New polyurethane compositions able to bond high amounts of both albumin and heparin

In order to prepare polymers provided with better haemocompatibility with respect both to the coagulative cascade and to platelet aggregation and activation, we have synthesized new polyurethanes containing in the chain extender [di-(2-hydroxyethyl) hexa-decylamine (DHHA)] both a long chain alkyl group (able to bond albumin) and a tertiary ammonium group able, after suitable quaternization reaction, to bind ionically significant amounts of heparin. The amounts of heparin and albumin bonded to the polymer films were determined spectrophotometrically. A biological in vitro evaluation of the heparinized and albuminized films was also carried out, with respect to the blood coagulation factors (by APTT measurements) and to platelet adhesion. For the sake of comparison, polyurethanes containing as chain extenders two different monomers (containing, respectively, the long alkyl and the quaternary ammonium group), and polymer blends consisting of these copolymers, were also prepared and evaluated as above. It was seen that the type of the adsorption sequence for albumin and heparin, respectively, onto films of the various homopolymers, copolymers and blends, plays an important role in their biological properties.