Biomimetic temporal self-assembly via fuel-driven controlled supramolecular polymerization

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.

ATP-Regulated Formation of Transient Peptide Amphiphiles Superstructures

Self-assembly of biotic systems serves as inspiration for the preparation of synthetic supramolecular assemblies to mimic the structural, temporal, and functional aspects of living systems. Despite peptide amphiphiles (PAs) being widely studied in the context of biomimetic and bioactive functional nanomaterials, very little is currently known about the reversible and spatiotemporal control of their hierarchical self-assemblies. Here, it is shown that PA-based supramolecular nanofibers can transiently form superstructures, through binding with oppositely charged adenosine triphosphate (ATP), leading to charge screening and stabilization of bundled nanofibers. Enzymatic hydrolysis of ATP to adenosine monophosphate and phosphates causes the disassembly of the superstructures and recovery of individual nanofibers. The lifetime of superstructures can be controlled by adjusting the concentration of either ATP or enzyme. The role that the formation of bundled PA nanofibers has on chemical reactivity and catalysis is also evaluated. It is observed that superstructuration is responsible for downregulation in the PA activity, which can then be recovered by gradual disassembly of the bundles. These results demonstrate the potential of reversible and controlled hierarchical self-assembly to modulate the reactivity and catalysis of peptide nanostructures.

Dynamic Co-Clustering and Self-Sorting in Interactive Protocell Populations

The design and implementation of collective actions in model protocell communities is an on-going challenge in synthetic protobiology. Herein, we covalently graft alginate or chitosan onto the outer surface of semipermeable enzyme-containing silica colloidosomes to produce hairy catalytic protocells with pH-switchable membrane surface charge. Binary populations of the enzymatically active protocells exhibit self-initiated stimulus-responsive changes in spatial organization such that the mixed community undergoes alternative modes of electrostatically induced self-sorting and reversible co-clustering. We demonstrate that co-clustering, but not self-sorting, mitigates signal attenuation in a binary community of enzyme-containing sender and receiver protocells due to increased proximity effects. The level of signal attenuation is correlated with a time-dependent pH-mediated switch in the spatial organization of the sender and receiver populations. Our results pave the way towards the development of programmable networks of adaptive life-like objects and could have implications for the development of interactive cytomimetic materials and agent-based robotics.

Fuel-Driven π-Conjugated Superstructures to Form Transient Conductive Hydrogels

Despite advances in creating dissipative materials with transient properties, such as hydrogels and active droplets, their application remains confined to temporal changes in structural properties. Developing out-of-equilibrium materials whose electronic functions are parameterized by a chemical reaction cycle is challenging. Yet, this class of materials is required to construct biomimetic materials. In contrast to traditional chemical reaction cycles that exploit molecularly dissolved building blocks at thermodynamic equilibrium, we show that fiber structures derived from reactive naphthalene diimide (NDI) building blocks can be used as resting states to form far-from-equilibrium conductive hydrogels after the addition of chemical fuels. Upon fueling the NDI-derived fibers, a dual-component activation and deactivation pathway is deduced by kinetic analysis and is absent when using a molecularly dissolved resting state. Investigating the solid-state morphologies of the structures formed throughout the fuel-driven reaction cycle using cryo-EM reveals that the resting thermodynamic fibers evolve to transient thicker fibrils and layered superstructures. We show that the transient redox-active hydrogels exhibit a nearly threefold increase in electrical conductivity upon fuel consumption before reverting to their original value over hours. These far-from-equilibrium materials are potential candidates in applications such as programmable biorobotics and chemical computing.

Biofuel-Driven Stepping Chiral Supramolecular Transfer Container

Herein, we reported a biofuel-driven recyclable chiral supramolecular transfer container based on hexacationic triphenylamine cage and nucleotides. Possessing rotatable paddle rigid backbones, the artificial receptor effectively encapsulated nucleotides with a high binding constant up to 5.37×105 M-1 in water, displaying guest-induced efficient fluorescence enhancement with quantum yield increased from 6.5 % to 16.6 %. Especially, the achiral cage could effectively bind with adenosine triphosphate to activate chirality transfer from substrates to the single molecular container, giving circularly polarized luminescence at 575 nm and positive Cotton effect peaks with significant asymmetric factor (gabs=+6.4×10-4). Meanwhile, the adaptive chiral supramolecule not only has reversible thermal responsiveness but also could stepwise regulate chirality transfer by the catalysis of hexokinase and apyrase in tandem, showing recovery adaptive chirality after refueled, achieving dynamically regulated programmable multistate chiral luminescent supramolecules. Therefore, the biofuel-driven chiral supramolecular transfer container could be successfully applied in chiral logic gates and multilevel information encryption, providing new insight into intelligent chiral materials.

Time-Encoded Information Encryption with pH Clock Guided Broad-Spectrum Emission by Dynamic Assemblies

With growing threats from counterfeiting-based security breaches, multi-level and specific stimuli-responsive anti-counterfeiting devices and message encryption methods have attracted immense research interest. Fluorescence-based encryption from aggregation-induced emission (AIE)-based materials solves the problems to a considerable extent. However, the development of smarter patterns with hierarchical security levels alongside dynamic display is still challenging. To screen out this complication, we bring forward a pH-switchable fluorescent assembly of an AIEgen and an aliphatic acid. We later temporally direct the molecular assembly with the aid of a chemical trigger-regulated pH clock, generating a transitory multicolor emission, including transient white light generation. The pH-dependent emissions were further implemented in constructing smart multi-input fluorescent chemical AND gates. Subsequently, we integrate the time-gated emissive system to develop an advanced multi-dimensionally secure data encryption strategy. This novel approach enhances anti-counterfeiting measures by introducing an additional layer of security based on temporal characteristics.

Amplification and Attenuation of Asymmetry via Kinetically Controlled Seed-Induced Supramolecular Polymerization

The amplification of asymmetry in supramolecular polymers has recently garnered significant attention. While asymmetry amplification has predominantly been explored under thermodynamic conditions, the kinetic aspect of this process unveils intriguing observations, yet is scarcely reported in the literature. Herein, drawing inspiration from macromolecular systems, we propose a novel strategy for enhancing asymmetry in supramolecular polymers through a seed-induced supramolecular polymerization approach under kinetic conditions, employing a naphthalene diimide-derived monomer (ANSG) for template-induced supramolecular polymerization, utilizing adenosine triphosphate (ATP) and pyrophosphate (PPi) as templates. A chiral seed comprising [ANSG-ATP]S effectively amplifies the overall supramolecular asymmetry when exposed to a mixture of achiral templates (PPi) and monomers (ANSG), owing to its efficient seeding characteristics under kinetic conditions. As a result of efficient co-operativity, conversely, employing an achiral seed [ANSG-PPi]S in a mixture of chiral templates (ATP) and monomers (ANSG) results in the attenuation of asymmetry, highlighting the effective modulation achievable through the seeding approach, an unprecedented observation in the field. Exploiting the efficient aggregation-induced emission enhancement (AIEE) of the resultant supramolecular polymers further extends the amplification and attenuation of circularly polarized luminescence (CPL) as a potential function.

