Research On Self-buffer Action Of Three-Dimensional Cell Scaffold

Based on the life sciences and fundamentals, theories, techniques and methods of engineering, Tissue Engineering is a science for the bio-active implant system construction used to replace or restore mal-functional tissue or organ. Tissue Engineering not only offers a new therapy method for alleviating patient's pain, but also provides new thought of copying the"tissue"and"organ". It indicates an epoch of human body bio-science and technology and a new era of regeneration medicine. It's a far-reaching signification revolution. Three key factors are involved in the Tissue Engineering, which are seeding cell, cell scaffold and tissue construction. Cell scaffold will affect cell bio-action and foster efficiency. Furthermore, it decides cell's adaptation, combination and rehabilitation after implantation. Cell scaffold is a hinge factor which restricts tissue engineering clinical application. It is very important to manufacture cell scaffold with good biocompatibility, high porosity and interconnection to meet the requirements of tissue engineering.Disodium hydrogen phosphate spherical porogen with variable sizes was prepared by Spray technique in this paper. A modified Solvent Casting / Particulate Leaching, called pressing molding technique, was developed to build PDLLA cell scaffold. The factors which will affect the pore structure, configuration and interconnection were studied. In order to characterize the self-buffer action of PDLLA scaffold with microcapsule, the infection of form and particle size of microcapsule, and content and release rate of lysine were discussed in different conditions. In vitro degradation of scaffolds was characterized and related factors were discussed. A method for detecting pH value of micro-liter solution was applied to assay acidity of scaffold inner part in the degradation process.Column PDLLA scaffolds of 0.826±0.079 cm in diameter and 0.314±0.016 cm in height were fabricated. The porosity of the porous PDLLA scaffold was over 93%. Results showed that the scaffold was homogeneous in pore distribution, regular in configuration, fully interconnected between pores, which suggested the pressing molding technique could satisfy Tissue Engineering requirements and it was one of the fast and useful methods to fabricate PDLLA scaffold. Microscopic photos and SEM showed microcapsule just only remained in the wall of scaffold and the pore configuration, structure and interconnection of PDLLA scaffold remained unchanged after joined with microcapsule. It implied that this was a potential technique to form scaffold with high porosity and interconnection. On the other hand, local acidity cumulation could be effectively avoided and inner-structure could be controlled when microcapsule was joined in scaffold produced by pressing molding technique. Acidity detection method for micro-liter solution was applied. It was validated that the method was stable, accurate, precision, and suitable for detection pH value of scaffold degradation. The results of scaffold degradation in vitro revealed that the medium and content of microcapsule were the major factors which would affect the molecular weight and acidity. No obvious pH difference was observed between inner and outer medium during degradation process, which suggested the medium exchange between inner and outer scaffold must be effective and the scaffold must have good interconnection between pores.In general, PDLLA scaffold with homogenous pore distribution, high porosity and interconnection can be fabricated through pressing molding technique. Furthermore, self-catalyzed hydrolyze of PLA can be effectively avoided and buffer action of microcapsule is promising. Therefore, the obtained PDLLA scaffold can satisfy the requirements of Tissue Engineering. It was also validated that the acidity assay in micro-liter solution was a potential application for characterizing scaffold degradation in vitro and in vivo.