P2O5 contents (10-30 mol%) were prepared from a sol-gel. An evaporation-induced self-assembly (EISA) technique was used with poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (EO20-PO70-EO20, P123) acting as a template. The structural, morphological and textural properties of MBGs were investigated by small-angle X-ray diffraction (SAXRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and a N-2 sorption/desorption technique. SAXRD and TEM results display the reduced long-range ordering of mesopores with increasing P2O5 content. N-2 sorption/desorption analysis shows that all three samples exhibit a type IV isotherm with type H1 hysteresis loops, characteristic of independent cylindrical slim pore channels and this material has a Barret-Joyner-Halenda (BJH) model pore size of similar to 4 nm and BET specific surface area similar to 430 m(2)/g. NMR results indicate a more condensed framework for samples with 30 mol% P2O5 than samples with 10 mol% P2O5. For in vitro bioactivity tests where samples were soaked in simulated body fluid (SBF), samples with 30 mol% P2O5 showed higher crystallinity than those with lower P2O5 contents Silicon concentration increased in SBF solution during the soaking period, which indicates MBGs can be degradable in SBF solution.