实验中选取了带有正电罗丹明6G分子、 带有负电荷荧光素分子、 中性的尼罗红分子和生物分子R-藻红蛋白为模型分子。 将这几种分子分别包封于海藻酸钙空心胶囊中。 实验表明囊芯分子的电性对其在海藻酸钙空心胶囊中缓释性能有影响, 带有正电荷罗丹明6G分子的扩散过程中, 多孔聚合物骨架扩散是主要过程。 中性分子则表现出来一个膜相溶出和多孔聚合物骨架扩散共同控制的过程。 带有负电荷荧光素分子, 由于静电排斥作用, 加剧囊芯分子的运动。 从而使得荧光素分子可以直接从膜相溶出。 此外, 由于胶囊囊壁上带有负电, 不论是带有正电荷还是带有负电荷的分子都会延长其达到扩散平衡的时间。 而电中性分子由于没有库仑相互作用的影响更容易达到平衡。 囊芯和囊壁相互作用强的其扩散系数小, 反之其扩散系数大。 R-藻红蛋白的扩散完全是一个多孔聚合物骨架扩散控制的过程。 由于分子的体积比较大, 因此扩散的平衡时间也比较长。

In this paper, the authors employ three different types of dye molecules, Nile red, Rhodamine 6G, fluorescein and a fluorescent protein-R-phycoerythrin (R-PE).The Rhodamine 6G is positively charged molecules, fluorescein is negatively charged molecules, and Nile red is neutral molecules.The R-phycoerythrins have either a net positive or negative charge which is balanced at the isoelectric point (4.22).It is negatively charged molecules also under our experimental condition.The Nile red, rhodamine 6G, fluorescein and R-phycoerythrin are trapped into alginate calcium hollow capsule respectively.The diffusion processes of those molecules from calcium alginate capsule to solution are measured based on a fluorescence method.The results indicate that electrical characteristics of encapsulated molecules have effect on their diffusion behaviors.The positively charged rhodamine 6G is well accordance with a model of control release from porous polymer membranes.The neutral molecules not only can be released from porous polymer framework, they also can directly dissolve out through polymer membrane.The electrostatic repulsion between fluorescein and negatively charged calcium alginate membranes will accelerate the molecular motion, which is propitious to molecules directly dissolving out through polymer membrane.Based on Fick’s law of diffusion, R-PEs can be releases from porous polymer framework.It shows the longest equilibrium time.Comparing neutral molecules, negatively and positively charge molecules show the stronger interaction on electric polymer membrane, which results in that the diffusion coefficients of rhodamine 6G and fluorescein are less than that of neutral molecule Nile red.The consequences obtained here should readily explain analogous control releasing behaviors of other functional molecules.