| Ti N film is a typical hard ceramic coating,which has been widely used in the surface modification of artificial joints and oral implants due to its high hardness,high melting point and good biocompatibility.In order to further improve the adhesion stability,wear resistance and antibacterial properties of the Ti N film during service,magnetron sputtering technology is usually used to dope metal elements in the film.Copper is one of the essential trace elements for the human body,which plays an important role in physiological activities and has certain antibacterial functions.Considering the low toxicity and biological function of copper,the researchers chose copper as the doping element to improve the mechanical properties and antibacterial properties of Ti N films.It has been reported that doping Cu atoms into the Ti N film can improve the antibacterial properties of the Ti N film.In addition,a small amount of Cu doping can increase the hardness and toughness of the Ti N films and reduce the wear rate.Although Cu is beneficial for human health,Cu ions exceeding a certain threshold can be toxic.Excessive amounts of copper can result in Fenton-type redox reactions,resulting in oxidative cell damage and cell death.Therefore,it is necessary to study the influence of Cu content in Cu-doped films on bio-safety when applying in vivo.In this paper,the direct current(DC)magnetron sputtering technology was used to prepare TiCuN films with Cu content of 2.4,4.2 and 11.1 at.%.The effects of Cu content on the TiCuN film structure were investigated by X-ray diffraction(XRD),transmission electron microscope(TEM)and scanning electron microscopy(SEM).The effects of Cu content on the physical and chemical properties of TiCuN films were investigated by water contact angle tester,four-probe resistance tester and atomic spectrophotometer,etc.The effects of Cu content on the surface energy,protein adsorption behavior,resistivity,corrosion resistance and Cu ion release behavior of TiCuN films were evaluated.The biocompatibility of TiCuN films with different Cu content was evaluated by osteoblasts and macrophages.On the basis of the above studies,the biocompatibility of different concentrations of TiCuN wear debris(10-100 μg/m L)was evaluated by using osteoblasts and macrophages.The results showed that Cu doping can inhibit the columnar structure growth of Ti N films,and with the increase of Cu content,a denser structure TiCuN film can be obtained.Compared with Ti N film without Cu doping,the surface of TiCuN films is hydrophobic and has low surface energy.Cu doping can significantly reduce the surface albumin(BSA)adsorption capacity of TiCuN films.When the Cu content increases to 11.1 at.%,the presence of Cu nanocrystals in TiCuN films will lead to a decrease in the resistivity of the films,a significant increase in the release of Cu ions and a decrease in the corrosion resistance of the films.The biocompatibility evaluation results of TiCuN films showed that,compared with Co Cr Mo alloy and Ti N film,the viability and morphology of osteoblasts on the TiCuN film with a Cu content of 2.4 at.% was significantly improved due to the release of appropriate Cu ions.The inflammatory response induced by the TiCuN films with Cu contents of 2.4 and 4.2at.% was lower than that induced by the Co Cr Mo alloy and Ti N film without Cu doping.In conclusion,compared with Co Cr Mo alloy and Ti N film,the TiCuN film with a Cu content of2.4 at.% has good osteoblast compatibility and lower inflammation.The biocompatibility of TiCuN(2.4 at.% Cu)wear debris was studied by using osteoblasts and macrophages.The results indicate that when cells(osteoblasts and macrophages)are stimulated by different concentrations of TiCuN wear debris,the interaction between wear debris and cells is mainly carried out in a concentration-dependent and timedependent manner.There was no significant difference in the viability of osteoblasts with different concentrations of wear debris when they were co-cultured for 24 h,when co-cultured for 72 h,the viability of osteoblasts decreased with the increase of the concentration of TiCuN(10-100 μg/m L)wear debris.When the concentration of TiCuN wear debris reached 30 μg/m L,the size of the osteogenous cells becomes small,and the cytoplasm expansion is not obvious,the morphology of osteoblasts showed a small and round trend.The morphology of macrophages gradually deformed with the increase of wear debris concentration,the morphology change of macrophages indicated that macrophages would be activated with the increase of wear debris concentration,and the release of pro-inflammatory factors TNF-α and IL-6 increased with the increase of wear debris concentration.The cytotoxicity of the samples co-cultured with osteoblasts for 72 h was evaluated.The results showed that the relative growth rate(RGR)of osteoblasts decreased with the increase of TiCuN wear debris concentration,but even when the TiCuN wear debris concentration reached 100 μg/m L,the relative growth rate of osteoblasts is 77.59%,which is greater than 75%,the cytotoxicity evaluation level still belongs to level 1,indicating that there is no cytotoxicity when the concentration of TiCuN wear debris is less than 100 μg/m L. |
