Synthesis and in-vitro bioactivity of mesoporous bioactive glasses with tunable macropores

By using a nonionic block copolymer surfactant as the mesostructure directing agent, polystyrene (PS) colloidal particles or polyester (Terylene®) fibers as the macropore templates, mesoporous bioactive glass (MBG) materials with tunable macropores in a wide range (0.6-200 μm) have been synthesized and their in vitro bioactivities have been studied. Macro-mesoporous bioactive glass (MMBG) materials obtained by using PS spherical templates have a uniform macropore size of ∼600 nm, while MBG materials synthesized in the presence of terylene fibers have tubular channels (denoted TMBG) with diameters in the range of 8-200 μm adjusted by the diameters of terylene fibers. Both MMBG and TMBG materials have uniform mesopores of ∼5 nm in diameter. Similar to MBG materials, MMBG and TMBG materials have superior in vitro bioactivity compared to conventional bioactive glass. It is also shown that the size of macropore exerts influence on the hydroxycarbonate apatite (HCA) growth behavior within macropores. After soaking MMBG in simulated body fluid, HCA spheres gradually grow to sizes comparable to that of macro-pores after 24 h. While in the case of TMBG, hollow HCA tubes form in the tubular channels of TMBG. It is expected MBG materials with tunable macropores and exceptional in vitro bioactivity may find potential applications in delivery of biological factors, tissue ingrowth, tissue regeneration and neovascularization.