New Nanocomposite Biomaterials Controlling Surface and Bulk Properties using Supercritical Carbon Dioxide
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1097-GG04-15
New Nanocomposite Biomaterials Controlling Surface and Bulk Properties using Supercritical Carbon Dioxide Toru Hoshi1, Takashi Sawagushi2, Ryosuke Matsuno1, Tomohiro Konno1, Madoka Takai1, and Kazuhiko Ishihara1 1
Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan 2
Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda Surugadai, Chiyoda-ku, Tokyo, 101-8308, Japan ABSTRACT The molecular composite composed of polyethylene (PE) and poly(vinyl acetate) (PVAc) prepared using supercritical carbon dioxide (scCO2) and its surface modification for biocompatible surface demonstrated the creation of novel polymer biomaterials. In this study, this modification process was applied to the PE narrow tube (inside diameter: 300µm, outside diameter: 600µm, length: 5m). It was confirmed that PVAc was uniformly generated in PE tube by infrared imaging measurement of cross-section. After the acetyl group on the surface was hydrolyzed, phospholipid polymer was immobilized to the hydroxyl group on the surface of the tube. The phospholipid polymer immobilized surface showed a drastic reduction in protein adsorption. The surface of the minute and slender tube can be effectively modified using the feature of carbon dioxide whose surface tension is near zero. The modification technology by scCO2 is a promising for creation of variously-shaped new biomaterials. INTRODUCTION Fundamental requirements for biomaterials used in the construction of medical devices and artificial organs are biocompatible surfaces and favorable mechanical properties [1]. Recently, the new method that is the preparation of the molecular composite composed of polyethylene (PE) and poly(vinyl acetate) (PVAc) using supercritical carbon dioxide (scCO2) and its surface modification demonstrated the creation of novel polymer biomaterials. This molecular composite (PE/PVAc composite) was obtained by the following processes: both the vinyl acetate and 2,2’-azobisisobutyronitrile (AIBN) dissolved in scCO2 were impregnated into the PE substrate and subsequently polymerized [2]. The PE/PVAc composite formed micro-phase separation structure comprising crystalline region and amorphous region.
This microstructure affected mechanical properties of the PE/PVAc composite. Then, mechanical properties of the molecular composite can be expected by controlling with a combination of substrate and monomer. It is probable that biomaterials with mechanical properties similar to various regions such as soft tissue, hard tissue, and organs can be created using scCO2. To prepare biocompatible surface, a phosphorylcholine (PC) group that is a major component of the outer membrane of cells was introduced on this hydroxyl group generated by surface hydrolysis of the acetyl group on the PE/PVAc composite [3]. Moreover, the biocompatible surface was prepared by the surface-initiated atom transfer radical polymerization of 2-methacryloyloxyethy
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