Aging Maxwell fluids

Abstract

Many experiments show that protein condensates formed by liquid-liquid phase separation exhibit aging rheological properties. Quantitatively, recent experiments by Jawerth et al. (Science 370, 1317, 2020) show that protein condensates behave as aging Maxwell fluids with an increasing relaxation time as the condensates age. Despite the universality of this aging phenomenon, a theoretical understanding of this aging behavior is lacking. In this work, we propose a mesoscopic model of protein condensates in which a phase transition from aging phase to non-aging phase occurs as the control parameter changes, such as temperature. The model predicts that protein condensates behave as viscoelastic Maxwell fluids at all ages, with the macroscopic viscosity increasing over time. The model also predicts that protein condensates are non-Newtonian fluids under a constant shear rate with the shear stress increasing over time. Our model successfully explains multiple existing experimental observations and also makes general predictions that are experimentally testable.

6 pages, 4 figures with a supplementary material

References in corpus (5)

• Salt-dependent rheology and surface tension of protein condensates using optical traps
• Phase behavior and morphology of multicomponent liquid mixtures
• Nonmonotonic Aging and Memory Retention in Disordered Mechanical Systems
• Aging in a mean field elastoplastic model of amorphous solids
• Aging and linear response in the Hébraud-Lequeux model for amorphous rheology