Multiphase Complex Coacervate Droplets

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 charge-driven 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.<br>

Multiphase Complex Coacervate Droplets

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 charge-driven 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.<br>

The Flocculation between Partial Hydrolyzed Polyacrylamide and Cationic Microshperes

A serial of micro-scale cationic particles was synthesized by inverse suspension polymerization. These particles formed flocs with hydrolyzed polyacrylamide through electrostatic attraction. The structure of these flocs evolved from a bulk state to insulated microspheres at a critical salt concentration, which increased with increasingly cationic degree of particles, corresponding to the change of Zeta potential. Moreover, the adsorbance of HPAM on the cationic particles attained a maximum about 409 mg/g at 500mg/L HPAM in salt-free water and 237 mg/g at 800mg/L HPAM in 2wt% NaCl solution at 20°C according to a semi-quantitative method implemented by viscosity contrast experiment. This adsorbance difference accounts for that the electrostatic shielding effect of salt stimulates the desorption rate of HPAM.

Proteins in Fish Muscle. IV. Denaturation by Salt

Study of the denaturation of cod muscle proteins by sodium chloride shows that the myosin fraction is denatured when a critical salt concentration, about 8 to 10 per cent in the muscle, is reached. Paralleling the rapid denaturation, a sudden increase of salt uptake and of moisture loss occurs.