Preparation Of NG/UHMWPE Composites And Its Friction And Cytocompatibility

Objective: Nitrgen-doped grapheme(NG) and Nitrogen-doped graphene /Ultrahighmolecular-weight polyethylene composite(NG/UHMWPE) samples were successfully synthesized, their friction properties and biological cytocompatibility were investigated.Materials and Methods: Using grapheme-oxide and melamine as raw material to prepare nitrogen-doped graphene. Utrahigh-molecular-weight polyethylene(UHMWPE) and nitrogendoped graphene composite(NG/UHMWPE) samples were successfully fabricated through an optimized hot-pressing molding method with different NG content gradient(0%wt, 0.1%wt, 0.3%wt, 0.5%wt, 1%wt). Friction and wear behavior of UHMWPE and NG/UHMWPE samples sliding against Zr O 2 ceramic ball under the lubrication of fetal bovine serum(FBS) were investigated with a high-speed reciprocating friction tester. The mechanical property and wear volume of pure UHMWPE and NG/UHMWPE samples were characterized with micro-hardness tester and MicroXAM 3D non-contact surface profiler. The worn morphology of pure UHMWPE and NG/UHMWPE samples were observed by scanning electron microscope(SEM). Addtionally, the cytocompatibility of the NG/UHMWPE composites was investigated by methyl thiazolyl tetrazolium assay(MTT), SEM and fluorescence staining observations to evaluate the attachment and proliferation of the MC3T3-E1 osteoblasts on the composites surfaces.Results:(1). Nitrogen-doped graphene and(NG/UHMWPE) samples were successfully fabricated. X-ray diffractometer, Ramman and X-ray photoelectron spectroscopy(XPS) measurements proved that N ion implantation induced introduction of N element, and the atomic percentage content of N was up to 9.11%. Detailed FESEM showed the lamellar structures of the NG/UHMWPE, and NG was well distributed in the doped graphene samples. The water contact angle decreases from 91.99° to 63.70° with the decreasing content of NG in the composite materials.(2). Friction properties of NG/UHMWPE composites:SEM result showed with increase of NG percentage, surface grinding crack ofcomposites becomes shallower gradually, The micro-hardnestester and Micro-XAM 3D non-contact surface profiler results indicated both microhardness and wear resistance of the NG/UHMWPE composite samples increased along with the increase of NG content. When the addition of NG adjust to 1%wt, wear resistance of composite sample decreased by 53%, while the micro-hardness increased by 29%.(3). MTT assay showed that UHMWPE composites with adding NG were superior to the control group on stimulating the proliferation of osteoblasts, and NG/UHMWPE was proved to improve the proliferation of the osteoblasts on the composites surfaces. The cell survival rate reached 151% after 96 h cultured on the 0.5% NG/UHMWPE composites surfaces. SEM and fluorescence staining observations both proved that NG/UHMWPE was superior to the control group in the cell adherence rate and the cell proliferation activity.Conclusion: The results showed that the NG/UHMWPE composites were obtained, and the biological materials were proved to possess well biological compatibilities, wear resistance and mechanical properties. These results of this work will be helpful in improving materials in artificial joints.