Protein Resistant or Repulsive Surface

A current hypothesis, which is receiving considerable attention, is that one can indeed produce a surface which actively repels proteins and other macromolecules123 124, 133). The basic idea is presented in Fig. 25, which shows that a neutral hydrophilic polymer, which exhibits considerable mobility or dynamics in the aqueous phase, can actively repel macromolecules from the interface by steric exclusion and interface entropy methods. This method has been well-known and applied in the field of colloid stability for many years 120). The most effective polymer appears to be polyethylene oxide, probably because of its very high chain mobility and only modest hydrogen bonding tendencies 121 123 . 

Merrill and Salzman have developed PEO soft segment polyurethanes and indeed have demonstrated minimal adsorption of blood proteins and minimal platelet adhesion on such surfaces121). Nagaoka et al. have studied various methacrylate copolymers with PEO side-chains of varying lengths and showed a direct correlation between minimization of platelet adhesion with increased PEO side-chain length and surface 

Gregonis et al. have shown that PEO bound to quartz surfaces greatly minimizes the adsorption of proteins from plasma and from singly component protein solutions 122). Bell and coworkers at Los Alamos have developed a theory of cell-cell adhesion based on the steric repulsion characteristics of the hydrophilic macromolecules present on cell surfaces 124). 

---