Feedback driven autonomous cycles of assembly and disassembly from minimal building blocks

The construction of complex systems by simple chemicals that can display emergent network dynamics might contribute to our understanding of complex behavior from simple organic reactions. Here we design single amino acid/dipeptide-based systems that exhibit multiple periodic changes of (dis)assembly under non-equilibrium conditions in closed system, importantly in the absence of evolved biocatalysts. The two-component based building block exploits pH driven non-covalent assembly and time-delayed accelerated catalysis from self-assembled state to install orthogonal feedback loops with a single batch of reactants. Mathematical modelling of the reaction network establishes that the oscillations are transient for this network structure and helps to predict the relative contribution of the feedback loop to the ability of the system to exhibit such transient oscillation. Such autonomous systems with purely synthetic molecules are the starting point that can enable the design of active materials with emergent properties.

Atomistic Insights into the Stabilization of TDP-43 Protofibrils by ATP

The aberrant accumulation of the transactive response deoxyribonucleic acid (DNA)-binding protein of 43 kDa (TDP-43) aggregates in the cytoplasm of motor neurons is the main pathological hallmark of amyotrophic lateral sclerosis (ALS). Previous experiments reported that adenosine triphosphate (ATP), the universal energy currency for all living cells, could induce aggregation and enhance the folding of TDP-43 fibrillar aggregates. However, the significance of ATP on TDP-43 fibrillation and the mechanism behind it remain elusive. In this work, we conducted multiple atomistic molecular dynamics (MD) simulations totaling 20 μs to search the critical nucleus size of TDP-43282-360 and investigate the impact of ATP molecules on preformed protofibrils. The results reveal that the trimer is the critical nucleus for TDP-43282-360 fibril formation and the tetramer is the minimal stable nucleus. When ATP molecules bind to the TDP-43282-360 trimer and tetramer, they can consolidate the TDP-43282-360 protofibrils by increasing the content of the β-sheet structure and promoting the formation of hydrogen bonds (H-bonds). Binding site analyses show that the N-terminus of TDP-43282-360 protofibrils is the main binding site of ATP, and R293 dominates the direct binding of ATP. Further analyses reveal that the π-π, cation-π, salt bridge, and H-bonding interactions together contribute to the binding of ATP to TDP-43282-360 protofibrils. This study decoded the detailed stabilization mechanism of protofibrillar TDP-43282-360 oligomers by ATP, and may provide new avenues for the development of drug design against ALS.

In situ biocatalytic ATP regulated, transient supramolecular polymerization

Temporal control over self-assembly processes is a highly desirable attribute that is efficiently exhibited by biological systems, such as actin filaments. In nature, various proteins undergo enzymatically catalysed chemical reactions that kinetically govern their structural and functional properties. Consequently, any stimuli that can alter their reaction kinetics can lead to a change in their growth or decay profiles. This underscores the urgent need to investigate bioinspired, adaptable and controllable synthetic materials. Herein we intend to develop a general strategy for controlling the growth and decay of self-assembled systems via enzymatically coupled reactions. We achieve this by the coupling of enzymes phosphokinase/phosphatase with a bolaamphiphilic cationic chromophore (PDI) which selectively self-assembles with ATP and disassembles upon its enzymatic hydrolysis. The aggregation process is efficiently regulated by the controlled in situ generation of ATP, through enzymatic reactions. By carefully managing the ATP generating components, we realize precise control over the self-assembly process. Moreover, we also show self-assembled structures with programmed temporal decay profiles through coupled enzymatic reactions of ATP generation and hydrolysis, essentially rendering the process dissipative. This work introduces a novel strategy to generate a reaction-coupled one-dimensional nanostructure with controlled dimensions inspired by biological systems.

Probing Phoretic Transport of Oxidative Enzyme-Bound Zn(II)-Metallomicelle in Adenosine Triphosphate Gradient via a Spatially Relocated Biocatalytic Zone

Although cellular transport machinery is mostly ATP-driven and ATPase-dependent, there has been a recent surge in understanding colloidal transport processes relying on a nonspecific physical interaction with biologically significant small molecules. Herein, we probe the phoretic behavior of a biocolloid [composed of a Zn(II)-coordinated metallomicelle and enzymes horseradish peroxidase (HRP) and glucose oxidase (GOx)] when exposed to a concentration gradient of ATP under microfluidic conditions. Simultaneously, we demonstrate that an ATP-independent oxidative biocatalytic product formation zone can be modulated in the presence of a (glucose + ATP) gradient. We report that both directionality and extent of transport can be tuned by changing the concentration of the ATP gradient. This diffusiophoretic mobility of a submicrometer biocolloidal object for the spatial transposition of a biocatalytic zone signifies the ATP-mediated functional transportation without the involvement of ATPase. Additionally, the ability to analyze colloidal transport in microfluidic channels using an enzymatic fluorescent product-forming reaction could be a new nanobiotechnological tool for understanding transport and spatial catalytic patterning processes. We believe that this result will inspire further studies for the realization of elusive biological transport processes and target-specific delivery vehicles, considering the omnipresence of the ATP-gradient across the cell.

Unraveling the structure-chirality sensing relationship between achiral anthracene-based tetracationic nanotubes and nucleosides in aqueous host-guest complexation

In biological systems, nucleosides play crucial roles in various physiological processes. In this study, we designed and synthesized four achiral anthracene-based tetracationic nanotubes (1-4) as artificial hosts and chiroptical sensors for nucleosides in aqueous media. Notably, different nanotubes exhibit varied chirality sensing on circular dichroism (CD)/circularly polarized luminescence (CPL) spectra through the host-guest complexation, which prompted us to explore the factors influencing their chiroptical responses. Through systematic host-guest experiments, the structure-chirality sensing relationship between achiral anthracene-based tetracationic nanotubes and nucleosides in the host-guest complexation was unraveled. Firstly, the CD response originates from the anthracene rings situated at the side-wall position, resulting from the right-handed (P)- or left-handed (M)-twisted conformation of the macrocyclic structure. Secondly, the CPL signal is influenced by the presence of anthracene rings at the linking-wall position, which results from intermolecular chiral twisted stacking between these anthracene rings. Therefore, these nanotubes can serve as chiroptical sensor arrays to enhance the accuracy of nucleotide recognition through principal component analysis (PCA) analysis based on the diversified CD spectra. This study provides insights for the construction of adaptive chirality from achiral nanotubes with dynamic conformational nature and might facilitate further design of chiral functional materials for several applications.

