The Study On The Transfection Mediated By Hydroxyapatitie Nanoparticles And Its Preservation

Objectives: To study the ability of hydroxyapatitie nanoparticles in binding DNA and transfection in vitro; and to explore the way of hydroxyapatitie preservation when it serves as gene carrier.Method: CaCl₂ solution was added into hydroxyapatitie suspension (offering Ca(2+) for hydroxyapatitie modification), and the Zeta potentials were tested at different pH. The ability of modified hydroxyapatitie nanoparticles in absorbing and protecting DNA, and the way of dissociation from DNA were analyzed by agarose gel electrophoresis analysis and ultraviolet spectrophotometer. Subsequently, the modified hydroxyapatitie were used to transfer plasmid pEGFP-N3 into Bel7402 cells. Hydroxyapatitie gel preserved at different temperatures (-20℃, 4℃and room temperature) were modified with Ca²⁺, and then the abilities of carrying DNA were tested by agarose gel electrophoresis analysis and fluorescence microscope, finally they were used in Bel7402 cells transfection.Results: The Zeta potentials of hydroxyapatitie nanoparticle with Ca²⁺ surface modification were positive in both acidic and alkaline environment, and the modified hydroxyapatitie can bind DNA efficiently. The absorbed DNA can be washed off by phosphate buffer solution. The transfection efficiency of modified hydroxyapatitie is much higher than that of the hydroxyapatitie without modification. The hydroxyapatitie suspension that were preserved in -20℃cannot bind DNA or transfer plasmid into cells by Ca²⁺ modification. However, preserved in 4℃and room temperature, hydroxyapatitie nanoparticles modified with Ca²⁺ can bind DNA and transfer target cells.Conclusions: Hydroxyapatitie nanoparticles with Ca²⁺ surface modification can be utilized as DNA carrier for gene delivery. As the gene carriers, hydroxyapatitie nanoparticles cannot be preserved by freezing.