Surface Immobilization of Bioactive Molecules on Polyurethane for Promotion of Cytocompatibility to Human Endothelial Cells

Polyurethane (PU)has beenwidely used asbiomaterials due to its excellent physical properties and blood compatibility. Hemocompatibility and resistance to biodegradation of PU had led to its application in both commercial and experimental blood-contacting areas, such as vascular grafts, catheters, chambers for artificial hearts, and pacemaker insulation and so on. Many implanted substitutes like vascular grafts, catheters etc. are inevitably encapsulated by the surrounding tissues to form an intima in the lumen after long-term application. Therefore, a surface that can accelerate this process, especially promote the formation of an endothelial layer at shortest time is favorable to gain better hemocompatibility at the initial stage. However, the intrinsic inert property of polyurethane results in a poor cell-material interaction which is unfavorable to endothelium formation. Hence, a modification of its property to improve its cytocompatibility is necessary. Manymodifications have focused on thematerial surface because thecell-material interaction ismostlymodulatedby the superlayer of amaterial, whilst the bulk properties of the material likemechanical strength are unchanged. It has been reported that several methods such as plasma treatment, ozone or photoinduced grafting and surface oxidation etc. have been employed to introduce hydrophilic compounds onto polymeric scaffold surfaces. Among these established surface modification methods, photoinduced surface Full Paper: Cytocompatible polymers are of increasing importance for tissue engineering scaffolds and implanted devices. Polyurethane (PU) membranes were modified by grafting polymerization of methacrylic acid (MAA) initiated byUV light and further covalent immobilization of gelatin or arginine-glycine-aspartic (RGD) peptide using 1-ethyl-3-(3dimethylaminopropyl) carbodiimide hydrochloride as a condensing agent. The immobilization of gelatin or RGD peptide was confirmed by FTIR attenuated total reflection (ATR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results for endothelial cells cultured in vitro proved that the PU membrane modified with gelatin or RGD peptide had better cytocompatibility than the control PU or the PMAA grafted PU membrane.