Heparin binding induced supramolecular chirality into the self-assembly of perylenediimide bolaamphiphile

Chirality is one of the hallmarks of biomolecules. Herein, we utilize heparin, a chiral biomolecule and potent drug, to induce chiral organization into the assembly of an achiral molecule. Polyanionic heparin binds with a dicationic perylenediimide derivative to induce supramolecular helical organization in aqueous medium as well as in a highly competitive cell culture medium.

Enzyme-Responsive Supramolecular Self-Assembly in Small Amphiphiles

Enzyme-responsive molecular assemblies have recently made remarkable progress, owing to their widespread applications. As a class of catalysts with high specificity and efficiency, enzymes play a critical role in producing new molecules and maintaining metabolic stability in living organisms. Therefore, the study of enzyme-responsive assembly aids in understanding the origin of life and the physiological processes occurring within living bodies, contributing to further advancements across various disciplines. In this Review, we summarize three kinds of enzyme-responsive assembly systems in amphiphiles: enzyme-triggered assembly, disassembly, and structural transformation. Furthermore, motivated by the fact that biological macromolecules and complex structures all originated with small molecules, our focus lies on the small amphiphiles (e.g., peptides, surfactants, fluorescent molecules, and drug molecules). We also provide an outlook on the potential of enzyme-responsive assembly systems for biomimetic development and hope this Review will attract more attention to this emerging research branch at the intersection of assembly chemistry and biological science.

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.

Enzymatic Dissociation of DNA-Histone Condensates in an Electrophoretic Setting: Modulating DNA Patterning and Hydrogel Viscoelasticity

Development of an energy-driven self-assembly process is a matter of interest for understanding and mimicking diverse ranges of biological and environmental patterns in a synthetic system. In this article, first we demonstrate transient and temporally controlled self-assembly of a DNA-histone condensate where trypsin (already present in the system) hydrolyzes histone, resulting in disassembly. Upon performing this dynamic self-assembly process in a gel matrix under an electric field, we observe diverse kinds of DNA patterning across the gel matrix depending on the amount of trypsin, incubation time of the reaction mixture, and gel porosity. Notably, here, the micrometer-sized DNA-histone condensate does not move through the gel and only free DNA can pass; therefore, transport and accumulation of DNA at different zones depend on the release rate of DNA by trypsin. Furthermore, we show that the viscoelasticity of the native gel increases in the presence of DNA and a pattern over gel viscoelasticity at different zones can be achieved by tuning the amount of enzyme, i.e., the dissociation rate of the DNA-histone condensate. We believe enabling spatiotemporally controlled DNA patterning by applying an electric field will be potentially important in designing different kinds of spatiotemporally distinct dynamic materials.

Temperature Control of the Self-Assembly Process of 4-Aminoquinoline Amphiphile: Selective Construction of Perforated Vesicles and Nanofibers, and Structural Restoration Capability

The construction of diverse and distinctive self-assembled structures in water, based on the control of the self-assembly processes of artificial small molecules, has received considerable attention in supramolecular chemistry. Cage-like perforated vesicles are distinctive and interesting self-assembled structures. However, the development of self-assembling molecules that can easily form perforated vesicles remains challenging. This paper reports a lower critical solution temperature (LCST) behavior-triggered self-assembly property of a 4-aminoquinoline (4-AQ)-based amphiphile with a tetra(ethylene glycol) chain, in HEPES buffer (pH 7.4). This property allows to form perforated vesicles after heating at 80 °C (> LCST). The self-assembly process of the 4-AQ amphiphile can be controlled by heating at 80 °C (> LCST) or 60 °C (< LCST). After cooling to room temperature, the selective construction of the perforated vesicles and nanofibers was achieved from the same 4-AQ amphiphile. Furthermore, the perforated vesicles exhibited slow morphological transformation into intertwined-like nanofibers but were easily restored by brief heating above the LCST.

ATP/azobenzene-guanidinium self-assembly into fluorescent and multi-stimuli-responsive supramolecular aggregates

Building stimuli-responsive supramolecular systems is a way for chemists to achieve spatio-temporal control over complex systems as well as a promising strategy for applications ranging from sensing to drug-delivery. For its large spectrum of biological and biomedical implications, adenosine 5'-triphosphate (ATP) is a particularly interesting target for such a purpose but photoresponsive ATP-based systems have mainly been relying on covalent modification of ATP. Here, we show that simply mixing ATP with AzoDiGua, an azobenzene-guanidium compound with photodependent nucleotide binding affinity, results in the spontaneous self-assembly of the two non-fluorescent compounds into photoreversible, micrometer-sized and fluorescent aggregates. Obtained in water at room temperature and physiological pH, these supramolecular structures are dynamic and respond to several chemical, physical and biological stimuli. The presence of azobenzene allows a fast and photoreversible control of their assembly. ATP chelating properties to metal dications enable ion-triggered disassembly and fluorescence control with valence-selectivity. Finally, the supramolecular aggregates are disassembled by alkaline phosphatase in a few minutes at room temperature, resulting in enzymatic control of fluorescence. These results highlight the interest of using a photoswitchable nucleotide binding partner as a self-assembly brick to build highly responsive supramolecular entities involving biological targets without the need to covalently modify them.

Increasing Dimensionality in Self-Assembly: Toward Two-Dimensional Supramolecular Polymers

Different approaches to achieve 2D supramolecular polymers, as an alternative to the covalent bottom-up approaches reported for the preparation of 2D materials, are reviewed. The significance of the operation of weak non-covalent forces to induce a lateral growth of a number of self-assembling units is collected. The examples of both thermodynamically and kinetically controlled formation of 2D supramolecular polymers showed in this review demonstrate the utility of this strategy to achieve new 2D materials with biased morphologies (nanosheets, scrolls, porous surfaces) and showing elegant applications like chiral recognition, enantioselective uptake or asymmetric organic transformations. Furthermore, elaborated techniques like seeded or living supramolecular polymerizations have been demonstrated to give rise to complex 2D nanostructures.

