Today, as the need of new regenerative solutions is steadily increasing, the demand for new bio-devices with smart functionality is pushing material scientists to develop new synthesis concepts. Indeed, the conventional approaches for biomaterials fail when it comes to generate nano-biocomposites with designed biomimetic composition and hierarchically organized architecture mimicking biologically relevant tissue features. In this respect, an emerging concept in material science is to draw inspiration from natural processes and products, which we may consider as the most advanced examples of smart nanotechnology. Natural processes of supramolecular assembly and mineralization of organic macromolecules, known as biomineralization, generate complex hybrid 3D constructs that are the basis of skeletons, exoskeletons, nacre and shells. On the other hand, natural structures such as woods and plants exhibit multi-scale hierarchic organization that is the source of smart and anisotropic mechanical properties associated with high porosity and lightness. The association of nature-inspired nano-technological products with smart functionalization can provide new advanced solutions to critical and still unmet clinical needs. In this respect, magnetic activation of biomaterials by the use of a recently developed biocompatible, resorbable magnetic apatite promises to represent a new safe and effective switching tool, enabling personalized applications in regenerative medicine and theranostics that so far were not feasible, due to the cytotoxicity of the currently used magnetic materials.
Part of the book: Advanced Techniques in Bone Regeneration
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