Modification And Biocompatibility Of Medical Polyurethane Materials

Bio medical material is a kind of advanced hi-tech materials which have special functions on reparation, replacement and regeneration of organic tissues. Polyurethanes (PU) have been widely used for biomedical material because of their excellent mechanical properties and good blood compatibility. However, the intrinsic hydrophobicity of PU limits their applications. An important and useful method to improve the surface hydrophilic properties is surface modification, which is not damage the bulk properties of the material.Hydrophilic Poly(N-vinylpyrrolidone)(PVP), natural electronegative Chondroitin sulfate and Chondroitin sulfate-Chitosan bimolecular layer were grafted onto PU films by surface-initiated atom transfer radical polymerization (SI-ATRP), chemical method, layer-by-layer self-assembly technique, respectively. Chemical and morphological changes of the modified films surface were systematically characterized by Attenuated total reflection-Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectrometer (XPS), atomic force microscope (AFM) and water contact angle measurements. The relationship between hydrophilic surface and cell adhesion had also been investigated. The results indicated that the hydrophilicity of the PU-PVP films increased after modification and the water contact angle decreasing from92°to46°. Compared with naked PU films, the modified PU films reduced the level of adsorption of Bovine serum fibrinogen (BFG), Bovine serum albumin (BSA) and Lysozyme (LYS) by88%,79%and63%, respectively. Moreover, L-929cell infrequent attached on the surface of the modified PU films. For chondroitin sulfate modified PU films, the water contact angle was52°. The reduction in the level of protein adsorption,77%for BFG,91%for BSA, was achieved compared to the unmodified PU. Layer-by-layer self-assembly modified PU films displayed excellent hydrophilicity and water contact angle minimized to35°. Besides, the proposed films possessed the ability to resist the nonspecific adsorption of proteins. The adsorption of BFG and BSA reduced by77%and60%compared with those of unmodified PU. Furthermore. L-929can proliferate well on the surface of modified PU.