Multiphase Complex Coacervate Droplets

Abstract

Liquid−liquid phase separation plays an important role in cellular organization. Many subcellular condensed bodies are hierarchically organized into multiple coexisting domains or layers. However, our molecular understanding of the assembly and internal organization of these multicomponent droplets is still incomplete, and rules for the coexistence of condensed phases are lacking. Here, we show that the formation of hierarchically organized multiphase droplets with up to three coexisting layers is a generic phenomenon in mixtures of complex coacervates, which serve as models of chargedriven liquid−liquid phase separated systems. We present simple theoretical guidelines to explain both the hierarchical arrangement and the demixing transition in multiphase droplets using the interfacial tensions and critical salt concentration as inputs. Multiple coacervates can coexist if they differ sufficiently in macromolecular density, and we show that the associated differences in critical salt concentration can be used to predict multiphase droplet formation. We also show that the coexisting coacervates present distinct chemical environments that can concentrate guest molecules to different extents. Our findings suggest that condensate immiscibility may be a very general feature in biological systems, which could be exploited to design self-organized synthetic compartments to control biomolecular processes.

Prebiotically-relevant low polyion multivalency can improve functionality of membraneless compartments

“…4B); these bright puncta are consistent with formation of a second coacervate phase in which RNA is the predominant anionic component. 21,31 Together, the results shown in Fig. 4 indicate that membraneless compartments formed by phase separation of relatively simple polyions ((Lys)10/ATP, (Lys)10/(Asp)5) provide strong accumulation of ssRNA oligonucleotides.…”

“…The simplicity of lower molecular weight molecules makes them more prebiotically relevant, but their greater translational entropy reduces their propensity to undergo coacervation and impacts phase composition. 11,20,21 Here, we investigate the functional consequences of using lower multivalency polyelectrolytes to produce membraneless compartments. Suprisingly, we find that membraneless compartments formed using the shorter molecules are functionally superior for some properties important for prebiotic compartmentalization.…”

ATP‐Responsive and ATP‐Fueled Self‐Assembling Systems and Materials

“…[165] Such coacervates are of great interest for artificial organelles as they can act as open reactors with facile exchanges of matter. [166][167][168][169][170][171] In the context of ATP-triggered coacervates, for instance, ATP/poly(diallyldimethyl ammonium chloride) [172] and ATP/poly-l-lysine (PLL) [173] ones were reported. Reversible coacervation and dissociation has been realized by mixing ATP with PLL and subsequent addition of potato apyrase to hydrolyze the ATP.…”

Interface Engineering in Multiphase Systems toward Synthetic Cells and Organelles: From Soft Matter Fundamentals to Biomedical Applications

“…[51,207,[223][224][225][226] They have rich phase behaviors, forming multiple coacervate droplets, which can be explained and predicted by Flory-Huggins mean-field theory and Voorn-Overbeek model (Figure 7a). [227][228][229][230] The stability of coacervate against concentrated salt solution is related to the polarity, charge density, and block chain length of polyelectrolytes. Lower polarity and higher molecular weight of polyelectrolytes produce more stable coacervate droplets, which allows a higher tolerance of salt.…”