PH sensitive tubules of a bile acid derivative: A tubule opening by release of wall leaves

M. Chiara Di Gregorio, N. Viorel Pavel, Aida Jover, Francisco Meijide, José Vázquez Tato, Victor H. Soto Tellini, Ariel Alfaro Vargas, Oren Regev, Yaron Kasavi, Karin Schillén, Luciano Galantini

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Tubules formed by self-assembly of organic molecules have vast potential for nanotechnology applications, and the introduction of sensitivity to stimuli into self-assembly tubules represents a particularly attractive feature. Here we report the preparation and characterization of a molecule obtained by chemical modification of a natural bile acid, a biological surfactant, that self-assembles in pH sensitive tubules in aqueous solutions. The tubules, which are rigid, single-walled and with a diameter of 60 nm, form at pH 8-9 and open up when the pH is increased. The transition is reversible, it occurs in the pH range of 9-10 with an opening mechanism that is remarkably different from those so far proposed in the literature. It involves a release of wall layers similar to leaves, and is determined by a drastic pH-triggered change in the molecular arrangement, which in turn induces a radical modification of the wall curvature. The description of the morphological transformation is provided by means of cryogenic transmission electron microscopy and represents, to our knowledge, the first detailed visualization of pH stimulated tubule opening. UV and circular dichroism spectroscopies are used to investigate the evolution at the molecular level.

Original languageEnglish
Pages (from-to)7560-7566
Number of pages7
JournalPhysical Chemistry Chemical Physics
Issue number20
StatePublished - 28 May 2013

ASJC Scopus subject areas

  • Physics and Astronomy (all)
  • Physical and Theoretical Chemistry


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