Preparation And Characteristic Of The Nature Polysaccharide Porous Materials

Tissue engineering is an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function. It is one of the most hopeful ways to provide regeneration or replacements of defected tissues or organs. While, tissue engineering approach to repair and regeneration is founded upon the use of polymer scaffolds that serve to support, reinforce and in some cases organize generated tissue there. On the other hand, the scaffold must have high porosity and interconnected porous structure to provide adequate space for cell seeding, growth, differentiation and proliferation, as well as exchanging of nutrients and metabolized products of the cells, so porous scaffolds play a very important role in tissue engineering, and the preparation and exploiture of porous scaffold materials has been an important researching subject in tissue engineering area.Chitosan and gelatin are very abundant natural biodegradable materials, and they also have good biocompatibility and biodegradability. In recent years, study on them has been a major focus of interest in the biodegradable scaffold. Therefore, we chose chitosan and gelatin for the raw materials in our research and utilized unidirectional freeze-drying technology to manufacture simplex or composite porous scaffold materials. The structures of porous scaffold materials were characterized by SEM. Meanwhile, the physical properties were tested through percent water absorption, measurement of mechanical properties etc. The biological properties of porous scaffold materials were also investigated by protein absorption, degradation in vitro and cell culture.The experimental results show that chitosan, gelatin and their composite porous materials all have orientation microtubules structure. The pores are not in round shape, and many of them look similar to oblate or rhombus. The width and length of microtubules are from 50 to 100μm and 100 to 500μm, respectively. The scaffold with different pore size and high porosity up to 98% can be obtained by adjusting the concentration of the polymer solution during the preparation process. By increasing polymer concentration, the regularity of the microtubular scaffold has been improved and the density of the microtubules is increased as well. The water absorption ability goes down with the decrease of pore diameter of porous scaffold, but increasing gelatin proportion of composite porous materials, the water absorption ability is improved. The compressive strength of porous scaffolds along the transverse direction and the longitudinal direction is completely different, and the compressive strength along the longitudinal direction of the microtubules is much higher than those along the transverse direction, but they all increase with increase of polymer concentration. If increasing gelatin proportion of composite porous materials, the compressive strength of porous scaffolds is also increased. There are two factors that affect the protein absorption ability of chitosan porous materials, one is the porosity of the scaffolds, and the other is electrostatic interaction between protein and chitosan molecules. In vitro enzymatic degradation results show that the degradation degree of the chitosan scaffolds shows an increasing trend from low concentration to high concentration, and the disintegration rate of gelatin scaffolds is a reverse trend, but increasing gelatin proportion of composite porous materials, the disintegration rate of porous scaffolds is improved. In vitro cell culture results show that porous scaffolds are nontoxic to cartilage cells and they can spread and grow well on scaffolds.