ABSTRACT This study presents a comprehensive investigation of the switching kinetics of a widely used spiropyran–merocyanine (SP–MC) photoswitch in different solvents. Under UV irradiation, the forward SP→MC conversion follows apparent first‐order kinetics, yielding a mono‐exponential increase in MC population toward a photostationary state (PSS). In contrast, green‐light irradiation and thermal relaxation drive the reverse MC→SP conversion via exponential decay kinetics. These processes must be treated independently, as they originate from distinct photophysical and thermodynamic mechanisms. The proposed rate laws are validated experimentally in different solvent environments. Temperature‐dependent studies reveal that thermal back‐isomerization increasingly shifts the equilibrium toward the SP‐enriched state and can substantially suppress MC formation at elevated temperatures. Solvent polarity strongly influences the forward switching kinetics: while MC formation exhibits ideal monoexponential behavior in a polar solvent such as acetonitrile, decreasing polarity induces pronounced deviations from first‐order behavior due to aggregation phenomena involving the highly polar MC species. In contrast, the reverse MC→SP conversion remains largely monoexponential and insensitive to solvent polarity, consistent with the greater thermodynamic stability of the less polar SP state in nonpolar environments.
ABSTRACT Autocatalysis plays a critical role in the self‐organization of chemical and biological systems, influencing phenomena such as bistability and reaction–diffusion front formation. In the rhizosphere, the regulation of reactive oxygen species (ROS) is mediated by intricate networks of reversible autocatalytic reactions, yet the mechanisms governing their spatiotemporal dynamics remain unclear. Here, we perform comprehensive numerical simulations of a reaction–diffusion model for ROS dynamics incorporating redox couples, sodium borohydride, and oxygen. We identify oxidation‐driven autocatalysis as the primary mechanism responsible for the emergence of stable reaction–diffusion fronts that propagate with constant velocity and shape, whereas reduction fronts display diffusive broadening attenuated by the local oxygen concentration. Furthermore, we demonstrate that reversible quadratic autocatalytic cycles coupled to a simple autocatalyst removal and diffusion are sufficient to reproduce these characteristic front behaviors. These results also provide insights that are transferable to a wide range of autocatalytic networks exhibiting spatiotemporal pattern formation.
ABSTRACT Lipophilic anchors are essential biomolecular modifications that mediate membrane‐dependent functions by tethering associated biomolecules, such as peripheral proteins, to the lipid bilayer. Inspired by natural multi‐lipidation systems, we introduce a DNA origami platform functionalized with lipophilic anchors spanning a wide hydrophobicity range to systematically investigate how anchor hydrophobicity governs membrane binding and lateral organization. By varying anchor type, number, and spatial arrangement, we evaluated the interactions of anchor‐modified DNA origami across homogeneous and phase‐separated giant unilamellar vesicles (GUVs). On homogeneous lipid membranes, stable attachment required a minimum per‐anchor hydrophobicity (cLogP ≈ 5) below which binding of origami to the membrane was ineffective regardless of anchor type or number. However, combining weak and strong anchors on a single nanostructure synergistically enhances binding through cooperative effects that exceed additive contributions of either anchor type. On phase‐separated GUVs, our combined‐anchor system revealed that anchor molecular identity and intrinsic hydrophobicity regulate membrane partitioning. Notably, weak anchors drive the nanostructure localization from the liquid‐ordered (Lo) to the liquid‐disordered (Ld) phase, with this shift inversely related to the hydrophobicity of the strong anchor. Collectively, our results establish design principles for multi‐anchor strategies enabling tunable membrane binding and controlled phase‐specific localization of DNA nanostructures.
ABSTRACT Catch bonds are interactions whose lifetimes paradoxically increase with applied force, in contrast to conventional slip bonds that dissociate faster under load. Over the past two decades, extensive biophysical research has uncovered catch bonds in diverse biological systems and investigated the molecular mechanisms that produce force‐stabilized binding. These insights have inspired a growing effort to engineer artificial catch bonds using proteins, DNA, polymers, and nanoparticle assemblies. Recent advances now provide experimental demonstrations of synthetic catch bonds with tunable force‐lifetime behaviors. In parallel, computational and experimental studies reveal how catch bond kinetics reshape the mechanics of polymer and biomolecular networks, enabling materials that strengthen or adapt under load. This review discusses the progress from natural systems and theoretical models to emerging strategies for engineering artificial catch bonds and their collective behaviors in networks.
The origin of life, marking the transition from nonliving to living matter, remains one of the unresolved mysteries in Earth's history. Despite significant progress, many aspects of this process are still poorly understood, particularly given that the environmental conditions of early Earth differ substantially from those of the present. This review examines the surface‐driven formation of protocells in geologically relevant early Earth settings, focusing on the interplay between geological substrates and prebiotic biochemistry. Rather than emphasizing homogeneous bulk reactions, it aims to highlight how solid–liquid interfaces could have facilitated the emergence of life. Recent theoretical and experimental advances prove that catalytic properties, surface charges, and organic molecule upconcentration capacities of mineral surfaces were crucial in enabling the synthesis of organics and compartmentalization of protocells. Multiple geological environments, including hydrothermal vents, volcanic terrains, and surface waters, will be considered in this review and examined as dynamic arenas fostering complex chemical networks. Environmental challenges such as molecular dilution and ultraviolet radiation are also discussed, along with the protective mechanisms that could have mitigated them. Linking geology to biology, this review offers a comprehensive framework for understanding the origins of life on Earth and how it could arise on other planets.