Enzymatic Reaction-Coupled, Cooperative Supramolecular Polymerization

Nature employs sophisticated mechanisms to precisely regulate self-assembly and functions within biological systems, exemplified by the formation of cytoskeletal filaments. Various enzymatic reactions and auxiliary proteins couple with the self-assembly process, meticulously regulating the length and functions of resulting macromolecular structures. In this context, we present a bioinspired, reaction-coupled approach for the controlled supramolecular polymerization in synthetic systems. To achieve this, we employ an enzymatic reaction that interfaces with the adenosine triphosphate (ATP)-templated supramolecular polymerization of naphthalene diimide monomers (NSG). Notably, the enzymatic production of ATP (template) plays a pivotal role in facilitating reaction-controlled, cooperative growth of the NSG monomers. This growth process, in turn, provides positive feedback to the enzymatic production of ATP, creating an ideal reaction-coupled assembly process. The success of this approach is further evident in the living-growth characteristic observed during seeding experiments, marking this method as the pioneering instance where reaction-coupled self-assembly precisely controls the growth kinetics and structural aspects of supramolecular polymers in a predictive manner, akin to biological systems.

Using a biocatalyzed reaction cycle for transient and pH-dependent host-guest supramolecular hydrogels

The formation of transient structures plays important roles in biological processes, capturing temporary states of matter through influx of energy or biological reaction networks catalyzed by enzymes. These natural transient structures inspire efforts to mimic this elegant mechanism of structural control in synthetic analogues. Specifically, though traditional supramolecular materials are designed on the basis of equilibrium formation, recent efforts have explored out-of-equilibrium control of these materials using both direct and indirect mechanisms; the preponderance of such works has been in the area of low molecular weight gelators. Here, a transient supramolecular hydrogel is realized through cucurbit[7]uril host-guest physical crosslinking under indirect control from a biocatalyzed network that regulates and oscillates pH. The duration of transient hydrogel formation, and resulting mechanical properties, are tunable according to the dose of enzyme, substrate, or pH stimulus. This tunability enables control over emergent functions, such as the programmable burst release of encapsulated model macromolecular payloads.

Controlled Supramolecular Polymerization via Bioinspired, Liquid-Liquid Phase Separation of Monomers

Dynamic supramolecular assemblies, driven by noncovalent interactions, pervade the biological realm. In the synthetic domain, their counterparts, supramolecular polymers, endowed with remarkable self-repair and adaptive traits, are often realized through bioinspired designs. Recently, controlled supramolecular polymerization strategies have emerged, drawing inspiration from protein self-assembly. A burgeoning area of research involves mimicking the liquid-liquid phase separation (LLPS) observed in proteins to create coacervate droplets and recognizing their significance in cellular organization and diverse functions. Herein, we introduce a novel perspective on synthetic coacervates, extending beyond their established role in synthetic biology as dynamic, membraneless phases to enable structural control in synthetic supramolecular polymers. Drawing parallels with the cooperative growth of amyloid fibrils through LLPS, we present metastable coacervate droplets as dormant monomer phases for controlled supramolecular polymerization. This is achieved via a π-conjugated monomer design that combines structural characteristics for both coacervation through its terminal ionic groups and one-dimensional growth via a π-conjugated core. This design leads to a unique temporal LLPS, resulting in a metastable coacervate phase, which subsequently undergoes one-dimensional growth via nucleation within the droplets. In-depth spectroscopic and microscopic characterization provides insights into the temporal evolution of disordered and ordered phases. Furthermore, to modulate the kinetics of liquid-to-solid transformation and to achieve precise control over the structural characteristics of the resulting supramolecular polymers, we invoke seeding in the droplets, showcasing living growth characteristics. Our work thus opens up new avenues in the exciting field of supramolecular polymerization, offering general design principles and controlled synthesis of precision self-assembled structures in confined environments.

Transient Metallo-Lipidoid Assemblies Amplify Covalent Catalysis of Aqueous and Non-Aqueous Reactions

Dissipative supramolecular assemblies are hallmarks of living systems, contributing to their complex, dynamic structures and emerging functions. Living cells can spatiotemporally control diverse biochemical reactions in membrane compartments and condensates, regulating metabolite levels, signal transduction or remodeling of the cytoskeleton. Herein, we constructed membranous compartments using self-assembly of lipid-like amphiphiles (lipidoid) in aqueous medium. The new double-tailed lipidoid features Cu(II) coordinated with a tetravalent chelator that dictates the binding of two amphiphilic ligands in cis-orientation. Hydrophobic interactions between the lipidoids coupled with intermolecular hydrogen bonding led to a well-defined bilayer vesicle structure. Oil-soluble SNAr reaction is efficiently upregulated in the hydrophobic cavity, acting as a catalytic crucible. The modular system allows easy incorporation of exposed primary amine groups, which augments the catalysis of retro aldol and C-N bond formation reactions. Moreover, a higher-affinity chelator enables consumption of the Cu(II) template leveraging the differential thermodynamic stability, which allows a controllable lifetime of the vesicular assemblies. Concomitant temporal upregulation of the catalytic reactions could be tuned by the metal ion concentration. This work offers new possibilities for metal ion-mediated dynamic supramolecular systems, opening up a massive repertoire of functionally active dynamic "life-like" materials.

Glucose-Triggered Gelation of Supramolecular Peptide Nanocoils with Glucose-Binding Motifs

Peptide self-assembly is a powerful tool to prepare functional materials at the nanoscale. Often, the resulting materials have high aspect-ratio, with intermolecular β-sheet formation underlying 1D fibrillar structures. Inspired by dynamic structures in nature, peptide self-assembly is increasingly moving toward stimuli-responsive designs wherein assembled structures are formed, altered, or dissipated in response to a specific cue. Here, a peptide bearing a prosthetic glucose-binding phenylboronic acid (PBA) is demonstrated to self-assemble into an uncommon nanocoil morphology. These nanocoils arise from antiparallel β-sheets, with molecules aligned parallel to the long axis of the coil. The binding of glucose to the PBA motif stabilizes and elongates the nanocoil, driving entanglement and gelation at physiological glucose levels. The glucose-dependent gelation of these materials is then explored for the encapsulation and release of a therapeutic agent, glucagon, that corrects low blood glucose levels. Accordingly, the release of glucagon from the nanocoil hydrogels is inversely related to glucose level. When evaluated in a mouse model of severe acute hypoglycemia, glucagon delivered from glucose-stabilized nanocoil hydrogels demonstrates increased protection compared to delivery of the agent alone or within a control nanocoil hydrogel that is not stabilized by glucose.

