Preparation, physicochemical properties and biocompatibility of biodegradable poly(ether-ester-urethane) and chitosan oligosaccharide composites

In the paper, novel composites of biodegradable poly(ether-ester-urethane) (PEEU) and water-soluble chitosan oligosaccharide (CHO) were prepared using a simple physical mixing method and their potential application as biomaterials was assessed. The PEEU and CHO were dissolved in N,N-dimethylformamide to get a homogenous solution, then the composite films were obtained by the solvent evaporation method. The composites were characterized by FT-IR, and the influence of CHO content on the physicochemical properties of the composite films, including thermal properties, surface morphologies, mechanical properties, surface and bulk hydrophilicity, and in vitro biodegradability, were researched. The thermal stability studies indicated that the composite films had lower initial decomposition temperature and higher maximum decomposition temperature than PEEU film. Only one broad endothermic peak found in DSC curves demonstrated the high compatibility of CHO with PEEU. The ultimate stress and elongation at break of composite films decreased with the increment of CHO content, and the CHO content in the composites should be controlled no more than 25 wt% in order to maintain the mechanical properties (ultimate stress: 18.5 MPa; elongation at break: 890%) to meet the requirement of implant materials. The surface morphologies of composite films were observed by cold field emission scanning electron microscope (FE-SEM), and the results indicated that the homogeneous-dispersed composites could be obtained with CHO content being less than 20 wt%. The results of water contact angle and water absorption showed that the surface and bulk hydrophilicity were closely related with the water-solubility of CHO component. In vitro degradation studies showed that the degradation rate increased with the increasing content of CHO in composites, indicating that the degradation rate of composite films could be controlled by adjusting CHO content. The surface blood compatibility of the composite films was examined by bovine serum albumin adsorption and platelet adhesion tests. It was found that composite films had improved resistance to protein adsorption and possessed excellent resistance to platelet adhesion.