Surface properties of polyurethanes modified by bioactive polysaccharide-based polyelectrolyte multilayers.

Lentinan, a mushroom polysaccharide, isolated from Lentinus edodes (Shiitake mushroom) was sulfated in dimethylsulfoxide to obtain a water-soluble derivative coded as LS. Then, two polysaccharide-based polyelectrolytes, polyanionic lentinan sulfate (LS) and polycationic chitosan (CS), were alternatively deposited onto the surfaces of polyurethane (PU) via layer-by-layer (LbL) assembly technique. The surfaces modified by polysaccharide-based multilayers were investigated by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measurements. The fibrinogen adsorption and platelet adhesion to the surfaces, cytocompatibility to L-929 cells, and antibacterial activity against Pseudomonas aeruginosa of unmodified PU and LbL-modified PU were tested in vitro, respectively. The results showed that the water contact angle decreased gradually during the successive buildup of the polysaccharide-based multilayers, and decreased slowly after four bilayers were assembled. The surface roughness of PU modified by five bilayers (LS as topmost layer) increased compared with that of unmodified PU. The fibrinogen adsorption on the surface decreased 81% after assembly of five bilayers (LS as topmost layer). The number of adherent platelets on the surface modified by five bilayers (LS as topmost layer) is reduced, in comparison with that of the unmodified PU. The tests of L-929 cells indicated that LbL-modified PU surfaces had better cytocompatibility than unmodified PU. In addition, PU modified by polysaccharide-based multilayers showed antibacterial activity against P. aeruginosa.