Transient control of lytic activity via a non-equilibrium chemical reaction system

The development of artificial non-equilibrium chemical reaction systems has recently attracted considerable attention as a new type of biomimetic. However, due to the lack of bioorthogonality, such reaction systems could not be linked to the regulation of any biological phenomena. Here, we have newly designed a non-equilibrium reaction system based on olefin metathesis to produce the Triton X-mimetic non-ionic amphiphile as a kinetic product. Using phospholipid vesicles encapsulating fluorescent dyes and red blood cells as cell models, we demonstrate that the developed chemical reaction system is applicable for transient control of the resulting lytic activity.

Emergence of Dynamic Instability by Hybridizing Synthetic Self-Assembled Dipeptide Fibers with Surfactant Micelles

Supramolecular chemistry currently faces the challenge of controlling nonequilibrium dynamics such as the dynamic instability of microtubules. In this study, we explored the emergence of dynamic instability through the hybridization of peptide-type supramolecular nanofibers with surfactant micelles. Using real-time confocal imaging, we discovered that the addition of micelles to nanofibers induced the simultaneous but asynchronous growth and shrinkage of nanofibers during which the total number of fibers decreased monotonically. This dynamic phenomenon unexpectedly persisted for 6 days and was driven not by chemical reactions but by noncovalent supramolecular interactions between peptide-type nanofibers and surfactant micelles. This study demonstrates a strategy for inducing autonomous supramolecular dynamics, which will open up possibilities for developing soft materials applicable to biomedicine and soft robotics.

CryoEM reveals the complex self-assembly of a chemically driven disulfide hydrogel

Inspired by the adaptability of biological materials, a variety of synthetic, chemically driven self-assembly processes have been developed that result in the transient formation of supramolecular structures. These structures form through two simultaneous reactions, forward and backward, which generate and consume a molecule that undergoes self-assembly. The dynamics of these assembly processes have been shown to differ from conventional thermodynamically stable molecular assemblies. However, the evolution of nanoscale morphologies in chemically driven self-assembly and how they compare to conventional assemblies has not been resolved. Here, we use a chemically driven redox system to separately carry out the forward and backward reactions. We analyze the forward and backward reactions both sequentially and synchronously with time-resolved cryogenic transmission electron microscopy (cryoEM). Quantitative image analysis shows that the synchronous process is more complex and heterogeneous than the sequential process. Our key finding is that a thermodynamically unstable stacked nanorod phase, briefly observed in the backward reaction, is sustained for ∼6 hours in the synchronous process. Kinetic Monte Carlo modeling show that the synchronous process is driven by multiple cycles of assembly and disassembly. The collective data suggest that chemically driven self-assembly can create sustained morphologies not seen in thermodynamically stable assemblies by kinetically stabilizing transient intermediates. This finding provides plausible design principles to develop and optimize supramolecular materials with novel properties.

Organelle-Mediated Dissipative Self-Assembly of Peptides in Living Cells

Implementing dissipative assembly in living systems is meaningful for creation of living materials or even artificial life. However, intracellular dissipative assembly remains scarce and is significantly impeded by the challenges lying in precisely operating chemical reaction cycles under complex physiological conditions. Here, we develop organelle-mediated dissipative self-assembly of peptides in living cells fueled by GSH, via the design of a mitochondrion-targeting and redox-responsive hexapeptide. While the hexapeptide undergoes efficient redox-responsive self-assembly, the addition of GSH into the peptide solution in the presence of mitochondrion-biomimetic liposomes containing hydrogen peroxide allows for transient assembly of peptides. Internalization of the peptide by LPS-stimulated macrophages leads to the self-assembly of the peptide driven by GSH reduction and the association of the peptide assemblies with mitochondria. The association facilitates reversible oxidation of the reduced peptide by mitochondrion-residing ROS and thereby dissociates the peptide from mitochondria to re-enter the cytoplasm for GSH reduction. The metastable peptide-mitochondrion complexes prevent the thermodynamically equilibrated self-assembly, thus establishing dissipative assembly of peptides in stimulated macrophages. The entire dissipative self-assembling process allows for elimination of elevated ROS and decrease of pro-inflammatory cytokine expression. Creating dissipative self-assembling systems assisted by internal structures provides new avenues for the development of living materials or medical agents in the future.

Enzyme-Mediated Temporal Control over the Conformational Disposition of a Condensed Protein in Macromolecular Crowded Media

Temporal regulation between input and output signals is one of the hallmarks of complex biological processes. Herein, we report that the conformational disposition of a protein in macromolecularly crowded media can be controlled with time using enzymes. First, we demonstrate the pH dependence of bovine serum albumin (BSA) condensation and conformational alteration in the presence of poly(ethylene glycol) as a crowder. However, by exploiting the strength of pH-modulatory enzymatic reactions (glucose oxidase and urease), the conversion time between the condensed and free forms can be tuned. Additionally, we demonstrate that the trapping of intermediate states with respect to the overall system at a particular α-helix or β-sheet composition and rotational mobility can be possible simply by altering the substrate concentration. Finally, we show that the intrinsic catalytic ability of BSA toward the Kemp elimination (KE) reaction is inhibited in the aggregated form but regained in the free form. In fact, the rate of KE reaction can also be actuated enzymatically in a temporal fashion, therefore demonstrating the programmability of a cascade of biochemical events in crowded media.

Metallosupramolecular polymers: current status and future prospects

Metallo-supramolecular polymers have gained increasing attention and witnessed continuous development as a vibrant new research interest in the domain of soft materials. These nonconventional polymers have found widespread application in materials and biology owing to their well-defined and diversified topologies and the distinct dynamic nature of the metallosupramolecular interactions against various stimuli. Because of the intriguing redox, photonic, electronic, and magnetic properties, these stimuli-responsive supramolecular structures have attracted considerable interest for optoelectronic device fabrication. However, it still remains challenging to develop stimuli responsive systems with offbeat applications. Furthermore, achieving spatiotemporal control remains elusive with thermoresponsive and sono-responsive metallosupramolecular polymers, which encounter the disadvantage of poor precision control. Additionally, controlling the morphology of these soft materials on the mesoscale, both in solution and on substrates, has many challenges. In this review, we discuss the recent developments and future directions for the construction of stimuli responsive metallosupramolecular systems targeting practical applications. Furthermore, we discuss the synthetic methodologies that have been used to regulate the mesoscale morphology of these materials, such as coordination modulation and pseudomorphic replication. Finally, we briefly cover the burgeoning field of programmed synthesis of metallosupramolecular polymers, emphasizing techniques, such as living polymerization and chemical fuel-driven transiently active systems, which we believe will be the major research directions in the future.

