Formation of tubules by p-tert-butylphenylamide derivatives of chenodeoxycholic and ursodeoxycholic acids in aqueous solution

The formation of tubules by p-tert-butylphenylamide derivatives of chenodeoxycholic and ursodeoxycholic acids in aqueous solution is investigated. The critical aggregation concentrations of the new surfactants are much lower than those of ursodeoxycholate and chenodeoxycholate, indicating the enhanced surfactant properties resulting by the presence of the hydrophobic p-tert-butylphenyl group. The molecular areas at the air–water interface suggest the formation of monolayer films with molecules upright oriented. The shape of the aggregates was investigated by TEM. The main structure present in solution corresponds to tubules. The estimated value for the wall thickness of tubules suggests that a bilayer structure is formed. Host of positively charged latex beads by tubules suggests that their inner and outer surfaces are negatively charged. The acid form of the chenodeoxycholate derivative was recrystallized from toluene and its crystal structure analyzed.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Formation of tubules by p-tert-butylphenylamide derivatives of bile acids. ► Enhancement of surfactant properties of natural bile acids. ► Host of a positively charged guest by negatively charged tubules. ► Crystal structure of a p-tert-butylphenylamide derivative of chenodeoxycholic acid.