On surface modification of polymeric biomaterials

Surface modification with hydrophilic polymers has been beneficial in improving blood compatibility of biomaterials. Formation of dense and tightly-bonded surface layers may prevent plasma protein adsorption owing to steric repulsion. General conditions for formation of layers, protecting blood components from direct contacts with the surface, are discussed. It seems to be necessary to ensure a delicate balance between adsorption energy of the attached chains and their length. The crucial point is to get a high grafting density which is more influential than high chain length. Length should be calibrated to the size of protein molecules to meet both effective repulsion and high density of the protecting chains and to avoid chain displacement by plasma proteins.