Asymmetrical, Symmetrical, Divalent, and Y-Shaped (Bola)amphiphiles: The Relationship between the Molecular Structure and Self-Assembly in Amino Derivatives of Sophorolipid Biosurfactants - Sorbonne Université
Journal Articles Journal of Physical Chemistry B Year : 2019

Asymmetrical, Symmetrical, Divalent, and Y-Shaped (Bola)amphiphiles: The Relationship between the Molecular Structure and Self-Assembly in Amino Derivatives of Sophorolipid Biosurfactants

Abstract

Conventional head-chain but also more exotic divalent, gemini or bolaform amphiphiles have in common well-defined hydrophilic and hydrophobic blocks with often a predictable self-assembly behaviour. However, new categories of amphiphiles, like microbial biosurfactants, challenge such conventional understanding, because of the poorly-defined boundaries between the hydrophilic and hydrophobic portions. Microbial glycolipids, like sophorolipids, rhamnolipids or cellobioselipids, interesting biodegradable, nontoxic, alternatives to synthetic surfactants, all represent interesting examples of atypical amphiphiles with partially predictable self-assembly properties. However, their limited molecular diversity strongly limits their application potential. For this reason, we used them as ready-made platform to prepare a whole class of new derivatives. In particular, a broad range of amino derivatives of sophorolipid biosurfactant was recently prepared with the goal of producing biobased antimicrobial and transfection agents, of which the efficiency strongly depends on their molecular structure and unpredictable self-assembly behavior. The new compounds contain a set of asymmetrical and symmetrical bolaamphiphiles, the latter with three or four hydrophilic centers, divalent amphiphiles with asymmetric polar headgroups and even a Y-shaped amphiphiles, bearing two sophorose groups connected to one nitrogen atom. In this contribution we employ small angle x-ray scattering (SAXS) to establish a relationship between their peculiar molecular structures and the self-assembly properties in water. We find that all divalent and Y- shaped compounds form micelles, of which the hydrophilic shell is composed of a bulky sophorose-C x (x= 8,11)-amine moiety, with aggregation numbers between 30 and 100. On the contrary, most symmetrical and asymmetrical bolaamphiphiles display poor self-assembly properties, generally showing aggregation numbers below 20, especially in the presence of either short spacers or large spacers containing hydrophilic centers.
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Dates and versions

hal-02128241 , version 1 (14-05-2019)

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Niki Baccile, Elisabeth I. P. Delbeke, Martha Brennich, Chloé Seyrig, Jonas Everaert, et al.. Asymmetrical, Symmetrical, Divalent, and Y-Shaped (Bola)amphiphiles: The Relationship between the Molecular Structure and Self-Assembly in Amino Derivatives of Sophorolipid Biosurfactants. Journal of Physical Chemistry B, 2019, 123 (17), pp.3841-3858. ⟨10.1021/acs.jpcb.9b01013⟩. ⟨hal-02128241⟩
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