Dynamical Behaviors of Oscillating Metallosurfactant Coacervate Microdroplets under Redox Stress

Abstract

Living systems create complex structures and functions by mastering self-organization in a variety of equilibrium and non-equilibrium states. Mimicking the dynamical phenomena with synthetic cell-like entities (protocells) under non-equilibrium conditions offers an important step toward the representation of minimum life. Here, the cell-sized coacervate microdroplets assembled from associative metallosurfactant coacervation via liquid-liquid phase separation (LLPS) that exhibits non-equilibrium behaviors are reported. The compartmentalized protocell coacervates display collective dynamics that synchronize into system oscillations, showing autonomous death/regeneration and contraction/expansion cycles with external redox stress. The collective oscillation of abiotic metallosurfactant microdroplets can sustain both in solution and at the colloidal interface, allowing for dynamic sequestration, mass transport, and passing through nanosized channels, reminiscent of red blood cells that can deform and squeeze through narrow capillaries. The design of self-oscillating cell-sized constructs will shed a light on the creation of life-like soft materials with autonomous motion driven by complex chemical stimuli, which can be further used as nonbiological models for dynamic aggregates and intercellular communication.

Collective chemomechanical oscillations in active hydrogels

“…It also shines light on previous experiments made with BZ gels, emulsions or coacervates at the nano/micro scale ( 26 ). For example, recent experimental results demonstrate that BZ polymeric shells of around 20 m in diameter undergo buckling unbuckling instabilities ( 27 ) and that BZ coacervates or BZ microgels of around 1 m in diameter sustain chemomechanical oscillations ( 28 , 29 ). Our interpretation of these results is that the oscillations of such small polymeric BZ microreactors might be the result of a collective chemical response.…”

Mechanically Active Supramolecular Systems

“…Synthetic out-of-equilibrium chemical oscillating networks, like the Belousov-Zhabotinsky reaction, have been devised to control spatiotemporal cycles. [54] Kim and his collaborators [55] employed sound waves as a guiding stimulus to generate spatiotemporal patterns in out-of-equilibrium chemical reactions and self-assembly systems (Figure 6a). The application of audible sound (40 Hz, threshold acoustic intensity of 0.06 W m À2 and a pressure 5.0-6.3 Pa) induced liquid vibrations controlled the dissolution of atmospheric gases (such as O 2 and CO 2 ) in water, resulting in the creation of spatiotemporal chemical patterns within the fluid.…”

Self-assembly of stabilized droplets from liquid–liquid phase separation for higher-order structures and functions

“…Scale bars: ( d ) 5 μm; ( e ) 1 μm. Adapted with permission from Copyright © 2023, Wiley-VCH GmbH 81 . …”

“…Oscillatory phenomena is abundant in biological systems across different scales: from metabolic and biochemical oscillations to embryonic oscillators and circadian clock. A recent development has mimicked oscillating behaviors using coacervates 81 based on an amphiphilic metal-organic complex that only phase separates when the metal is in a reduced oxidation state (Fig. 5c ).…”