CHRISTINE EBEL
Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, Grenoble Cedex, France

Dear reader,
This editorial is dedicated to surfactants, their properties, and their wide application both in academia and industry. Within this issue you will in fact find a focus on surfactants with various articles addressing the matter from different angles: a new biosurfactant formulation with sophorolipid-chitosan and the importance of sustainability certification of surfactants.

For those who are not aware of what surfactants are, surfactants are amphipathic molecules with both hydrophilic and hydrophobic moieties. While hydrophilic groups have the tendency to mix with water, to dissolve in water, or be wetted by water, the hydrophobic ones repel water and are poorly or not soluble in water. Because of this dual character, these molecules in aqueous media forms colloidal sized globular auto assemblies named micelles, above a given concentration named the Critical Micelle Concentration (CMC). The hydrophobic parts are located inside the micelle, avoiding their interaction with water and defining a hydrophobic, apolar, similar to oil, medium. The hydrophilic parts are located at the periphery of the micelle, in such a way they are exposed and ...