Regensburg 2022 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 7: Poster 1

BP 7.13: Poster

Montag, 5. September 2022, 18:00–20:00, P1

Nucleation of chemically active droplets — •Noah Ziethen and David Zwicker — Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany

Liquid-liquid phase separation emerged as a crucial organizing principle inside biological cells giving rise to a plethora of intracellular compartments. Unique to the cellular context, these condensates can consist of only a few hundred molecules and are affected by non-equilibrium processes. In particular, active chemical conversion between condensate material and proteins in the surrounding cytoplasm can control their size. Moreover, the significant concentration fluctuations due to the small molecule numbers imply that spontaneous nucleation and dissolution are likely. Yet, it is unclear how the driven reactions affect these stochastic processes. Here, we investigate the influence of chemical reactions on the nucleation behavior of active droplets using a stochastic field theory. We find a decrease in the nucleation rate with the increased strength of the chemical reactions. Using classical nucleation theory, we can reduce the full dynamics to an analytical expression for the free energy, which only depends on the droplet radius and the strength of the chemical reactions. The chemical reactions increase the energy barrier, which the system needs to overcome to form a droplet. Additionally, the binodal and the spinodal line are moved towards the center of the phase diagram. Cells might use these effects to control the nucleation behavior of intracellular droplets or even suppress their formation completely.