Effects of materials parameters on mineralization and degradation of sol-gel bioactive glasses with 3D-ordered macroporous structures

Bioactive glasses (BGs) with three-dimensionally ordered macroporous (3DOM) structures were prepared by combining a sol-gel synthesis with colloidal crystal templating. 3DOM sol-gel BGs with two compositions (20 mol % CAO-80% SiO₂ and 20 mol % CAO-4% P₂O₅-76% SiO ₂) and three macropore sizes (average: 345, 440, and 790 nm) were prepared. Glasses were separated into two particle sizes (212 μm < small < 355 μm and 600 μm < large < 1000 μm). The glasses were soaked in simulated body fluid at 37°C for 2 or 4 days and the effects of composition, particle size, and macropore size on the formation of apatite and glass degradation were characterized. Within the parameter range of the experiments, several comparisons could be made. First, the formation of apatite and degradation of the glass were slightly enhanced for the phosphate containing composition. Second, large particles formed less apatite and degraded less completely compared with small particles. Lastly, an increase in macropore size slowed down the glass degradation and apatite formation processes, an effect related to the decreased internal surface area of the larger pore materials.