Preparation and evaluation of polyurethane surfaces containing immobilized plasminogen

Plasminogen has been immobilized onto a segmented polyurethane containing amino groups, using glutaraldehyde as coupling agent. It was also aspecifically adsorbed, for sake of comparison, onto polyurethane films containing different functional groups and, in particular, epsilon-amino caproic acid and lysine residues. The differently immobilized plasminogen has been converted to plasmin by activation with urokinase, and the percentage of active plasmin for the various polymer films was determined using a tripeptide (S-2251) as a synthetic substrate. The biological behaviour of the differently treated polymer films has been evaluated in vitro by measurements of partial thromboplastin time (PTT) and platelet adhesion.