SURFACE MODIFICATION BY RADIATION-INDUCED GRAFTING OF PEO/PPO/PEO TRIBLOCK COPOLYMERS

Poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) (PEO/PPO/PEO) triblock copolymers (Pluronics) were covalently grafted to dimethyldichlorosilane-treated glass (DDS-glass) by γ-irradiation. Pluronic F-68 (PEO/PPO/PEO = 76/30/76) was adsorbed at the bulk concentration of 10 mg/ml and irradiated either in the presence of bulk Pluronic solution, after washing with buffer solution, or after washing followed by drying. Pluronic F-68, when grafted in the presence of bulk Pluronic solution, formed a crosslinked hydrogel on the surface after 2.30 Mrad of irradiation. The surface Pluronic concentration was 45.1 µg/cm2. A monolayer of Pluronic F-68 was grafted to the surface, if bulk Pluronic was washed with phosphate buffered saline (PBS) solution before irradiation. The surface Pluronic concentration was 0.16 µg/cm2 which is similar to the concentration of the physically adsorbed Pluronic layer. Only a few platelets were contact adherent on the Pluronic-grafted surface, while numerous platelets were fully activated on the control surface. Platelets could adhere and activate on DDS-glass, if the adsorbed Pluronic F-68 was dried before irradiation. The surface concentration of grafted Pluronic was 0.15 µg/cm2. Pluronic F-68 which was grafted by irradiation after washing with PBS was most efficient in preventing platelet activation. Grafting of Pluronic copolymers by γ-irradiation provides a simple method for improvement of blood compatibility of biomaterials. © 1993 Academic Press, Inc.