Abstract
Bile Salts as a biosurfactant have been frequently developed as solubilizers, emulsifiers and dispersion agents for water-insoluble substances in many fields of cosmetics, medical and chemical industries, and then many chemical papers and their reviews concerning the colloidal and interfacial properties of aqueous solutions of bile salts have so far been reported. As these bile salts have bulky and hydrophobic steroidal rings and one carboxyl group at the end of alkyl chain on a position of 17 carbon atom of the rings in a molecule, their colloidal and interfacial properties are different from those of ordinary surfactants with a linear hydrocarbon chain. Furthermore, their properties depend remarkably on the numbers and configuration of hydroxyl groups bound to the rings. In this report, the unique structures of bile salts will be discussed about how to reflect fundamental colloidal and interfacial properties on the basis of the results from various interfacial measurements and applications of bile salts.
