Anticoagulant hydrogels derived from crosslinked dextran. Part II: Mechanism of thrombin inactivation

Sephadex derivatives bearing carboxymethyl, sulphonated benzylamine and amino acid groups exhibit heparin-like behaviour as demonstrated by the kinetic study of the thrombin inactivation in the presence of antithrombin III. Furthermore, whatever the chemical composition of these hydrogels, the diffusion coefficient of thrombin remained approximately constant and could not be connected with the variation of the antithrombin activity of the resins. Hence, in the heparin-like mechanism, the diffusion rate of thrombin inside the beads of hydrogels was not the limiting step. In fact, the swelling ratio (varying according to the chemical composition of these biomaterials) was involved in the anticoagulant properties of the resins.