Rosiński S, Grigorescu G, Lewińska D, Ritzén L G, Viernstein H, Teunou E, Poncelet D, Zhang Z, Fan X, Serp D, Marison I, Hunkeler D
Institute of Biocybernetics and Biomedical Engineering, Warsaw, Poland.
J Microencapsul. 2002 Sep-Oct;19(5):641-59. doi: 10.1080/02652040210142533.
Alginate beads, as well as microcapsules based on alginate, cellulose sulphate and polymethylene-co-guanidine, were produced at diameters of 0.4, 1.0 and 1.5 mm. These standard materials were tested, by independent laboratories, in regards to water activity, bead or capsule size, mechanical resistance and transport behaviour. The water activity and mechanical resistance were observed to increase with bead and capsule size. Transport properties (ingress) were assessed using a variety of low molar mass and macromolecular probes. It was observed that the penetration of Vitamin B12 increased with bead diameter, as did dextran penetration. However, for the membrane-containing microcapsules, larger membrane thickness, observed for the larger capsules, retarded ingress. The authors, who are part of a European working group, recommend that permeability be assessed either using a large range of probes or a broad molar mass standard, with measurements at one or two molar masses insufficient to simulate the behaviour in application. Mechanical compression is seen as a good means to estimate elasticity and rupture of beads and capsules, with the sensitivity of the force transducer, which can vary from microN to tens of N, required to be tuned to the anticipated bead or capsule strength. Overall, with the exception of the mechanical properties, the precision in the inter-laboratory testing was good. Furthermore, the various methods of assessing transport properties agreed, in ranking, for the beads and capsules characterized, with gels having smaller radii being less permeable. For microcapsules, the permeation across the membrane dominates the ingress, and thicker membranes have lower permeability.
制备了直径为0.4、1.0和1.5毫米的藻酸盐珠以及基于藻酸盐、硫酸纤维素和聚亚甲基胍的微胶囊。这些标准材料由独立实验室对水分活度、珠或胶囊尺寸、机械抗性和传输行为进行了测试。观察到水分活度和机械抗性随珠和胶囊尺寸的增加而增加。使用多种低摩尔质量和大分子探针评估传输特性（进入情况）。观察到维生素B12的渗透率随珠直径的增加而增加，葡聚糖的渗透率也是如此。然而，对于含膜微胶囊，较大胶囊的膜厚度更大，这阻碍了物质进入。作为欧洲工作组一部分的作者建议，应使用大范围的探针或宽摩尔质量标准来评估渗透率，仅在一两个摩尔质量下进行测量不足以模拟实际应用中的行为。机械压缩被视为估计珠和胶囊弹性及破裂情况的一种好方法，需要将力传感器的灵敏度（其范围可从微牛到几十牛）调整到预期的珠或胶囊强度。总体而言，除机械性能外，实验室间测试的精度良好。此外，对于所表征的珠和胶囊，评估传输特性的各种方法在排序上是一致的，半径较小的凝胶渗透性较低。对于微胶囊，跨膜渗透主导物质进入，膜越厚渗透率越低。
