Lu M Z, Lan H L, Wang F F, Chang S J, Wang Y J
Institute of Biomedical Engineering, National Yang Ming University, Shih-Pai, Taipei, Taiwan, ROC.
Biotechnol Bioeng. 2000 Dec 5;70(5):479-83. doi: 10.1002/1097-0290(20001205)70:5<479::aid-bit1>3.0.co;2-e.
In general, microcapsules prepared from alginate and polycations lack mechanical strength because the interaction between alginate and polycations is ionic instead of covalent, which represents a much stronger bond. To increase the mechanical strength of the capsule, we prepared photosensitive microcapsules that could form covalent bonds between polymers in the capsular membrane by light irradiation. Two types of photosensitive poly(allylamine), with 5% and 10% of amino groups modified by alpha-phenoxycinnamylidene acetylchloride, were synthesized. Both photopolymers exhibited an absorption maximum at 325 nm and were capable of crosslinking upon light exposure. These photosensitive polymers were used for the preparation of microcapsules. The capsules formed from this photosensitive poly(allylamine) and alginate were strengthened significantly by light irradiation. Only 28% of the microcapsules prepared from the 5%-modified photopolymer fractured after 48 h of shaking at 150 rpm. This fracture percentage is much lower when compared with the 60% of capsules fractured when prepared from the untreated poly(allylamine). By using poly(allylamine) at 10% modification, the mechanical strength was improved only slightly, with 26% of capsules fractured. Analysis of the permeability test indicated that the photo-crosslinked capsular membrane was freely permeable to cytochrome c and myoglobin, but less permeable to serum albumin. The encapsulation method was used to entrap and culture IW32 mouse leukemia cells. The cells proliferated to a density of about 1.1 x 10(7) cells/mL in the capsules after 7 days of cultivation. Concurrently, the concentration of erythropoietin in the microcapsules increased to 800 mU/mL. This new encapsulation technique has great potential in the application of a bioindustrial cell-culturing process.
一般来说，由藻酸盐和聚阳离子制备的微胶囊缺乏机械强度，因为藻酸盐和聚阳离子之间的相互作用是离子键而非共价键，而共价键是更强的化学键。为了提高微胶囊的机械强度，我们制备了光敏微胶囊，通过光照在囊膜中的聚合物之间形成共价键。合成了两种光敏聚烯丙胺，其中5%和10%的氨基被α-苯氧基肉桂叉乙酰氯修饰。两种光聚合物在325nm处都有最大吸收，并且在光照下能够交联。这些光敏聚合物用于制备微胶囊。由这种光敏聚烯丙胺和藻酸盐形成的微胶囊在光照后显著增强。由5%修饰的光聚合物制备的微胶囊在150rpm振荡48小时后，只有28%破裂。与由未处理的聚烯丙胺制备的微胶囊60%破裂相比，这个破裂百分比要低得多。使用10%修饰的聚烯丙胺时，机械强度仅略有提高，26%的微胶囊破裂。渗透性测试分析表明，光交联的囊膜对细胞色素c和肌红蛋白可自由渗透，但对血清白蛋白的渗透性较低。采用包封方法包埋和培养IW32小鼠白血病细胞。培养7天后，细胞在微胶囊中增殖至密度约为1.1×10⁷个细胞/mL。同时，微胶囊中促红细胞生成素的浓度增加到800mU/mL。这种新的包封技术在生物工业细胞培养过程的应用中具有巨大潜力。
