pH-triggered formation of nanoribbons from yeast-derived glycolipid biosurfactants

Soft Matter. 2014 Jun 14;10(22):3950-9. doi: 10.1039/c4sm00111g. Epub 2014 Apr 14.

Abstract

In the present paper, we show that the saturated form of acidic sophorolipids, a family of industrially scaled bolaform microbial glycolipids, unexpectedly forms chiral nanofibers only at pH below 7.5. In particular, we illustrate that this phenomenon derives from a subtle cooperative effect of molecular chirality, hydrogen bonding, van der Waals forces and steric hindrance. The pH-responsive behaviour was shown by Dynamic Light Scattering (DLS), pH-titration and Field Emission Scanning Electron Microscopy (FE-SEM) while the nanoscale chirality was evidenced by Circular Dichroism (CD) and cryo Transmission Electron Microscopy (cryo-TEM). The packing of sophorolipids within the ribbons was studied using Small Angle Neutron Scattering (SANS), Wide Angle X-ray Scattering (WAXS) and 2D (1)H-(1)H through-space correlations via Nuclear Magnetic Resonance under very fast (67 kHz) Magic Angle Spinning (MAS-NMR).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Circular Dichroism
  • Glycolipids / chemistry*
  • Glycolipids / metabolism
  • Hydrogen Bonding
  • Hydrogen-Ion Concentration
  • Hydrophobic and Hydrophilic Interactions
  • Molecular Conformation
  • Nanofibers / chemistry
  • Nanotubes, Carbon / chemistry*
  • Nanotubes, Carbon / ultrastructure
  • Saccharomyces cerevisiae / metabolism*
  • Static Electricity
  • Stereoisomerism
  • Surface-Active Agents / chemistry
  • Surface-Active Agents / metabolism

Substances

  • Glycolipids
  • Nanotubes, Carbon
  • Surface-Active Agents