HEPARIN ADSORPTION ONTO MODEL POLY(ETHYLENE TEREPHTALATE) (PET) SURFACES MONITORED BY QCM-D

SPREMLJANJE ADSORPCIJE HEPARINA NA MODELNE POLIETILENTEREFTALATNE (PET) POVRŠINE S POMOČJO KREMENOVE MIKROTEHTNICE

Aleš Doliška1,2, Simona Strnad2, Karin Stana-Kleinschek1,2

1Center of excellence for polymer materials and technologies (PoliMaT), Tehnološki park 24, SI-1000 Ljubljana, Slovenia
2University of Maribor, Faculty of Mechanical Engineering, Laboratory for Characterization and Processing of Polymers, Smetanova 17, SI-2000 Maribor, Slovenia

[email protected]

Prejem rokopisa – received: 2011-09-30; sprejem za objavo – accepted for publication: 2011-10-06

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.

Keywords: poly(ethyleneterephtalate), PET, heparin, QCM-D, haemocompatibility

Adsorpcijo antikoagulanta heparina na modelni film polietilentereftalata (PET) smo merili s pomočjo kremenove mikrotehtnice s spremljanjem dušenja nihanja (QCM-D). PET, ki se uporablja za izdelavo sintetičnih žilnih vsadkov, ima sicer primerne mehanske lastnosti, vendar slabšo hemokompatibilnost. Heparin, ki izboljša hemokompatibilnost površine polimera v stiku s krvjo, ima močno negativen naboj, zato je njegova adsorpcija na hidrofobni in zato prav tako bolj negativen PET, zanemarljiva. Zato je bilo za uspešno adsorpcijo potrebno uporabiti vmesni vezivni sloj kationskega polimera. Preverili smo učinke več različnih kationskih polimerov in ugotovili, da se heparin najbolje adsorbira na sloj polietilenimina (PEI). Heparin smo adsorbirali iz vodne raztopine in iz fiziološke raztopine (PBS). Heparin se je iz raztopine PBS znatno bolje adsorbiral. Meritve smo ovrednotili z uporabo Sauerbreyeve enačbe in Voigtovega viskoelastičnega modela in ugotovili, da heparin na površini PET tvori čvrst film.

Ključne besede: polietilentereftalat, PET, heparin, QCM-D, hemokompatibilnost