Effect of photografting 2-hydroxyethyl acrylate on the hemocompatibility of electrospun poly(ethylene-co-vinyl alcohol) fibroporous mats.

Poly(ethylene-co-vinyl alcohol) (EVAL) has been recommended as a material suitable for blood contacting applications. Effect of ethylene content and associated hydrophobicity of EVAL on the blood-material interactions have been documented in the literature. In this work, surface chemistry of EVAL substrate was altered by photografting a hydrophilic monomer, 2-hydroxyethyl acrylate (HEA) with the aid of a photoinitiator, benzophenone (BP), and the effect of surface modification on the blood-material interactions was investigated. Since the modified material was intended to be used as leukodepletion filters, a solution containing EVAL, HEA and BP was electrospun into fibroporous mats and UV treated to induce grafting. Degree of grafting, bonding between fibers and fiber diameter increased with increase in UV exposure time whereas mechanical properties showed a decreasing trend. Decreased water contact angle indicated improved wetting characteristics. In vitro hemocompatibility tests revealed that the modified EVAL surface exhibited significantly lower hemolytic activity, protein adsorption and platelet adhesion than neat EVAL. The modification did not have any substantial effect on the activation of the complement system and coagulation parameters. Photografting led to significant reduction in the adhesion of red blood cells (RBC) whereas white blood cell (WBC) consumption remained above 90%. The results implied that photografting HEA on EVAL substantially improves hemocompatibility of EVAL and when it is used as a filter, it selectively removes leukocytes and allows easy passage of other blood components.