title: Facile synthesis of both needle-like and spherical hydroxyapatite nanoparticles: effect of synthetic temperature and calcination on morphology, crystallite size and crystallinity.
abstract: Synthetic hydroxyapatite (HA) nanoparticles, that mimic natural HA, are widely used as biocompatible coatings on prostheses to repair and substitute human bones. In this study, HA nanoparticles are prepared by precipitating them from a precursor solution containing calcium sucrate and ammonium dihydrogen orthophosphate, at a Ca/P mole ratio of 1.67:1, at temperatures, ranging from 10°C to 95°C. A set of products, prepared at different temperatures, is analyzed for their crystallinity, crystallite size, morphology, thermal stability and composition, by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopic techniques, while the other set is analyzed after calcining the respective products, soon after their synthesis, for 3h, at 700°C. The as-prepared products, after 2h of drying, without any calcination, are not crystalline, but they grow very slowly into needle-like morphologies, as they are ripened with time. The percentage crystallinity of the final products increases from 15% to 52%, with increasing the preparative temperature. The calcined samples always produce spherical nanoparticles of essentially the same diameter, between 90 nm and 100 nm, which does not change due to aging and preparative temperatures. Therefore, the same method can be utilized to synthesize both spherical and needle-like nanoparticles of hydroxyapatite, with well-defined sizes and shapes. The ability to use readily available cheap raw materials, for the synthesis of such well-defined crystallites of hydroxyapatite, is an added advantage of this method, which may be explored further for the scaling up of the procedures to suit to industrial scale synthesis of such hydroxyapatite nanoparticles.
authors: Department of Chemistry, Faculty of Science, University of Peradeniya, Peradeniya 20400, Sri Lanka; Post-graduate Institute of Science, P.O. Box: 25, University of Peradeniya, Peradeniya 20400, Sri Lanka.
authors: W P S L
authors: WP
authors: Wijesinghe
authors: Department of Chemistry, Faculty of Science, University of Peradeniya, Peradeniya 20400, Sri Lanka; Post-graduate Institute of Science, P.O. Box: 25, University of Peradeniya, Peradeniya 20400, Sri Lanka.
authors: M M M G P G
authors: MM
authors: Mantilaka
authors: Department of Materials Science, Shizuoka University, Johoku, Naka-ku Hamamatsu, 432-8011, Japan.
authors: E V A
authors: EV
authors: Premalal
authors: Department of Medical Laboratory Science, Faculty of Allied Health Sciences, University of Peradeniya, Peradeniya 20400, Sri Lanka.
authors: H M T U
authors: HM
authors: Herath
authors: Department of Mechanical Engineering, University College London, London WC1E 7JE, UK.
authors: S
authors: S
authors: Mahalingam
authors: Department of Mechanical Engineering, University College London, London WC1E 7JE, UK.
authors: M
authors: M
authors: Edirisinghe
authors: Department of Veterinary Pathobiology, Faculty of Veterinary, University of Peradeniya, Peradeniya 20400, Sri Lanka.
authors: R P V J
authors: RP
authors: Rajapakse
authors: Department of Chemistry, Faculty of Science, University of Peradeniya, Peradeniya 20400, Sri Lanka; Post-graduate Institute of Science, P.O. Box: 25, University of Peradeniya, Peradeniya 20400, Sri Lanka. Electronic address: rmgr@pdn.ac.lk.
authors: R M G
authors: RM
authors: Rajapakse
mesh_terms: D002118:Calcium; D017886:Durapatite / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D017886:Durapatite; D002118:Calcium
keywords: Calcination; Calcium sucrate; Crystallinity; Hydroxyapatite; Morphology