ABSTRACT
Tubular polymeric materials modified by radiation techniques can be used as vascular prosthesis and components of prosthetic devices. The biological interction 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 techniques. The irradiation was performed with y-rays from a 60Co 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 surface adsorption of 125I-albumin and 125I-fibrinogen was studied. All graft copolymers show a preference for albumin, and the degree of preference appears to correlate with antithrombogenic tendency. In the ex vivo experiment with animals, tubes were implanted in the carotid artery of dogs and the blood flow in the graft copolymers was detected with an ultrasonic flow meter. The blood flow rate in the ungrafted implants decreased more rapidly (stopped completely after 15 to 210 min) compared to the flow rate in the grafted ones (decreased slowly from 38 to 35 ml/min and 70 to 60 ml/min). There was a direct relationship between both methods in the study of blood compatibility of the materials. The results suggest that the graft copolymers can be used as biomaterials for long-term use in cardiovascular systems
Subject(s)
Animals , Dogs , Carotid Arteries/physiology , Biocompatible Materials , Blood Vessel Prosthesis , Polymers/radiation effects , Acrylamides/radiation effects , Albumins/metabolism , Silicone Elastomers/radiation effects , Fibrinogen/metabolism , Pyrrolidinones/radiation effects , Regional Blood Flow , Surface Properties , Time FactorsABSTRACT
The use of alumina (Ó-Al2O3) as a material for cardiovascular applications was investigated on the basis of protein adsorption and thrombus formation on the material. The adsorption of 125I-labelled albumin and fibrinogen from phosphate buffered saline (pH 7.35, 0.100 M NaCl, 8.66 mM KH2PO4 and 41 mM Na2HPO4) solution on ceramic discs of alumina was studied. Both albumin and fibrinogen presented affinity for ceramic surfaces, with adsorptions of 1.47 + or - 0.6 ng/cm2 and 0.198 + or - 0.01 ng/cm2, respectively. Scanning electron micrographs of the Ó-Al2O3 surfaces after contact of the discs with whole human blood showed a thrombogenic behavior of alumina alpha. These results indicate a hemoincompatible property. Although critical surface tension (YC: 21.8 dynes/cm) of the disc surfaces determined by contact angle technique of sessile drops indicates that alumina alpha is a biocompatible material, by this criterion, the data reported here indicate that Ó-Al2O3 cannot be used for cardiovascular applications