Photoswitchable gating of non-equilibrium enzymatic feedback in chemically communicating polymersome nanoreactors

Post-Synthesis of Donor-Acceptor Stenhouse Adducts into Photochromic Microparticles

Encapsulating photoresponsive molecules into polymers is an effective strategy to achieve fast and efficient photochromism in the solid state. Water is often used as the dispersion phase for the formation of polymeric microparticles; however, it reacts with the photoresponsive molecules and induces irreversible structural degradation. In this work, we report a post-synthesis strategy to fabricate photochromic microparticles, where donor-acceptor Stenhouse adducts (DASAs) are applied as the photoresponsive molecules. Unlike direct loading, hydrostable precursors are loaded during the formation of polymeric microparticles, followed by synthesizing the DASAs inside the microparticles in a water-free environment. The photochromic microparticles are reversibly switched between colored and colorless states under the control of visible light irradiation and heat, while also exhibiting improved stability under hygrothermal conditions. Further applications of the photochromic microparticles as smart additives are demonstrated for controlling color-switching of bulk materials and rewritable photopatterning on surfaces. The post-synthesis approach is envisioned as a general strategy to fabricate microparticles with water-sensitive functional molecules.

Ultrathin Polymersomes with Controllable Light-Responsivity via Adjusting the Electronic Effect from Para-Substituents of Azobenzene

Achieving ultrathin polymersomes (UTPSs) with controllable light-responsive kinetics poses a prospective strategy to address the growing demands of intelligent and miniature systems, but it remains challenging. Herein, we reported the self-assembly of numerous side-chain-type amphiphilic alternating azocopolymers (AAACs) into a series of UTPSs with diameters spanning 210-270 nm and ultrathin vesicular thickness spanning 1.91-2.14 nm. The light-triggered reversible size transitions for these UTPSs are rendered by the photo-isomerization of azobenzene moiety upon alternating irradiation with UV and visible light. The systematical isomerization kinetic study proved that the light-responsive rate of distinct UTPSs was highly dependent on the electronic effect of para-substituents of azobenzenes within AAACs. Notably, the rate constant of electron-withdrawing nitro-modified UTPSs was 6.7 times greater than that of electron-donating hydroxyl-modified UTPSs. The proof-of-concept cargo release activity for different UTPSs was evaluated using a hydrophilic model drug of methylene blue (MB), with a light-controllable releasing performance that highly depended on the para-substituent-induced light-responsive kinetics. Our work offers an innovative strategy to fabricate stimuli-responsive UTPSs with a controllable responsive performance for the targeted applications in bionanotechnology.

Osmotic Pressure Induced Morphological Transformation of Membranized Coacervates

The stimulus-response behavior of protocells under environmental osmotic pressure changes has long been a subject of scientific inquiry. Herein, we demonstrate a way to membranized coacervate microdroplets based on cholesterol anchoring of phospholipids, which provides enhanced stability, enabling morphological transformations instead of dissociation during subsequent osmotic pressure changes. In hypotonic environments, these membranized coacervates equilibrate osmotic pressure through transient internal vacuole formation, concomitant with a transmembrane substrate influx that triggers enzymatic reaction acceleration. By contrast, in a hypertonic environment, the membranized coacervate responds with bursting-like deformation that can then quickly recover due to the anchoring effect of cholesterol on phospholipids. Notably, it is found that such bursting-like deformation could even successfully induce endocytosis of Staphylococcus aureus by the membranized coacervates. Furthermore, through the integration of Coa@DMPC's osmotic responsiveness, internal actin polymerization activated by the endocytic S. aureus is achieved. Not only our proposed method of phospholipid membranization of the coacervate could contribute a new model to mimic more complex bionic structures, but also the revealed morphological response behavior of the membranized coacervate under various osmotic pressure changes is expected to help explain the stress behaviors and emerging unique properties of cells in similar environments.

Chemically active colloidal superstructures

Mimicking biological systems, artificial active colloidal motors that continuously dissipate energy can dynamically self-assemble to form active colloidal superstructures with specific spatial configurations and complex functionalities, which offers a promising pathway for developing new active soft matter materials with adaptability, self-repair, and reconfigurability. Beyond merely propelling their own motion, chemically driven colloidal motors can also induce phoretic effects and osmotic flows to affect the motion of neighboring colloidal motors through local fluid fields generated by chemical reactions, thereby achieving spontaneous chemical communication and promoting dynamic self-assembly between motors. This review summarizes the latest progress in the dynamic self-assembly of chemically driven colloidal motors, ranging from single chemically driven colloidal motors to chemically driven colloidal motors with passive colloidal particles and then to different chemically driven colloidal motors, ultimately forming active colloidal superstructures with complex dynamic behaviors. Not only are the interactions between chemically driven colloidal motors with different self-propulsion mechanisms and passive colloidal particles focused on, but also the communication behaviors between chemically driven colloidal motors are explored. We explain the fundamental physicochemical mechanisms that regulate the assembly behavior of chemically driven colloidal motors, propose general strategies for the controlled construction of active colloidal superstructures, and discuss the potential applications that may emerge from the directed dynamic self-assembly of these superstructures.

Protonation State Insights into the Influence of Biocatalytic Function for Acetylcholinesterase Mediated by Neonicotinoids

The catalytic efficiency of acetylcholinesterase (AChE) is likely regulated by the protonation states and conformational adaptations of its catalytic residues. While neonicotinoid insecticides are recognized for impairing AChE function through neurotoxic mechanisms, the precise molecular mechanisms governing this inhibition remain poorly characterized. This investigation elucidates how structural variations among neonicotinoids modulate the protonation equilibria of Glu-202 and His-447 in AChE's catalytic triad. Comparative analysis reveals that nitro-substituted neonicotinoids (imidacloprid, clothianidin) induce more pronounced protonation state transitions compared to their cyano-containing counterparts (thiacloprid, acetamiprid). Specifically, the strong electron-withdrawing nitro groups facilitate the conversion of Glu-202 from the deprotonation (GLU) to protonation (GLH) state and His-447 from the δ- (HID) to ε-position protonation (HIE) state through enhanced electrostatic interactions. These electronic perturbations trigger structural reorganization within the active site, evidenced by nitro group-directed residue realignment and subsequent H-bond formation. Energy decomposition analysis identifies electrostatic contributions as the primary determinant of binding affinity differences, with nitro-neonicotinoids exhibiting stronger interactions than cyano-neonicotinoids. QM/MM metadynamics reveals that substantial protonation state alterations disrupt AChE's biocatalytic function, particularly its capacity for acetylcholine hydrolysis. Finally, SH-SY5Y-based cellular assays show that imidacloprid exhibits the strongest inhibitory effect on AChE intracellular activity, while thiacloprid and acetamiprid show weaker inhibitory effects, aligning with the computational predictions. This study provides insights into the protonation-state-induced biocatalytic function for acetylcholinesterase mediated by neonicotinoids, contributing to the assessment of exogenous ligand-induced potential ecological and human health risks.

