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

TY - JOUR

T1 - Microstructure and transitions in mixed micelles of cetyltrimethylammonium tosylate and bile salts

AU - Chavda, S.

AU - Danino, D.

AU - Aswal, V. K.

AU - Singh, K.

AU - Marangoni, D. G.

AU - Bahadur, P.

N1 - Publisher Copyright: © 2016 Elsevier B.V.

PY - 2017/1/5

Y1 - 2017/1/5

N2 - 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.

AB - 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.

KW - Bile salt

KW - CTAT

KW - Cryo-TEM

KW - NOESY

KW - SANS

KW - Worm-like micelle

UR - http://www.scopus.com/inward/record.url?scp=85002189038&partnerID=8YFLogxK

U2 - 10.1016/j.colsurfa.2016.10.047

DO - 10.1016/j.colsurfa.2016.10.047

M3 - 文章

AN - SCOPUS:85002189038

SN - 0927-7757

VL - 513

SP - 223

EP - 233

JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects

JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects

ER -