Laboratoire Matière et Systèmes Complexes

Léa-Laetitia Pontani

Institut des Nanosciences de Paris

Tinkering with emulsion droplets

Emulsions are a model system for jammed matter but can also be used for the synthesis of adhesive and patchy particles. The interactions between the droplets are tuned to control the packing configurations and to program their self-assembly into complex mesoscopic structures. Those interactions can be driven by depletion, or can be mediated by biological molecules. To this aim we produce bio-inspired emulsions where the interactions mimic specific cellular functions, such as lipid domain formation, cell-cell adhesion or even hemifusion. For example, immiscible lipids on the surface of emulsion droplets create stable domain patterns, which provides a route for patchy particle synthesis. Functionalizing the patches with binders allows the droplets to aggregate with a given valency. The mobile adhesion patches can therefore self-assemble linear chains of thermal droplets into well-defined compact structures. Alternatively, functionalizing the lipids with E-cadherin allows the droplets to fuse together up to a given droplet size through a processus that depends largely on the lateral cis-clustering of cadherins. This biologically inspired system thus provides a molecular switch for droplets fusion. Bio-inspired emulsions are therefore a useful system for problems in biophysics, but also provide a new class of liquid patchy particles for self-assembly.