Cytomimetic calcification in chemically self-regulated prototissues

The fabrication of cytomimetic materials capable of orchestrated and adaptive functions remains a significant challenge in bottom-up synthetic biology. Inspired by the cell/matrix integration of living bone, here we covalently tether distributed single populations of alkaline phosphatase-containing inorganic protocells (colloidosomes) onto a crosslinked organic network to establish viscoelastic tissue-like micro-composites. The prototissues are endogenously calcified with site-specific mineralization modalities involving selective intra-protocellular calcification, matrix-specific extra-protocellular calcification or gradient calcification. To mirror the interplay between osteoblasts and osteoclasts, we prepare integrated prototissues comprising a binary population of enzymatically active colloidosomes capable of endogenous calcification and decalcification and utilize chemical inputs to induce structural remodelling. Overall, our methodology opens a route to the chemically self-regulated calcification of homogeneous and gradient tissue-like mineral-matrix composites, advances the development of bottom-up synthetic biology in chemical materials research, and could provide potential opportunities in bioinspired tissue engineering, hydrogel technologies and bone biomimetics.

Biomineralization-Inspired Membranization Toward Structural Enhancement of Coacervate Community

The design and assembly of protocell models that can mimic the features and functions of life present a significant research challenge with the potential for far-reaching impact. Inspired by the natural phenomenon of microbe-induced mineralization, a way is developed to induce the spontaneous formation of mineralized membrane on the surface of coacervate droplets utilizing Fe3+ ions. In particular, the effect of Fe3+ ions on the microstructure of droplets at the molecular level is dissected by combining theoretical and experimental approaches. The reversible formation process of membrane can be regulated by redox reactions involving Fe2+/Fe3+ ions within the coacervate. The formation of mineralized membrane not only enhances the stability of the coacervate droplets and prevents aggregation and coalescence, but also allows the aggregation of adjacent droplets together. The membranized coacervate assemblages retain the inherent properties of biomolecule sequestration and enzyme catalysis, and also demonstrate excellent resistance to high temperatures and pressures as well as good stability for over 30 days. This study will offer a new platform for the assembly of coacervate-based life-like biomimetic systems, as well as enhance the understanding of the interactions underlying various biological phenomena at the molecular level.

Spatio-Temporal Processes of Diffusion-Controlled Communication in Hierarchical Multi-Compartments

Exploring the synergy of feedback behavior and molecular communication between micro- and nanocompartments is of great implication for the development of advanced hierarchical living-like materials. Non-covalent interactions are the driving forces for dynamic and temporal events in biomimetic structures. Herein, pH-responsive hierarchical multi-compartments (HMC) are constructed via hydrophobic-hydrophobic interactions between azobenzene units and phospholipid layers through the integration of two distinct structural units: phospholipid-membranized coacervates (Coa@DMPC) and azobenzene-functionalized polymersomes (Azo-Psomes). This enables us to study spatio-temporal signal pathways for biomimetic pH homeostasis and the triggering of feedback-controlled peroxidase-like behavior of Azo-Psomes within HMC. Compared with undocking systems, the information transmission process within HMC shows a high efficiency. Besides the continuous addition of nutrients, the synchronization of two different biomimetic reactions in HMC requires the spatial loading of glucose oxidase and L-phenylalanine ammonia lyase in coacervates and of L-phenylalanine or beta-cyclodextrin/hemin complexes in Azo-Psomes. Azo-Psomes exhibit pH-responsive feedback-controlled behavior. The pH-responsive membrane of Azo-Psomes is responsible for the spatio-temporal peroxidase-like activity of lumen-integrated beta-cyclodextrin/hemin complexes in Azo-Psomes. Finally, this strategy provides a new approach for constructing more complex biomimetic systems by interconnecting at least two membrane-containing compartments to further explore the synergistic mechanisms and feedback behaviors among artificial cell communities.

Adenosine Triphosphate Harnessed Transient Aggregations of Nanoparticles for Efficient Nanoreactors in Water

Living cells utilize diverse biochemical reactions occurring in microcompartments to regulate important biological functions. Although transient nanoreactors mediated by diverse fuels are achieved in discrete nanoassemblies of synthetic building blocks, the slow diffusion of substrates in and out of these solvent-dispersed nanoassemblies greatly compromises the reaction efficiency. Herein, we report adenosine triphosphate (ATP)-driven transient aggregation of nanoreactors that enable the acceleration of nucleophilic aromatic substitution (SNAr) in an aqueous solution. This system is composed of nanoparticles self-assembled from an amphiphilic molecule containing an ATP receptor, ATP, and potato apyrase (PA). The sequential addition of ATP and PA results in a reversible aggregation and disaggregation of the nanoparticles, which serve as smart nanoreactors to accelerate the SNAr reaction on demand. Notably, this reaction is temporally regulated by the autonomous aggregation and disaggregation of the nanoparticles. Furthermore, the azobenzene moiety in amphiphilic molecules allows the further modulation of the SNAr reaction in the nanoreactors using ultraviolet light.

Urease-coupled systems and materials: design strategies, scope and applications

Synthetic systems have co-opted urease, a crucial enzyme serving many biological functions, to recapitulate complex biological features. Therefore, the urease-urea feedback reaction network (FCRN) is reciprocated with soft materials to induce various animate-like features, including self-regulation, error correction, and decision-making capabilities, that are processed through a variety of non-linear functions. Although free-urease-based homogeneous systems are capable of adhering to many non-linear characteristics, they lack the ability to showcase the diffusion-controlled spatiotemporal phenomena. Therefore, it demands urease immobilization, whereby a compartmentalized reaction hub can facilitate the interplay of FCRN with reaction diffusion to regulate the system's operation, allowing various non-linear responses and spatiotemporal self-organization. Indeed, the beneficial framework of urease-based commercial systems in modern technology necessitates the accessibility, reusability, and long-term stability of urease. Consequently, several techniques for urease immobilization merit attention. This review highlights the diverse covalent and non-covalent approaches for urease immobilization on different substrates and illustrates several chemical reactions and non-covalent interactions as tools for creating targeted systems and soft materials to realize many on-demand functions. We also emphasize how the advancement of systems chemistry has propelled research in soft materials to comprehend system-level applications by demonstrating several emerging non-linear functions with potent applications in many directions, including sensing, soft robotics, regulation of material properties and many more.

4D Assembly of Time-dependent Lanthanide Supramolecular Multicolor Phosphorescence for Encryption and Visual Sensing

Supramolecular dynamic room temperature phosphorescence (RTP) is the focus of current research because of its wide application in biological imaging and information anti-counterfeiting. Herein, a time-dependent supramolecular lanthanide phosphorescent 4D assembly material with multicolor luminescence including white, which is composed of 4-(4-bromophenyl)-pyridine salt derivative (G), inorganic clay (LP)/Eu complex and pyridine dicarboxylic acid (DPA) is reported. Compared with the self-assembled nanoparticle G, the lamellar assembly G/LP showed the double emission of fluorescence at 380 nm and phosphorescence at 516 nm over time. Within 60 min, the phosphorescence lifetime and the quantum yield increases from none to 7.4 ms and 27.53% respectively, achieving the time-dependent phosphorescence emission, due to the limitation of progressive stacking of LP electrostatically driven "domino effect." Furthermore, the 4D assembly of DPA and G/LP/Eu leads to a time-resolved multicolor emission from colorless to purple to white, which is successfully applied to information multi-level logic anti-counterfeiting and efficiently antibiotic selective sensor.

