Protein adsorption is the first phenomenon that occurs when synthetic materials come into contact with a living organism. The uncontrolled protein adsorption functions as a trigger for foreign body reactions to materials from a host. For biomedical applications, control of protein adsorption becomes quite important in the preparation of synthetic materials. Many concepts have been proposed for non-protein-fouling surfaces using physicochemical, biochemical, and biological approaches. One of the most robust approaches is phosphorylcholine immobilization as a mimicker of a biomembrane (Iwasaki and Ishihara 2005). A well-known model of the

Yasuhiko Iwasaki, Nobuo Nakabayashi: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062, Japan, E-mail: [email protected]

Kazuhiko Ishihara: Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

Principles and Practice Proteins at Solid-Liquid Interfaces Philippe Dejardin (Ed.) © Springer-Verlag Berlin Heidelberg 2006

Fig. 1. Fluid-mosaic model of biomembrane

structure of a biomembrane is the fluid-mosaic model (Fig. 1; Singer and Nicolson 1972). According to this model, amphiphilic phospholipids are arranged in a bilayer structure and proteins are located in or upon it. In all cells for which lipid compositional asymmetry has been described, negatively charged phospholipids such as phosphatidylserine are found predominantly on the inner, cytoplasmic side of the membrane, whereas the neutral, zwitterionic phosphorylcholine lipids such as phosphatidylcholines are located in the outer leaflet. The phosphorylcholine surface provides an inert surface for biological reactions of proteins and glycoproteins to occur smoothly on the membrane. This fact provides very significant information in the development of nonfouling polymer surfaces.

In this chapter, a variety of methodologies for making biomimetic phosphorylcholine-bearing surfaces, including well-defined surface preparation (i. e., self-assembled monolayers, SAMs) and polymer brushes, and the surface characteristics of the surfaces are introduced. In addition, an explanation is given as to how securing protein adsorption onto the surface enables the control of cell-material interactions.

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