Study On Colloidal Stability And Hemocompatibility Of Hydroxyapatite Nanoparticles Via Intravenous Injection

When the size was between 1¹00nm, HAP particles had unique biological activity. For example, our former research found that nano-HAP sol was able to restrain some carcinoma cells from growing and proliferating while it has no effect on normal cells. Its colloidal dispersion stability, however, is poor because HAP nanoparticles exhibit sediment formation on standing at short time periods, where agglomerates form and lead to non-homogeneous suspensions. The result is an obstacle to further research on HAP nanoparticles, Furthermore, non-homogeneous dispersed HAP nanoparticles cannot be used as a material drug via intravenous injection. The purpose of this work is to investigate the colloidal stability of HAP nanoparticles in aqueous system and its blood compatibility. Ca(OH)₂ and Ca(H₂PO₄)₂·H₂O were used in the experiment as raw material, The characteristics of the sol fabricated using chemical precipitation method and the fabricating condition and process were investigated. Surface modification to improve the colloidal stability of HAP particles in aqueous systems was discussed especially in this work. The mechanism of stabilization of polysaccharide, anion surfactant and polyelectrolytes as dispersants were also investigated. The experiment results show that reaction temperature, ionic strength, pH and molecular weight of the stabilizer were the key factors that affect dispersion stability, morphology, particle size and size distribution. Through optimizing the various factors which would influence HAP-sol stability, highly monodispersed nano HAP-sol can be acquired. The dispersant peculiarity was analyzed and compared. Among these dispersants, at the presence of anion-surfactant, sodium polyacrylate had. better effect on dispersion stability of the HAP nanoparticles.Nano-HAP sols were lyophilized to obtain HAP powder. By means of using particle sizer, Zeta potential meter measurement, X-ray diffraction (XRD) and Transmission Election Microscope (TEM), The highly dispersed nano-HAP was studied. Results show that the HAP particles are in the shape of short-rod or needle with a length 20⁸0nm. They have a narrow distribution of particle size with excellent dispersity and its aqueous solution was transparent colloids. The HAP particle Zeta potential changed obviously by adjusting the pH value of the aqueoussolution and adding the dispersant. The Zeta potential of the nanoparticle sols is a token of the stability. The stably highly dispersed nano-HAP sols were obtained. The experiment results show that Zeta potential of the HAP sol is about -33mV. This reflected the stability of HAP sol of surface modification.Erythrocyte hemolytic test in vitro and lymphocyte cytotoxicity test in vitro were conducted for evaluating the hemocompatibility of modified HAP nanoparticles. The cultured lymphocyte cytotoxicity test in vitro was conducted for evaluating influence of HAP-sol on the morphology, growth and relative growth rate of lymphocyte by MTT method. Results show that the cytotoxicity score of the HAP-sol was grade 0 orl. The findings imply highly dispersed HAP-sol had no toxicity on the proliferation of blood lymphocyte. Erythrocyte hemolytic test in vitro was performed by rabbit blood. Hemolytic test results show hemolytic rate was 0% to 3% and had no effect on their morphology. At the presence of stabilizer, sodium polyacrylate, prepared HAP sols by chemical precipitation method had good hemocompatibility. It demonstrated that the obtained stable nano HAP sol was safe for its application when it was used as a drug via intravenous injection.