Membrane Transport Modulates the pH-Regulated Feedback of an Enzyme Reaction Confined within Lipid Vesicles

Understanding ion transport dynamics in reactive vesicles is pivotal for exploring biological and chemical processes and essential for designing synthetic cells. In this work, we investigate how proton transport and membrane potential regulate pH dynamics in an autocatalytic enzyme reaction within lipid vesicles. Combining experimental and numerical methods, we demonstrate that compartmentalization within lipid membranes accelerates internal reactions, attributed to protection from the external acidic environment. In experiments, we explored how proton movement significantly impacts internal reactions by changing bilayer thickness, adding ion transporters, and varying buffers. Numerical investigations incorporated electrical membrane potential and capacitance into a kinetic model of the process, elucidating the mechanisms that dictate the control of reaction time observed in the experiment, driven by both electrical and chemical potential gradients. These findings establish a framework for controlling pH clock reactions via membrane changes and targeted manipulation of proton movement, which could aid in the design of synthetic cells with precise, controlled functionalities.

A molecular strategy for creating functional vesicles with balancing structural stability and stimuli-responsiveness

Vesicles, closed bilayer structures composed of amphiphiles, have attracted considerable attention as functional materials. Structural stability and stimulus responsiveness are required for next-generation functional vesicles. However, there is a dilemma between these properties because the desired membrane structure varies in terms of structural stability and stimulus sensitivity. Herein, we propose a new approach for the development of giant vesicles (GVs) through the molecular design and synthesis of amphiphiles with or without amide linkages, forming hydrogen bonding. From the 1H NMR analysis and fluorescence spectra of environment-responsive probes, intermolecular hydrogen bonding between the amide linkages in the membrane contributed to the enhanced structural stability of the GVs. Moreover, by adding amphiphiles containing a photoresponsive azobenzene moiety to GVs composed of amphiphiles with or without amide linkages, a distinct mechanism of photoresponsive deformation was observed: the former exhibited large and irreversible deformation, while the latter showed a modest and reversible manner due to the photoisomerisation of azobenzene under ultraviolet and subsequent visible light illumination. This difference was also attributed to the membrane structure affected by intermolecular hydrogen bonding. Based on these results, the finding provides a molecular methodology for developing highly functional vesicles.

Evolution of Supramolecular Coordination Assemblies Visually Monitored by Time-Dependent Multicolor Fluorescence

Supramolecular coordination assemblies play an important role in both material science and biological systems. Despite significant efforts in their development, most existing examples are thermodynamically controlled, which lack the adaptability and autonomy essential for the creation of advanced materials. In this work, we have developed non-equilibrium coordination assembly systems that can evolve over time through a combination of thermodynamic and kinetic controls. The introduction of zinc ions resulted in the formation of metastable fiber assemblies in a kinetically trapped state, which autonomously converted to thermodynamically stable nanosheets over time. This evolution process can be regulated by external stimuli and visually monitored by the time-dependent multicolor fluorescence. The construction strategy was versatile across other various ions such as Ca2+, Mg2+, and Al3+, offering inspiring insights for the design of complex systems that operated both in and out of their thermodynamic equilibrium.

Physical Isolation of Single Protein Molecules within Well-Defined Coordination Cages to Enhance Their Stability

Encapsulation of a single protein within a confined space can lead to distinct properties compared to bulk solutions, but controlling the number of encapsulated proteins and their environment remains challenging. This study demonstrates the encapsulation of single proteins within well-defined, tunable cavities of self-assembled coordination cages, thereby enhancing protein stability. Within uniform cavities of size-tunable coordination cages, 15 different proteins of varying sizes (3-6 nm in diameter) and properties (e.g., isoelectric points and hydrophobicity) were successfully confined. Various analytical techniques confirmed that the proteins maintained their secondary structures and enzymatic activities under denaturing conditions such as exposure to organic solvents, heat, and buffers. These findings suggest that such coordination cages have the potential to serve as synthetic hosts for precisely controlling protein functions within their customizable cavities.

A Urease-Based pH Photoswitch: A General Route to Light-to-pH Transduction

New approaches for the integration of chemical and physical stimuli to control the dynamics of artificial enzymatic reaction networks (ERNs) are needed. Here, we present a general approach to convert a light stimulus into a time-programmed pH response. We developed and characterized a panel of photoswitchable inhibitors of urease. Urease activity, now regulated by light via the photoinhibitors, leads to an increase in pH upon hydrolysis of urea into ammonia. Careful choice of characteristics of light, and concentrations of enzyme, substrate, and photoinhibitor, allowed us to control the timing of the pH transition. Furthermore, as all enzymes have an activity-pH profile, the urease photoinhibitor system can be used to regulate the activities of other enzymes in small reaction networks.

Transforming an ATP-dependent enzyme into a dissipative, self-assembling system

Nucleoside triphosphate (NTP)-dependent protein assemblies such as microtubules and actin filaments have inspired the development of diverse chemically fueled molecular machines and active materials but their functional sophistication has yet to be matched by design. Given this challenge, we asked whether it is possible to transform a natural adenosine 5'-triphosphate (ATP)-dependent enzyme into a dissipative self-assembling system, thereby altering the structural and functional mode in which chemical energy is used. Here we report that FtsH (filamentous temperature-sensitive protease H), a hexameric ATPase involved in membrane protein degradation, can be readily engineered to form one-dimensional helical nanotubes. FtsH nanotubes require constant energy input to maintain their integrity and degrade over time with the concomitant hydrolysis of ATP, analogous to natural NTP-dependent cytoskeletal assemblies. Yet, in contrast to natural dissipative systems, ATP hydrolysis is catalyzed by free FtsH protomers and FtsH nanotubes serve to conserve ATP, leading to transient assemblies whose lifetimes can be tuned from days to minutes through the inclusion of external ATPases in solution.

Compartmentalizing Donor-Acceptor Stenhouse Adducts for Structure-Property Relationship Analysis

The development of photoswitches that absorb low energy light is of notable interest due to the growing demand for smart materials and therapeutics necessitating benign stimuli. Donor-acceptor Stenhouse adducts (DASAs) are molecular photoswitches that respond to light in the visible to near-infrared spectrum. As a result of their modular assembly, DASAs can be modified at the donor, acceptor, triene, and backbone heteroatom molecular compartments for the tuning of optical and photoswitching properties. This Perspective focuses on the electronic and steric contributions at each compartment and how they influence photophysical properties through the adjustment of the isomerization energetic landscape. An emphasis on current synthetic strategies and their limitations highlights opportunities for DASA architecture, and thus photophysical property expansion.

Unlocking Intracellular Protein Delivery by Harnessing Polymersomes Synthesized at Microliter Volumes using Photo-PISA

Efficient delivery of therapeutic proteins and vaccine antigens to intracellular targets is challenging due to generally poor cell membrane permeation and endolysosomal entrapment causing degradation. Herein, these challenges are addressed by developing an oxygen-tolerant photoinitiated polymerization-induced self-assembly (Photo-PISA) process, allowing for the microliter-scale (10 µL) synthesis of protein-loaded polymersomes directly in 1536-well plates. High-resolution techniques capable of analysis at a single particle level are employed to analyze protein encapsulation and release mechanisms. Using confocal microscopy and super-resolution stochastic optical reconstruction microscopy (STORM) imaging, their ability to deliver proteins into the cytosol following endosomal escape is subsequently visualized. Lastly, the adaptability of these polymersomes is exploited to encapsulate and deliver a prototype vaccine antigen, demonstrating its ability to activate antigen-presenting cells and support antigen cross-presentation for applications in subunit vaccines and cancer immunotherapy. This combination of ultralow volume synthesis and efficient intracellular delivery holds significant promise for unlocking the high throughput screening of a broad range of otherwise cost-prohibitive or early-stage therapeutic protein and vaccine antigen candidates that can be difficult to obtain in large quantities. The versatility of this platform for rapid screening of intracellular protein delivery can result in significant advancements across the fields of nanomedicine and biomedical engineering.

