Analytical Chemistry Group, Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
Biomacromolecules. 2011 Sep 12;12(9):3243-51. doi: 10.1021/bm200709r. Epub 2011 Aug 3.
To scrutinize materials for specific biomedical applications, we need sensitive and selective analytical methods that can give more insight into the process of their biodegradation. In the present study, the enzymatic degradation of multiblock poly(ester amide) based on natural amino acids, such as lysine and leucine, was performed with serine proteases (α-chymotrypsin (α-CT) and proteinase K (PK)) in phosphate-buffered saline solution at 37 °C for 4 weeks. Fully and partially degraded water-soluble products were analyzed by liquid chromatography hyphenated with time-of-flight mass spectrometry using an electrospray interface (LC-ESI-ToF-MS). Tracking the release of monomeric and oligomeric products into the enzyme media during the course of enzymatic degradation revealed the preferences of α-CT and PK toward ester and amide bonds: both α-CT and PK showed esterase and amidase activity. Although within the experimental time frame up to 30 and 15% weight loss was observed in case of α-CT and PK, respectively, analysis by size exclusion chromatography showed no change in the characteristic molecular-weight averages of the remaining polymer. This suggests that the enzymatic degradation occurs at the surface of this biomaterial. A sustained and linear degradation over a period of 4 weeks supports the potential of this class of poly(ester amide)s for drug delivery applications.
为了针对特定的生物医学应用仔细研究材料，我们需要灵敏且有选择性的分析方法，以便更深入地了解它们的生物降解过程。在本研究中，在 37°C 的磷酸盐缓冲溶液中，使用丝氨酸蛋白酶（α-糜蛋白酶（α-CT）和蛋白酶 K（PK））对基于天然氨基酸（如赖氨酸和亮氨酸）的多嵌段聚（酯酰胺）进行了酶降解。完全和部分降解的水溶性产物通过液相色谱与飞行时间质谱联用（LC-ESI-ToF-MS），采用电喷雾接口进行分析。在酶降解过程中追踪单体和低聚物产物释放到酶介质中，揭示了 α-CT 和 PK 对酯键和酰胺键的偏好：α-CT 和 PK 均表现出酯酶和酰胺酶活性。尽管在实验时间范围内 α-CT 和 PK 分别观察到 30%和 15%的重量损失，但尺寸排阻色谱分析表明剩余聚合物的特征重均分子量平均值没有变化。这表明酶降解发生在这种生物材料的表面。在 4 周的时间内持续线性降解支持了这类聚（酯酰胺）在药物输送应用中的潜力。
