Study of the Dependency of pH Values on HAp Synthesis

Hydroxyapatite (Ca10(PO4)6(OH))2, HAp has been one of the cheapest and well-known ceramics for diversified applications including clinical bone graft procedures for more than 30 years. Synthetic calcium phosphates, such as calcium hydroxyapatite, are an important inorganic biomaterial which has attracted the attention of researchers related to the biomaterials field in recent years. HAp is widely used for hard tissues repair due to its chemical and structural similarity with the mineral phase of bone and teeth. As a result, this inorganic phosphate has been studied extensively for medical applications in the form of powders, composites, and coatings [1–11]. HAp has many bone replacement applications and is used as bone substitutes in dental and orthopedic sites, immediate tooth replacement, augmentation of alveolar ridges, pulp capping material and maxillofacial reconstruction, etc. [12]. HAp implants exhibit relatively good tissue compatibility, and new bone is formed directly on the implants [13-19]. For repairing or substituting the bone, the designed HAp material must have the ability to create a bond with the host living bone [20]. Hence, it is desirable to include a high degree of crystallinity and chemical stability among the desirable properties of an ideal hydroxyapatite [21-23] HAp has poor mechanical properties, e.g., low strength and toughness, restrict monolithic HAp applications to those that require little or no load-bearing parts [24]. Due to its diverse applications, the materials properties accordingly need to be tailored for an application. Hence, researchers have tried to customize its properties such as bioactivity, mechanical strength, solubility and sinter ability by controlling its composition, particle size and morphology [9,10]. The objectives of this work are to synthesize hydroxyapatite nanoparticles by chemical precipitation method for different pH value and to investigate the effects of the pH value variation during the reaction.