Boosting Microfluidic Enzymatic Cascade Reactions with pH-Responsive Polymersomes by Spatio-Chemical Activity Control

Microfluidic flow reactors permit the implementation of sensitive biocatalysts in polymeric environments (e.g., hydrogel dots), mimicking nature through the use of diverse microstructures within defined confinements. However, establishing complex hybrid structures to mimic biological processes and functions under continuous flow with optimal utilization of all components involved in the reaction process represents a significant scientific challenge. To achieve spatial, chemical, and temporal control for any microfluidic application, compartmentalization is required, as well as the unification of different sensitive compartments in the reaction chamber for the microfluidic flow design. This study presents a self-regulating microfluidic system fabricated by a sequential photostructuring process with an intermediate chemical process step to realize pH-sensitive hybrid structures for the fabrication of a microfluidic double chamber reactor for controlled enzymatic cascade reaction (ECR). The key point is the adaptation and retention of the function of pH-responsive horseradish peroxidase-loaded polymersomes in a microfluidic chip under continuous flow. ECR is successfully triggered and controlled by an interplay between glucose oxidase-converted glucose, the membrane state of pH-responsive polymersomes, and other parameters (e.g., flow rate and fluid composition). This study establishes a promising noninvasive regulatory platform for extended spatio-chemical control of current and future ECR and other cascade reaction systems.

Self-adaptive photochromism

Organisms with active camouflage ability exhibit changeable appearance with the switching of environments. However, manmade active camouflage systems heavily rely on integrating electronic devices, which encounters problems including a complex structure, poor usability, and high cost . In the current work, we report active camouflage as an intrinsic function of materials by proposing self-adaptive photochromism (SAP). The SAP materials were fabricated using donor-acceptor Stenhouse adducts (DASAs) as the negative photochromic phases and organic dyes as the fixed phases (nonphotochromic). Incident light with a specific wavelength induces linear-to-cyclic isomerization of DASAs, which generates an absorption gap at the wavelength and accordingly switches the color. The SAP materials are in the primary black state under dark and spontaneously switch to another color upon triggering by transmitted and reflected light in the background. SAP films and coatings were fabricated by incorporating polycaprolactone and are applicable to a wide variety of surfaces.

Crowding for Confinement: Reversible Isomerization of First-Generation Donor-Acceptor Stenhouse Adduct Derivatives in Water Modulated by Thermoresponsive Dendritic Macromolecules

Mimicking nature, the reversible isomerization of hydrophobic dyes in aqueous solutions is appealing for bio-applications. Here, we report on the reversible isomerization of first-generation solvatochromic donor-acceptor Stenhouse adducts (DASAs) in water within dendritic matrices, realized either through the dendronization of DASAs or the incorporation of DASA pendants into dendronized copolymers. These dendritic macromolecules contain three-fold dendritic oligoethylene glycols (OEGs), which afford the macromolecules water-solubility and unprecedented thermoresponsive behavior. The thermoresponsive behavior of both dendronized DASAs and dendronized copolymers is dominated by the peripherals of dendritic OEGs. However, the hydrophilicity of the acceptor from DASA moieties also play a role in mediating their thermal phase transitions, and more importantly, tailor the hydrophobic interactions between dendritic OEGs and DASA moieties. Intriguingly, dendritic topologies contribute confinement to encapsulate the DASA moieties through crowding effects, and cooperative interactions from the crowded dendritic OEGs modulate the DASA moieties with different isomerization in aqueous media. The thermally induced collapse of dendritic OEGs, accompanied by the aggregation of dendritic macromolecules, leads to the formation of hydrophobic domains, which exert enhanced crowding effects to efficiently encapsulate the DASA moieties. Compared to the low molar mass of dendronized DASAs, thermally collapsed dendronized copolymers can efficiently retard the hydration of DASA pendants through cooperation between neighboring dendritic OEGs and afford the DASA pendants with better confined microenvironments to mediate their isomerization recovery by up to 90% from a cyclic charged (hydrophilic) state into a noncharged (hydrophobic) linear state in water. This dendritic confinement exhibits excellent fatigue resistance after several cycles of alternating photo-irradiation and thermal annealing at elevated temperatures.

Supramolecular fibrillation in coacervates and other confined systems towards biomimetic function

As in natural cytoskeletons, the cooperative assembly of fibrillar networks can be hosted inside compartments to engineer biomimetic functions, such as mechanical actuation, transport, and reaction templating. Coacervates impose an optimal liquid-liquid phase separation within the aqueous continuum, functioning as membrane-less compartments that can organise such self-assembling processes as well as the exchange of information with their environment. Furthermore, biological fibrillation can often be controlled or assisted by intracellular compartments. Thus, the reconstitution of analogues of natural filaments in simplified artificial compartments, such as coacervates, offer a suitable model to unravel, mimic, and potentially exploit cellular functions. This perspective summarises the latest developments towards assembling fibrillar networks under confinement inside coacervates and related compartments, including a selection of examples ranging from biological to fully synthetic monomers. Comparative analysis between coacervates, lipid vesicles, and droplet emulsions showcases the interplay between supramolecular fibres and the boundaries of the corresponding compartment. Combining inspiration from natural systems and the custom properties of tailored synthetic fibrillators, rational monomer and compartment design will contribute towards engineering increasingly complex and more realistic artificial protocells.

Neutral and ionic N-methyl phenylazo-3,5-(di-2-pyridyl)pyrazole photoswitches: probes for reversible pH modulation by light

We report the design, synthesis, photoswitching and computational studies of N-methyl arylazo-3,5-(di-2-pyridyl)pyrazole and its N-alkyl pyridinium derivatives with an ionic center proximally located to the azo group. Besides achieving excellent photoswitching characteristics, particularly at longer wavelengths, and tuning Z isomer stability due to the effects of counter ions and pH, the utility of neutral and ionic photoswitches for pH modulation by light was achieved.

Transient cucurbit[7]uril-mediated host-guest complexes for time-dependent fluorescence and information-self-erasing hydrogel

A non-equilibrium cucurbit[7]uril-mediated supramolecular host-guest system is fabricated by using urea/urease to control aqueous solution pH on time dimension, showing transient assembly behavior and time-dependent fluorescence. The dynamic assembly can be also achieved in hydrogel network, resulting in a time-dependent fluorescent hydrogel for information encryption.

