ABSTRACT
This chapter discusses the contemporary use of hydroxyapatite (HAP)-based biomaterials for therapeutic drug delivery, with a particular emphasis on their fabrication, stability, dissolution, and interaction with drugs. Calcium phosphate biomaterials such as HAP-based biomaterials are particularly interesting vehicles for localized therapeutic delivery, as they have a long tenure as osteoconductive bone graft substitutes in orthopedic, dental, and plastic/reconstructive surgery applications. Biomineralization constitutes the formation of inorganic minerals within biological systems, which typically involves induction, nucleation, and mineral growth facilitated by the presence of an organic matrix and cellular activity. One of the common themes in biomineralization, and by extension in biomimetic mineralization, is heterogeneous nucleation. This type of nucleation occurs when nuclei are energetically stabilized on an organic surface. The precise mechanism by which calcium phosphate minerals nucleate in nature has been debated for many years, and several studies have postulated that anionic functional groups serve to concentrate clusters that contain inorganic cations, creating local supersaturation that promotes nucleation.
