| Titanium and its alloys(Ti6Al4V)are widely used in biomedical applications,especially in the fields of bone fusion,bone fixation and joint replacement surgery,due to their good corrosion resistance,biocompatibility,mechanical properties and other physical and chemical properties,However,after a few years of implantation of unmodified titanium-based alloys,they may fail to establish a strong chemical bond with surrounding tissues and bacterial infections,which leads to the gradual loss of osseointegration and loosening of the implant.Surface modification coating technology will not damage the overall performance of the material,which is a promising method for modifying and inducing the surface of the titanium alloy to possess antibacterial and osseointegration capabilities.In this paper,in order to improve the wettability,corrosion resistance and antibacterial properties of Ti6Al4V alloy,fabricate hydroxyapatite/graphene oxide/zinc oxide(HA/GO/ZnO)nano composite coating on the surface of Ti6Al4V alloy by the chelation effect of polydopamine(PDA)on metal ions.The phase structure,microscopic morphology,wettability,antibacterial properties and corrosion resistance of the composite coating in Ringer's solution are systematically analyzed.In this paper,the improved Hummers method was used to prepare GO powder with rich oxygen-containing functional groups and good dispersibility in aqueous media,and the GP/T composite coating was prepared on the surface of Ti6Al4V alloy pretreated with PDA by the coating method.The microscopic morphology shows that the GP/T composite coatings prepared with different GO concentrations have two morphologies,including light yarn-like and translucent layered structures.Contact angle and electrochemical tests show that the corrosion current density of the GP/T coating is still about 5 times lower than that of the bare substrate due to the presence of dense PDA and GO coatings when water contact angle is below 60 degree.The study used E.coli to test the antibacterial properties of the GP/T coating.The results show that the coating has excellent antibacterial activity,and the antibacterial rate increases with the increase of GO concentration.The GO/ZnO composite coating(GZP/T)was prepared based on the PDA coating by hydrothermal and coating methods.The phase composition and microscopic morphology analysis shows that super-hydrophilic clustered nano-ZnO coatings with a diameter of less than 200 nm were successfully synthesized by PDA chelating Zn2+ions without seeds.And after the composite coating is dried at 37?,25 KPa,GO remains rich oxygen functional groups.After the GO coating is introduced,the chemical interaction between Zn2+ions and GO is confirmed by XPS.GZP/T composite coating exhibits good wettability and excellent antibacterial activity against E.coli and S.aureus.Moreover,it is found that the antibacterial rate of the ZnO/PDA coating without GO coating was higher than that of the GZP/T composite coating,indicating that ZnO in the composite coating plays a major antibacterial effect.The corrosion properties test shows that GZP/T composite coating has a better corrosion resistance,compared to ZnO/PDA coating and bare substrate.The hydroxyapatite coating(HA)was synthesized in modified simulated body fluid(1.5 SBF)by the biomineralization method on the surface of the GZP/T composite coating.SEM,XRD and FTIR show that the HA coating has been synthesized successfully,and the nano HA particles are uniformly distributed on the surface of the substrate,due to the synergistic mineralization of GO,ZnO and PDA.After HA coating is mineralized,the surface roughness and wettability of Ti6Al4V alloy are improved,and the wettability decreases with the decrease in roughness.Electrochemical test shows that the corrosion resistance of HA-GZP/T composite coating is further enhanced than before mineralization.In addition,the HA-ZP/T coating performs an excellent antibacterial rate of 98.76%against E.coli,but the HA-GZP/T composite coating gots a lower antibacterial rate. |
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