Attractive Forces Between Molecular Condensates Cause Movement

Physicists have discovered that attractive forces between molecular condensates can lead to unexpected movement. This finding challenges the assumption that systems with only attractive forces would form a single, stationary condensate. The research offers new insights into cellular organization and the design of molecular machines.

Scientists at the Max Planck Institute for Dynamics and Self-Organization (MPI-DS) developed a model to describe phase separation dynamics. This model focuses on the condensation of material into dense droplets within cells. These droplets dynamically rearrange, and their interactions shape the condensates.

The model used a minimal system of two droplets. Researchers introduced mutual attraction into this system. They observed varied behaviors based on the condensates' size, shape, and chemical activity.

One observed behavior was a "run-and-chase" mechanism. This mechanism is typically seen in nonreciprocal systems that include both attraction and repulsion. In this model, only attraction was present. The behavior is comparable to a lanternfish following prey that is also following the lantern, resulting in movement.

Jacopo Romano, the study's first author, noted that this demonstrates how a nonequilibrium emulsion can be engineered to exhibit nonreciprocal chasing interactions. Ramin Golestanian, director of the Department of Living Matter Physics, highlighted the significance of this emergent property. The study's findings were published in *Physical Review Letters*.