New Heparinizable Materials: Surface Grafting of Poly (Amido Amine) Chains on Polyurethane

Abstract

Poly(Amido-amine)s chains are capable of forming stable complexes with heparin thus their grafting on the surface of devices renders the surface non-thrombogenic. A calorimetric study performed on the heparin-poly(amido-amine)s system indicate that mainly electrostatic interactions between heparin and poly(amido-amine)s occur in aqueous solution at pH=7.4. Furthermore the FTIR spectrum of the solid heparin-poly(amido-amine) complex obtained from aqueous solution shows that it is not a simple mixture of the two polymers. Grafting of poly(amido-amine) N₂LL on polyurethane surface has been studied along with all the chemical steps. In addition, immobilized heparin was monitored by FTIR technique. Biological tests shows that the anticoagulant activity of heparin remains even if it is linked to poly(amido-amine) grafted on a PU surface. The sequence of SEM photos shows that after N₂LL treatment the PU surfaces are covered by platelets and fibrinogen. No deposit is observed, however, on heparinized surfaces.