In-depth review of synthesis of hydroxyapatite biomaterials from natural resources and chemical regents for biomedical applications

Hydroxyapatite (HAp) is a popular ceramic biomaterial, which has extensively been employed in numerous biomedical applications. It has drawn the attention of scientists primarily owing to its properties similar to the bones and teeth of human beings. Due to its organic similarity, HAp has exceptional biocompatibility and can activate osteoconduction and osteoinduction occurrence. Hence, HAp has been used in a broad collection of healing applications extending from common dental implant, and bioactive coatings on grafts to purposefully premeditated drug delivery methods, and even for tissue engineering (TE) applications. The production method is essential in controlling the physicochemical properties of HAp, which in turn affects its mechanical and biological properties. The anticipated physiognomies of HAp can be accomplished using a suitable technique of production and sources. This in-depth review discussed the various natural sources of HAp, and synthesis techniques for producing HAp, alongside their advantages and disadvantages, applications, and essentials of HAp for therapeutic applications. From the review, it was found that the sol–gel route is preferred over other routes because of its even molecular mixing, high purity of products, low production temperature, and ability to synthesize nanosized particles of HAp. As a result, it is provisional that upon the cautious blend of key considerations such as sources, synthesis technique, and production parameters for the manufacture of natural HAp (NHAp), mechanical properties can be improved and the product can be employed as a drug delivery system. These are important extents for the prospect of the research.