Hydrogen Phosphate (HPO42-) ions Substitution in Hydrated Layers of OCP by Dicarboxylate ions to Hexagonal HAP Nanocrystals System

Abstract

The octacalcium phosphate (OCP) crystals are apatite bases with hydrated layers in producing of needle or plate-shaped hydroxyapatite (HAP) nanocrystals, which prepared by a dissolution precipitation reaction. The reaction led to a hexagonal HAP nanocrystals formation under hydrothermal condition via OCP at 180? for 3h with pH of solution adjusted to 5.5 with incorporating dicarboxylate or succinate ions having Ca/P molar ratio is expected to be 1.56±0.02, where the morphology of OCP are retained. During incorporating of succinate ions in OCP crystals, the hydrogen phosphate (HPO42-) ions in the hydrated layers of OCP are being substituted by succinate ions. These organically modified OCP which generated to HAP with unique nanostructures have been characterized by using of SEM, FTIR and X-ray diffraction analysis. Since the crystal system of HAP is hexagonally and its crystalline size in the direction of various (a,b,c) axes depending on the thickness of the plate-shaped HAP crystals where their size as perpendicular to the (100) plane is calculated by using of Scherrer equation D100 = K?/(? cos?). The formed hexagonal HAP are used in soft and hard tissue engineering system for biomedical application.