ADVANCED POLYURETHANES FOR BLOOD CONTACTING APPLICATIONS CONTAINING PIME AS 'SMART' HEPARIN-ADSORBING MOIETIES

摘要

The new compound PIME can be successfully used for the synthesis of polyurethanes. A 2-steps synthesis in solution allows a better control of the polymer structure (i.e. soft/hard segments alternation). On the other hand, the synthesis in bulk lets to obtain much larger batch quantities, with much lower amounts of catalysts that make the purification procedure easier. However, the method in bulk still needs to be optimized. The obtained results indicate that the heparin binding of PIME-containing PUs is significantly higher and more stable than that of the other polyurethanes, with a time-dependent kinetic. The interaction with heparin appears to be prevalently ionic, with the contribution of other electrostatic and hydrophobic interactions. Coagulation tests performed on human plasma with poly-urethane-coated, heparinized test tubes indicated that heparin maintains its biological activity after the adsorption and after sterilization. PIME shows a very good cytocompatibility, and therefore well fits with the synthesis of biomedical polymers. Even though not heparinized, PIME-containing polyurethanes showed the capability of promoting cell adhesion and growth. The preparation of polyurethane hydrogels containing PIME as chain extender is now under investigation. PU-PIME hydrogels are expected to present all favorable characteristics of analogous PU-butanediol hydrogels previously described (peculiar mechanical properties and the capability of mimicking the hydrophilicity of natural tissues), associated to the capability of binding heparin. PU-PIME hydrogels, therefore, are of high potentiality in tissue engineering and blood contacting applications.