Microstructure and transitions in mixed micelles of cetyltrimethylammonium tosylate and bile salts

S. Chavda*, D. Danino, V. K. Aswal, K. Singh, D. G. Marangoni, P. Bahadur

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The effect of bile salts viz. sodium cholate (NaC) and sodium deoxycholate (NaDC) on the size and transition of cetyltrimethylammonium tosylate (CTAT) micelles is examined by viscosity, cryogenic transmission electron microscopy (Cryo-TEM), small angle neutron scattering (SANS), nuclear Overhauser enhancement spectroscopy (NOESY) and 1H NMR. The viscosity of worm-like micelles of CTAT solution strongly decreases as the temperature increases favoring the transformation to spheroidal micelles. At low NaC concentration (5–10 mM), viscosity of 20 mM CTAT solutions decreases, reaching a constant value close to that of water. However, for NaDC, a peak in viscosity is seen followed by a drop around 3 mM concentration. The microstructure of CTAT micelles gets altered by bile salts as revealed by cryo-TEM. As manifested by SANS results, NaC transforms worm-like CTAT micelles into small spherical/ellipsoidal mixed micelles. However, there was no difference in SANS plot of worm-like CTAT micelles in D2O and in presence of NaDC; these clearly suggest the presence of worm-like micelles. NaDC behaves differently, showing a maximum in viscosity for 20 mM CTAT at ∼3 mM concentration and phase separation at equimolar ratio. The results are discussed in terms of location of bile salt in mixed micelles determined by NOESY and 1H NMR experiments.

Original languageEnglish
Pages (from-to)223-233
Number of pages11
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Volume513
DOIs
StatePublished - 5 Jan 2017
Externally publishedYes

Keywords

  • Bile salt
  • CTAT
  • Cryo-TEM
  • NOESY
  • SANS
  • Worm-like micelle

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