Production of Hydroxyapatite (HAp) Nanoparticles by wet chemistry methods for biomedical usage

Abstract

Hydroxyapatite, (HAp), Ca10(PO4)6(OH)2, is a physically occurring mineral found in the inorganic component of human bone and enamel. The basic elements of HAp are mainly calcium and phosphorous, with a stoichiometric calcium to phosphorous ratio of 1.67 capable of promoting intimate bone growth onto femoral implants. HAp is rendered a bioactive material since it has the ability to promote such growth with rapid fixation in what is also considered an osteoconductive process. The present study aims to produce HAp powders via the wet chemical precipitation technique, in order to evaluate the critical process parameters (mixing temperature, stirring rate, and Ca/P molar ratio) and their effect (main and interaction) on controlling the final HAp powder characteristics, such as, phase composition, crystallinity, crystallite size and particle size. 48.052 nm of HAp crystallite size was produced at 0.60 Ca/P molar ratio, 200 rpm of stirring rate and 600°C of mixing temperature. These powders were synthesised with a view to satisfying regulatory requirements which is favaourable particle size for biomedical usage is for the smallest particle as possible which is in this study the particle size should be in range of 30-50nm. These effects were quantified using Design of Experiments (Design Expert) to develop mathematical models, in terms of the chemical precipitation process parameters. The HAp nanoparticles were also analyzed by using Fourier Transform Infrared (FTIR), X-ray Diffractometer (XRD) and Scanning Electron Microscope (SEM).