Synthesis And Properties Of Hierarchically Structured Polymer Scaffolds For Tissue Engineering

Three-dimensional porous tissue engineering scaffolds provide the microenvironment for the cell growth, which have been one of the irreplaceable elements in tissue engineering. Therefore, it has become the current research hotspot in this area. Ideally, the tissue engineering scaffolds should have the following characteristics-high porosity, a highly interconnected porous structure, suitable mechanical strength and good biocompatibility. Therefore, how to fabricate an ideal scaffold in line with the demand for tissue engineering has very important practical significance.This dissertation pays attention on the fabrication method of three-dimensional porous tissue engineering scaffolds, micro-morphology, and property. The novel porous tissue engineering scaffolds with high porosity and highly interconnected structure were manufactured by choosing suitable method, designing rational material composition, adjusting micro-morphology, porosity, water absorption, and mechanical properties. This paper includes the following content and results:PLA and PLA/P(3HB-co-4HB) composite scaffolds were prepared by modified solution casting/particle leaching method. The influence of material composition on the micro-morphology, porosity, swelling ratio degradation speed and mechanical strength was systematic studied. The results indicated that the composite scaffolds presented3-D highly interconnected porous structure and the porosity was more than90%. As the content of P(3HB-co-4HB) increased, the saturation swelling ratio and degradation speed increased, but the compression modulus and50%strain strengthen decreased.Bone marrow stem cells (BMSCs) were used as seed cells to culture on scaffolds in vitro to evaluation the biocompatibility of scaffolds. MTT results showed that the composite scaffolds were all non-toxic and had good biocompatibility. The BMSCs proliferated greatly After10days of culture. The LSCM image indicated that BMSCs grew well in the scaffolds and could penetrate into the inner of the scaffold. Especially, The BMSCs grew best on the PLA/P(3HB-co-4HB) composite scaffolds (PP50/50and PP33/67scaffold) with fibrous pore walls.Oriented P(3HB-co-4HB) scaffolds with oriented microtubules were fabricated by gradient temperature thermal induced phase separation method. The influence of polymer concentration, temperature on the microstructure and properties was systematic investigated. The micro-morphology of scaffolds were observed by SEM, and the porosity, swelling ratio, contact angle and mechanical strengthen were measured. The results indicated that P(3HB-co-4HB) scaffolds with the porosity greater than90%had an oriented microtubules microstructure and the size of microtubules was100-150μm. The mechanical of oriented scaffolds showed anisotropy in longitudinal and transverse direction. The compression modulus and50%strain strengthen in longitudinal direction were much more than in transverse direction.