Synthesis Methods of Doped Hydroxyapatite: A Brief Review

Abstract

Hydroxyapatite (HA) has drawn great attention to biomedical applications due to their bone mineral similarity, strong bioactivity, biocompatibility and osteoconductive. Despite the fact that HA has many advantages, several properties are still lacking, emphasising the crucial need for ion doping/substitution. Many attempts have been made to incorporate ions into HA structure to increase their physical, chemical, and biological properties. With such a diverse range of methods available for the synthesis of doped HA, this article discussed the importance of doping for HA and summarizes four common techniques used to prepare doped hydroxyapatites which include precipitation, hydrothermal, sol-gel and mechanochemical method.

Freeze casting of hydroxyapatite‐titania composites for bone substitutes

“…Doping of weaker materials like HA with stronger materials like TiO 2 and other ceramics or metals has been shown to improve the mechanical strength of HA. [72][73][74][75] This doping effect for increased mechanical properties was observed in all composite loadings since they had greater mechanical properties than HA.…”

Tackling current production of HAp and HAp-driven biomaterials

“…75 The introduction of foreign ions into the crystal lattice of HAp during its synthesis involved the following steps: (1) preparation of precursor solutions containing the ions that will be incorporated into the HAp lattice. 76,77 These precursor solutions can include calcium and phosphate sources along with the doping ions. During the precipitation process, ions from the precursor solutions are incorporated into the growing HAp crystal lattice.…”

“…78 After substitution, HAp retains its hexagonal structure. [75][76][77][78] These substitutions result in unique characteristics of the final molecule and are possible due to the high ion exchangeability of HAp. 79 For the bulk material, these differences can be perceived in the macro crystal morphology, mechanical properties and even biological behavior (Table 2).…”

In Vitro and In Vivo Bone Regeneration Assessment of Titanium-Doped Waste Eggshell-Derived Hydroxyapatite in the Animal Model

“…Many earlier researchers have tried different chemical reagents and methods to prepare HAp (referred to as synthetic HAp or pure HAp in this report) in the laboratory through precipitation, sol–gel, hydrothermal, or mechanochemical methods. However, in contrast to synthetic HAp, natural HAp is nonstoichiometric, poorly crystalline, and also contains several ions as impurities . Thus, the biochemical reactions of the HAp implants in the physiological environment are different for synthetic and natural HAp.…”

“…However, in contrast to synthetic HAp, natural HAp is nonstoichiometric, poorly crystalline, and also contains several ions as impurities. 9 Thus, the biochemical reactions of the HAp implants in the physiological environment are different for synthetic and natural HAp. Only a few researchers have tried to synthesize HAp from a natural origin-based source.…”