Research On Preparation And Performance Of Antibacterial Coating On The Surface Of Biomedical Mg-Zn-Ca Alloy

Magnesium alloy has attracted much attention in the field of bone implant materials due to its excellent mechanical properties,biocompatibility and corrosion degradation characteristics.However,due to the excessively fast degradation rate,the implant loses its mechanical properties prematurely and cannot match the growth of new tissue,hindering its clinical application process.In addition,the initial bacterial infection of the implant in the host is also very worthy of attention.In order to improve the corrosion resistance and antibacterial properties of biomedical magnesium alloys,this paper uses the bio-safe and completely degradable Mg-3Zn-0.2Ca alloy as the matrix,and uses a one-step method to prepare nano-silver-hydrotalcite(Ag-LDH)dual-phase coating,studied the influence of various process parameters on the morphology and corrosion resistance of the coating;preliminary explored the preparation of Ag-LDH coating on the surface of Mg-3Zn-0.2Ca alloy by micro-arc oxidation(MAO),To further improve its corrosion resistance process.XRD,SEM,EDS,FT-IR and other characterization methods were used to characterize and analyze the phase composition and morphology of the two coatings,and the in vitro degradation properties of the coating samples were tested by immersion experiments and hydrogen evolution experiments,and the biological properties of the coatings were preliminarily evaluated.Compatibility and antibacterial properties.The main conclusions are as follows:(1)With a certain concentration of AgNO₃ and Al(NO₃)₃·9H₂O aqueous solution as reactants,the Ag-LDH two-phase coating was formed on the surface of Mg-3Zn-0.2Ca alloy by hydrothermal reaction method.The reaction was studied by the controlled variable method.The influence of temperature and reaction time on the morphology,phase composition and corrosion resistance of the coating.Based on a series of characterization analysis and electrochemical tests,the optimal reaction conditions of the coating are selected:the reaction temperature is 110?,and the reaction time is 10h.(2)The hydrogen evolution experiment showed that the corrosion rate of Ag-LDH coated magnesium alloy was only 0.69±0.03 mm/year under the reaction conditions of 110?and 10h after immersion for 7 days,which was 1 times lower than that of bare magnesium alloy.The results of the in vitro immersion experiment also showed that Ag-LDH coating has a good protective effect on magnesium alloy substrate.The MTT method evaluation showed that the magnesium alloy with or without coating has good biocompatibility,and the antibacterial test showed that the number of E.coli colonies on the surface of the coated magnesium alloy sample plate was significantly reduced,indicating that the silver-loaded coating has good antibacterial performance.(3)Combining MAO pretreatment and hydrothermal treatment,Ag-LDH/MAO coating was prepared on the surface of Mg-3Zn-0.2Ca substrate.The Ag-LDH formed by hydrothermal treatment played a certain role in sealing the MAO coating.At the same time,the effect of different silver ion reducing agents on coating morphology and corrosion resistance shows that when the reducing agent is ethylene glycol and sodium citrate,the sealing effect of Ag-LDH/MAO coating is the best,and the reducing agent is ethylene glycol.The resistance value of the Ag-LDH/MAO coating is the highest at the time,and the corrosion degree is the lightest after in vitro immersion.