Fibers and Polymers 2012, Vol.13, No.8, 985-993 985 Thrombin Immobilization to Enzymatic Modified PET and PAN Fabrics and Their Applications Alper Akkaya* and Nurdan Kasikara Pazarlioglu Biochemistry Department, Faculty of Science, Ege University, Bornova-Izmir 35100, Turkey (Received January 31, 2012; Revised March 15, 2012; Accepted March 23, 2012) Abstract: Enzymatic modification of synthetic materials has immense potential both of the functionalization of polymeric materials, such as poly(acrylonitrile) or polyesters, and the production of polymers for special applications, such as medical devices and enzyme immobilization. In this study, poly(ethyleneterephtalate) and poly(acrylonitrile) fabrics were modified with commercial laccase and nitrilase, respectively. Contact angles of enzymatic modified and unmodified fabrics were measured and it was found contact angles of enzymatic modified fabrics were less than those of unmodified fabrics. Attenuated-Total-Reflection-Fourier-Transform infrared spectroscopy showed that carboxylic acid groups occurred on fabrics after enzymatic modifications. Surfaces of modified and unmodified fabrics were investigated using scanning electron microscopy. Surfaces of unmodified fabrics were smooth but surfaces of modified fabrics were rugged and cracked. Thrombin was immobilized in modified fabrics by using 1-Ethyl-3-(3-dimetylaminopropyl)-carbodiimide. Optimization studies were also performed for the immobilization of thrombin. After prepared material was tested to stop bleeding in vitro conditions and it was found that thrombin immobilized poly(ethyleneterephtalate) and poly(acrylonitrile) fabrics had a reduced recalcification time to 51 % and 89 %, respectively. Thrombin immobilized poly(ethyleneterephtalate) fabric was also tested in in vivo conditions by using Cavia porcellus and it was observed that this material caused bleeding to stop at a ratio of 24.6 %. The results were statistically significant. Keywords: Enzymatic modification, Synthetic fabrics, Thrombin, Immobilization, Bleeding Introduction Synthetic fibers form an important part of the textile industry. Poly(ethyleneterephtalate) (PET) and poly(acrylonitrile) (PAN) fibers have high crystallinity and low moisture regain. They exhibit excellent physical properties of strength, flexibility, toughness, stiffness, wear and abrasion resistance. Beside these properties, they also demonstrate a good dyeing ability, low friction coefficient and good chemical resistance. However, the poor wetability and hydrophilicity make them difficult to apply to finishing compounds, colouring agents, and coupled with flame retardants or covalently immobilize proteins or enzymes [1,2]. Modifications must be made and functional groups should be added or formed to make them functional or improve properties. Classical chemical modification of synthetic polymers, using strong alkaline or acid agents, requires high amounts of energy and chemicals (binders, coupling agents, etc.), which are partially discharged to the environment. Furthermore, some of the substances used, due to their weak bonding, are released from the end-products, presenting potential health risks and reducing the lifetime of the products. Although alkaline products render synthetic fibers more hydrophilic, they also lead to the deterioration of other properties causing irreversible yellowing and loss of resistance [3]. Instead of chemical modification, this process could be realized in milder conditions by using enzymes. This is a relatively new and interesting alternative method for modification of synthetic fibers [4-10]. The application of enzymes in polymer modification has major advantages compared to chemical agents, such as milder reaction conditions, easier control, specific non-destructive transforma- tions, and environmental friendly processes [11]. Modification of PET fibers has previously been studied with a hydrolase class of enzymes until now. It is known as hydrolysis of ester bonds in polyester, resulting in the generation of hydroxyl and carboxyl groups on the surface and in the formation of terephthalic acid and ethylene glycol as reaction products [12,13]. Hydroxyl and carboxyl groups could be used as functional groups for different purposes such as hydrophilization, enzyme or protein immobilization, etc… For the enzymatic modification of PET, potential and studied enzymes can be listed as lipases [7,14,15], cutinases [16], polyhydroxyalkanoate depolymerases [17], esterases [18], polyesterase [10] etc… Oxidative enzymes, such as laccases, have been investigated for the modification of PET surface [19]. Although oxidative modification with laccases would be especially interesting since functionalization could be achieved without cleavage of the polymer, there is no detailed mechanistic or application related data available yet [6,20]. Laccase (E.C. 1.10.3.2, benzenediol:oxygen oxidoreductase) is a multicopper oxidase, widely distributed among plants, fungi [21], and bacteria [22]. It catalyzes the oxidation of a broad range of organic and inorganic substrates, including diphenols, polyphenols, diamines, aromatic amines, through by one-electron transfer mechanism [23]. Due to its broad substrate specificity, laccase has great potential in varied applications including pulp delignification, textile dye bleaching, xenobiotics degradation and polymer modifications [24,25]. *Corresponding author: alper.akkaya@ege.edu.tr DOI 10.1007/s12221-012-0985-z