Surface characterization and in vitro blood compatibility of poly(ethylene terephthalate) immobilized with insulin and/or heparin using plasma glow discharge

Poly(ethylene terephthalate)(PET) film was exposed to oxygen plasma glow discharge to produce peroxides on its surfaces. These peroxides were then used as catalysts for the polymerization of acrylic acid (AA) in order to prepare a carboxylic acid group-introduced PET (PET-AA). Insulin and heparin co-immobilized PET (PET-I-H) was prepared by the grafting of poly(ethylene oxide) (PEO) on to PET-AA, followed by reaction first with insulin and then heparin. These surface-modified PETs were characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, electron spectroscopy for chemical analysis (ESCA), and a contact angle goniometer. The concentration of the heparin (1.23 μg/cm 2) bound to the PEO-grafted PET (PET-PEO) was higher than that (0.77 μg/cm 2) on the insulin-immobilized PET (PET-In). The blood compatibilities of the surface-modified PETs were examined using in vitro thrombus formation, plasma recalcification time (PRT), activated partial thromboplastin time (APTT), and platelet adhesion and activation. In the experiment with plasma proteins, the PRT and APTT were significantly prolonged for both the heparin-immobilized PET (PET-He) and the PET-I-H, suggesting the binding of immobilized heparin to antithrombin III. The percentage of platelet adhesion slightly increased with the introduction of AA on the PET surfaces, decreased with the introduction of PEO and insulin, and decreased further with the immobilization of heparin. The release of serotonin was highly suppressed on PET-He and PET-I-H, and on surface-modified PETs the percentage of its release increased with an increase in platelet adhesion.