Fabrication of Hydroxyapatite with Three-dimensional Pore Frame by Colloidal Template Method

SiO2 colloidal template was prepared through Stber method,followed by gravitational sedimentation.Hydroxyapatite(HA) with highly ordered three-dimensional pores was fabricated through infiltrating the template with HA precursor,sintering and then removing the template by immersing in NaOH solution.The samples were characterized by X-ray diffraction(XRD),transmission electron microscope(TEM),field emission scanning electron microscope(FESEM).The effects of the concentration and amount of HA precursor,and the time of immersion in NaOH solution on the preparation technique,the porous structure and the porosity were investigated.The results show that the Zeta potential of SiO2 spheres increase after surface modification by H2O2,thus improving the order degree of the silica colloidal template.The sizes of SiO2 colloid spheres and the pores formed by dissolved spheres are about 250nm and 200nm,respectively.There are a great number of micro-pores with dimension of 20nm on the wall of the HA pore formed by removing SiO2 spheres.The well-ordered HA with three-dimension pores are fabricated on the condition that the HA precursor concentration is 0.8mol/L,the volume ratio of HA precursor to the whole template is 30%,immersion in 4mol/L NaOH solution for 3d.