| Inflammation and infection of wound is a thorny clinical issue in the surgical replacement surgery.Stainless steel(SS)has been a potential candidate for implantation.Surface processing of SS with bactericidal and anti-inflammatory function is an important strategy to solve this problem.Here,SS was functionalized with TiN and Ag because of their good mechanical and antibacterial properties.TiN/Ag nano-composite films were deposited on SS using magnetron sputtering system to meet the required characteristics.The targets were achieved by varying the Ag contents and annealing temperature.The structural properties of the samples were investigated using scanning electron microscopy(SEM)equiped with energy dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),scanning probe microscopy(SPM)and X-ray photoelectron spectroscopy(XPS).While their suitability for implantation were tested and analyzed using nanoindentation,friction and wear testing machine,scratch tester,electrochemical workstation,video wetting angle tester.The anti-bacterial properties were tesed by antibacteria rate,bacteriostatic ring size,adhesion resistance for Escherichia coli(E.C.),Staphylococcus aureus(S.A.)and Ag+ dissolution rate.Finally,biocompatibility was tested by MTT cytotoxicity assay.The results showed:(1)TiN/Ag nanocomposite films with 0 at%,1.21 at%,3.30 at%,6.87 at% Ag concentrations were successfully deposited on SS by magnetron sputtering.The increase in Ag contents could refine the TiN grains,reduce the roughness and increase TiN(111)crystal orientation.The films mainly composed of TiN and Ag elements.Hardness,elastic modulus,elastic deformation ability,corrosion resistance and adhesion resistance properties were first increased up to 1.21 at% of Ag contents and then gradually decreased.While friction coefficient of the samples was found to decrease up to 0.326 with increase in Ag concentration.The wear rate and wettability were slowly increased by increasing Ag contents but slightly reduced after 6.87 at% of Ag.However,wear rate and wettability of the composite coating on SS were not more than that of the naked SS.The antibacterial properties and bacteriostatic ring size against E.C.and S.A.were gradually increased by increasing Ag contents.At 6.87 at% of Ag,the antibacterial efficiency was 100% for both E.C.and S.A.The adhesion resistance for E.C.and S.A.was increased significantly by increasing Ag content and become 100% at 3.30 at% Ag.Ag+ dissolution rate was also studied and it increased with Ag contents.After 30 days immersion,only the sample with6.87 at% Ag had 100% antibacterial efficiency for E.C.while all other samples were degraded.The cytotoxic level of all the samples was retained in between 0 and 1 for 72 h but at 6.87 at% Ag,the cell proliferation rate was slightly decreased with increasing cell culture time whereas had no cytotoxicity.Moreover,the cell morphology was approximately same as negative control group.However,at the 6.87 at% Ag,the number of cells was less than that of the negative control group and not have more daughter cells.(2)TiN/Ag nanocomposite films of 6.87 at% Ag was vacuum annealed sequentially at300 ?,400 ?,500 ? and 600 ?.With increasing annealing temperature,average Ag particle size and the roughness increased significantly and TiN(111)preferred orientation was weakened.Hardness,modulus and elastic deformation ability of the film were first increased and then decreased by increasing the annealing temperature.The friction coefficient,the wear rate and wettability were gradually decreased by increasing annealing temperature.The antibacterial properties against E.C.and S.A.were gradually increased by increasing annealing temperature.However,at the same annealing temperature,the rate of increase was higher in the presence of Escherichia coli.Ag+ dissolution rate was increased significantly by increasing annealing temperature. |
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