Bergmann Alexander M, Bauermann Jonathan, Bartolucci Giacomo, Donau Carsten, Stasi Michele, Holtmannspötter Anna-Lena, Jülicher Frank, Weber Christoph A, Boekhoven Job
School of Natural Sciences, Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, 85748, Garching, Germany.
Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01187, Dresden, Germany.
Nat Commun. 2023 Oct 17;14(1):6552. doi: 10.1038/s41467-023-42344-w.
Liquid-liquid phase separation yields spherical droplets that eventually coarsen to one large, stable droplet governed by the principle of minimal free energy. In chemically fueled phase separation, the formation of phase-separating molecules is coupled to a fuel-driven, non-equilibrium reaction cycle. It thus yields dissipative structures sustained by a continuous fuel conversion. Such dissipative structures are ubiquitous in biology but are poorly understood as they are governed by non-equilibrium thermodynamics. Here, we bridge the gap between passive, close-to-equilibrium, and active, dissipative structures with chemically fueled phase separation. We observe that spherical, active droplets can undergo a morphological transition into a liquid, spherical shell. We demonstrate that the mechanism is related to gradients of short-lived droplet material. We characterize how far out of equilibrium the spherical shell state is and the chemical power necessary to sustain it. Our work suggests alternative avenues for assembling complex stable morphologies, which might already be exploited to form membraneless organelles by cells.
液-液相分离产生球形液滴，这些液滴最终会粗化形成一个由最小自由能原理支配的大的稳定液滴。在化学驱动的相分离中，相分离分子的形成与燃料驱动的非平衡反应循环相耦合。因此，它产生由连续燃料转化维持的耗散结构。这种耗散结构在生物学中无处不在，但由于它们受非平衡热力学支配，人们对其了解甚少。在这里，我们通过化学驱动的相分离弥合了被动的、接近平衡的结构与主动的、耗散结构之间的差距。我们观察到球形的活性液滴可以经历形态转变形成液体球形壳。我们证明该机制与短寿命液滴物质的梯度有关。我们表征了球形壳状态偏离平衡的程度以及维持它所需的化学能量。我们的工作为组装复杂的稳定形态提供了替代途径，细胞可能已经利用这些途径来形成无膜细胞器。
