Multiphase Complex Coacervation of Polyelectrolyte Solution

The liquid-liquid phase separation (LLPS) plays an important role in many fields, especially it is closely related to the partitioning inside a cell, various biochemical reaction related microenvironments and the formation of membrane-less organelle. The complex coacervation, which means the macrophase separation from oppositely charged polyelectrolytes in solutions, is an important representation of LLPS. The electrostatic interaction plays a key role in determining the phase separation. Present studies focus on the two-component polyelectrolyte system containing simple polyanion/polycation. However, in real cellular environments, there are numerous components and the resulting phases includes a dilute phase coexisting with multiple condensed phases, such as nucleoli. There is a lack of theoretical exploration on the physical mechanism about the multiphase separation induced by electrostatic force. Here, for three-component polyelectrolyte mixtures, we investigated the multiphase separation process. Our calculations indicate that the multiphase coacervation can be induced by either the asymmetry of linear charge density or the asymmetry of charge sequence. These asymmetries may results in different electrostatic correlations and result in effective repulsion between same charged chains. The theoretical results provide insights towards the designing of LLPS of polyelectrolyte molecules.