Biocompatible Polyamides and Polyurethanes Containing Phospholipid Moiety

Abstract

The non-thrombogenic biomaterial has been received a great interest for the development of medical devices or implants in these few decades. When any medical device contacts with flowing blood or internal organs, the material surface of device should avoid the initiation of the process leading to a thrombosis. Such a biocompatible property of artificial biomaterials is a very important factor to use the materials for long-term implantable devices, extracorporeal circulation and intravenous catheters sensors. Although a lot of medical devices are used clinically, the universal non-thrombogenic material has not yet been developed and these devices have been limited to be used for long-term implantation. On the other hand, phospholipids are the main components of cell membranes and act as interesting substances in biological and biomedical fields (Chapman, 1968; Gregoriadis & Allison, 1980; Hayward & Chapman, 1984). Several attempts have been made to translate the natural compatibility between blood and phospholipid membranes for the application of medical devices. The phosphorylcholine (PC) group is a polar component of phospholipid molecules, which covers the surface of cell membranes. It has been well known that synthetic polymer materials containing PC group exhibit biocompatibility including blood compatibility (Sugiyama et al., 1995; Ohishi et al., 1997; Gong et al., 2005). Especially, the so-called MPC polymer, which is typically a copolymer of 2-methacryloyloxyethyl phosphorylcholine (MPC) with butyl methacrylate, has been reported as ideal non-thrombogenic and excellent biocompatible materials (Ishihara et al., 1990a, 1990b, 1991; Ueda et al., 1992). This polymer was designed based on the inspiration from the outer surface of the cell membrane, i.e. the biomembrane, which is mainly constructed of natural phospholipid molecules. In particular, the adhesion and the activation of platelets were completely suppressed on the surface of the MPC polymer, and the amount of plasma proteins adsorbed on the surface of MPC polymer film was clearly decreased. Since PC group consists of a zwitterion, MPC polymer behaves as an entire neutrality molecule and exhibited no interaction with specific ions in the living organism. Furthermore, the applications to medical devices and other uses have been greatly advanced in these years (Sawada et al., 2006; Patel et al., 2005; Iwasaki et al., 1997; Uchiyama et al., 2002; Ye et al., 2006; Goda & Ishihara, 2006; Snyder et al., 2007). Therefore, MPC polymers are useful polymeric biomaterials not only in the biomedical field but also in the tissue engineering and bioengineering fields.