title: Nanoscale Platelet Formation by Monounsaturated and Saturated Sophorolipids under Basic pH Conditions.
abstract: The self-assembly behavior of the yeast-derived bolaamphiphile sophorolipid (SL) is generally studied under acidic/neutral pH conditions, at which micellar and fibrillar aggregates are commonly found, according to the (un)saturation of the aliphatic chain: the cis form, which corresponds to the oleic acid form of SL, spontaneously forms micelles, whereas the saturated form, which corresponds to the stearic acid form of SL, preferentially forms chiral fibers. By using small-angle light and X-ray scattering (SLS, SAXS) combined with high-sensitivity transmission electron microscopy imaging under cryogenic conditions (cryo-TEM), the nature of the self-assembled structures formed by these two compounds above pH 10, which is the pH at which they are negatively charged due to the presence of a carboxylate group, has been explored. Under these conditions, these compounds self-assemble into nanoscale platelets, despite the different molecular structures. This work shows that the electrostatic repulsion forces generated by COO(-) mainly drive the self-assembly process at basic pH, in contrast with that found at pH below neutrality, at which self-assembly is driven by van der Waals forces and hydrogen bonding, and thus, is in agreement with previous findings on carbohydrate-based gemini surfactants.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Collège de France UMR 7574, Chimie de la Matière Condensée de Paris, UMR 7574, 75005 Paris (France).
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Cuvier
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Collège de France UMR 7574, Chimie de la Matière Condensée de Paris, UMR 7574, 75005 Paris (France).
authors.forename: Florence
authors.initials: F
authors.lastname: Babonneau
authors.affiliation: SynBioC, Department of Sustainable Organic Chemistry and Technology, Ghent University, Ghent (Belgium).
authors.forename: Jan
authors.initials: J
authors.lastname: Berton
authors.affiliation: SynBioC, Department of Sustainable Organic Chemistry and Technology, Ghent University, Ghent (Belgium).
authors.forename: Christian V
authors.initials: CV
authors.lastname: Stevens
authors.affiliation: Laboratoire Léon Brillouin, LLB, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France).
authors.forename: Giulia C
authors.initials: GC
authors.lastname: Fadda
authors.affiliation: Institut Pasteur, UMR3528, 28 Rue du Docteur Roux, 75015 Paris (France).
authors.forename: Gérard
authors.initials: G
authors.lastname: Péhau-Arnaudet
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Collège de France UMR 7574, Chimie de la Matière Condensée de Paris, UMR 7574, 75005 Paris (France).
authors.forename: Patrick
authors.initials: P
authors.lastname: Le Griel
authors.affiliation: ESRF - The European Synchrotron, High Brilliance Beamline ID02, 38043 Grenoble (France).
authors.forename: Sylvain
authors.initials: S
authors.lastname: Prévost
authors.affiliation: SWING, Synchrotron Soleil, BP 48, 91192 Gif-sur-Yvette, (France).
authors.forename: Javier
authors.initials: J
authors.lastname: Perez
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Collège de France UMR 7574, Chimie de la Matière Condensée de Paris, UMR 7574, 75005 Paris (France). niki.baccile@upmc.fr.
authors.forename: Niki
authors.initials: N
authors.lastname: Baccile
mesh_terms: D001792:Blood Platelets / Q000737:chemistry*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008055:Lipids / Q000737:chemistry*; D008823:Micelles; D015394:Molecular Structure; D049329:Nanostructures; D013501:Surface-Active Agents / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D008055:Lipids; D008823:Micelles; D013501:Surface-Active Agents
keywords: amphiphiles; basicity; micelles; nanostructures; self-assembly