Study on Intermicellar Interactions and Micellar Size in Aqueous Solutions of Sodium Taurocholate by Measurements of Collective Diffusion and Self-Diffusion Coefficients

Aqueous micellar solutions of sodium taurocholate (NaTC) have been studied by using quasi-elastic light-scattering (QELS) and 1 H pulse-gradient-stimulated-echo NMR (PGSTE-NMR). The collective and self-diffusion coefficients have been obtained as a function of NaTC concentration (0.05−0.20 M) and the ionic strength of the solution (0−0.8 M NaCl added). The comparison of the two techniques' data in each solution has been performed in the context of micellar growth and intermicellar interactions. The model of monodisperse Brownian particles with hydrodynamic interaction and hard core repulsion gives rise to a satisfactory agreement with the experimental data. The translational diffusion coefficient of the single micellar aggregate has been calculated for each solution. The size of the micellar aggregates depends on the ionic strength and bile salt concentration.