Surface modification of hydroxyapatite crystals by Mg–Al–CO3-layered double hydroxides in HA/Mg–Al–CO3–LDH nanocomposite

Abstract

In this article, a novel approach for surface modification of hydroxyapatite (HA) by Mg–Al-layered double hydroxides (LDH) is described. A HA-based composite reinforced by LDH nanocrystals was synthesized by in situ growing of the LDH on HA. The influences of experimental conditions on HA/Mg–Al–CO₃–LDH nanocomposite formation, including pH of the aqueous solution and reaction temperature, are investigated. The nanocomposite was characterized by XRD, FTIR, TGA, SEM and EDX. In order to determine the hardness and density of the nanocomposite, and also to investigate the microstructure and morphology of it, the samples were sintered at 500, 600, 800, 900, 1000, 1100 and 1200 °C. The hardness increased from 50 HV for pure HA to 180 HV for the nanocomposite sintered at 800 °C. Changes in the morphology and structure upon the increasing of sintering temperature suggest the formation of metal oxide (MgO) and MgAl₂O₄ spinel which was confirmed by XRD analysis. The microstructure and chemical composition of the obtained phases from sintered powders were characterized by various methods. In addition, a bioactivity test was performed by immersing the nanocomposite in simulated body fluid (SBF). Indeed, this method has advantages in preparing and sintering with low temperatures.