Material scientists are increasingly looking to natural structures as inspiration for new-generation functional devices. Particularly in the medical field, the need to regenerate tissue defects claims, since decades, biomaterials with the ability to instruct cells toward formation and organization of new tissue. It is today increasingly accepted that biomimetics is a leading concept for biomaterials development. In fact, there is increasing evidence that the use of biomedical devices showing substantial mimicry of the composition and multi-scale structure of target native tissues have enhanced regenerative ability. As a relevant example, biomimetic materials have high potential to solve degenerative diseases affecting the musculoskeletal system, namely, bone, cartilage and articular tissues, which is of pivotal importance for most of human abilities, such as walking, running, manipulating, and chewing. In this respect, the adoption of nature-inspired processes and structures is an emerging fabrication concept, uniquely able to provide biomaterials with superior biological performance. The chapter will give an overview of the most recent results obtained in the field of hard tissue regeneration by using 3D biomaterials obtained by nature-inspired approaches. The main focus is given to porous hydroxyapatite-based ceramic or hybrid scaffolds for regeneration of bone and osteochondral tissues in neurosurgery and orthopedics.
Part of the book: Bio-Inspired Technology
Hydroxyapatite represents the natural inorganic component of the bone and may be considered an essential element required for the development of bone substitutes in the field of regenerative medicine. Hydroxyapatite bone substitutes own biomimetic, osteoconductive, and osteoinductive properties thanks to their chemical-physical properties and nanostructure that play a critical role for the reconstruction of calcified tissues. Controlling the structure of hydroxyapatite nanocrystals is vital for obtaining a sustained product, and it should be an advantage on the final materials suitable for bone replacement, in terms of adsorptive activity, drug delivery system, etc. Compared to other synthesis techniques, hydrothermal processing (refers to a synthesis in aqueous solution at elevated pressure and temperature, in a closed system) has the ability to precipitate the hydroxyapatite from overheated solution, regulating the rate and uniformity of nucleation, growth, and maturation, which affect size, morphology, and aggregation of the crystals. This chapter wants to provide an overview of realization of nanosized hydroxyapatite-based bioceramics (e.g., powder and 3D structures) with desired morphology of crystallites, by hydrothermal processing. In this way, some critical hydrothermal parameters fundamental on the control of the crystal shape and dimension (pH, temperature, starting precursors, etc.) are discussed.
Part of the book: Biomaterial-supported Tissue Reconstruction or Regeneration