Visualizing Formation and Dynamics of a Three-Dimensional Sponge-like Network of a Coacervate in Real Time

Abstract

Coacervates, which are formed by liquid−liquid phase separation, have been extensively explored as models for synthetic cells and membraneless organelles, so their in-depth structural analysis is crucial. However, both the inner structure dynamics and formation mechanism of coacervates remain elusive. Herein, we demonstrate real-time confocal observation of a threedimensional sponge-like network in a dipeptide-based coacervate. In situ generation of the dipeptide allowed us to capture the emergence of the sponge-like network via unprecedented membrane folding of vesicle-shaped intermediates. We also visualized dynamic fluctuation of the network, including reversible engagement/disengagement of cross-links and a stochastic network kissing event. Photoinduced transient formation of a multiphase coacervate was achieved with a thermally responsive phase transition. Our findings expand the fundamental understanding of synthetic coacervates and provide opportunities to manipulate their physicochemical properties by engineering the inner network for potential applications in development of artificial cells and life-like material fabrication.

Unveiling the Liquid‐Liquid Phase Separation of Benzene‐1,3,5‐Tricarboxamide in Water

“…To elucidate the energy landscape of BTA self‐assembly, [37,38] a heat‐cool cycle for 40 uM BTA in water was conducted at a temperature ramp of 1 °C/min while monitoring three distinct wavelengths. At 200 nm, the monomer was tracked, 225 nm depicted the polymeric state of BTA, and 400 nm measured sample turbidity and LLPS (Figure 2a).…”

Cell‐Like Synthetic Supramolecular Soft Materials Realized in Multicomponent, Non‐/Out‐of‐Equilibrium Dynamic Systems

“…Also, we recently developed a new structural motif, tert‐butyl diphenylalaninate (FF‐OtBu) to generate liquid–liquid phase separation (LLPS). [ 53,54 ] A bulky tBu group newly introduced at the C ‐terminus of a diphenylalanine peptide may suppress β‐sheet‐based nanofiber formation, and induce LLPS. Unlike the peptide‐type hydrogelators, several types of hydrophilic functional groups are attached at the N ‐terminus of the FF‐OtBu motif and we have found unique coacervates composed of a short peptide.…”

“…[ 47,102–110 ] We recently found that a coacervate comprising PEG 9 ‐FF‐OtBu with a thermally responsive nonaethylene glycol group at the N ‐terminus of FF‐OtBu undergoes a pathway‐dependent phase transition ( Figure a,b). [ 54 ] In the low temperature (LT) phase, PEG 9 ‐FF‐OtBu forms coacervate droplets with a 3D sponge‐like inner network, whereas in the high temperature (HT) phase, the coacervate droplets transform into a homogenous structure through a coacervate‐to‐coacervate transition (Figure 7c,d). Time‐lapse confocal imaging revealed that the LT‐to‐HT or HT‐to‐LT phase transition produces distinct intermediate structures.…”

Porous Morphology of High Grafting Density Mixed Polyelectrolyte Brushes Grown from a Y-Inimer Coating

“…Studies so far on PE brushes have mostly been limited to simulations − or homopolymers and copolymers. − Only one simulation study to date has explored the formation of lateral aggregates via microphase separation in mixed PE brushes. This study explored a relatively low grafting density regime and predicted the formation of lateral aggregates in a ripple structure when both polyelectrolytes were highly charged .…”