pH=7.4 was added drop-wise over 4 h. The pH of the system was maintained at 10.8 throughout the stirring process, by using 0.1 M sodium hydroxide. The mixture was allowed to remain stirred overnight. A white precipitate was formed. The precipitate was vacuum dried and cleaned with distilled water and ethanol simultaneously for three or four times. The prepared powder was used for further characterization. The schematic presentation of the procedure is given in Figure 1. This precipitation reaction for synthesis of hydroxyapatite nanoparticles was first proposed by Yagai and Aoki, as indicated by Bouyer et al. (2000).