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

为了在可生物降解聚酯材料中制备三维多孔结构，以蛋白酶K为降解剂，在37℃下对具有纳米泡孔结构的聚L-乳酸（PLLA）基纳米复合泡沫材料进行了酶降解。利用扫描电镜对酶解不同时间后泡沫的表面和截面形貌进行了研究。纳米纤维素吸收了大量的水，由于纳米纤维素结构内部的大表面积，这导致了泡沫的溶胀，并且与本体（预发泡）样品相比，促进了基质PLLA的酶降解。因此，我们已经成功地制备了多孔的3-D结构作为纳米复合泡沫的核心部分中的剩余支架，反映了结晶PLLA的球晶。为了了解泡沫结构对酶降解和多孔结构发展的影响，我们研究了具有不同孔密度（微孔和纳米孔）的聚（L-乳酸）（PLLA）基纳米复合泡沫的酶降解，使用蛋白酶-K作为降解剂，在37℃下。利用扫描电镜和压汞法分析了酶解后不同时间段泡沫的表面和横截面形貌。研究了多孔三维结构组织工程支架材料的制备及其在纳米复合泡沫材料中的降解性能。

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.