Co-assembly-mediated biosupramolecular catalysis: thermodynamic insights into nucleobase specific (oligo)nucleotide attachment and cleavage

Gaining control over the stability and cleavage of phosphoester and phosphodiester remains a matter of interest for their application in biotechnology to oligonucleotide-based therapeutics. Herein, we report an efficient unactivated phosphoester hydrolysis (stable mono/di/tri/cyclic nucleotide to nucleoside conversion) via a biosupramolecular system comprising of a non-covalent complex of enzyme, alkaline phosphatase (ALP), and Zn(II)-metallosurfactant. We also demonstrate the nucleobase selective activation or inhibition of ALP-mediated oligonucleotide digestion process using that complex. The higher binding affinity of Zn(II)-containing headgroup with phosphate-containing substrate enhanced the effective substrate concentration surrounding the enzyme, which, in turn, results in a drastic decrease in the Michaelis constant (KM), along with an increase in the turnover (kcat). The catalytic activation or inhibition of nucleobase-specific oligonucleotide digestion depends on the hydration, localization of the substrates, and viscosity of the resultant co-assembly upon substrate binding with the enzyme-metallosurfactant complex. Additionally, through isothermal titration calorimetry experiment, we demonstrate enthalpy-entropy change during both the supramolecular binding of (oligo)nucleotides and simultaneous activation/inhibition in catalytic cleavage. Overall, it showed the possible modularity of Zn(II)-mediated biosupramolecular interaction, describing intrinsic thermodynamic aspects in developing complex biocatalytic circuits with nucleobase-specific oligonucleotides inputs, which are relevant in designing nucleic acid-based cargo for drug delivery and bioimaging.

Transient co-assemblies of micron-scale colloids regulated by ATP-fueled reaction networks

Self-assembly of colloidal particles offers an attractive bottom-up approach to functional materials. Current design strategies for colloidal assemblies are mostly based on thermodynamically controlled principles and lack autonomous behavior. The next advance in the properties of colloidal assemblies will come from coupling these structures to out-of-equilibrium chemical reaction networks furnishing them with autonomous and dynamic behavior. This, however, constitutes a major challenge of carefully modulating the interparticle potentials on a temporal circuit program and avoiding kinetic trapping and irreversible aggregation. Herein, we report the coupling of a fuel-driven DNA-based enzymatic reaction network (ERN) to micron-sized colloidal particles to achieve their transient co-assembly. The ERN operating on the molecular level transiently releases an Output strand which links two DNA functionalized microgel particles together into co-assemblies with a programmable assembly lifetime. The system generates minimal waste and recovers all components of the ERN after the consumption of the ATP fuel. The system can be reactivated by addition of new fuel as shown for up to three cycles. The design can be applied to organize other building blocks into hierarchical structures and materials with advanced biomimetic properties.

Controlled Noncovalent Synthesis of Secondary Supramolecular Polymers

Dynamic supramolecular polymers, with their functional similarities to classical covalent polymers and their adaptive and self-repairing nature reminiscent of biological assemblies, have emerged as highly promising systems for the design of smart soft materials. Recent advancements in mechanistic investigations and novel synthetic strategies, such as living supramolecular polymerization, have significantly enhanced our ability to control the primary structure of these supramolecular polymers. However, realizing their full functional potential requires expanding their topological diversity in a manner akin to classical polymers as well as achieving precise molecular organization at higher hierarchical levels of self-assembly. In this paper, we present a remarkable advancement in this field, introducing an unprecedented and controlled synthesis of secondary supramolecular polymers. Our innovative strategy combines chirality-controlled surface-catalyzed secondary nucleation and a bioinspired peptide design, effectively stabilizing higher-order assembly. Furthermore, by harnessing this stereoselective nucleation process, we demonstrate the successful synthesis of racemic supramolecular polymers featuring parallelly stacked conglomerate microstructures─a previously unreported topology in synthetic self-assembled systems. Additionally, we elucidate that the extent of secondary supramolecular polymers can be regulated by modulating the enantiomeric excess of the chiral monomers. Consequently, our study unveils new topologies that exhibit enhanced higher-order structural complexity in the realm of supramolecular polymers.

Real-Time Single-Particle Imaging of a Dynamic Host-Guest Interaction-Initiated Nanoconfinement Effect on Iodine Uptake

Fundamentally understanding the nanoconfinement effect within porous crystals is crucial for improving and extending their applications. Here, we report the real-time single-particle imaging of dynamic adaptive host-guest interaction between acetic acid (HAc) and covalent organic framework-300 (COF-300) to generate HAc-confined COF-300 (HAc@COF-300) under in situ reaction conditions, which initiates subsequent iodine uptake in an aqueous solution using a dark-field optical microscope (DFM). Operando DFM imaging reveals the adaptive deformation of COF-300 particles during the host-guest interaction process, which is attributed to the Lewis acid-base interaction-induced crystal contraction. Moreover, quantitative analysis shows that the HAc@COF-300 exhibits 65,000-fold higher binding affinity toward iodine than free HAc because of the increase in local concentration and close proximity under the nanoconfinement environment. With the guidance of the nanoconfinement effect, an adsorption reaction system consisting of HAc and COF-300 for capturing I2 is rationally designed and validated by macroscopic ensemble measurements, resulting in significantly improved adsorption performance by 7- to 8-fold. These findings highlight the nanoconfinement effects in adsorption/separation reactions.

Chiroptical Amplification of Induced Circularly Polarized Luminescence in Nucleotide-Templated Supramolecular Polymer

Efficient circularly polarized luminescence (CPL) from purely organic molecules holds great promise for applications in displays, sensing, and bioimaging. However, achieving high dissymmetry values (glum ) from organic chromophores remains a significant challenge. Herein, we present a bioinspired approach using adenosine triphosphate (ATP)-triggered supramolecular polymerization of a naphthalene diimide-derived monomer (ANSG) to induce CPL with a remarkable glum value of 1.1×10-2 . The ANSG molecules undergo a templated, chiral self-assembly through a cooperative growth mechanism in the presence of ATP, resulting in scrolled nanotubes with aggregation-induced enhanced emission (AIEE) and induced CPL. Furthermore, we demonstrate the concept of chiroptical amplification of induced CPL by efficiently amplifying asymmetry using a mixture of chiral ATP and achiral pyrophosphate. This innovative approach opens numerous opportunities in the emerging field of circularly polarized luminescence.

