Thu B, Bruheim P, Espevik T, Smidsrød O, Soon-Shiong P, Skjåk-Braek G
Norwegian Biopolymer Laboratory, Department of Biotechnology, Norwegian Institute of Technology, University of Trondheim, Norway.
Biomaterials. 1996 Jun;17(11):1069-79. doi: 10.1016/0142-9612(96)85907-2.
The main cause of alginate polycation capsule breakage under physiological conditions is probably the osmotic swelling of the alginate core owing to the Donnan equilibrium set up by the negative charges of the carboxyl groups not involved in cooperative binding of counterions in the junction zones of the network. In the present paper we show how capsules can be stabilized extensively by reducing their swelling capacity in various ways. Alginate polycation capsules with good chemical and mechanical stability have been made by controlling their swelling behaviour through selection of capsule material according to chemical structure and molecular weight, as well as by controlling the kinetics of the capsule formation. Stable capsules have been made either by increasing the strength of the polyanion-polycation membrane, or by keeping a low-swelling gel network in the core. The latter capsules are made from an alginate rich in guluronic acid both in the core and in an outer coating, and with anisotropic distribution of the polymer material in the core where the concentration at the surface is higher than that in the centre of the capsule. Some functional properties of these capsules, such as porosity, have also been studied.
藻酸盐聚阳离子胶囊在生理条件下破裂的主要原因可能是藻酸盐核心的渗透膨胀，这是由于在网络连接区未参与抗衡离子协同结合的羧基负电荷建立的唐南平衡所致。在本文中，我们展示了如何通过多种方式降低胶囊的膨胀能力来广泛地稳定胶囊。通过根据化学结构和分子量选择胶囊材料来控制其膨胀行为，以及通过控制胶囊形成的动力学，制备出了具有良好化学和机械稳定性的藻酸盐聚阳离子胶囊。稳定的胶囊可以通过增强聚阴离子-聚阳离子膜的强度来制备，也可以通过在核心中保持低膨胀凝胶网络来制备。后一种胶囊的核心和外层涂层均由富含古洛糖醛酸的藻酸盐制成，并且聚合物材料在核心中呈各向异性分布，表面浓度高于胶囊中心浓度。还研究了这些胶囊的一些功能特性，如孔隙率。