Advancing Artificial Cells with Functional Compartmentalized Polymeric Systems - In Honor of Wolfgang Meier

The fundamental building block of living organisms is the cell, which is the universal biological base of all living entities. This micrometric mass of cytoplasm and the membrane border have fascinated scientists due to the highly complex and multicompartmentalized structure. This specific organization enables numerous metabolic reactions to occur simultaneously and in segregated spaces, without disturbing each other, but with a promotion of inter- and intracellular communication of biomolecules. At present, artificial nano- and microcompartments, whether as single components or self-organized in multicompartment architectures, hold significant value in the study of life development and advanced functional materials and in the fabrication of molecular devices for medical applications. These artificial compartments also possess the properties to encapsulate, protect, and control the release of bio(macro)molecules through selective transport processes, and they are capable of embedding or being connected with other types of compartments. The self-assembly mechanism of specific synthetic compartments and thus the fabrication of a simulated organelle membrane are some of the major aspects to gain insight. Considerable efforts have now been devoted to design various nano- and microcompartments and understand their functionality for precise control over properties. Of particular interest is the use of polymeric vesicles for communication in synthetic cells and colloidal systems to reinitiate chemical and biological communication and thus close the gap toward biological functions. Multicompartment systems can now be effectively created with a high level of hierarchical control. In this way, these structures can not only be explored to deepen our understanding of the functional organization of living cells, but also pave the way for many more exciting developments in the biomedical field.

Dynamic Near-Infrared Circularly Polarized Luminescence Encoded by Transient Supramolecular Chiral Assemblies

Circularly polarized luminescence (CPL) is promising for applications in many fields. However, most systems involving CPL are within the visible range; near-infrared (NIR) CPL-active materials, especially those that exhibit high glum values and can be controlled spatially and temporally, are rare. Herein, dynamic NIR-CPL with a glum value of 2.5×10-2 was achieved through supramolecular coassembly and energy-transfer strategies. The chiral assemblies formed by the coassembly between adenosine triphosphate (ATP) and a pyrene derivative exhibited a red CPL signal (glum of 10-3). The further introduction of sulfo-cyanine5 resulted in a energy-transfer process, which not only led to the NIR CPL but also increased the glum value to 10-2. Temporal control of these chiral assemblies was realized by introducing alkaline phosphatase to fabricate a biomimetic enzyme-catalyzed network, allowing the dynamic NIR CPL signal to be turned on. Based on these enzyme-regulated temporally controllable dynamic CPL-active chiral assemblies, a multilevel information encryption system was further developed. This study provides a pioneering example for the construction of dynamic NIR CPL materials with the ability to perform temporal control via the supramolecular assembly strategy, which is expected to aid in the design of supramolecular complex systems that more closely resemble natural biological systems.

Kinetically Controlled and Nonequilibrium Assembly of Block Copolymers in Solution

Covalent polymers are versatile macromolecules that have found widespread use in society. Contemporary methods of polymerization have made it possible to construct sequence polymers, including block copolymers, with high precision. Such copolymers assemble in solution when the blocks have differing solubilities. This produces nano- and microparticles of various shapes and sizes. While it is straightforward to draw an analogy between such amphiphilic block copolymers and phospholipids, these two classes of molecules show quite different assembly characteristics. In particular, block copolymers often assemble under kinetic control, thus producing nonequilibrium structures. This leads to a rich variety of behaviors being observed in block copolymer assembly, such as pathway dependence (e.g., thermal history), nonergodicity and responsiveness. The dynamics of polymer assemblies can be readily controlled using changes in environmental conditions and/or integrating functional groups situated on polymers with external chemical reactions. This perspective highlights that kinetic control is both pervasive and a useful attribute in the mechanics of block copolymer assembly. Recent examples are highlighted in order to show that toggling between static and dynamic behavior can be used to generate, manipulate and dismantle nonequilibrium states. New methods to control the kinetics of block copolymer assembly will provide endless unanticipated applications in materials science, biomimicry and medicine.

Advances in biomaterials for oral-maxillofacial bone regeneration: spotlight on periodontal and alveolar bone strategies

The intricate nature of oral-maxillofacial structure and function, coupled with the dynamic oral bacterial environment, presents formidable obstacles in addressing the repair and regeneration of oral-maxillofacial bone defects. Numerous characteristics should be noticed in oral-maxillofacial bone repair, such as irregular morphology of bone defects, homeostasis between hosts and microorganisms in the oral cavity and complex periodontal structures that facilitate epithelial ingrowth. Therefore, oral-maxillofacial bone repair necessitates restoration materials that adhere to stringent and specific demands. This review starts with exploring these particular requirements by introducing the particular characteristics of oral-maxillofacial bones and then summarizes the classifications of current bone repair materials in respect of composition and structure. Additionally, we discuss the modifications in current bone repair materials including improving mechanical properties, optimizing surface topography and pore structure and adding bioactive components such as elements, compounds, cells and their derivatives. Ultimately, we organize a range of potential optimization strategies and future perspectives for enhancing oral-maxillofacial bone repair materials, including physical environment manipulation, oral microbial homeostasis modulation, osteo-immune regulation, smart stimuli-responsive strategies and multifaceted approach for poly-pathic treatment, in the hope of providing some insights for researchers in this field. In summary, this review analyzes the complex demands of oral-maxillofacial bone repair, especially for periodontal and alveolar bone, concludes multifaceted strategies for corresponding biomaterials and aims to inspire future research in the pursuit of more effective treatment outcomes.

Development and characterization of amino donor-acceptor Stenhouse adducts

Donor-acceptor Stenhouse adducts (DASAs) are molecular photoswitches spurring wide interest because of their dynamic photophysical properties, complex photoswitching mechanism, and diverse applications. Despite breakthroughs in modularity for the donor, acceptor, and triene compartments, the backbone heteroatom remains static due to synthetic challenges. We provide a predictive tool and sought-after strategy to vary the heteroatom, introduce amino DASA photoswitches, and analyze backbone heteroatom effects on photophysical properties. Amino DASA synthesis is enabled by aza-Piancatelli rearrangements on pyrrole substrates, imparting an aromaticity-breaking rearrangement that capitalizes on nitrogen's additional bonding orbital and the inductive properties of sulfonyl groups. Amino DASA structure is confirmed by single crystal X-ray diffraction, the photochromic properties are characterized, and the photoswitch isomerization is investigated. Overall, the discovered pyrrole rearrangement enables the study of the DASA backbone heteroatom compartment and furthers our insight into the structure-property relationship of this complex photoswitch.

Robust Red-Absorbing Donor-Acceptor Stenhouse Adduct Photoswitches

Donor-Acceptor Stenhouse Adduct (DASA), a class of push-pull negative photochrome, has received large interest lately owing to its versatile synthesis, modularity and excellent photoswitching in solutions. From a technological perspective, it is imperative for this class of photoswitches to work robustly in solid state, e. g. thin films. We feature a molecular framework for the optimized design of DASAs by introducing a new thioindoline donor (D3) and assessing its performance against known 2nd generation indoline-based donors. The systematic structure-function investigations suggest that to achieve robust reversible photoswitching, a ground state with low charge separation is desired. DASAs with stronger electron donors and a larger charge separation in the ground state result in a low population of the photothermalstationary state (PTSS) and reduced photostability. The DASA with thioindoline donor (D3A3) seems to be a special case among the donor series as it causes a red shift (ca. 15 nm), however with less polarization of the ground state and marginally better photostability as compared to the unsubstituted 2-methyl indoline (D1A3). We also emphasize the consideration of the key additional factors that can modulate the red-light photoswitching properties of DASA chromophores in polymer thin films, which might not be dominant in homogenous solution state.