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.

Pathway Control of π-Conjugated Supramolecular Polymers by Incorporating Donor-Acceptor Functionality

Controlling the nanoscale orientation of π-conjugated systems remains challenging due to the complexity of multiple energy landscapes involved in the supramolecular assembly process. In this study, we have developed an effective strategy for programming the pathways of π-conjugated supramolecular polymers, by incorporating both electron-rich methoxy- or methanthiol-benzene as donor unit and electron-poor cyano-vinylenes as acceptor units on the monomeric structure. It leads to the formation of parallel-stacked supramolecular polymers as the metastable species through homomeric donor/acceptor packing, which convert to slip-stacked supramolecular polymers as the thermodynamically stable species facilitated by heteromeric donor-acceptor packing. By further investigating the external seed-induced kinetic-to-thermodynamic transformation behaviors, our findings suggest that the donor-acceptor functionality on the seed structure is crucial for accelerating pathway conversion. This is achieved by eliminating the initial lag phase in the supramolecular polymerization process. Overall, this study provides valuable insights into designing molecular structures that control aggregation pathways of π-conjugated nanostructures.

Aqueous coordination polymer complexes: From colloidal assemblies to bulk materials

1-dimensional (1D) coordination polymers refer to the macromolecules that have metal ions incorporated in their pendent groups or main chain through metal-binding ligand groups. They have intrinsic advantages over traditional polymers to regulate the polymer structures and functions owing to the nature of the metal-ligand bond. Consequently, they have great potential for the development of smart and functional structures and materials and therapeutic agents. Water-soluble 1D coordination polymers and assemblies are an important subtype of coordination polymers with distinctive interests for demanding applications in aqueous systems, such as biological and medical applications. This review highlights the recent progress and research achievements in the design and use of water-soluble 1D coordination polymers and assemblies. The overview covers the design and structure control of 1D coordination polymers, their colloidal assemblies, including nanoparticles, nanofibers, micelles and vesicles, and fabricated bulk materials such as membraneless liquid condensates, security ink, hydrogel actuators, and smart fabrics. Finally, we discuss the potential applications of several of these coordination polymeric structures and materials and give an outlook on the field of aqueous coordination polymers.

Nanoparticle Self-Assembly: From Design Principles to Complex Matter to Functional Materials

The creation of matter with varying degrees of complexities and desired functions is one of the ultimate targets of self-assembly. The ability to regulate the complex interactions between the individual components is essential in achieving this target. In this direction, the initial success of controlling the pathways and final thermodynamic states of a self-assembly process is promising. Despite the progress made in the field, there has been a growing interest in pushing the limits of self-assembly processes. The main inception of this interest is that the intended self-assembled state, with varying complexities, may not be "at equilibrium (or at global minimum)", rendering free energy minimization unsuitable to form the desired product. Thus, we believe that a thorough understanding of the design principles as well as the ability to predict the outcome of a self-assembly process is essential to form a collection of the next generation of complex matter. The present review highlights the potent role of finely tuned interparticle interactions in nanomaterials to achieve the preferred self-assembled structures with the desired properties. We believe that bringing the design and prediction to nanoparticle self-assembly processes will have a similar effect as retrosynthesis had on the logic of chemical synthesis. Along with the guiding principles, the review gives a summary of the different types of products created from nanoparticle assemblies and the functional properties emerging from them. Finally, we highlight the reasonable expectations from the field and the challenges lying ahead in the creation of complex and evolvable matter.

A light-fueled dissipative aggregation-induced emission system for time-dependent information encryption

A light-fueled dissipative aggregation-induced emission (LDAIE) system is successfully fabricated based on reversible electrostatic interactions between cationic AIE luminogens (AIEgens) and anionic spiropyran (ASP) transformed from sulfonato-merocyanine photoacid (SMEH) upon 420 nm light irradiation. The novel LDAIE system can exhibit reversible and spontaneous AIE fluorescence on/off, showing potential in time-dependent information encryption with self-erasing ability. This work opens new opportunities to fabricate a unique fluorescent anti-counterfeiting platform with high-level security.

CO2 -Fueled Transient Breathing Nanogels that Couple Nonequilibrium Catalytic Polymerization

Here we present a "breathing" nanogel that is fueled by CO₂ gas to perform temporally programmable catalytic polymerization. The nanogel is composed of common frustrated Lewis pair polymers (FLPs). Dynamic CO₂ -FLP gas-bridging bonds endow the nanogel with a transient volume contraction, and the resulting proximal effect of bound FLPs unlocks its catalytic capacity toward CO₂ . Reverse gas depletion via a CO₂ -participated polymerization can induce a reverse nanogel expansion, which shuts down the catalytic activity. Control of external factors (fuel level, temperature or additives) can regulate the breathing period, amplitude and lifecycle, so as to affect the catalytic polymerization. Moreover, editing the nanogel breathing procedure can sequentially evoke the copolymerization of CO₂ with different epoxide monomers preloaded therein, which allows to obtain block-tunable copolycarbonates that are unachievable by other methods. This synthetic dissipative system would be function as a prototype of gas-driven nanosynthesizer.

Transient and Dissipative Host-Guest Hydrogels Regulated by Consumption of a Reactive Chemical Fuel

The transient self-assembly of molecules under the direction of a consumable fuel source is fundamental to biological processes such as cellular organization and motility. Such biomolecular assemblies exist in an out-of-equilibrium state, requiring continuous consumption of high energy molecules. At the same time, the creation of bioinspired supramolecular hydrogels has traditionally focused on associations occurring at the thermodynamic equilibrium state. Here, hydrogels are prepared from cucurbit[7]uril host-guest supramolecular interactions through transient physical crosslinking driven by the consumption of a reactive chemical fuel. Upon action from this fuel, the affinity and dynamics of CB[7]-guest recognition are altered. In this way, the lifetime of transient hydrogel formation and the dynamic modulus obtained are governed by fuel consumption, rather than being directed by equilibrium complex formation.

