Surface modification of PE porous membranes based on the strong adhesion of polydopamine and covalent immobilization of heparin

▶ Surface heparinization is regarded as an effective way to improve the blood compatibility of hydrophobic polymeric membrane. ▶ The polydopamine could form a stable reactive layer that tightly attached upon the membrane, which affords opportunities to further surface modification and functionalization such as heparinization in present study. ▶ After dopamine modification and heparin immobilization, the hydrophilicity of PE membranes has been remarkably improved, and the heparin-immobilized PE membranes show very good hemocompatibility. Based on the self-polymerization and strong adhesion characteristic of dopamine in wet conditions, the hydrophobic polyethylene (PE) porous membranes were surface-modified via simply immersing them into dopamine aqueous solution for 24 h. Subsequently, heparin was immobilized covalently onto the resultant membrane by the coupling between heparin and reactive polydopamine layer. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were utilized to determine the chemical compositions of membrane surface, which confirmed the successful introduction of polydopamine and immobilization of heparin molecules. Scanning electronic microscopy (SEM) and atomic force microscopy (AFM) were employed to investigate the changes in surface morphologies after surface modification. The data of water contact angle measurements indicated that the hydrophilicity of PE membranes was remarkably improved after polydopamine coating and heparin immobilization. The results of in vitro hemocompatibility test proved that surface heparinization significantly suppressed the adhesion of platelet and enhanced the anticoagulation ability of PE membranes. This work offered a convenient approach to improve the permeability and biocompatibility of inert PE porous membranes for their biomedical and blood-contacting applications.