Tuning interfacial fluidity and colloidal stability of membranized coacervate protocells.

The cell membrane not only serves as the boundary between the cell's interior and the external environment but also plays a crucial role in regulating fundamental cellular behaviours. Interfacial membranization of membraneless coacervates, formed through liquid-liquid phase separation (LLPS), represents a reliable approach to constructing hierarchical cell-like entities known as protocells. In this study, we demonstrate the capability to modulate the interfacial membrane fluidity and thickness of dextran-bound coacervate protocells by adjusting the molecular weight of dextran or utilizing dextranase-catalyzed hydrolysis. This modulation allows for rational control over colloidal stability, interfacial molecular transport and cell-protocell interactions. Our work opens a new avenue for surface engineering of coacervate protocells, enabling the establishment of cell-mimicking structures and behaviours.

Plant Cell-Inspired Membranization of Coacervate Protocells with a Structured Polysaccharide Layer.

The design of compartmentalized colloids that exhibit biomimetic properties is providing model systems for developing synthetic cell-like entities (protocells). Inspired by the cell walls in plant cells, we developed a method to prepare membranized coacervates as protocell models by coating membraneless liquid-like microdroplets with a protective layer of rigid polysaccharides. Membranization not only endowed colloidal stability and prevented aggregation and coalescence but also facilitated selective biomolecule sequestration and chemical exchange across the membrane. The polysaccharide wall surrounding coacervate protocells acted as a stimuli-responsive structural barrier that enabled enzyme-triggered membrane lysis to initiate internalization and killing of Escherichia coli. The membranized coacervates were capable of spatial organization into structured tissue-like protocell assemblages, offering a means to mimic metabolism and cell-to-cell communication. We envision that surface engineering of protocells as developed in this work generates a platform for constructing advanced synthetic cell mimetics and sophisticated cell-like behaviors.

Artificial receptor-mediated phototransduction toward protocellular subcompartmentalization and signaling-encoded logic gates.

Engineering artificial cellular systems capable of perceiving and transmitting external signals across membranes to activate downstream targets and coordinate protocellular responses is key to build cell-cell communications and protolife. Here, we report a synthetic photoreceptor-mediated signaling pathway with the integration of light harvesting, photo-to-chemical energy conversion, signal transmission, and amplification in synthetic cells, which ultimately resulted in protocell subcompartmentalization. Key to our design is a ruthenium-bipyridine complex that acts as a membrane-anchored photoreceptor to convert visible light into chemical information and transduce signals across the lipid membrane via flip-flop motion. By coupling receptor-mediated phototransduction with biological recognition and enzymatic cascade reactions, we further develop protocell signaling-encoded Boolean logic gates. Our results illustrate a minimal cell model to mimic the photoreceptor cells that can transduce the energy of light into intracellular responses and pave the way to modular control over the flow of information for complex metabolic and signaling pathways.

Modulating liquid-liquid phase separation of FUS: mechanisms and strategies.

Liquid-liquid phase separation (LLPS) of biomolecules inspires the construction of protocells and drives the formation of cellular membraneless organelles. The resulting biomolecular condensates featuring dynamic assembly, disassembly, and phase transition play significant roles in a series of biological processes, including RNA metabolism, DNA damage response, signal transduction and neurodegenerative disease. Intensive investigations have been conducted for understanding and manipulating intracellular phase-separated disease-related proteins (e.g., FUS, tau and TDP-43). Herein, we review current studies on the regulation strategies of intracellular LLPS focusing on FUS, which are categorized into physical stimuli, biochemical modulators, and protein structural modifications, with summarized molecular mechanisms. This review is expected to provide a sketch of the modulation of FUS LLPS with its pros and cons, and an outlook for the potential clinical treatments of neurodegenerative diseases.

Coacervate microdroplets incorporating J-aggregates toward photoactive membraneless protocells.

Cooperative coacervation of a porphyrin and a polycation electrolyte gives birth to photoactive membraneless protocells via liquid-liquid phase separation, where J-aggregates are formed to offer energy transduction pathways, rendering an adaptive platform for confining photocatalytic reactions within protocell compartments.

Coordination-Assisted Precise Construction of Metal Oxide Nanofilms for High-Performance Solid-State Batteries.

The application of solid-state batteries (SSBs) is challenged by the inherently poor interfacial contact between the solid-state electrolyte (SSE) and the electrodes, typically a metallic lithium anode. Building artificial intermediate nanofilms is effective in tackling this roadblock, but their implementation largely relies on vapor-based techniques such as atomic layer deposition, which are expensive, energy-intensive, and time-consuming due to the monolayer deposited per cycle. Herein, an easy and low-cost wet-chemistry fabrication process is used to engineer the anode/solid electrolyte interface in SSBs with nanoscale precision. This coordination-assisted deposition is initiated with polyacrylate acid as a functional polymer to control the surface reaction, which modulates the distribution and decomposition of metal precursors to reliably form a uniform crack-free and flexible nanofilm of a large variety of metal oxides. For demonstration, artificial Al2O3 interfacial nanofilms were deposited on a ceramic SSE, typically garnet-structured Li6.5La3Zr1.5Ta0.5O12 (LLZT), that led to a significant decrease in the Li/LLZT interfacial resistance (from 2079.5 to 8.4 Ω cm2) as well as extraordinarily long cycle life of the assembled SSBs. This strategy enables the use of a nickel-rich LiNi0.83Co0.07Mn0.1O2 cathode to deliver a reversible capacity of 201.5 mAh g-1 at a considerable loading of 4.8 mg cm-2, featuring performance metrics for an SSB that is competitive with those of traditional Li-ion systems. Our study demonstrates the potential of solution-based routes as an affordable and scalable manufacturing alternative to vapor-based deposition techniques that can accelerate the development of SSBs for practical applications.

Directing Transition of Synthetic Protocell Models via Physicochemical Cues-Triggered Interfacial Dynamic Covalent Chemistry.

As the preliminary synthetic analogs of living cells, protocells with life-like features serve as a versatile platform to explore the origin of life. Although protocells constructed from multiple components have been developed, the transition of primitive cellular compartments toward structural complexity and advanced function remains a scientific challenge. Herein, a programmable pathway is established to exploit a simple chemistry to construct structural transition of protocell models from emulsion droplets, nanocapsules to molecularly crowded droplets. The transitional process toward distinct cell-like compartments is driven by interfacial self-assembly of simple components and regulated by physicochemical cues (e.g., mechanical force, solvent evaporation, acid/base equilibrium) triggered dynamic covalent chemistry. These protocell models are further studied by comparing their compartmentalization behavior, sequestration efficiency, and the ability to enrich biomolecules (e.g., enzyme and substrate) toward catalytic reaction or biological activity within the compartments. The results showcase physiochemical cues-driven programmable transition of life-like compartments toward functionalization, and offer a new step toward the design of living soft materials.