Effect Of Composition And Structure Of Ti-Cu Film Using DCMS/HiPIMS Co-sputtering On The Biocompatibility

Coronary heart disease is the main disease that endangers human health.At present,the most important treatment is based on vascular stent intervention,but restenosis after stent implantation is an important problem to be solved during stent intervention.Endothelial cell damage and vascular smooth muscle cell proliferation are the main pathological processes of restenosis after interventional therapy for coronary heart disease.A certain concentration of Cu ions can promote endothelial cell growth,inhibit the proliferation of smooth muscle cells,and copper has good antibacterial properties,which can effectively avoid bacterial infection of implanted devices.Therefore,the bio-inert Ti and the bio-functional Cu are combined to prepare a Ti-Cu film with different composition structure to modify the surface of the traditional material,and the physiological function of Cu is used to realize the endothelial cell on the surface of the material.It inhibits the proliferation of smooth muscle cells and reduces the problems of restenosis and thrombosis after vascular stent implantation.In this paper,Ti-Cu films with gradient copper content?3-65 at.%?were prepared by two-target co-sputtering method with Ti target DC and Cu target.The compatibility of endothelial cells and smooth muscle cells was studied.The antibacterial properties of the film were also studied.Cell test and antibacterial test results showed that 5-30 at.%Cu film has the effect of promoting endothelial cells and inhibiting the activity of smooth muscle cells.The release of specific concentration of Cu²⁺is the basis of Ti-Cu film with biological function;the copper content is greater than 55 at.%of the samples have 99%bactericidal effect on Staphylococcus aureus.The mechanism of action is mainly two aspects.One is that the surface of the Ti-Cu film directly contacts the bacteria,and the other is that the accumulation of copper ions released by the film in the bacteria eventually leads to the death of the bacteria.A sample of 16 at.%Cu having a function of promoting endothelial cell growth and inhibiting smooth muscle cell proliferation was subjected to a long-term immersion test in PBS for 120 days.The results showed that 16 at.%Cu film was immersed in PBS for 120 days.Still stable on the 316L SS.After depositing the film on the surface of the vascular stent,the film in the stent binding test showed that there was no film shedding in the press-holding,and the 16 at.%Cu film could be stably combined with the 316L SS stent.In order to study the effect of different structure Ti-Cu films on the properties of the films,16 at.%Cu films were annealed at different temperatures by vacuum annealing.The results of elemental analysis showed that the Ti and Cu films before and after annealing were evenly distributed on the two-dimensional surface.TEM section line sweep and surface sweep elemental analysis found that Cu precipitated at 500°C,30 min annealing conditions,resulting in Cu enrichment inside the film;XRD results show that the phase structure of the deposited film is Ti?002?The broadening peak and the electron diffraction pattern show that it is an amorphous structure containing Ti,Cu nanocrystals and CuTi₃ compounds,and the annealed film has CuTi₃ and Ti-O compounds.The TEM shows that there is an inside of the 500°C annealed film.The obvious crystallization phenomenon and clear grain boundary indicate that the annealing process increases the order of the crystal grains.The film properties show that the Ti-Cu film decreases with the increase of annealing temperature,and the resistivity of Ti-Cu film decreases.The water contact angle results show that the hydrophilicity of Ti-Cu film increases with the increase of annealing temperature.The Ti-Cu film annealed in the as-deposited state and 300°C has the best corrosion resistance,and is stronger than the 316L SS and the higher temperature annealed Ti-Cu film.Copper ion release results show that Ti-Cu film can release Cu ions in PBS solution,and there is a sudden release phenomenon,and the cumulative concentration of Cu ion released in the as-deposited and 300°C annealed Ti-Cu film is higher than the high temperature annealed Ti-Cu film.The results of cell experiments showed that 16 at.%Cu deposited films have the effect of promoting endothelial cell growth compared with 316L SS.The activity of endothelial cells cultured on Ti-Cu film annealed at300°C and the activity of endothelial cells cultured on 316L SS surface,and the Ti-Cu film annealed at 400°C-600°C is less active on endothelial cells than 316 L SS.For smooth muscle cells,the Ti-Cu film before and after annealing could be inhibited proliferation of smooth muscle cells compared with 316L SS.