Nano-sized Porous Calcium Phosphate Ceramics

1. Nano-sized Porous Calcium Phosphate Ceramics S. Tepavitcharova1, D. Rabadjieva1, K. Sezanova1, E.Vassileva2, R. Gergulova1 1Bulgarian Academy of Sciences, Institute of General and Inorganic Chemistry, “Acad. G. Bonchev” Str., bl. 11, 1113, Sofia, Bulgaria 2University of Sofia “St. Kliment Ohridski”, Faculty of Chemistry, Laboratory on Structure and Properties of Polymers, 1, James Bourchierblvd., 1164, Sofia, Bulgaria INTRODUCTION PURPOSE Non-stoichiometric nano-sized apatites are one of the main components that build up the hard bone tissue. Thus nano-sized calcium phosphates with predetermined properties and structures obtained by varying their composition are of continuous interest in the field of the biocompatible materials as they could be used for bone repairing, reconstructive and remodeling applications. To investigate the crystallization of nano-sized precursors for preparation of calcium phosphate ceramics and to follow the influence of the reagents and the reaction environment on the composition, crystal size and morphology. EXPERIMENTS Reagents: Aqueous solutions - 0.3 М K2HPO4 and 0.5 М /1.5М CaCl2; Simulated body fluid(SBF), Propylene glycol , Olive oil; Natural polysaccharides - Xantan Gum and Guar Gum Case studies: (i) Gel-mediated crystal growth (ii) Continuous precipitation • Precipitation in buffer aqueous solution, propylene glycolaqueous solution (1:5) and oil-in-water emulsion (1:20) • pH 8, room temperature; • Xanthan Gum gelling and lyophilization • Washing with water and secondary lyophilization • Sintering at 1000oC for 1 h • Adsorption in polymers • Ca2+ diffusion in hydrogels • pH 3-6; and 10-12 • Crystallization time – 2 – 120 h • Drying – room temperature RESULTS Gel-mediated crystal growth pH 3-6 pH 10 - 12 Crystal growth of DCPD ■Calcium apatite; KCl; ▲Ca2P2O7 XRD of precipitated samples ■CaHPO4.2H2O (DCPD); KCl; XRD and SEM of precipitated samples XRD of calcified precipitate (600oC) Continuous Precipitation Inbuffer aqueous solution Inpropylene glycolaqueous solution (1:5) Inoil-in-water emulsion (1:20) Non-gelling ■ HA; -TCP; Gelling by Xanthan Gum XRD data CONCLUSIONS • Nano-sized porous calcium phosphate ceramics were prepared by the techniques: • Continuous precipitation; • Xanthan Gum gelling and lyophilization; • Washing and secondary lyophilization; • Sintering at 1000оС. Acknowledgements:This work was financially supported by the Bulgarian Ministry of Education, Youth and Science under contracts DTK – 02-70/09 and CVP-09-0003