Characterization of Magnetic Hydroxyapatite Nanocrystallites and Potential Application for MRI Contrast Agent

In this study, synthetic hydroxyapatite nanoparticles (Hap NPs) were rendered magnetic by treatment with iron ions using a wet-chemical process. The magnetized Hap (mHap) NPs were fabricated by the addition of iron precursor in various ratios of Fe:Ca (X-Fe/ (Ca)). The physicochemical properties of mHap NPs were evaluated respectively, by X-ray diffraction (XRD) for the crystal structure, Fourier transform infrared (FTIR) spectroscopy for functional groups detection, Energy-Dispersive X-ray Spectroscopy (EDS) for composition analysis, transmission electron microscopy (TEM) for particle morphology characterization, and superconducting quantum interference device (SQUID) for magnetization property. The size distribution of mHap randomly in rod and needle-like shape was in average 80 to 120 nm. We found that the mHap was the result of the hetero-epitaxial growth of magnetite on the Hap crystallites. The magnetic NPs with sphere shape less than 10 nm in diameters were tightly surrounded on Hap crystallites and possessed superparamagnetic property. The magnetization of all groups of mHap NPs increased with the increasing of X-Fe/ Ca and with no toxic effect to cultured cells. In brief, mHap NPs demonstrated suitable physicochemical properties and good biocompatibility, suggesting that these NPs have potential applications as new biodegradable MRI contrast agent in medicine.