Chiral Hierarchical Architecture Induced by Confinement-Assisted Living Supramolecular Polymerization of Simple Achiral Molecules

Chiral supramolecular assembly (CSA) based on achiral molecules has provided important clues to understand the origin of biological chirality. However, a simple achiral monomer faces the challenge of chiral stacking with the absence of a chiral resource. The difficulty is that simple achiral monomer lacks steric repulsion to provide asymmetry during hierarchical assembly, which is a prerequisite for chiral stacking with an angle. Moreover, during chiral stacking of achiral molecules or units, the right-handed and left-handed chiral supramolecular isomers (CSIs) are equally formed due to the mirror-imaged conformation, which leads to chirality silence. Here, with the benefit of two-dimensional confinement space of layered double hydroxide (LDH), simple achiral molecules can be arranged to staggered bilayer arrays by imprinting the topological structure of LDH. Once LDH is removed, these staggered arrays can form asymmetric living seeds, which can further elongate to living units with the advantage of living supramolecular polymerization (LSP) by following off-pathway. Due to the asymmetry of living units, the possible chiral stacking outcomes, CSIs, are not mirror-imaged. With the increase of the molecular number in living units, the energy difference between CSIs can be amplified by self-replication of LSP, leading to handedness preference. Thus, the detectable CSA is mainly derived from the CSI with energetically favored hierarchical structure. Thus, our strategy breaks the stereotype that the complex molecular structure and symmetry breaking mechanism are necessary for the formation of detectable CSA by achiral molecules.

Control of the stepwise self-assembly process of a pH-responsive amphiphilic 4-aminoquinoline-tetraphenylethene conjugate

Controlling the kinetic processes of self-assembly and switching their kinetic properties according to the changes in external environments are crucial concepts in the field of supramolecular polymers in water for biological and biomedical applications. Here we report a new self-assembling amphiphilic 4-aminoquinoline (4-AQ)-tetraphenylethene (TPE) conjugate that exhibits kinetically controllable stepwise self-assembly and has the ability of switching its kinetic nature in response to pH. The self-assembly process of the 4-AQ amphiphile comprises the formation of sphere-like nanoparticles, a transition to short nanofibers, and their growth to long nanofibers with ∼1 μm length scale at room temperature (RT). The timescale of the self-assembly process differs according to the pH-responsivity of the 4-AQ moiety in a weakly acidic to neutral pH range. Therefore, after aging for 24 h at RT, the 4-AQ amphiphile forms metastable short nanofibers at pH 5.5, while it forms thermodynamically favored long nanofibers at pH 7.4. Moreover, the modulation of nanofiber growth proceeding spontaneously at RT was achieved by switching the kinetic pathway through changing the pH between 7.4 and 5.5.

Waste-Free Fully Electrically Fueled Dissipative Self-Assembly System

The importance and prevalence of energy-fueled active materials in living systems have inspired the design of synthetic active materials using various fuels. However, several major limitations of current designs remain to be addressed, such as the accumulation of chemical wastes during the process, unsustainable active behavior, and the lack of precise spatiotemporal control. Here, we demonstrate a fully electrically fueled (e-fueled) active self-assembly material that can overcome the aforementioned limitations. Using an electrochemical setup with dual electrocatalysts, the anodic oxidation of one electrocatalyst (ferrocyanide, [Fe(CN)₆]^4-) creates a positive fuel to activate the self-assembly, while simultaneously, the cathodic reduction of the other electrocatalyst (methyl viologen, [MV]²⁺) generates a negative fuel triggering fiber disassembly. Due to the fully catalytic nature for the reaction networks, this fully e-fueled active material system does not generate any chemical waste, can sustain active behavior for an extended period when the electrical potential is maintained, and provides spatiotemporal control.

Density-tunable pathway complexity in a minimalistic self-assembly model

An open challenge in self-assembly is learning how to design systems that can be conditionally guided towards different target structures depending on externally-controlled conditions. Using a theoretical and numerical approach, here we discuss a minimalistic self-assembly model that can be steered towards different types of ordered constructs at the equilibrium by solely tuning a facile selection parameter, namely the density of building blocks. Metadynamics and Langevin dynamics simulations allow us to explore the behavior of the system in and out of equilibrium conditions. We show that the density-driven tunability is encoded in the pathway complexity of the system, and specifically in the competition between two different main self-assembly routes. A comprehensive set of simulations provides insight into key factors allowing to make one self-assembling pathway prevailing on the other (or vice versa), determining the selection of the final self-assembled products. We formulate and validate a practical criterion for checking whether a specific molecular design is predisposed for such density-driven tunability of the products, thus offering a new, broader perspective to realize and harness this facile extrinsic control of conditional self-assembly.

Insights into Chemically Fueled Supramolecular Polymers

Supramolecular polymerization can be controlled in space and time by chemical fuels. A nonassembled monomer is activated by the fuel and subsequently self-assembles into a polymer. Deactivation of the molecule either in solution or inside the polymer leads to disassembly. Whereas biology has already mastered this approach, fully artificial examples have only appeared in the past decade. Here, we map the available literature examples into four distinct regimes depending on their activation/deactivation rates and the equivalents of deactivating fuel. We present increasingly complex mathematical models, first considering only the chemical activation/deactivation rates (i.e., transient activation) and later including the full details of the isodesmic or cooperative supramolecular processes (i.e., transient self-assembly). We finish by showing that sustained oscillations are possible in chemically fueled cooperative supramolecular polymerization and provide mechanistic insights. We hope our models encourage the quantification of activation, deactivation, assembly, and disassembly kinetics in future studies.

Synthesis and Emergent Photophysical Properties of Diketopyrrolopyrrole-Based Supramolecular Self-Assembly

Diketopyrrolopyrrole (DPP)-based molecular semiconductors exhibit intriguing optical and charge transport properties. Herein, we rationally design a series of electronically identical but structurally distinct Hamilton receptor (HR)-based supramolecular assembly of DPP. The HR endows supramolecular assemblies via hydrogen bonding with enhanced structural ordering and excitonic couplings. The mechanism of supramolecular self-assembly was probed by diffusion ordered spectroscopy (DOSY) nuclear magnetic resonance (NMR) and solid-state IR spectroscopy studies. We investigated the morphology of self-assembly, photophysical and electrochemical properties and compared them with the identical DPP molecular structures without HRs. The microstructure of self-assembly was probed with atomic force microscopy in thin films. Subsequently, the influence of solid-state packing was studied by single-crystal X-ray diffraction. The single-crystal structure of HR-TDPP-C20 reveals slipped stack arrangements between the two neighboring chromophores with π-π stacking distance and slip angle of 3.55 Å and 35.4°, respectively. Notably, the slight torsional angle of 1° between thiophene and lactam rings and small π-π stacking distance suggest a significant intermolecular coupling between thiophene (D) and lactam (A) rings. This intramolecular coupling between two π-π chromophore stacks manifests in their optical properties. In this manuscript, we report rational design and synthesis of supramolecular self-assembly of DPP with a collection of compelling structural and optical properties.