Robust, Ultrafast and Reversible Photoswitching in Bulk Polymers Enabled by Octupolar Molecule Design

Improving the photoswitching rate and robustness of photochromic molecules in bulk solids is paramount for practical applications but remains an on-going challenge. Here, we introduce an octupolar design paradigm to develop a new family of visible light organic photoswitches, namely multi-branched octupolar Stenhouse Adducts (MOPSAs) featuring a C3-symmetrical A3-(D-core) architecture with a dipolar donor-acceptor (D-A) photochrome in each branch. Our design couples multi-dimensional geometric and electronic effects of MOPSAs to enable robust ultrafast reversible photoswitching in bulk polymers. Specifically, the optimal MOPSA (4 wt %) in commercial polyurethane films accomplishes nearly 100 % discoloration in 6 s under visible light with ∼ 100 % thermal-recovery in 17.4 s at 60 °C, while the acquired kinetics constants are 3∼7 times that of dipolar DASA counterpart and 1∼2 orders of magnitude higher than those of reported DASAs in polymers. Importantly, the MOPSA-doped polymer films sustain 500 discoloration/recovery cycles with slow degradation, superior to the existing DASAs in polymers (≤30 cycles). We discover that multi-dipolar coupling in MOPSA enables enhanced polarization and electron delocalization, promoting the rate-determining thermal cyclization, while the branched and non-planar geometry of MOPSA induces large free volume to facilitate the isomerization. This design can be extended to develop spiropyran or azobenzene-based ultrafast photochromic films. The superior photoswitching performance of MOPSAs together with their high-yield and scalable synthesis and facile film processing inspires us to explore their versatile uses as smart inks or labels for time-temperature indicators, optical logic encryption and multi-levelled data encryption.

Photoswitchable Cascades for Allosteric and Bidirectional Control over Covalent Bonds and Assemblies

Studies of complex systems and emerging properties to mimic biosystems are at the forefront of chemical research. Dynamic multistep cascades, especially those exhibiting allosteric regulation, are challenging. Herein, we demonstrate a versatile platform of photoswitchable covalent cascades toward remote and bidirectional control of reversible covalent bonds and ensuing assemblies. The relay of a photochromic switch, keto-enol equilibrium, and ring-chain equilibrium allows light-mediated reversible allosteric structural changes. The accompanying distinct reactivity further enables photoswitchable dynamic covalent bonding and release of substrates bidirectionally through alternating two wavelengths of light, essentially realizing light-mediated signaling cycles. The downfall of energy by covalent bond formation/scission upon photochemical reactions offers the driving force for the controlled direction of the cascade. To show the molecular diversity, photoswitchable on-demand assembly/disassembly of covalent polymers, including structurally reconfigurable polymers, was realized. This work achieves photoswitchable allosteric regulation of covalent architectures within dynamic multistep cascades, which has rarely been reported before. The results resemble allosteric control within biological signaling networks and should set the stage for many endeavors, such as dynamic assemblies, molecular motors, responsive polymers, and intelligent materials.

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

Dynamic microscale droplets produced by liquid-liquid phase separation (LLPS) have emerged as appealing biomaterials due to their remarkable features. However, the instability of droplets limits the construction of population-level structures with collective behaviors. Here we first provide a brief background of droplets in the context of materials properties. Subsequently, we discuss current strategies for stabilizing droplets including physical separation and chemical modulation. We also discuss the recent development of LLPS droplets for various applications such as synthetic cells and biomedical materials. Finally, we give insights on how stabilized droplets can self-assemble into higher-order structures displaying coordinated functions to fully exploit their potentials in bottom-up synthetic biology and biomedical applications.

Artificial Homeostasis Systems Based on Feedback Reaction Networks: Design Principles and Future Promises

Feedback-controlled chemical reaction networks (FCRNs) are indispensable for various biological processes, such as cellular mechanisms, patterns, and signaling pathways. Through the intricate interplay of many feedback loops (FLs), FCRNs maintain a stable internal cellular environment. Currently, creating minimalistic synthetic cells is the long-term objective of systems chemistry, which is motivated by such natural integrity. The design, kinetic optimization, and analysis of FCRNs to exhibit functions akin to those of a cell still pose significant challenges. Indeed, reaching synthetic homeostasis is essential for engineering synthetic cell components. However, maintaining homeostasis in artificial systems against various agitations is a difficult task. Several biological events can provide us with guidelines for a conceptual understanding of homeostasis, which can be further applicable in designing artificial synthetic systems. In this regard, we organize our review with artificial homeostasis systems driven by FCRNs at different length scales, including homogeneous, compartmentalized, and soft material systems. First, we stretch a quick overview of FCRNs in different molecular and supramolecular systems, which are the essential toolbox for engineering different nonlinear functions and homeostatic systems. Moreover, the existing history of synthetic homeostasis in chemical and material systems and their advanced functions with self-correcting, and regulating properties are also emphasized.

Facilitating Interskin Communication in Artificial Polymer Systems through Liquid Transfer

Chemical communication is a ubiquitous process in nature, and it has sparked interest in the development of electric-sense-based robotic perception systems with chemical components. Here, a novel liquid crystal polymer is introduced that combines the transferring, receiving, and sensing of chemical signals, providing a new principle to achieve chemical communication in robotic systems. This approach allows for the transfer of cargo between two polymer coatings, and the transfer can be monitored through an electrical signal. Additionally, cascade transfer can be achieved through this approach, as the transfer of cargo is not limited to only two coatings, but can continue from the second to a third coating. Furthermore, the two coatings can be infused with different reagents, and upon exchange, a reaction takes place to generate the desired species. The novel method of chemical communication that is developed presents a notable improvement in embodied perception. This advancement facilitates human-robot and robot-robot interactions and enhances the ability of robots to efficiently and accurately perform complex tasks in their environment.

Exploring Emergent Properties in Enzymatic Reaction Networks: Design and Control of Dynamic Functional Systems

The intricate and complex features of enzymatic reaction networks (ERNs) play a key role in the emergence and sustenance of life. Constructing such networks in vitro enables stepwise build up in complexity and introduces the opportunity to control enzymatic activity using physicochemical stimuli. Rational design and modulation of network motifs enable the engineering of artificial systems with emergent functionalities. Such functional systems are useful for a variety of reasons such as creating new-to-nature dynamic materials, producing value-added chemicals, constructing metabolic modules for synthetic cells, and even enabling molecular computation. In this review, we offer insights into the chemical characteristics of ERNs while also delving into their potential applications and associated challenges.

Synthetic Cells Revisited: Artificial Cells Construction Using Polymeric Building Blocks

The exponential growth of research on artificial cells and organelles underscores their potential as tools to advance the understanding of fundamental biological processes. The bottom-up construction from a variety of building blocks at the micro- and nanoscale, in combination with biomolecules is key to developing artificial cells. In this review, artificial cells are focused upon based on compartments where polymers are the main constituent of the assembly. Polymers are of particular interest due to their incredible chemical variety and the advantage of tuning the properties and functionality of their assemblies. First, the architectures of micro- and nanoscale polymer assemblies are introduced and then their usage as building blocks is elaborated upon. Different membrane-bound and membrane-less compartments and supramolecular structures and how they combine into advanced synthetic cells are presented. Then, the functional aspects are explored, addressing how artificial organelles in giant compartments mimic cellular processes. Finally, how artificial cells communicate with their surrounding and each other such as to adapt to an ever-changing environment and achieve collective behavior as a steppingstone toward artificial tissues, is taken a look at. Engineering artificial cells with highly controllable and programmable features open new avenues for the development of sophisticated multifunctional systems.

