Biological performance of two materials based on sulfated hyaluronic acid and polyurethane

Polyurethane bound with sulfated hyaluronic acid was synthesized by two different chemical routes. Both the materials obtained consist of a hydrophilic component, sulfated hyaluronic acid (HyalS3.5), and a hydrophobic component, polyurethane (PU). In the material named Puhmdi, the HyalS3.5 was cross-linked to the PU chains via hexamethylene diisocyanate (HMDI) while in that named Pubrac, the binding of HyalS3.5 to the PU chains occurred only through a few carboxy groups via N,N'-dicyclohexylcarbodiimide (DCC) and bromoacetic acid. The surface characteristics of the polymers were investigated by ATR FT-IR spectroscopy while the surface morphology was analyzed by scanning electron microscopy. There was a signi®cant difference between the surface characteristics of the ®lms in dry and hydrated environments. In both materials the hydrophilic component (HyalS3.5) migrates from the bulk to the surface, thus minimizing the surface free energy of the polymer when exposed to the hydrated environment. The different biological behavior of the two materials was demonstrated with the thrombin time test and platelet adhesion test. Pubrac inhibits the coagulation process while Puhmdi does not.