Spherical hydroxyapatite with colloidal stability prepared in aqueous solutions containing polymer/surfactant pair

Colloidal hydroxyapatite (HA) with long-term stability was essential for its potential applications in the biomedical field. Polymer/surfactant pair of poly(ethylene oxide) and sodium oleate were used for surface modification of spherical HA particles with nanoscale sizes. Suspensions with different solid loadings were prepared and observed through sedimentation studies with purpose of investigating the effect of surface modification on the colloidal stability. It was found that after decorated with polymer/surfactant pair, colloidal HA particles were obtained with satisfied dispersion stability and less conglomeration due to the existence of both electrostatic repulsion and steric hindrance effects. Based on the investigation of surface chemistry of modified HA powders, a schematic illustration about multilayered surface structures with polymer/surfactant pair was put forward and might favor to prepare a wide range of dispersible particles in aqueous solutions.