Signal Transduction in Artificial Cells

In recent years, significant progress has been made in the emerging field of constructing biomimetic soft compartments with life-like behaviors. Given that biological activities occur under a flux of energy and matter exchange, the implementation of rudimentary signaling pathways in artificial cells (protocells) is a prerequisite for the development of adaptive sense-response phenotypes in cytomimetic models. Herein, recent approaches to the integration of signal transduction modules in model protocells prepared by bottom-up construction are discussed. The approaches are classified into two categories involving invasive biochemical signals or non-invasive physical stimuli. In the former mechanism, transducers with intrinsic recognition capability respond with high specificity, while in the latter, artificial cells respond through intra-protocellular energy transduction. Although major challenges remain in the pursuit of a sophisticated artificial signaling network for the orchestration of higher-order cytomimetic models, significant advances have been made in establishing rudimentary protocell communication networks, providing novel organizational models for the development of life-like microsystems and new avenues in protoliving technologies.

Visible light-responsive materials: the (photo)chemistry and applications of donor-acceptor Stenhouse adducts in polymer science

Donor-acceptor Stenhouse adduct (DASA) photoswitches have gained a lot of attention since their discovery in 2014. Their negative photochromism, visible light absorbance, synthetic tunability, and the large property changes between their photoisomers make them attractive candidates over other commonly used photoswitches for use in materials with responsive or adaptive properties. The development of such materials and their translation into advanced technologies continues to widely impact forefront materials research, and DASAs have thus attracted considerable interest in the field of visible-light responsive molecular switches and dynamic materials. Despite this interest, there have been challenges in understanding their complex behavior in the context of both small molecule studies and materials. Moreover, incorporation of DASAs into polymers can be challenging due to their incompatibility with the conditions for most common polymerization techniques. In this review, therefore, we examine and critically discuss the recent developments and challenges in the field of DASA-containing polymers, aiming at providing a better understanding of the interplay between the properties of both constituents (matrix and photoswitch). The first part summarizes current understanding of DASA design and switching properties. The second section discusses strategies of incorporation of DASAs into polymers, properties of DASA-containing materials, and methods for studying switching of DASAs in materials. We also discuss emerging applications for DASA photoswitches in polymeric materials, ranging from light-responsive drug delivery systems, to photothermal actuators, sensors and photoswitchable surfaces. Last, we summarize the current challenges in the field and venture on the steps required to explore novel systems and expand both the functional properties and the application opportunities of DASA-containing polymers.

Polymersome Membrane Engineering with Active Targeting or Controlled Permeability for Responsive Drug Delivery

Polymersomes have been extensively investigated for drug delivery as nanocarriers for two decades due to a series of advantages including high stability under physiological conditions, simultaneous encapsulation of hydrophilic and hydrophobic drugs inside inner cavities and membranes, respectively, and facile adjustment of membrane and surface properties, as well as controlled drug release through incorporation of stimuli-responsive components. Despite these features, polymersome nanocarriers frequently suffer from nontargeting delivery and poor membrane permeability. In recent years, polymersomes have been functionalized for more efficient drug delivery. The surface shells were explored to be modified with diverse active targeting groups to improve disease-targeting delivery. The membrane permeability of the polymersomes was adjusted by incorporation of the stimuli-responsive components for smart controlled transportation of the encapsulated drugs. Therefore, being the polymersome-biointerface, tailorable properties can be introduced by its carefully modulated engineering. This review elaborates on the role of polymersome membranes as a platform to incorporate versatile features. First, we discuss how surface functionalization facilitates the directional journey to the targeting sites toward specific diseases, cells, or intracellular organelles via active targeting. Moreover, recent advances in the past decade related to membrane permeability to control drug release are also summarized. We finally discuss future development to promote polymersomes as in vivo drug delivery nanocarriers.

Nanomechanical action opens endo-lysosomal compartments

Endo-lysosomal escape is a highly inefficient process, which is a bottleneck for intracellular delivery of biologics, including proteins and nucleic acids. Herein, we demonstrate the design of a lipid-based nanoscale molecular machine, which achieves efficient cytosolic transport of biologics by destabilizing endo-lysosomal compartments through nanomechanical action upon light irradiation. We fabricate lipid-based nanoscale molecular machines, which are designed to perform mechanical movement by consuming photons, by co-assembling azobenzene lipidoids with helper lipids. We show that lipid-based nanoscale molecular machines adhere onto the endo-lysosomal membrane after entering cells. We demonstrate that continuous rotation-inversion movement of Azo lipidoids triggered by ultraviolet/visible irradiation results in the destabilization of the membranes, thereby transporting cargoes, such as mRNAs and Cre proteins, to the cytoplasm. We find that the efficiency of cytosolic transport is improved about 2.1-fold, compared to conventional intracellular delivery systems. Finally, we show that lipid-based nanoscale molecular machines are competent for cytosolic transport of tumour antigens into dendritic cells, which induce robust antitumour activity in a melanoma mouse model.

A microfluidic double emulsion platform for spatiotemporal control of pH and particle synthesis

The temporal control of pH in microreactors such as emulsion droplets plays a vital role in applications including biomineralisation and microparticle synthesis. Typically, pH changes are achieved either by passive diffusion of species into a droplet or by acid/base producing reactions. Here, we exploit an enzyme reaction combined with the properties of a water-oil-water (W/O/W) double emulsion to control the pH-time profile in the droplets. A microfluidic platform was used for production of ∼100-200 μm urease-encapsulated double emulsions with a tuneable mineral oil shell thickness of 10-40 μm. The reaction was initiated on-demand by addition of urea and a pulse in base (ammonia) up to pH 8 was observed in the droplets after a time lag of the order of minutes. The pH-time profile can be manipulated by the diffusion timescale of urea and ammonia through the oil layer, resulting in a steady state pH not observed in bulk reactive solutions. This approach may be used to regulate the formation of pH sensitive materials under mild conditions and, as a proof of concept, the reaction was coupled to calcium phosphate precipitation in the droplets. The oil shell thickness was varied to select for either brushite microplatelets or hydroxyapatite particles, compared to the mixture of different precipitates obtained in bulk.

Tuning the Organ Tropism of Polymersome for Spleen-Selective Nanovaccine Delivery to Boost Cancer Immunotherapy

The past few decades have witnessed explosive development in drug delivery systems. However, in vivo delivery suffers from non-specific distribution in non-targeted organs or tissues, which may cause undesired side effects and even genotoxicity. Here, a general strategy that enables tuning the tropism of polymersomes for liver- and spleen-selective delivery is reported. By using a library screening approach, spleen-targeted polymersome PH9-Aln-8020 and liver-targeted polymersome PA9-ZP3-5050 are identified accordingly. Meanwhile, the second near-infrared (NIR-II) fluorescence imaging allows for in vivo dynamic evaluation of their spatial and temporal accumulation in specific tissues. O ur findings indicate that both polymer composition and protein corona on the surface are essential to determine the in vivo fate of polymersomes and tendency for specific organs. Importantly, PH9-Aln-8020 is employed as a systemic nanocarrier to co-deliver the antigen and adjuvant, which remarkably boost splenic immune responses in acute myeloid leukemia, melanoma, and melanoma lung metastasis mouse models. This study may open a new frontier for polymersomes in organ-selective delivery and other biomedical applications.

