Formation of polymerized mixed heparin/albumin surface layer and cellular adhesional responses

The aim of this study was to create a dense albuminated layer, a heparinized layer, and a mixed layer on a poly(acrylic acid)-grafted surface via visible light induced photopolymerization. The procedure is comprised of four reaction steps: first, by visible light irradiation, acrylic acid (AA) was graft-polymerized on a segmented polyurethane (SPU) film that was preimpregnated with camphorquinone. The second step was adsorption of multiply styrenated albumin or styrenated heparin or their mixture, followed by visible light irradiation in the presence of carboxylated camphorquinone. The third step was covalent bonding between polyAA graft chain and polymerized biomacromolecule and between polymerized biomacromolecule to enforce the formation of a stable immobilized multilayer. X-ray photoelectron spectroscopic and Fourier transform-infrared spectroscopic measurements were conducted to analyze the surfaces formed at each step. Confocal laser scanning microscopy was utilized to determine the thickness of the biomacromolecule-immobilized layer with several tenths of a micrometer thickness. Platelet adhesion was markedly reduced on polymerized albuminated, polymerized heparinized, and copolymerized layers, whereas adhesive and proliferative potentials of endothelial cells, which were comparable to those of commercial tissue culture dishes, were observed on these surfaces. Co-immobilization of fibronectin and basic fibroblast growth factor enhanced these potentials. These densely multilayered surfaces may be suitable for artificial and tissue-engineered devices.