The effect of postadded ethylene glycol surfactants on DNA-cationic surfactant/water mesophases

Cecilia Leal, Azat Bilalov, Björn Lindman

Research output: Contribution to journalArticle

Abstract

The addition of amphiphiles grafted with polyethylene glycol units to constructs of DNA-amphiphiles is of most relevance for applications demanding colloidal stability. In this work, we study the self-assembly behavior of a true ternary mixture comprising (i) an electroneutral complex of DNA and a cationic surfactant (dodecyltrimethylammonium, DTA), (ii) water, and (iii) nonionic surfactant (dodecyl tetraethylene glycol, C12EO4; and dodecyl octaethylene glycol, C12EO8). The phase diagrams of the two systems: DNA-DTA/C12EO4/water and DNA-DTA/C12EO8/water were carried out using 2H NMR, and small-angle X-ray scattering (SAXS). In both mixtures, the DNA-DTA complex incorporates the postadded nonionic surfactant and large liquid crystalline regions were found. The supramolecular assemblies evolve from a 2D hexagonal structure of the normal type to a lamellar phase as the content of nonionic surfactant is increased. The effect of ethylene glycol unit size in the phase behavior is discussed. We suggest that when longer ethylene glycol units (C12EO8 vs C12EO4) are used, the DNA-DTA aggregate gets saturated with the nonionic surfactant and there exists a coexistence of a fully swollen mesophase phase of C12EO8 alone presumably of the normal hexagonal type with the lamellar and hexagonal phases of DNA-DTA/C12EO8/water.

Original languageEnglish (US)
Pages (from-to)9909-9914
Number of pages6
JournalJournal of Physical Chemistry B
Volume113
Issue number29
DOIs
StatePublished - Jul 23 2009
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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