A transient vesicular glue for amplification and temporal regulation of biocatalytic reaction networks

Regulation of enzyme activity and biocatalytic cascades on compartmentalized cellular components is key to the adaptation of cellular processes such as signal transduction and metabolism in response to varying external conditions. Synthetic molecular glues have enabled enzyme inhibition and regulation of protein-protein interactions. So far, all the molecular glue systems based on covalent interactions operated under steady-state conditions. To emulate dynamic biological processes under dissipative conditions, we introduce herein a transient supramolecular glue with a controllable lifetime. The transient system uses multivalent supramolecular interactions between guanidinium group-bearing surfactants and adenosine triphosphate (ATP), resulting in bilayer vesicle structures. Unlike the conventional chemical agents for dissipative assemblies, ATP here plays the dual role of providing a structural component for the assembly as well as presenting active functional groups to "glue" enzymes on the surface. While gluing of the enzymes on the vesicles achieves augmented catalysis, oscillation of ATP concentration allows temporal control of the catalytic activities similar to the dissipative cellular nanoreactors. We further demonstrate temporal upregulation and control of complex biocatalytic reaction networks on the vesicles. Altogether, the temporal activation of biocatalytic cascades on the dissipative vesicular glue presents an adaptable and dynamic system emulating heterogeneous cellular processes, opening up avenues for effective protocell construction and therapeutic interventions.

Recent advances in permeable polymersomes: fabrication, responsiveness, and applications

Polymersomes are vesicular nanostructures enclosed by a bilayer-membrane self-assembled from amphiphilic block copolymers, which exhibit higher stability compared with their biological analogues (e.g. liposomes). Due to their versatility, polymersomes have found various applications in different research fields such as drug delivery, nanomedicine, biological nanoreactors, and artificial cells. However, polymersomes prepared with high molecular weight components typically display low permeability to molecules and ions. It hence remains a major challenge to balance the opposing features of robustness and permeability of polymersomes. In this review, we focus on the design and strategies for fabricating permeable polymersomes, including polymersomes with intrinsic permeability, the formation of nanopores in the membrane bilayers by protein insertion, and the construction of stimuli-responsive polymersomes. Then, we highlight the applications of permeable polymersomes in the fields of biomimetic nanoreactors, artificial cells and organelles, and nanomedicine, to underline the challenges in the development of polymersomes as soft matter with biomedical utilities.

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.

A Red-Light-Responsive DASA-Polymer with High Water Stability for Controlled Release

Photoresponsive polymers hold vast potential in the realm of drug delivery. Currently, most photoresponsive polymers use ultraviolet (UV) light as the excitation source. However, the limited penetration ability of UV light within biological tissues serves as a significant hindrance to their practical applications. Given the strong penetration ability of red light in biological tissues, the design and preparation of a novel red-light-responsive polymer with high water stability, incorporating the reversible photoswitching compound and donor-acceptor Stenhouse adducts (DASA) for controlled drug release is demonstrated. In aqueous solutions, this polymer exhibits self-assembly into micellar nanovectors (~33 nm hydrodynamic diameter), facilitating the encapsulation of the hydrophobic model drug Nile red (NR) within the micellar core. Upon irradiation by a 660 nm LED light source, photons are absorbed by DASA, leading to the disruption of the hydrophilic-hydrophobic balance of the nanovector and thereby resulting in the release of NR. This newly designed nanovector incorporates red light as a responsive switch, successfully avoiding the problems of photodamage and limited penetration of UV light within biological tissues, thereby further promoting the practical applications of photoresponsive polymer nanomedicines.

Triggered Polymersome Fusion

The contents of biological cells are retained within compartments formed of phospholipid membranes. The movement of material within and between cells is often mediated by the fusion of phospholipid membranes, which allows mixing of contents or excretion of material into the surrounding environment. Biological membrane fusion is a highly regulated process that is catalyzed by proteins and often triggered by cellular signaling. In contrast, the controlled fusion of polymer-based membranes is largely unexplored, despite the potential application of this process in nanomedicine, smart materials, and reagent trafficking. Here, we demonstrate triggered polymersome fusion. Out-of-equilibrium polymersomes were formed by ring-opening metathesis polymerization-induced self-assembly and persist until a specific chemical signal (pH change) triggers their fusion. Characterization of polymersomes was performed by a variety of techniques, including dynamic light scattering, dry-state/cryogenic-transmission electron microscopy, and small-angle X-ray scattering (SAXS). The fusion process was followed by time-resolved SAXS analysis. Developing elementary methods of communication between polymersomes, such as fusion, will prove essential for emulating life-like behaviors in synthetic nanotechnology.

Overcoming the Dilemma of Permeability and Stability of Polymersomes through Traceless Cross-Linking

In nature, cells are highly compartmentalized into many organelles that are well separated from the rest of the cellular space by unique membrane structures, which are of crucial importance to allow cells to perform various physiological functions in such a small and crowded space. Learning from the ubiquitous membrane structures of cells and organelles has continuously inspired the development of artificial self-assembled nanostructures, with lipid vesicles (liposomes) and polymer vesicles (polymersomes) being the most representative examples. Similar to the membrane-bound structures of cells and organelles, both liposomes and polymersomes contain an aqueous interior enclosed by a bilayer membrane. Therefore, liposomes and polymersomes have been extensively investigated to mimic the fundamental structures and functions of living cells. For example, liposomes and polymersomes have been successfully engineered as nanocarriers, smart nanoreactors, artificial organelles, and so on. Notably, living cells can exchange both energy and materials with surrounding environments, benefiting from the selective permeability of lipid membranes. The permselectivity of cell membranes is thus an essential attribute of living organisms. Compared to liposomes, polymersomes have increased structural stability but low membrane permeability. Indeed, polymersomes are almost impermeable to small molecules, ions, and even water molecules. To improve the permeability of polymersomes, much effort has been devoted to the incorporation of channel proteins, the coassembly of oppositely charged block copolymers (BCPs), the development of stimuli-responsive BCPs, and so on. Despite great achievements, these approaches generally lead to decreased stability of polymersomes and, sometimes, polymersome disintegration. In this Account, we discuss our recent efforts to reconcile the stability and permeability of polymersomes via a traceless cross-linking approach. Although cross-linking reactions within bilayer membranes generally lead to decreased permeability, the traceless cross-linking approach can concurrently improve the stability and permeability of polymersomes. Specifically, stimuli-responsive polymersomes undergo either covalent cross-linking or noncovalent cross-linking reactions under specific stimuli to increase bilayer stability, while the cross-linking processes can concurrently permeabilize polymersome bilayers through cross-linking-driven hydrophobic-to-hydrophilic transitions. Notably, unlike conventional cross-linking processes requiring additional cross-linkers, the traceless cross-linking process does not involve extra cross-linking agents but takes full advantage of the in situ generated active moieties. By taking advantage of the simultaneous modulation of the stability and permeability of polymersomes via traceless cross-linking, these polymersomes can be further engineered as smart nanocarriers and nanoreactors. The robustness and generality of this approach have been validated by both extracellular and intracellular stimuli such as light irradiation, glutathione, and hydrogen peroxide. Moreover, many functional groups such as fluorescent dyes and contrast agents can be integrated into this versatile platform as well, enabling the construction of theranostic nanovectors capable of responding to pathological microenvironments. This Account provides a new approach to regulating the permeability of polymersomes while maintaining their structural stability.