Preparation of Magnetic, Luminescent and Mesoporous Hydroxyapatite Nanospindles with High Specific Surface Area

Magnetic, luminescent and mesoporous nanospindles of Sm3+-Fe3+ co-doped hydroxyapatite (HAP) were prepared in the presence of monododecyl phosphate as templates. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), vibration sample magnetometer (VMS), photoluminescence (PL) spectrum and nitrogen adsorption-desorption isotherm were used to characterize the products. The results show that the doped Sm3+ and Fe3+ existed in two forms: being solid-soluted in the HAP, or as oxides (amorphous Sm2O3 and γ-Fe2O3) nanoparticles embedded in the HAP. The doped HAP samples, both the as-dried and the calcined, display a good superparamagnetism. The calcination increases the magnetization from 13.45 emu/g to 19.51 emu/g. The calcined Sm3+-Fe3+ co-doped HAP has a spindle-like morphology with a length of 200∼350 nm and a diameter of 50∼100 nm, and possesses a large amount of mesopores with biomodal pore sizes of 3.64 and 9.01 nm. The biomodal mesoporous Sm3+-Fe3+ co-doped HAP nanospindles have a large pore volume of 0.3286 cm3/g and a high specific surface area of 153.52 m2/g. These make the mesoporous HAP nanospindles have a high drug payload ratio of 33.68wt% and a great application potential in drug delivery system.