Biomimetic fabrication of hydroxyapatite hollow spheres with polyoxyethylene chain-containing quaternary ammonium salt cationic Gemini surfactant as template

This paper reports a biomimetic fabrication of hydroxyapatite (HAp) with a hollow spherical three-dimensional architecture, using Ca(NO3)(2) and (NH4)(3)PO4 as the starting materials, and a polyoxyethylene chain-containing quaternary ammonium salt cationic Gemini surfactant [C12C2C12 (EO)] as the template. The effects of the surfactant concentration, aging time, and temperature on the morphology and the degree of crystallinity of HAp were investigated. We also proposed a possible mechanism for the formation of hollow spherical HAp. The results showed that the cationic Gemini surfactant was the most important parameter for the formation of spherical HAp. We obtained uniform well-defined hollow spherical HAp with semidiameter about 1.5 mu m, using 0.1% mass fraction of template, at 37 degrees C for 7 days.