Micellar properties and solubilization of cholesterol in aqueous binary mixed solutions consisting of sodium cholate and non-ionic surfactant

The micellar properties and behavior of cholesterol solubilization in aqueous binary mixed solutions of sodium cholate (NaC) and octaoxyethylene glycol mono n-decyl ether (C₁₀E₈) were studied by examination of the composition of the mixed micelles, polarities of the micelle interior, mean aggregation number and saturated amounts of the solubilized cholesterol in the mixed solutions. The mole fraction of NaC in the mixed micelles near the CMC was found to be less than that in aqueous mixed solution. The hydrophobicity of the interior of the mixed micelles increased with the mole fraction of NaC in the mixed solution, and the mean aggregation number abruptly decreased in the range of the low mole fraction of NaC. The saturated amount of the solubilized cholesterol in the mixed solution depends on the mean aggregation number of mixed micelles. The cholesterol solubilization behavior, studied by thermodynamic analysis, was similar to the variation of the hydrophobicity of the mixed micelles.