胆酸盐是一种表面活性剂，它分子中具有亲水性的羟基和羧基，也具有疏水性的类固醇环，因此在水溶液中，它的疏水部分会通过氢键、范德华力等各种弱作用力聚在一起形成胆酸盐独特的聚集形态。众多的研究发现金属离子的存在以及不同离子的浓度，对于聚集体的结构、大小和形状有着重要的影响。 本文以NaDC为例，利用显微拍照和偏振显微拍照观察其在一系列较低浓度的外加金属离子（如： Mg2+、Ca2+、Na2+-Ca2+、Ba2+）影响下的聚集行为，并通过SEM细致地观察了这些聚集体的微观结构特点。比较各不同离子和不同浓度的同种离子影响下聚集结果的相同点和区别，可以知道这些聚集体是由许多的纳米丝组成扇形的片层结构，然后由这些片层结构的扇形球心再进一步的聚集相连，形成各种不同的高级结构。进一步用芘荧光探针显示金属离子的加入使得NaDC溶液I1/I3的值变小，也即芘周围环境的极性变小。这样推理出的聚集体结构变化与显微镜和SEM观察的结果基本吻合。

Bile salts are a kind of surfactant, which has both the hydrophilic carboxyl and hydroxyl, and the hydrophobic steroid ring. So when being in aqueous solution, it will form unique self-assembled patterns through hydrogen bonding, Van der Waals forces, and other weak force together between these hydrophobic parts. Many studies have found that the presence of many additional metal ions and the different concentrations of these ions, have an important effect on the structures, sizes and shapes of these aggregations. Sodium deoxycholate　(NaDC), as the one of most usual bile salts, is used as an example in this article. Lots of microscopic photos have been taken, with or without polarization, to record the aggregation phenomenon under the influence of different ions or under a series of different low concentrations of metal ions. SEM is also taken, by which we can observe the micro-structrue. Learning from the same and different phenomenon between these pictures, we can conclude that all these aggregations, although having different appearance, are made of many fan-like flakes. And these flakes are made of abundant silk. Further show the micro-environment changing during the process of aggregating, measured by the ratio of I1 and I3. Results through different means agree with each other very well.