Liquid crystalline behavior of concentrated aqueous solutions of biosurfactants

In the current global context of the search for renewable resources, bioamphiphiles appear as a promising alternative to conventional oil-based surfactants. However, to commercialize these compounds, all their structural and physical properties should be known. Although their self-assembly and interfacial properties at low concentrations are currently an active research topic, their self-organization into liquid crystalline (LC) phases at high concentrations has yet hardly been addressed. This article reviews the few studies devoted to the identification of LC properties of bioamphiphiles. It highlights the fact that only two bioamphiphile families (mannosylerythritol lipids, sophorolipids) have been investigated in some detail and that much more structural and thermodynamic knowledge is still needed to reach the level of understanding achieved with conventional surfactants.