Adrien Izzet (NYU) - Dynamics and contact interactions of bio-inspired emulsion droplets
The mechanical response and the relaxation dynamics of heterogeneous media such as granular systems or emulsions, depends on the nature of the physical interaction between their elementary bricks.
While dense granular media exhibit solid over-damped contacts dominated by friction, emulsions droplets are characterized by liquid-liquid interfaces, which properties can be tuned by chemistry. They are a good model system to study cell-cell interaction. Here, we focus on the role of cell-cell adhesion mediator proteins called cadherins. We designed an experimental system which consists in a bio-inspired emulsion in which the droplets are covered with cadherins. We managed to quantify the binding energy and provide evidence of cadherin crystallization in adhesion patches. We show that cadherin-induced cell-cell adhesion is a mechano-sensitive process, where confining pressure activates binding.
In a dilute limit, emulsions can also be designed to mimic active biological system, such as active Brownian particles or bacteria exhibiting chemotaxis. In this context, we designed a bio-inspired system of swimming droplets which speed and persistence time can be tune independently. In a sufficiently large diameter limit, these swimmers interact with the trail of material they excrete as they dissolve, hence exhibiting self-avoidance. We show that the chemico-physical model of the system, characterized by two equations, can be reduced to a single closed equation of a random walk with memory. Our study lies on the comparison of the experimental data with the results from numerical simulation of such self-avoiding random walks.
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- 2021-01-12 14:30