PLATELET INTERACTIONS WITH PLASMA-POLYMERIZED ETHYLENE-OXIDE AND N-VINYL-2-PYRROLIDONE FILMS AND LINEAR POLY(ETHYLENE OXIDE) LAYER

Dimethyldichlorosilane (DDS)-treated glass (DDS-glass) was modified wi th either poly(ethylene oxide) (PEO) films or poly(N-vinyl-2-pyrrolido ne) (PNVP) films by plasma polymerization. The thickness of the plasma polymerized films was varied between 40 and 700 nm. The results showe d that the hydrophilic plasma polymerized PEO and PNVP films on DDS-gl ass did not prevent platelet adhesion and activation. The film thickne ss had only marginal influence on the prevention of platelet activatio n. In contrast, platelet adhesion was prevented on DDS-glass adsorbed with a PEO-containing block copolymer (Pluronic(R) F-108 surfactant) e ven at a calculated thickness of the PEO layer of less than 40 nm. Thi s study shows that surface hydrophilization is not sufficient for prev ention of platelet adhesion and activation. The contrasting results in platelet adhesion between cross-linked plasma polymers and linear PEO -containing block copolymers may be explained qualitatively by a steri c repulsion mechanism that is achieved by the conformational freedom o f the linear PEO chains interacting with water.