Chen Victor J, Ma Peter X
Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109-1078, USA.
Biomaterials. 2006 Jul;27(20):3708-15. doi: 10.1016/j.biomaterials.2006.02.020. Epub 2006 Mar 7.
In vitro hydrolytic degradation behavior was examined for nano-fibrous (NF) poly(L-lactic acid) (PLLA) foams prepared by phase separation. NF foams were incubated in phosphate-buffered saline at 37 degrees C for 15 months. Upon removal, changes in mass, molar mass, morphology, BET specific surface area, mechanical properties, and thermal properties were compared with those of similarly incubated solid-walled (SW) PLLA foams. Initial surface area in NF foams was over 80 times higher than in SW foams. During incubation, NF surface area decreased steadily, only possessing 17% of the original specific surface area after 15 months, SW surface area stayed constant throughout. While molar mass decreased for both types of samples, degradation was much more rapid in NF foams. In NF foams, overall mass loss was 51% while mass loss in SW foams was only 6% after 15 months. Morphology of NF foams began as a mesh of fibers, and became increasingly porous as fibers began to aggregate, thus diminishing the mechanical properties. In SW foams, morphology was non-fibrous and remained unchanged which helped maintain their mechanical properties. These results suggest that the high surface area in NF foams accelerated the rate of hydrolytic degradation.
对通过相分离制备的纳米纤维（NF）聚（L-乳酸）（PLLA）泡沫材料的体外水解降解行为进行了研究。将NF泡沫材料在37℃的磷酸盐缓冲盐溶液中孵育15个月。取出后，将其质量、摩尔质量、形态、BET比表面积、机械性能和热性能的变化与同样孵育的实心壁（SW）PLLA泡沫材料进行比较。NF泡沫材料的初始表面积比SW泡沫材料高80多倍。在孵育过程中，NF的表面积稳步下降，1个月后仅占原始比表面积的17%，而SW的表面积在整个过程中保持不变。虽然两种样品的摩尔质量都降低了，但NF泡沫材料的降解速度要快得多。在NF泡沫材料中，15个月后的总质量损失为51%，而SW泡沫材料的质量损失仅为6%。NF泡沫材料的形态最初是纤维网，随着纤维开始聚集，孔隙越来越多，从而降低了机械性能。在SW泡沫材料中，形态是非纤维状的，并且保持不变，这有助于保持其机械性能。这些结果表明，NF泡沫材料的高表面积加速了水解降解速率。
