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

摘要

Mesoporous bioactive glasses (MBGs) of the CaO-SiO_2-P_2O_5 system containing relatively high P_2O_5 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) (EO_(20)-PO_(70)-EO_(20), 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 N2 sorption/desorption technique. SAXRD and TEM results display the reduced long-range ordering of mesopores with increasing P_2O_5 content. N2 sorption/desorption analysis shows that all three samples exhibit a type IV isotherm with type HI hysteresis loops, characteristic of independent cylindrical slim pore channels and this material has a Barret-Joyner-Halenda (BJH) model pore size of ~ 4 nm and BET specific surface area ~430 m2/g. NMR results indicate a more condensed framework for samples with 30 mol% P_2O_5 than samples with 10 mol% P_2O_5. For in vitro bioactivity tests where samples were soaked in simulated body fluid (SBF), samples with 30 mol% P_2O_5 showed higher crystallinity than those with lower P_2O_5 contents Silicon concentration increased in SBF solution during the soaking period, which indicates MBGs can be degradable in SBF solution.