A hydrated phospholipid polymer-grafted layer prevents lipid-related oxidative degradation of cross-linked polyethylene

Masayuki Kyomoto; Toru Moro; Shihori Yamane; Yoshio Takatori; Sakae Tanaka; Kazuhiko Ishihara

doi:10.1016/j.biomaterials.2016.10.021

A hydrated phospholipid polymer-grafted layer prevents lipid-related oxidative degradation of cross-linked polyethylene

Biomaterials. 2017 Jan:112:122-132. doi: 10.1016/j.biomaterials.2016.10.021. Epub 2016 Oct 11.

Authors

Masayuki Kyomoto¹, Toru Moro², Shihori Yamane¹, Yoshio Takatori², Sakae Tanaka³, Kazuhiko Ishihara⁴

Affiliations

¹ 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.
² 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.
³ Sensory & Motor System Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
⁴ 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.

PMID: 27760396
DOI: 10.1016/j.biomaterials.2016.10.021

Abstract

The surface and substrate of a cross-linked polyethylene (CLPE) liner are designed to achieve resistance against oxidative degradation in the construction of hip joint replacements. In this study, we aimed to evaluate the oxidative degradation caused by lipid absorption of a highly hydrophilic nanometer-scaled thickness layer prepared by grafting a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer and a high-dose gamma-ray irradiated CLPE with vitamin E blending (HD-CLPE[VE]). The HD-CLPE(VE) and PMPC-grafted HD-CLPE(VE) exhibited extremely high oxidation resistance regardless of lipid absorption, even though residual-free radical levels were detectable. The water wettability of the PMPC-grafted CLPE and PMPC-grafted HD-CLPE(VE) surfaces was considerably greater than that of untreated surfaces. The hydrated PMPC-grafted layer also exhibited extremely low solubility for squalene. Lipids such as squalene and cholesterol esters diminished the oxidation resistance of CLPE despite the vitamin E improvement. Notably, the PMPC-grafted surface was resistant to lipid absorption and diffusion as well as subsequent lipid-related oxidative degradation, likely because of the presence of the hydrated PMPC-grafted layer. Together, these results provide preliminary evidence that the resistance against lipid absorption and diffusion of a hydrated PMPC-grafted layer might positively affect the extent of resistance to the in vivo oxidation of orthopedic implants.

Keywords: Joint replacement; Lipids; Oxidation; Phosphorylcholine; Polyethylene.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Absorption, Physicochemical
Biocompatible Materials / chemistry*
Cross-Linking Reagents / chemistry*
Diffusion
Lipids / chemistry*
Materials Testing
Oxidation-Reduction
Phosphorylcholine / analogs & derivatives*
Phosphorylcholine / chemistry
Polyethylene / chemistry*
Polymethacrylic Acids / chemistry*
Solubility
Surface Properties
Water / chemistry*

Substances

Biocompatible Materials
Cross-Linking Reagents
Lipids
Polymethacrylic Acids
poly(2-methacryloyloxyethyl-phosphorylcholine)
Water
Phosphorylcholine
Polyethylene