Mixed Micelles of Sodium Glycodeoxy Cholate (NaGDC) and Polyoxyethylene Tert-Octylphenyl Ether (Triton X-100)

The micellar properties of sodium glycodeoxycholate (NaGDC) and polyoxyethylene tert-octylphenyl ether (Triton X-100) and their binary combinations have been investigated using tensiometry and fluoresence techniques. The critical micelle concentrations of the micellar species were determined from surface tension and spectrofluorimetric methods. The CMC's of mixed micelles are found to be lower than the ideal values according to Clint's equation. The microenvironment of the micelles were explored from the viewpoint of aggregation characteristics and polarity index. The mean aggregation numbers were obtained from steady state quenching experiments. The values decreased with increasing mole-fraction of the bile salt in the co-micelle. The ratio of the first and third vibronic peaks (I₁/I₃) in a monomeric pyrene emission spectrum provided an estimate of the polarity index of the micelle interior. The results indicate that the pyrene solubilization site changes with the concentration of the micellar species and the hydrophobic character of the mixed agregates increases with the increase of NaGDC mole-fraction. The CMC's and composition of the mixed systems have been calculated following molecular thermodynamic approach. The calculated mole-fractions of NaGDC are lower than the analytical ones and the evaluated interaction parameter gives a measure of the synergism of the interacting amphiphiles.