Bioactive SiO₂-K₂O-CaO-P₂O₅ glass-ceramic scaffold prepared using polyurethane foam template

Abstract

A glass-ceramic in the SiO₂-K₂O-CaO-P₂O₅ quaternary system was prepared by substituting the Na₂O component with K₂O to avoid Na₂Ca₂Si₃O₉ formation upon thermal treatment since this phase decreases apatite formation kinetics on glass material. To form the glass-ceramic, a modified sol-gel method involving solution precipitation, followed by reagents encapsulation in citric acid was adopted to enable the use of sodium metasilicate as a cheap substitute for traditional alkoxysilane silica precursors. The foam replication method using polyurethane foam as a sacrificial template was used to obtain the scaffold, which on analysis gave a porosity of 92% and an average pore size of 36±6 mm. In vitro bioactivity evaluation in simulated body fluid for a maximum of 14 days indicated the formation of hydroxyapatite on the sample surface. Phase analysis showed that CaSiO₃ and K₂CaSiO₄ crystals formed in the sintered sample as the main phases, which exhibited biodegradability in simulated body fluid (SBF). Therefore, economically-derived porous bioactive glass-ceramic scaffolds based on the current method (a simple process) are feasible.

Keywords:
bioactive glass-ceramic; carbonated hydroxyapatite; bioactivity; foam replication; polyurethane foam; crystallization; biodegradability