Poly3,4-ethylenedioxythiophene/Chitosan Conductive Porous Scaffolds For Tissue Engineering,Preparation And Characterization

The regeneration and function restoration of peripheral nerve injury have been a hot topic in neuroscience. At present, autologous nerve transplantation works best but it is restricted by problems such as limited donor sources, repair length and formation of scar tissue, therefore it is not the best choice. Recently, Professor Cederma in University of Michigan, Ann Arbor developed In Situ polymerization of a conductive polymer-poly(3,4-ethylenedioxythiophene)(PEDOT) in acellular muscle tissue constructs, in order to build a neural pathway. This research causes a wide attention of PEDOT applications in medical science. Current research is focused on developing an improved scaffold which could be used in connecting and regenerating of peripheral nerve injury.Conductive polymers not only have good biocompatibility, but also could modify multiple functions of the cells such as adhesion, proliferation, migration and differentiation, also the synthesis of DNA, and the secretion of protein. Therefore, in biomedical engineering, conductive polymers have a potential of broad applications and important research value. PEDOT is an insoluble polymer in water; it has excellent environmental stability and high electrical conductivity; It is not easy to oxidation. As a biomaterial, it can provide electrical conductivity while support tissue growth.Chitosan is obtained from chitin by removing the acetyl group on C2position from the molecule. It is the only known alkaline polysaccharide among natural polysaccharides, which has excellent biocompatibility and biodegradability, and its degradation products generally are not harmful to human body, would not accumulate in body and have no immunogenicity. In addition, chitosan is also antibacterial, antiseptic, antitumor, and has biological activity such as promoting tissue repair and hemostasis. Chitosan can be used as wound dressings, drug delivery system and tissue engineering material (cartilage, nerve and liver tissue). Its mild processing conditions, controllable mechanical properties, controllable biodegradable properties, suitable functional groups which can attach to other molecules make it suitable as a candidate for tissue engineering. Thus, chitosan are widely used in biomedical field, especially in tissue restoration.Based on the analysis above, this thesis prepared PEDOT polymer material through chemical oxidation method. The structure and properties were characterized and ion doping was discussed. Using lyophilized method, a series of porous chitosan scaffolds with different chitosan concentration and crosslinking density were prepared. Through scanning electron microscopy (SEM), we found the pore size of the scaffolds is about100～200μm, and the porosity is90%or above, they have high water absorption and excellent mechanical properties. Based on these researches, PEDOT/Chitosan Porous-Conductive composite materials were prepared by in situ polymerization of PEDOT on the surface of chitosan scaffolds. The experimental results indicate that the electrical conductivity of this composite material is above10-4S/cm, which is effective in vitro or in vivo physiological stimulation, as well as high porosity and excellent mechanical properties.PEDOT/chitosan porous-conductive composite materials could be used as supporter of artificial nervous scaffold, which are expected to greatly promote regeneration after nervous injury and would become a promising research area.