3D Printed Zirconia Ceramic Hip Joint With Precisely Structure And Broad-Spectrum Antibacterial Properties

Background and Objective:With the prolongation of life expectancy,especially the occurrence of various traffic accidents and sports injuries,the number of arthroplasty operations is increasing steadily every year.At present,the materials applied to the hip prosthesis are mainly metals represented by titanium.This kind of metal material generally has a service life of less than 20 years.Due to the limited wear resistance,the long-term use of titanium based implants will result in the emergence of metal grinding particles,which would cause inflammation around the surrounding tissue.Nowadays,zirconia ceramic implants are widely used as a kind of hip prosthesis material because of their excellent biocompatibility and long-term wear resistance.However,the hip joint is one of the major joints with complex 3D morphological structure and greatly individual differences,which usually causes great material waste during the process of surgical selection of prosthesis.In this paper,by combining ceramic 3D printing technology with antibacterial nano-modification,zirconia ceramic implant material was obtained with precise 3D structure and effective antibacterial properties.Methods:?1?.The implants with precise matching structure can be customized by the method of gel-casting molding combined with 3D printing technology;?2?.The dried samples were sintered by the method of two-step sintering;?3?.Deposition of ZnO nanocrystals on the surface of ceramics to form ZnO modified ceramics?ZrO₂-ZnO?through coating;?4?.Solving two technical problems?irregular shrinkage caused by fragility and sintering?by optimizing the reaction conditions and selecting the area reverse compensation;?5?.The field-emission scanning electron microscope?FE-SEM?was used to examine the surface morphologies of the pure ZrO₂ and ZrO₂-ZnO.The crystal structure of the sample was determined by X-ray diffraction;?6?.The ZrO₂ and ZrO₂-ZnO ceramic materials were respectively co-cultured with S.aureus?S.aureus,ATCC 25923?and E.coli?E.coli,ATCC 25922?.The antibacterial effects of the three groups of samples were compared by plate counting method;?7?.The ZrO₂ and ZrO₂-ZnO ceramic materials and S.aureus were simultaneously implanted into the vivo.The sections were stained with hematoxylin-eosin?HE?for optical microscopy examination to evaluate the inflammatory response with S.aureus;?8?.The cytotoxicity of the ZrO₂-ZnO materials was analyzed by Cell counting kit-8?CCK-8?assay;?9?.The ZrO₂-ZnO ceramic material was implanted into the animal,and after 4weeks of feeding,the position of the implant was observed by X-ray.The bones adjacent to the implant were removed together with the muscles and stained with the conventional hematoxylin-eosin?HE?method.Results:?1?.Two technical problems?fragile and sintering induced irregular shrinkage?of 3D printed ceramics were effectively minimized by optimizing the reaction conditions and selective area inversing compensation;?2?.It could be seen that the surface of the ZrO₂ material was covered with a layer of ZnO nano-particles.A universal testing machine was used to measure the tensile,bending and compression experiments of ceramic samples.It could be found that ZnO had no significant effect on the mechanical properties of ZrO₂ ceramics;?3?.According to the plate counting results,ceramics modified with ZnO exhibited significantly higher antibacterial efficiency than pure ZrO₂ ceramics,the ZrO₂-ZnO ceramics had a significant killing effect after 8 hours?Gram-negative antibacterial rate was 91.7±1.1%,Gram-positive antibacterial rate was 99.8±0.25%?;?4?.The removed implants and the tissue surrounding the implant were subjected to HE staining.For ZrO₂-ZnO ceramics,inflammation was slight,while for pure ZrO₂ ceramics,the inflammatory response was remarkably serious.It could be seen that the antibacterial rate of the ZrO₂-ZnO ceramics was significantly better than that of the pure ZrO₂ ceramics group;?5?.It could be seen that the cytotoxicity did not increase proportionally with the increase of concentration,all of viability were still above 80%.This suggested that our materials were safe and could be applied as a type of potential biomaterial in the future;?6?.It could be seen that the implant was in good position without dislocation.This resulted implied that the proposed method can achieve accurate 3D printing preparation of ceramic joints.In addition,the femurs and surrounding muscles around the implant were then sectioned and HE stained.Results of muscle tissue sections further showed no significant tissue abnormalities,and the growth of new bone tissue was seen in the sections of bone tissue.Conclusion:?1?.The ceramic 3D printing technology combined with antibacterial nano-modification can quickly customize the ideal implant material with precise structure,wear-resistant and effective antibacterial properties;?2?.Two technical problems?fragile and sintering induced irregular shrinkage?of 3D printed ceramics were effectively minimized by optimizing the reaction conditions and selective area inversing compensation;?3?.We added ZnO nano-materials to the ceramic surface,which could effectively killing pathogenic bacteria.