Preparation Of Zinc-copper Oxide Coating By Magnetron Sputtering And Its Propertie

Titanium is commonly used as an implant material in orthopaedic surgery,although it has the advantages of high strength,non-toxicity and good biocompatibility,it still has no antibacterial activity and often causes bacterial infections and inflammation after surgery,low corrosion resistance in complex body fluid environments and short service life of implants due to easy decomposition,and lower biological activity,making it difficult to bind tightly to bone tissue in the short term.To address these performance shortcomings,surface-modified coatings containing antibiotic,organic or inorganic antimicrobial components are often coated onto titanium substrates,compared to antibiotics and organic fungicides,inorganic nano-fungicidal substances are of interest because they have strong broad-spectrum antibacterial activity and do not cause bacterial resistance.Among them,Znand Cuoxides are commonly used as materials for preparing inorganic nano antibacterial coatings,which have the advantage of releasing ions to achieve broad-spectrum antibacterial resistance,in addition to the better corrosion resistance brought by the stability of metal oxides,moreover,zinc and copper have been shown to have a positive effect in stimulating cell proliferation.But also due to the stability of metal oxides,it is difficult to obtain excellent antimicrobial properties solely on the basis of the metal ions they release,therefore,more ideal multifunctional antibacterial coating must be found from the bactericidal mechanism.In this paper,the structural design of antibacterial nano-coatings composed of zinc and copper oxides has resulted in excellent antibacterial properties while exhibiting good corrosion resistance and cytocompatibility.Analysis of the physical composition and microstructure of the coatings by XRD,XPS,FE-SEM and AFM,evaluation of different properties of the prepared multifunctional antibacterial coatings using water contact angle tests,electrochemical tests,antibacterial tests and cytocompatibility tests.In this work,the main research achievements are as follows:1.The multifunctional coatings in forms of mono,double,and co-existance based on CuO and ZnO were created by changing the sputtering orders under DC reactive magnetron sputtering.It showed ZnO and CuO were pure phases,deposited CuO grains performed large and uneven while ZnO grains were fine and homogeneous,such features remerged on double-layered coatings.The surface roughness（R_q）of the monolayer to the double layer then to the co-existing one was increased from 2.58 nm to 18 nm to 22.6 nm.All multifunctional coating helped to lower the contact angle to the minimum of 18.82°,and enhanced the corrosion potential to the maximum of-0.261 V.The released ions,the grains piercing and the ROS produced by p-n junctions co-contributed the ZnO/CuO composite coatings to receive the antibacterial rates of 90.24%～100%as directly contacting with the Staphylococcus aureus or the Escherichia coli within 0.5 h.Owing to the strong metal-oxygen bonding and the rough surface,all coatings supported the cell viabilities to satisfy 137.92%～145.27%through 120 h co-culturing,MC3T3-E1 cells could healthily proliferate and adhere on surface.The double-layered coating that ZnO as bottom and CuO as upper performed a better overall property.2.The multifunctional coating is formed by controlling O₂percentage content and sputtering mode（single sputtering,co-sputtering）in the process of DC reactive magnetron sputtering process with ZnO as the bottom layer,separate sputtering copper target or co-sputtering zinc and copper target to prepare oxides as the surface layer.The results shown that,compared to the pure phases of ZnO and CuO generated by sputtering zinc and copper targets separately,the thickness of the surface layer of the composite coating gradually increases and the phase composition changes from a two-phase coexistence of ZnO and CuO to a three-phase coexistence of ZnO,CuO and Cu₂O,as the percentage content of O₂changes from 30%,20%and then 10%.The shape of the grain growing on the surface has changed from sharp needle to block to tall vertical,and the composite coating prepared at 10%O₂content have the highest surface mean square roughness of 43.6 nm.All coatings are hydrophilic,with contact angles down to 9.94°.Compared to the self-corrosive potential of-0.694 V for titanium substrates,the composite coating can be raised to a maximum of-0.247 V,thus giving the titanium substrate good corrosion resistance.UV-Vis DRS,PL and photocatalytic degradation experiments confirm that the double p-n junction structure formed in the longitudinal and horizontal directions of the composite coatings prepared by co-sputtering is superior to that of the longitudinal single p-n junction structure formed by sputtering alone for enhanced photocatalytic activity,and the increased specific surface area due to its unique surface profile also provides more photocatalytic active sites.Under the combined effect of three mechanisms,namely the synergistic enhancement effect of Znand Cuions,the mechanical puncture of surface grains and the ROS generated by the enhancement of p-n junctions,the composite coating prepared with 10%O₂content of the co-sputtered surface layer can achieve nearly 100%antibacterial rate under visible light in contact with Escherichia coli and Staphylococcus aureus respectively for 1h.Cytocompatibility experiments have shown that the morphological characteristics of the coating and the amount of ions released affect the spreading adhesion and proliferation effect of MC3T3-E1osteoblasts on the surface.