Plasma graft polymerization of Acrylic Acid and immobilization of Heparin to improve blood compatibility of Polyethylene
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Plasma graft polymerization of Acrylic Acid and immobilization of Heparin to improve blood compatibility of Polyethylene terephthalate (PET). Samin Eftekhari1, Hamid Mirzadeh2 1 Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada, M5B 2K3, Fax: 416-979-5153 2
Polymer Science Engineering Department, Amirkabir University of Technology, 424 HafezAve.,15875-4413, Tehran, Iran ABSTRACT Polymeric materials have been attracted the attention of researchers in various R&D applications. In this research, attempts were made to evaluate the changes in blood compatibility of polyethylene terephthalate (PET) by grafting acrylic acid (AAc) and immobilizing heparin by employing two-step plasma treatment. The PET surface was modified by using a novel method named “two-step plasma treatments” (TSPT). While first plasma is creating active sites for grafting, the second plasma polymerizing pre-adsorbed reactive monomer onto the surface of films. Finally, heparin immobilization was performed in the presence of 1-ethyl-3(dimethylaminopropyl) carbodiimide. All films were characterized by attenuated total reflection Fourier transformed infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM). The surface hydrophilicity of films was studied by water contact angle test and blood compatibility evaluated by Lactate dehydrogenase method (LDH Test). In vitro studies based on LDH results demonstrared that platelet adhesion onto the modified surfaces with heparin was drastically reduced in comparison with unmodified PET. INTRODUCTION The nature of the contact surface plays an important role in the blood compatibility of a biomaterial. Since many polymers do not possess the proper surface characteristics for biomedical applications, improving the surface of it attracted the great attention of researchers. Many techniques including chemical modification or physical modification of polymers by plasma or laser have been utilized to change the surface properties [1-3]. However, utilization of plasma is much more attractive than other treatments because plasma-based techniques change only surface characteristics of material such as chemical, optical, and biological properties without altering the bulk properties [4]. In this research, a novel method by using plasma for graft polymerization, introduced to functionalize the PET surface with new hydrophilic groups. Improvement of hydrophilicity attributed to the grafted acrylic acid (AAc) on the PET surfaces which significantly improves the hydrophilicity of it. In our study, pre-adsorbed AAc was grafted onto the surface of PET films using oxygen plasma via a new method named ‘‘twostep plasma treatment (TSPT).’’ Briefly, the plasma pre-treated film was first immersed in an aqueous monomer solution with different monomer concentrations of AAc and in the second step the plasma graft polymerization was carried out onto treated PET films. Finally, heparin was immobilized onto films to obtain blood compatible surface. Plasma treatment of PET can
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