Experimental Physics III, TU Dortmund University, 44227 Dortmund, Germany.
J Magn Reson. 2012 Aug;221:11-8. doi: 10.1016/j.jmr.2012.05.009. Epub 2012 May 26.
Microscopic capsules made from polysaccharides are used as carriers for drugs and food additives. Here, we use NMR microscopy to assess the permeability of capsule membranes and their stability under different environmental conditions. The results allow us to determine the suitability of different capsules for controlled drug delivery. As a measure of the membrane permeability, we monitor the diffusion of paramagnetic molecules into the microcapsules by dynamic NMR microimaging. We obtained the diffusion coefficients of the probe molecules in the membranes and in the capsule core by comparing the measured time dependent concentration maps with numerical solutions of the diffusion equation. The results reveal that external coatings strongly decrease the permeability of the capsules. In addition, we also visualized that the capsules are stable under gastric conditions but dissolve under simulated colonic conditions, as required for targeted drug delivery. Depending on the capsule, the timescales for these processes range from 1 to 28 h.
由多糖制成的微观胶囊可用作药物和食品添加剂的载体。在这里，我们使用 NMR 显微镜来评估胶囊膜的渗透性及其在不同环境条件下的稳定性。结果使我们能够确定不同胶囊在控制药物释放方面的适用性。作为膜渗透性的度量标准，我们通过动态 NMR 微观成像监测顺磁分子扩散到微胶囊中的情况。我们通过将测量的时变浓度图与扩散方程的数值解进行比较，获得了探针分子在膜中和胶囊核中的扩散系数。结果表明，外部涂层强烈降低了胶囊的渗透性。此外，我们还观察到胶囊在胃条件下稳定，但在模拟结肠条件下溶解，这是靶向药物输送所必需的。根据胶囊的不同，这些过程的时间尺度范围从 1 到 28 小时。
