Heparin Adsorption Onto Model Poly(Ethylene Terephtalate) (Pet) Surfaces Monitored By QCM-D

The adsorption of anticoagulant heparin onto model poly(ethylene terephtalate) (PET) film was monitored using a quartz crystal microbalance with a dissipation unit (QCM-D). Synthetic vascular grafts are usually made from PET, a material with appropriate mechanical properties but moderate haemocompatibility. Therefore anticoagulant heparin is usually used to improve haemocompatibility of PET surfaces. Heparin possesses a high negative charge and as such does not adsorb directly onto hydrophobic PET, which is also negatively charged. To increase heparin adsorption different cationic polymers were investigated as spacers and the highest adsorption was achieved using polyethyleneimine (PEI) as an anchoring agent. The heparin was adsorbed from water solution as well as from phosphate buffer saline (PBS). Heparin dissolved in PBS adsorb better onto PET than heparin from water solution. The results were characterized using Sauerbrey equation and Voigt based viscoelastic model. We found out that heparin adsorbed onto PET formed a thin and rigid film and that Sauerbrey equation is appropriate for characterization of heparin adsorption onto PET.