Transformation of Lipid Vesicles into Micelles by Adding Nonionic Surfactants: Elucidating the Structural Pathway and the Intermediate Structures

Igor Kevin Mkam Tsengam, Marzhana Omarova, Elizabeth G. Kelley, Alon McCormick, Geoffrey D. Bothun, Srinivasa R. Raghavan, Vijay T. John

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The phospholipid lecithin (L) and the nonionic surfactant Tween 80 (T) are used together in various contexts, including in drug delivery and oil spill remediation. There is hence a need to elucidate the nanostructures in LT mixtures, which is the focus of this paper. We study these mixtures using cryogenic transmission electron microscopy (cryo-TEM), coupled with dynamic light scattering and small-angle neutron scattering. As the concentration of Tween 80 is increased, the vesicles formed by lecithin are transformed into spherical micelles. We identify bicelles (i.e., disc-like micelles) as well as cylindrical micelles as the key stable nanostructures formed at intermediate L/T ratios. The bicelles have diameters ∼13-26 nm, and the bicelle size decreases as the Tween 80 content increases. We propose that the lecithin lipids form the body of the discs, while the Tween 80 surfactants occupy the rims. This hypothesis is consistent with geometric arguments because lecithin is double-tailed and favors minimal curvature, whereas the single-tailed Tween 80 molecules prefer curved interfaces. In the case of cylindrical micelles, cryo-TEM reveals that the micelles are short (length < 22 nm) and flexible. We are able to directly visualize the microstructure of the aggregates formed by lecithin-Tween 80 mixtures, thereby enhancing the understanding of morphological changes in the lecithin-Tween 80 system.

Original languageEnglish (US)
Pages (from-to)2208-2216
Number of pages9
JournalJournal of Physical Chemistry B
Volume126
Issue number11
DOIs
StatePublished - Mar 24 2022

Bibliographical note

Funding Information:
Funding from the Gulf of Mexico Research Initiative is gratefully acknowledged. Access to the VSANS instrument was provided by the Center for High-Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement no. DMR-2010792. Certain commercial products were identified to foster understanding, this identification does not imply endorsement or recommendation by the National Institute of Standards and Technology.

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

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