BLOOD COMPATIBILITY OF TUBULAR POLYMERIC MATERIALS STUDIED BY BIOLOGICAL SURFACE INTERACTIONS

Tubular polymeric materials modified by radiation techniques can be us ed as vascular prosthesis and components of prosthetic devices. The bi ological interaction between these materials and blood was studied by in vitro and ex vivo methods. Silicone rubber tubes were copolymerized with acrylamide and N-vinylpyrrolidone by radiation-grafting techniqu es. The irradiation was performed with gamma-rays from a Co-60 source at a constant dose rate (0.2 kGy/h) for various time intervals (4-15 h ). To evaluate the antithrombogenicity of the grafted tubes, the surfa ce adsorption of I-125-albumin and I-125-fibrinogen was studied. All g raft copolymers show a preference for albumin, and the degree of prefe rence appears to correlate with antithrombogenic tendency. In the ex v ivo experiment with animals, tubes were implanted in the carotid arter y of dogs and the blood flow in the graft copolymers was detected with an ultrasonic flow meter. The blood flow rate in the ungrafted implan ts decreased more rapidly (stopped completely after 15 to 210 min) com pared to the flow rate in the grafted ones (decreased slowly from 38 t o 35 ml/min and 70 to 60 ml/min). There was a direct relationship betw een both methods in the study of blood compatibility of the materials. The results suggest that the graft copolymers can be used as biomater ials for long-term use in cardiovascular systems.