Surface modification of hydroxyapatite by stearic acid: characterization and in vitro behaviors.

Hydroxyapatite was modified by stearic acid (Sa) in the organic mediated solution using a reflux setup. Activation ratio was introduced to characterize the effect of organic solvents, reaction times and adding amounts of Sa. HA before and after surface modification were investigated by XRD, FTIR, particle size distribution, TEM and ICP. The optimal adding amount of Sa is about 3 wt%, and there are Sa molecules on the surface of HA with a chemical reaction between HA and Sa. Sa did not change the phases and particle size of HA. HA after modified has good bioactivity in vitro. Sa has great potential as surface modifier to improve the properties of inorganic fillers in the organic matrix.