Sol–gel silica-based biomaterials and bone tissue regeneration

The impact of bone diseases and trauma in developed and developing countries has increased significantly in the last decades. Bioactive glasses, especially silica-based materials, are called to play a fundamental role in this field due to their osteoconductive, osteoproductive and osteoinductive properties. In the last years, sol–gel processes and supramolecular chemistry of surfactants have been incorporated to the bioceramics field, allowing the porosity of bioglasses to be controlled at the nanometric scale. This advance has promoted a new generation of sol–gel bioactive glasses with applications such as drug delivery systems, as well as regenerative grafts with improved bioactive behaviour. Besides, the combination of silica-based glasses with organic components led to new organic–inorganic hybrid materials with improved mechanical properties. Finally, an effort has been made to organize at the macroscopic level the sol–gel glass preparation. This effort has resulted in new three-dimensional macroporous scaffolds, suitable to be used in tissue engineering techniques or as porous pieces to be implanted in situ. This review collects the most important advances in the field of silica glasses occurring in the last decade, which are called to play a lead role in the future of bone regenerative therapies.