PU/chitosan Composite Materials Of Biological Properties

With their special properties, biomedical materials can be applied in disease prevention, diagnosis, treatment, rehabilitation, tissue function promotions and as substitutes for damaged or disabled human organs. Polyurethane (PU) is a common biomedical material with good biological compatibility and mechanical properties. Chitosan (CS) is a natural polysaccharide with excellent performance in abundant storage, biocompatibility, biodegradability, and bioactivity. Au nanoparticles (AuNPs) are favored in biomaterials due to it biocompatibility. Layer-by-layer (LBL) multilayer films are widely applied in biomaterials because of their special multilayer structures. In this thesis, on one hand we use different amounts of AuNPs to modify PU/CS biocompatible materials; on the other hand multilayer films are formed by PU and CS through electrostatic interaction of oppositely charged polyelectrolytes by using spin coating technology. The following work has been carried out based on the information above.(1) PU/CS biocompatible materials by different concentrations of AuNPs. A series of studies were carried out by testing the Recalcification Time, three part of hemoglutination items, including Thrombin Time, Prothrombin Time and Activated Partial Thromboplastin Time, and cell culture experiments, to check the biocompatibility, cell toxicity, and anticoagulation of the modified materials. This thesis concentrated on the influence of different AuNPs incorporations to the improvement of biological properties. Based on the results, it was decided to incorporate 100μg/g of AuNPs into the PU/CS substrate for further research.(2) In order to improve the ability of anticoagulation, we introduced LBL conception into our research. We take an initial attempt of the spin-coating process to form LBL. A serial studies, including SEM, AFM, Water Contact Angle and drag controlled release, are carried to characterize the properties of film-thickness, hydrophilicity, and surface roughness. A linear growth of LBL films and a regular change of water contact angle were observed. The surface became smoother as the film thickness increased. And the curve during drug release was almost linear.In conclusion, AuNPs modified PU/CS show good biocompatibility. It gives us greater confidence for its implantation in the human body. LBL surface modification produced significant changes of surface properties. We believe it have certain value in improving anticoagulant proporties.