Rehor A, Canaple L, Zhang Z, Hunkeler D
Department of Chemistry, Swiss Federal Institute of Technology, Lausanne.
J Biomater Sci Polym Ed. 2001;12(2):157-70. doi: 10.1163/156856201750180898.
The clinical application of microcapsules for the immunoisolation of living tissue requires knowledge about the mechanical stability of polymer membranes. Microcapsules of 400-1000 microm in diameter were formed through the gelation of sodium alginate/sodium cellulose sulfate droplets through calcium chloride, with the membrane produced via complex coacervation between polyanions and poly(methylene-co-guanidine) hydrochloride. The deformation behavior of these multicomponent microcapsules was investigated by uniaxial compression experiments. Specifically, the influence of the deformation speed, capsule diameter, and membrane thickness on the mechanical properties was evaluated. The bursting force was found to be dependent on the deformation speed. Therefore, the measurement of the bursting work, a speed-independent value of the resistance to high stresses and deformations, was recommended as the most valid for capsule mechanical resistance. Furthermore, the bursting force was positively correlated with membrane thickness only for membrane-radius ratios up to 20%. For thicker membranes, the bursting event occurred because the opposite membranes touched each other, and not, because of insufficient strength. Indeed, the resistance to smaller deformations was positively correlated to the membrane thickness over the whole range of membrane-radius ratios. Moreover, the forces for constant deformation were linearly correlated to the total membrane volume, independently of capsule size and membrane thickness.
用于活组织免疫隔离的微胶囊的临床应用需要了解聚合物膜的机械稳定性。通过氯化钙使海藻酸钠/硫酸纤维素钠液滴凝胶化形成直径为400 - 1000微米的微胶囊，其膜是通过聚阴离子与聚（亚甲基 - 共 - 胍）盐酸盐之间的复合凝聚产生的。通过单轴压缩实验研究了这些多组分微胶囊的变形行为。具体而言，评估了变形速度、胶囊直径和膜厚度对机械性能的影响。发现破裂力取决于变形速度。因此，建议测量破裂功，这是一个与速度无关的抗高应力和变形的值，作为对胶囊机械抗性最有效的测量方法。此外，仅当膜半径比高达20%时，破裂力才与膜厚度呈正相关。对于较厚的膜，破裂事件的发生是因为相对的膜相互接触，而不是因为强度不足。实际上，在整个膜半径比范围内，对较小变形的抗性与膜厚度呈正相关。此外，恒定变形所需的力与总膜体积呈线性相关，与胶囊大小和膜厚度无关。
