Alpha-tocopherol in CTAB/NaCl systems - The light scattering studies

摘要

The light scattering techniques - laser Doppler electrophoresis (LDE) and dynamic light scattering method (DLS) - were applied to characterize properties of the cetyltrimethylammonium bromide (CTAB) micellar solutions in the presence of alpha-tocopherol (vitamin E) and NaCI at 25 degrees C. The surfactant concentration changed from 2 mM to 25 mM and the molar ratio of vitamin E to CTAB was in the range 0.01-0.18. It was found that the incorporation of et-tocopherol molecules into the palisade layer of CTAB micelles increases the ionization degree of mixed aggregates even at 0.5 M NaCl. At the same time it does not cause a significant increase of the mixed micelle sizes (the number of CTAB molecules in the aggregates). The observed increase of surface electrical charge of micelles in the presence of vitamin E leads to an increase of their electrophoretic mobility. A small size of the mixed micelles (about 5.0 and 6.0 nm at 0.15 and 0.50 M NaCI, respectively) points at full solubilisation of the active substance. This effect can be useful for elaboration of bioactive substance carriers in the micellar systems in the presence of electrolyte. (C) 2017 Elsevier B.V. All rights reserved.