Polymorphic Behaviour and Supramolecular Association in Systems Containing Bile acid Salts

A review. A wide no. of supra-mol. assocn. modes are obsd. in mixts. contg. water and bile salts, BS, (with, eventually, other components). Mol. or micellar solns. transform into hydrated solids, fibers, lyotropic liq. crystals and/or gels by raising the concn., the temp., adding electrolytes, surfactants, lipids and proteins. Amorphous or ordered phases may be formed accordingly. The forces responsible for this very rich polymorphism presumably arise from the unusual combination of electrostatic, hydrophobic and hydrogen-bond contributions to the system stability, with subsequent control of the supra-mol. organization modes. The stabilizing effect due to hydrogen bonds does not occur in almost all surfactants or lipids and is peculiar to bile acids and salts. Some supra-mol. organization modes, supposed to be related to malfunctions and dis-metabolic diseases in vivo, are briefly reported and discussed.