Surface Modification Of Nano-hydroxyapatite And Their Cellular Compatibility

Hydroxyapatite nanoparticles (nHA) have been applied in the biomaterial field bcause of their good bioactivity and biocompatibility. But their application for loaded-hard tissue has been limited due to poor mechanical properties. In addition, their synthetic techanique and biological function need improving. In the paper, nHA nanoparticles were synthesized through chemical co-precipitation method in the presence of surfactant (cetyltrimethylammonium bromide, CTAB). And then obtained HA nanoparticles were modified using polyacrylic acid (PAA) and polyethylenimine (PEI) to change their surface potential. The physical and chemical properties of the nHA were investigated by x-ray diffraction (XRD), fourier transform infrartd spectroscopy (FTIR), transmission electron microscope (TEM), laser light scattering (LLS), Zeta potential apparatus and agarose gel electrophoresis etc. Cell cytotoxicity of nHA samples was evaluated from a view-point of the effect of zeta potential, concentration and coculture time of particles on cell proliferation and morphology using MTT and fluorescence method in vitro.The results showed HA nanoparticles with average diameter of ca. 10–20 nm were prepared with the assistant of CTAB. But HA agglomerate formed after the surfactant was removed. The zeta potential of nHA particles could be changed remarkably with PEI and PAA, which resulted in better dispersivity of nanoparticle in solution. On the other hand, surface properties of samples affected greatly their adsorption ability. Among them, PEI-nHA samples had the strongest loaded ability for DNA due to its positive zeta potential, which probably was a potential carrier of DNA and drug. The cytotoxicity of nHA particles was depended on the zeta potential, particle concentration in the cell culture medium and coculture time. PAA-nHA with negative zeta potentials held a stronger ability to improve cell proliferation than PEI-nHA with positive zeta potentials, which was similar to normal nHA particles. Furthermore, lower concentration of particle and longer coculture time were help to improve cell viability. Compared to PAA-nHA, cytotoxity of PEI-nHA was notable, which could inhibit cell proliferation even after a longer coculturing period.So, we offered a simple and efffcient method for nHA preparation and modification. nHA modified with PAA showed a good biocompatibility and nHA modified with PEI held higher load ability for DNA, which probably could be used as perfect replacer of bone and carrier of DNA and drug, respectively.