Non-equilibrium behaviour in coacervate-based protocells under electric-field-induced excitation

Abstract

Although numerous strategies are now available to generate rudimentary forms of synthetic cell-like entities, minimal progress has been made in the sustained excitation of artificial protocells under non-equilibrium conditions. Here we demonstrate that the electric field energization of coacervate microdroplets comprising polylysine and short single strands of DNA generates membrane-free protocells with complex, dynamical behaviours. By confining the droplets within a microfluidic channel and applying a range of electric field strengths, we produce protocells that exhibit repetitive cycles of vacuolarization, dynamical fluctuations in size and shape, chaotic growth and fusion, spontaneous ejection and sequestration of matter, directional capture of solute molecules, and pulsed enhancement of enzyme cascade reactions. Our results highlight new opportunities for the study of non-equilibrium phenomena in synthetic protocells, provide a strategy for inducing complex behaviour in electrostatically assembled soft matter microsystems and illustrate how dynamical properties can be activated and sustained in microcompartmentalized media.

Complex coacervate‐based materials for biomedicine

“…Historically, one particularly contentious topic surrounding complex coacervation was the potential for these phase-separated compartments to serve as a type of protocell that could form the basis for the evolution of life. 7,30,[238][239][240][241][242][243][244][245] This hypothesis, originally put forth by Oparin,156,240,[245][246][247][248] has reemerged in the scientific literature though there are contentious discussions about the functional practicality of such membraneless compartments, 88,91,95,249 particularly with respect to their ability to sequester materials such as RNA without exchange. However, such systems do allow for the formation of model protocell environments that allow for the testing of specific aspects of biogenesis.…”

Reentrant Phase Transition Drives Dynamic Substructure Formation in Ribonucleoprotein Droplets

“…Nearly half a century ago, the existence of nucleolar vacuoles displaying similar dynamics was first reported [19] . Recent in vitro and in vivo studies have further reported such observations, wherein applying an external electric field [20] and overexpressing a disordered protein [21] resulted in vacuolization. Our study sheds light on a possible molecular origin of such dynamic internal substructures, suggests a fundamental cellular process that can control the reentrant phase behavior, and offers new prospects to study non-equilibrium processes in model intracellular MLOs as well as in synthetic coacervate-based protocells.…”

Spatial Positioning and Chemical Coupling in Coacervate‐in‐Proteinosome Protocells

“…Micro‐compartmentalized systems enriched with biomimetic functions offer a bottom‐up approach to the chemical construction of synthetic protocells . To date, the design of artificial cells has focused primarily on two key architectural modes: i) semi‐permeable membrane‐enclosed spherical assemblies such as vesicles prepared from lipids or polymers, water droplet‐in‐oil emulsions, inorganic nanoparticle‐stabilized colloidosomes, and protein‐polymer microcapsules (proteinosomes); and ii) membrane‐free droplets such as coacervates or soft colloidal microgels that comprise molecularly crowded interiors capable of sequestering diverse molecular and macromolecular components . Recently, hybrid protocells based on combinations of these two modules have been explored as a step towards more realistic models of cell‐like structure and organization.…”