Impact of adhesion on the shape and rearrangements of biomimetic emulsions in static and dynamical packings

During morphogenesis, cells differentiate and reorganize to acquire their shape and function. In addition to biological cues, the mechanical properties of cells and their interactions are essential to this process. Yet, in biological systems, it is challenging to isolate the role of one parameter. We developed adhesive emulsions as a simpler and more controlled model system to study the role of adhesion in tissue mechanics. We can thus extract the sole contribution of adhesion to the organization of soft particles assemblies.
We imaged droplet monolayers in confocal microscopy, both in static packings and dynamically sheared through a microfluidic constriction. Using synthetic complementary DNA sequences, we could tune the level of cell adhesion by modulating the binding energy of ligands. We then compared how the level of adhesion impacted the relationship between the particle deformation and the local topology in static packings. In dynamics, we found that T1 rearrangement events occur slower and at much higher deformation in the presence of adhesion, however the global topology of rearrangements remains the same. At a global scale, the topology of rearrangements is not impacted, however, the adhesion creates a global polarization of the deformation in the direction of the flow.