Serp D, Cantana E, Heinzen C, Von Stockar U, Marison I W
Laboratory of Chemical and Biochemical Engineering, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland.
Biotechnol Bioeng. 2000 Oct 5;70(1):41-53.
An encapsulation device, designed on the basis of the laminar jet break-up technique, is characterized for cell immobilization with different types of alginate. The principle of operation of the completely sterilizable encapsulator, together with techniques for the continuous production of beads from 250 microm to 1 mm in diameter, with a size distribution below 5%, at a flow rate of 1-15 mL/min, is described. A modification of the device, to incorporate an electrostatic potential between the alginate droplets and an internal electrode, results in enhanced monodispersity with no adverse effects on cell viability. The maximum cell loading capacity of the beads strongly depends on the nozzle diameter as well as the cells used. For the yeast Phaffia rhodozyma, it is possible to generate 700 microm alginate beads with an initial cell concentration of 1 x 10(8) cells/mL of alginate whereas only 1 x 10(6) cells/ml could be entrapped within 400 microm beads. The alginate beads have been characterized with respect to mechanical resistance and size distribution immediately after production and as a function of storage conditions. The beads remain stable in the presence of acetic acid, hydrochloric acid, water, basic water, and sodium ions. The latter stability applies when the ratio of sodium: calcium ions is less than 1/5. Complexing agents such as sodium citrate result in the rapid solubilization of the beads due to calcium removal. The presence of cells does not affect the mechanical resistance of the beads. Finally, the mechanical resistance of alginate beads can be doubled by treatment with 5-10 kDa chitosan, resulting in reduced leaching of cells.
一种基于层流射流破碎技术设计的封装装置，其特点是能够用不同类型的藻酸盐固定细胞。描述了这种完全可消毒封装器的工作原理，以及以1 - 15毫升/分钟的流速连续生产直径从250微米到1毫米、尺寸分布低于5%的珠子的技术。对该装置进行了改进，在藻酸盐液滴和内部电极之间引入静电势，可提高单分散性且对细胞活力无不利影响。珠子的最大细胞装载量很大程度上取决于喷嘴直径以及所使用的细胞。对于红发夫酵母，初始细胞浓度为每毫升藻酸盐1×10⁸个细胞时，能够生成700微米的藻酸盐珠子，而在400微米的珠子中只能包埋每毫升1×10⁶个细胞。已对藻酸盐珠子在生产后立即以及作为储存条件的函数的机械抗性和尺寸分布进行了表征。珠子在乙酸、盐酸、水、碱性水和钠离子存在的情况下保持稳定。当钠与钙离子的比例小于1/5时，后一种稳定性成立。柠檬酸钠等络合剂会由于钙的去除导致珠子迅速溶解。细胞的存在不影响珠子的机械抗性。最后，用5 - 10 kDa的壳聚糖处理可使藻酸盐珠子的机械抗性提高一倍，从而减少细胞的渗漏。
