The Production And Biocompatibility Of Mg-6%Zn-10%β/Ca₃（PO₄）₂Composites

Abstract:Magnesium matrix biological materials with the advantages of good mechanics compatibility, biocompatibility and biodegradability, have the potential to become a new generation of biomedical implant. Mg-6%Zn-10%βCa3(PO4)2composites are prepared through powder metallurgy method. Surface treatment has been done after the preparation. The degradation behavior of Mg-6%Zn-10%βCa3(PO4)2composites in Ringer’s solution and its cytotoxicity have been studied.The experimental results show that the high purity β/Ca3(PO4)2powder is prepared by liquid phase method, of which the average particle size is2.60μm. The composites can be sintered with magnesium powder, zinc powder and βCa3(PO4)2powder. Material density is1.9126g/cm3, Brinell hardness is68.3, three-point bending strength is237.7MPa. It is shown that the mechanical performance of Mg-6%Zn-10%β/Ca3(PO4)2composites meets the basic requirements of bone repairing materials.Mg-6%Zn-10%β/Ca3(PO4)2composites is coated with titanium nitride (TiN) and titanium (Ti) through multi-arc ion sputtering. Electrochemical potentiodynamic polarization curve shows that TiN/Ti inorganic coating can improve the corrosion potential of Mg-6%Zn-10%βCa3(PO4)2composites, but cannot reduce the corrosion current density of the materials. As a result of the existence of galvanic corrosion, the corrosion rate of the composites is increased. The technique of preparation of TiN/Ti coating material will improve the electrochemical corrosion rate and hydrogen evolution rate of material, it is difficult to improve the corrosion resistance of materials effectively.Chitosan (CS) and polycaprolactone (PCL) coating are sprayed on the surface of composites. The corrosion resistance of Mg-6%Zn-10%βCa3(PO4)2composites in vitro corrosion can be improved by those two kinds of polymer coating. Hydrogen evolution rate of polymer coated samples for6days on average is VCS=13.83mL/cm2·d, VPCL=12.98mL/cm2·d respectively. Among these two plymer coating, Composites coated with polycaprolactone appear smaller effect on the change of Ringer’s solution and lower hydrogen evolution rate.Uncoated samples, chitosan coated samples and polycaprolactone coated samples are soaked in medium to prepare water extract.3-(4,5-dimethilthiazol-2-y1)-2,5-diphenyl-tetrazolium bromide (MTT) colorimetric method is used to identify cytotoxicity grade of water extract. A grade of0～1for the in vitro cytotoxicity towards L-929cells indicates that these three groups of material is safe for cellular applications. After culturing L-929cells with water extract of three groups, polycaprolactone coating group shows maximum cell proliferation rate, chitosan coating group, uncoated group followed. Cytotoxicity test illustrates materials with polycaprolactone coating have minimum cell toxicity and good biocompatibility.