Hydroxyapatite-based hydrogel nanocomposites for bone tissue engineering applications

Hydroxyapatite (HA) is considered the main component of the bone of all living organisms. For instance, it occupies around 70% of the weight of the human bone. Moreover, it shows outstanding biological properties such as bioactivity, biocompatibility, and osteoconductivity. Because of these amazing characteristics, the most prominent applications of HA are believed to be for bone replacement purposes, but unfortunately, its fragility greatly limits its wide applications in this field. Therefore, one strategy to solve this serious problem is to prepare HA-containing nanocomposites along with a substance that has better elasticity. Based on this concept, one of the most suitable candidate materials used with HA to prepare these attractive composites is polymeric hydrogels. Nanocomposite hydrogels can be considered nanomaterials containing networks of hydrated polymers, which reveal superior strength and flexibility comparative to hydrogels that are conventionally prepared. Consequently, the properties obtained as a result of this combination have helped researchers interested in materials science and biomaterials to develop advanced materials that can be used in different applications of biomedical field including regenerative medicine and delivery of drugs and biosensors, thanks to a diversity of normal and artificial polymers that are used for designing these desired hydrogels. This chapter briefly discussed bone anatomy, some statistics on orthopedic surgeries, biomaterials used for orthopedics, the concept of tissue engineering applications, nanomaterials and composites and their remarkable properties, and the importance of hydrogel nanocomposites in the treatment of bone defects.