Testing of Pur-Biomaterials for Enzymaticauy Induced Degradation: An in Vitro Study

The enzymatically induced degradation of a group of medical grade polyurethanes (PUR) for cardiovascular applications such as heart valve prostheses and blood pumps has been investigated. Mechanical stability of these polyether-, polyester- and polyurethaneureas has been tested by incubation of microtensile specimens according to ASTM 1708–79 into enzymatic solutions and bovine blood plasma for up to 4 months. The degree of degradation is assessed by measuring tensile properties, water absorption and molecular weight. Changes in surface quality are determined by SEM and contact angle measurements. The results so far reveal degradative changes depending on PUR-type and type of enzyme but to a degree not impairing the implant function within the chosen test period and test conditions.