Surface Immobilization and Mechanical Properties of Catanionic Hollow Faceted Polyhedrons

Abstract : We report here for the first time on surface immobilization of hollow faceted polyhedrons formed fromcatanionic surfactant mixtures. We find that electrostatic interaction with the substrate dominates their adhesionbehavior. Using polyelectrolyte coated surfaces with tailored charge densities, polyhedrons can thus beimmobilized without complete spreading, which allows for further study of their mechanical properties usingAFM force measurements. The elastic response of individual polyhedrons can be locally resolved, showingpronounced differences in stiffness between faces and vertexes of the structure, which makes these systemsinteresting as models for structurally similar colloidal scale objects such as viruses, where such effects arepredicted but cannot be directly observed due to the smaller dimensions. Elastic constants of the wall materialare estimated using shell and plate deformation models and are found to be a factor of 5 larger than those forneutral lipidic bilayers in the gel state. We discuss the molecular origins of this high stiffness