The Fabrication And Osteogenic Properties Of 3D Printed Porous Amorphous Polyaryletherketone Composite Scaffold

BackgroundWith the aging of the population,bone defects caused by tumors,inflammation,trauma and degenerative diseases have become common problems in clinical practice.At present,using biomaterials to repair bone defects and function is a common treatment.Traditional implants like titanium and its alloy process excellent mechanical properties and good biocompatibility,however,the elastic modulus of titanium is approximately 110 GPa,which is too far from that of human cortical bone.It will cause the stress shielding effect and lead to the loosening of implants.Polyetheretherketone(PEEK),a semi-crystalline polyaryletherketone(PAEK),has an elastic modulus similar to that of bone tissue and good biocompatibility,and possess a bright future in the fields of dentistry and orthopedics.In recent years,3D printing technology has been closely related to clinical treatments.It can quickly and accurately print implants in specific shapes to repair bone defects.However,3D printed PEEK has a decrease in mechanical strength and interlayer bonding.Amorphous polyaryletherketone(PEK-CN)contains polar nitrile groups(-CNs),which can increase the interlayer strength by enhancing the van der Waals force between molecules to maintain good mechanical properties and interlayer adhesion after 3D printing.In order to improve the biological activity of PEK-CN,porous structure can be prepared through 3D printing technology to promote osseointegration.In addition,nanohydroxyapatite(nHA)is highly similar to the hydroxyapatite in bone tissue in composition,structure and size,which can effectively enhance bone regeneration and interact with the polar groups of PEK-CN to improve the compatibility of the composite.Consequently,nHA can be used as a bioactive filler for 3D printed PEK-CN.Objective3D printed PEK-CN,nHA/PEK-CN and porous nHA/PEK-CN scaffold were prepared through fused deposition modeling 3D printing technology.The material properties,biocompatibility and osteogenic properties in vitro and in vivo were studied to provide a theoretical basis for the clinical application of PEK-CN.Methods1.The best extruder temperature and speed were determined through the rheological performance test of PEK-CN.The solution method was employed to blend different mass fractions of nHA with PEK-CN.The compatibility of the two phases was observed by scanning electron microscope,and the mechanical properties were analyzed.Then,nHA with appropriate mass fraction was selected for 3D printing.Subsequently,the surface morphology,elemental distribution and mechanical properties of 3D printed PEK-CN and nHA/PEK-CN composites were analyzed.2.The biocompatibility of 3D printed PEK-CN,nHA/PEK-CN and porous nHA/PEK-CN scaffold were evaluated by L929 cell viability staining,CCK-8 test,RAW264.7 macrophage inflammation-related gene expression test,hemolysis test,protein adsorption test and simulated body fluid(SBF)test.3.Rabbit bone marrow mesenchymal cells(BMSCs)were isolated and cultured,and their phenotypes were identified by flow cytometry.The effects of 3D printed PEKCN,nHA/PEK-CN and porous nHA/PEK-CN scaffold on cell viability were evaluated by cell apoptosis assay.To evaluate the cell attachment,proliferation,osteogenic differentiation and expression of osteogenic related genes of these materials,we employed the observation of cell adhesion,CCK-8 test,alkaline phosphatase(ALP)assay and cell mineralization assay.4.The distal femur bone defects of rabbits was established.3D printed PEK-CN,nHA/PEK-CN and porous nHA/PEK-CN scaffold were implanted into the bone defects.After 12 weeks of implantation,the osseointegration effect was evaluated through micro-CT,Van Gieson staining and push-out test.Results1.PEK-CN,PEK-CN blended with 10wt% nHA and porous nHA/PEK-CN scaffold with porosity of 70% which had good mechanical properties were fabricated by fused deposition 3D printing technology.It's worth noting that the mechanical properties of porous nHA/PEK-CN scaffold were similar to those of human cancellous bone.2.3D printed PEK-CN,nHA/PEK-CN and porous nHA/PEK-CN scaffold had good biocompatibility,blood compatibility and did not cause inflammatory reaction.3D printed nHA/PEK-CN and porous nHA/PEK-CN scaffold could significantly promote protein adsorption and apatite formation in SBF.3.3D printed PEK-CN,nHA/PEK-CN and porous nHA/PEK-CN scaffold did not induce apoptosis of BMSCs.3D printed nHA/PEK-CN and porous nHA/PEK-CN scaffold could significantly promote BMSCs adhesion and proliferation,ALP activity,cell mineralization and expression of ALP,RUNX2,BMP-2,COL-1,OCN and OPN.4.3D printed nHA/PEK-CN and porous nHA/PEK-CN scaffold could significantly improve the formation of new bone around and inside the material and the bonding strength of the bone-implant interface.Conclusions3D printed PEK-CN and its composites have good mechanical properties and biocompatibility.nHA/PEK-CN and porous nHA/PEK-CN scaffold can promote osteogenesis abilities in vitro and osseointegration in vivo,which provides a new method for personalized repairment of bone defects.