title: Prevention of bacterial adhesion and biofilm formation on a vitamin E-blended, cross-linked polyethylene surface with a poly(2-methacryloyloxyethyl phosphorylcholine) layer.
abstract: In the construction of artificial hip joint replacements, the surface and substrate of a cross-linked polyethylene (CLPE) liner are designed to achieve high wear resistance and prevent infection by bacteria. In this study, we fabricated a highly hydrophilic and antibiofouling poly(2-methacryloyloxyethyl phosphorylcholine [MPC]) (PMPC)-graft layer on the vitamin E-blended CLPE (HD-CLPE(VE)) surface. The 100-nm-thick, smooth, and electrically neutral PMPC layer was successfully fabricated on the HD-CLPE(VE) surface using photoinduced graft polymerization. The PMPC-grafted HD-CLPE(VE) was found to prevent bacterial adherence and biofilm formation on the surface because of the formation of a highly hydrophilic polyzwitterionic layer on the surface of HD-CLPE(VE), which can serve as an extremely efficient antibiofouling layer. The number of bacterial adhered on the PMPC-grafted HD-CLPE(VE) surface was reduced by 100-fold or more by PMPC grafting, regardless of the biofilm-production characteristics of the strains. In contrast, vitamin E blending did not affect bacterial adhesion. Moreover, the number of planktonic bacteria did not differ significantly, regardless of PMPC grafting and vitamin E blending. In conclusion, the PMPC-grafted HD-CLPE(VE) provided bacteriostatic effects associated with smooth, highly hydrophilic surfaces with a neutral electrostatic charge owing to the zwitterionic structure of the MPC unit. Thus, this modification may prove useful for the production of artificial hip joint replacement materials.
  
  
  CONCLUSIONS
  Our preliminary in vitro findings suggest that improved bacteriostatic performance of the HD-CLPE(VE) surface in orthopedic implants is possible via PMPC grafting. The results also indicate that surface modifications affect the anti-infection properties of the orthopedic implants and demonstrate that the application of a PMPC-grafted HD-CLPE(VE) surface may be a promising approach to extend the longevity and clinical outcomes of total hip arthroplasty. Further research is needed to evaluate the resistance to infection of PMPC-grafted HD-CLPE(VE) in terms of the varieties of biofilm formation tests including fluid flow conditions and animal experiments, which may offer useful clues to the possible performance of these materials in vivo.
authors.affiliation: Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; Division of Science for Joint Reconstruction, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; Research Department, KYOCERA Medical Corporation, 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kyomoto
authors.affiliation: Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Shobuike
authors.affiliation: Division of Science for Joint Reconstruction, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; Sensory & Motor System Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Moro
authors.affiliation: Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; Division of Science for Joint Reconstruction, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; Research Department, KYOCERA Medical Corporation, 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003, Japan.
authors.forename: Shihori
authors.initials: S
authors.lastname: Yamane
authors.affiliation: Division of Science for Joint Reconstruction, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; Sensory & Motor System Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takatori
authors.affiliation: Sensory & Motor System Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Sakae
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyamoto
authors.affiliation: Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. Electronic address: ishihara@mpc.t.u-tokyo.ac.jp.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ishihara
mesh_terms: D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D006622:Hip Prosthesis / Q000382:microbiology*; D006801:Humans; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000737:chemistry; D020959:Polyethylene / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000502:physiology*; D014810:Vitamin E / Q000737:chemistry*
chemical_list: D011109:Polymethacrylic Acids; C115766:poly(2-methacryloyloxyethyl-phosphorylcholine); D010767:Phosphorylcholine; D014810:Vitamin E; D020959:Polyethylene
keywords: Antibacterial adhesion; Biofilm; Joint replacement; Phosphorylcholine group; Polyethylene