Hydrophobic Tetramer Structures of Cholic Acid

Cholic
acid (CA) is a primary bile acid which possesses facial
amphiphilicity and self-assembly ability. CA is slightly soluble in
water, which makes it impossible to form the self-assembled structures
spontaneously in aqueous solutions. To increase the water solubility,
a cholic acid ester (CA-4EG) with a hydrophilic tail (tetraethyleneglycol,
4EG) was synthesized, which forms self-assembled structures in aqueous
solutions. The self-assembled crystals of CA are obtained by acidic
hydrolyzing the ester bond of CA-4EG. The rhombic hydrophobic tetramer
structure units and fiber-layer structures are found in the self-assembled
crystals of CA.

胆酸（Cholic acid, CA）是一类兼具面两亲性与自组装能力的初级胆汁酸。其微溶于水，无法在水溶液中自发形成自组装结构。为改善其水溶性，研究者合成了带有亲水尾端四甘醇（tetraethyleneglycol, 4EG）的胆酸酯（CA-4EG），该衍生物可在水溶液中形成自组装结构。通过酸性水解CA-4EG的酯键，可制备得到胆酸的自组装晶体。在该胆酸自组装晶体中，可观测到菱形疏水四聚体结构单元与纤维层状结构。