Fablication of porous 3-D structure from poly(L-lactide)-based nano-composites.

为了在可生物降解的聚酯材料中制备多孔三维结构，我们以酶K为降解剂，在37℃的条件下，对具有纳米细胞结构的聚L-丙交酯(PLLA)基纳米复合泡沫进行了降解。用扫描电子显微镜观察了酶解不同时间后回收的泡沫的表面和截面形貌。与块体(预发泡)相比，纳米泡沫塑料吸水量大，比表面积大，导致泡沫塑料溶胀，有利于基质PLLA的酶降解。因此，我们成功地制备了一个多孔的三维结构，作为纳米复合泡沫核心部分的剩余支架，反映了结晶的PLLA的球晶。为了了解泡沫塑料的结构对酶降解和孔结构发展的影响，我们在37℃下，以蛋白水解酶K为降解剂，研究了具有不同泡孔密度(微孔和纳米细胞)的聚乳酸-聚乳酸纳米复合泡沫塑料的酶降解行为。用扫描电子显微镜和压汞法研究了酶解不同时间后回收的泡沫的表面和截面形貌。研究了组织工程支架多孔三维结构的制备及其在纳米复合泡沫塑料中的降解性能。

In order to prepare the porous three-dimensional(3-D) structure in biodegradable polyester materials we have conducted the enzymatic degradation of a poly(L-lactide)(PLLA)-based nano-composite foam having nanocellular structure, using proteinase-K as a degrading agent at 37℃. The surface and cross sectional morphologies of the foam recovered after enzymatic hydrolysis for different intervals were investigated by using scanning electron microscope. The nanocelluar took up large amount of water, which led to the swelling of the foam due to the large surface area inside the nanocelluar structure, and facilitated the enzymatic degradation of matrix PLLA as compared with the bulk(pre-foamed) sample. Consequently, we have successfully prepared a porous 3-D structure as a remaining scaffold in the core part of the nano-composite foam, reflecting the spherulite of the crystallized PLLA. To understand the effect of the foam structure on the enzymatic degradation and porous structure development, we have examined the enzymatic degradation of a poly(L-lactide)(PLLA)-based nano-composite foam having different cell density(microcellular and nanocellular), using proteinase-K as a degrading agent at 37℃. The surface and cross sectional morphologies of the foam recovered after enzymatic hydrolysis for different intervals were investigated by using scanning electron microscopic and mercury porosimetric analyses. The fabrication of porous three-dimensional structure for tissue engineering scaffolds and the degradation performance in nano-composite foams were demonstrated.