Non-conclusive results on bile salt solutions: the use of TMA-DPH species for CMCs determination

Abstract

Abstract: A study of aggregation behaviour of cholate and deoxycholate anions (as sodium salts) in aqueous solutions at 298.2K is reported here. Two CMCs (primary and secondary critical micellar concentrations) of both bile salts have been determined using TMA-DPH (NNN-Trimethyl-4-(6-phenyl-1, 3,5-hexatriene-1-yl)phenylammonium-p-toluenesulfonate) as a probe molecule in the presence of [Ru(NH3)5pz]2+ (pz=pyrazine), and in its absence, for comparison of the results. These CMCs were obtained from shifts of TMA-DPH absorption spectrum as a function of bile salt concentration. Although our results suggest the existence of two CMCs, they can also be explained by taking into account a single CMC. Therefore, in this sense, these results cannot be considered as conclusive; the probe molecule (TMA-DPH) does not provide sufficient information on the existence of the secondary aggregates of bile salts.Physical