PGLA降解产物对材料降解性能影响的体外研究

为了探讨PGLA材料的降解产物对材料本体降解性能的影响，本研究设计了体外两种浸泡体系——磷酸缓冲液（PBS）和人工血浆，分别在替换和不替换浸泡介质两组不同条件下，分析材料的质量损耗情况，并将不替换组的各时间段降解液进行pH值的测定，以判断环境的酸碱度对材料本体降解的作用。实验降解周期分别为2、3、4、6、8、10周。结果显示：在浸泡初期，人工血浆和PBS降解液中的质量损耗两者间无显著性差异（P〉0．05）；大约从2周到6周，不替液组中材料在两种介质内的降解速度显著快于相对应的同期换液组（P〈0．01）；不替换液组材料在PBS液中的降解快于在人工血浆中的降解，而且在整个降解周期内PBS降解液的pH值基本保持稳定（pH≈7．0～7．4），而人工血浆降解液中的pH值随着降解过程的不断进行，其pH值由7．5逐渐降到5．7左右，两种降解液pH值变化之间的差异具有显著的统计学意义（P〈0．01）。由此提示：在不替换浸泡介质的条件下，降解液中持续存在的降解产物显然影响材料本体的降解速度，PGLA材料的降解产物具有加速材料质量损耗的作用；环境的酸碱度对材料的降解会产生一定的影响，pH值越低，材料的降解速度越缓慢。

Effect of Degradable Products on Degradable Property of PGLA In Vitro

In order to investigate the effect of degradable products on degradable property of PGLA in vitro, two kinds of media-PBS and artificial plasma were prepared for immersing PGLA under changing or non-changing media condition. The mass loss rate of PLGA was calculated and the pH value in the non-changing media was measured before and after immersing 2 w, 3 w, 4 w, 6 w, 8 w and 10 w respectively. The results showed that there was almost no statistically significant difference of mass loss rate of PGLA immersing in two kinds of media at 2 w (P > 0.05). But from 2 w to 6 w, the degradation of PGLA immersing in both media under non-changing media group was remarkably faster than those at the same period of changing media group (P < 0.01). During the whole degradable period, the pH value in PBS kept stable around 7.0-7.4, while the pH value in artificial plasma showed gradually decreased as the degradation of PGLA from 7.5 to 5.7. The change of pH values had statistically significant difference between two degradable media (P < 0.01). It was implied that the degradable products existed in immersing media had an effect on degradable speed of PGLA itself if the media was unchanged. It could accelerate the mass loss of material. The pH value also affected the degradable property of PGLA, the lower the pH value, the slower the degradable speed.