Inside cells, certain functions are fulfilled by locally adjusting the molecular composition. This condensation of material results in the formation of dense droplets which can re-arrange dynamically. For this, particularly the interaction between such dense regions determines the shaping of condensates. Scientists from the department of Living Matter Physics at the MPI-DS recently developed a model that can describe such phase separation dynamics solely based on attraction.
It’s natural to think that a system with only attractive forces would form one large, stationary condensate," explains Jacopo Romano, first author of the study. “However, instead we observed an unexpected emergent property of chasing dynamics resulting in movement and propulsion,” he explains. In their model, the physicists used a minimal system consisting of two droplets as a basis. After introducing mutual attraction to the system, they observed different behavior, depending on the size, shape and chemical activity of the condensates. One of these behaviors resembled the run-and-chase mechanism that is also observed in non-reciprocal systems with attraction and repulsion being present. As only attraction is present in this model, it can be compared to a lantern fish following the prey which is following the lantern, ultimately resulting in movement.
This is an interesting example of how a non-equilibrium emulsion can be engineered to exhibit non-reciprocal chasing interactions between droplets.,” comments Ramin Golestanian, director of the department Living Matter Physics. The findings of the study give new insights in how cells can organize themselves, ensuring their vitality. Likewise, they can be used for the design of molecular machines where self-propelling behavior is required.
Original publication
Jacopo Romano, Martin Kjøllesdal Johnsrud, Benoît Mahault, and Ramin Golestanian
Nonreciprocal Interactions between Condensates in Chemically Active Mixtures
Phys. Rev. Lett. 136, 198301
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