Macroporous Bioglass Scaffolds Prepared by Coupling Sol–Gel with Freeze Drying

Free-standing macroporous bioglass scaffolds were prepared by a sol–gel route. The ice-segregation-induced self-assembly method was employed to structure a bioglass aqueous sol in the form of green monoliths with a well-defined macroporosity. The achieved texture was essentially preserved after a mild annealing at 873 K. The texture can be properly tuned by typical variables such as the freezing rate or sol concentration. In addition to these physical preparative variables, the acidity level plays a key role in preventing the silica condensation, keeping the primary building units in the early stages of the sol–gel transition and allowing the obtainment of large macropores. The chemical homogeneity of the resulting bioglass was enough to ensure a proper in vitro biomineralization response, resulting in a well-distributed hydroxyaopatite-like nanoparticulated layer.