title: Photoinduced phospholipid polymer grafting on Parylene film: advanced lubrication and antibiofouling properties.
abstract: Poly(p-xylylene) (Parylene C) coatings have been applied in implantable electronic devices because of their electrical insulation and moisture barrier properties. To provide lubrication and an antibiofouling surface, a biomimetic phospholipid polymer--poly(2-methacryloyloxyethyl phosphorylcholine (MPC))--was grafted from the surface using UV irradiation with benzophenone as an initiator. The poly(MPC) grafting on the Parylene C films was confirmed by attenuated total reflection-Fourier transfer inflated irradiation, X-ray photoelectron spectroscopy and ellipsometry. These analyses indicated that the Parylene C films were completely covered by the poly(MPC)-graft layer with an average thickness of 140 nm under dry condition. The atomic force microscope (AFM) images revealed that the poly(MPC)-graft chains extended under wet condition. However, they formed globular structures under dry condition. Water contact angle measurements revealed a decreased receding angle of 29.5 degrees on the poly(MPC)-grafted surface with a high hysteresis of 41.4 degrees. These results indicate that the poly(MPC)-graft chains gain mobility in a wet environment. The average kinetic friction coefficient of the poly(MPC)-grafted surface in water was 0.018, which was 90% lower than that of the original surface. The in vitro single protein adsorption reduced by over 70% due to the poly(MPC) grafting. The hydrated poly(MPC)-graft chains are considered to provide lubrication and antibiofouling properties. The surface zeta potential measurement clarified the electroneutrality of the poly(MPC)-grafted surface. We concluded that the poly(MPC) grafting from the Parylene C layer significantly improved its surface properties and, subsequently, its biological properties.
authors.affiliation: Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Goda
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Konno
authors.forename: Madoka
authors.initials: M
authors.lastname: Takai
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ishihara
mesh_terms: D000818:Animals; D002417:Cattle; D004777:Environment; D005340:Fibrinogen / Q000737:chemistry; D007700:Kinetics; D008153:Lubrication; D018625:Microscopy, Atomic Force; D015394:Molecular Structure; D010743:Phospholipids / Q000737:chemistry*; D010777:Photochemistry; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014992:Xylenes / Q000737:chemistry*
chemical_list: D010743:Phospholipids; D011108:Polymers; D014992:Xylenes; C011055:parylene; D005340:Fibrinogen