Aggregation of different amino acid conjugates of cholic acid in aqueous solution

A series of cholic acid derivatives was synthesized with a variety of α-amino acids coupled via an amide bond. These conjugates form aggregates in aqueous solutions. Cryo-transmission electron microscopy (TEM) images show the presence of small micelles with a size of about 5 nm for all compounds. Critical micelle concentration (CMC) values vary slightly with the molecular structure. A small decrease in CMC was found upon increasing the hydrophobicity of the amino acid. The CMC of the tyrosine conjugate showed a small pH-effect, increasing at high pH.