Monosaccharide-induced growth and higher order transitions in TPGS micelles

D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) is a nonionic surfactant with low critical micelle concentration. It usually forms spherical core-shell micelles in aqueous media. In this work, we show that these spherical micelles transform to ellipsoid and cylindrical structures upon the incorporation of commonly available monosaccharides, Glucose (GLC), mannose (MAN) and galactose (GAL).

Highlights

Solution properties of TPGS were investigated in the presence of monosaccharides (glucose, mannose and galactose).

Monosaccharide-induced dehydration of micelles was accompanied with structural transitions.

Transitions were studied with neutron and light scattering techniques.

Depending upon sugar concentration, spherical micelles transformed to ellipsoid and cylindrical structures.

The aggregates have been characterized by dynamic light scattering (DLS), small angle neutron scattering (SANS) and nuclear magnetic resonance (NMR) spectroscopy. Our analysis is focused to discuss (a) the effect of sugar concentration, and (b) comparative ability of sugars in triggering structural transitions. It is shown that the transitions and micelle growth arose from the sugar-driven dehydration of head group region. With their higher affinity, sugar molecules approached the shell region and triggered expulsion of water molecules.

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Although the pattern of transition (micelle to ellipsoid to cylinder) remained common for each sugar, it began at lower concentration of GLC and GAL. NMR experiments showed structural reorganizations in TPGS molecule in the presence of sugar. The outcomes of our study can be applied to tune the viscosity of nonionic surfactant-based long-standing pharmaceutical dispersions.

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Article information: Sachin Rathod, Rajesh Patidar, Debes Ray, Vinod K. Aswal, Shailesh A. Shah, Nihar Ranjan, Pratap Bahadur, Sanjay Tiwari, Monosaccharide-induced growth and higher order transitions in TPGS micelles, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2021. https://doi.org/10.1016/j.colsurfa.2021.127792.