Metabolism is a critical process for biology and is of great interest to those researching geobiological processes and the origins of life. A metabolism comprises a network of chemical reactions for molecular synthesis, energy conversion pathways, and cellular function. Understanding the mechanisms underlying metabolic processes provides insight into the evolution of electrochemical processes in complex systems and informs the possible pathways by which abiotic chemistry transitioned to biochemistry. Modern enzymes utilize cofactors to mediate chemical reactions and overcome energetic limitations. While enzymes are specific, large, and complex biological proteins, cofactors are simpler ions and molecules incorporated within the larger protein complex. Cofactors play a fundamental role in supplementing an enzyme's catalytic role and may represent a convergence between abiotic and biotic chemistry, allowing studies of cofactors to reveal potential prebiotic processes. Here, we review some of the organic / nucleotide cofactors participating in the electron transport chain (ETC): their structures, capacity for energy conversion, and their putative role in the origins of life. We choose to focus on four specific organic cofactors that have evolved to be key in extant mitochondrial ETCs—adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NADH), flavins (FAD, FMN), and quinones (ubiquinone)—to conceptually bridge the gap between the earliest inorganic cofactors and the protein complexes of modern biochemistry. We then make recommendations for future research topics and avenues.
The emergence of genetic polymers such as RNA and DNA from prebiotically available building blocks represents a key step toward the origin of life. Nucleotides, the building blocks of RNA and DNA, may have existed on the prebiotic Earth, but their oligomerization is energetically unfavorable in aqueous solution. Consequently, chemically activated nucleotides and/or catalytic agents have typically been invoked. The extent of oligomerization of non-activated nucleotides is sensitive to experimental subtleties, and detection uncertainties and potential artefacts complicate its interpretation. Further clarification is therefore required. Here, we present experimental evidence for the oligomerization of non-activated RNA and DNA nucleotides in hot, acidic wet-dry cycling environments, resembling a simplified model of geothermal pools on the prebiotic Earth. No catalytic agents were added, and pH was naturally buffered by the nucleotides, minimizing external interferences. The resulting oligonucleotides were short (<= 4 nt), with yields up to similar to 3%. While previous studies under similar conditions usually employ catalytic agents such as minerals, lipids, or salts, our findings demonstrate that phosphodiester bonds form in their absence. However, generating and sustaining long, genetically capable polymers in acidic hot wet-dry cycling environments remains challenging.
We report an autocatalytic molecular amplification system based on the double masking of benzoquinones with boronate ester protecting groups (i.e., diboronate ester probes). This design extends a previously described redox cross-catalytic (RCC) reaction scheme, in which hydrogen peroxide (H2O2) and quinones are exponentially co-generated through coupled catalytic loops. The double protection aims to enhance the chemical stability of the diboronate probes while preserving their ability to undergo autocatalytic deprotection. Through kinetic modeling and experimental validation, we demonstrate that complete deprotection to the corresponding quinones can occur even under substoichiometric H2O2 conditions, thereby sustaining autocatalytic behavior. Comparative studies of symmetric and asymmetric diboronate probes reveal how molecular structure and electronic effects control the kinetics of each deprotection step and so the overall amplification efficiency. Finally, we show that these doubly protected systems enable efficient responses to H2O2 across more than two orders of magnitude in concentration (from & micro;M to sub-millimolar range) and within minutes, while providing improved probe stability and tunable reactivity. This work offers mechanistic insights and design principles for next-generation autocatalytic redox amplification systems with enhanced analytical performance.
Because of the feature of noncovalent interactions, supramolecular assemblies show intrinsic dynamics, whose structures and functions usually depend on their self-assembly pathways. However, the Hofmeister effect, an important factor capable of modulating intermolecular interactions, is underexplored in its potential of controlling the self-assembly pathway. Here, on the basis of a hydrazone-based supramolecular gelation system, we show that the Hofmeister effect can accelerate the self-assembly of gelators into a hydrogel that cannot be achieved under thermodynamic conditions. By decreasing the concentration of gelators to the corresponding critical gelation level, gelation fails to occur under standard conditions. However, with the addition of sufficient kosmotropic anions that can strengthen intermolecular interactions via the disruption of solvation, we surprisingly find that the gelator solution is rapidly converted into a hydrogel state. More importantly, the resultant hydrogel network remains sustained even after a subsequent removal of the kosmotropic anions, indicating that the addition of kosmotropic anions enables a gelation pathway that is inaccessible by the standard approach. Our findings suggest that the Hofmeister effect can serve as an effective approach to interfere with the self-assembly pathway, and therefore, it should be considered in future studies of supramolecular chemistry.
The emergence of life is hypothesized to have been driven by a series of chemical processes constituting protometabolism, that are still preserved in the heart of biological metabolism, including numerous redox reactions. However, a longstanding problem is how critical oxidative and reductive protometabolic reactions could have been achieved simultaneously, especially in the absence of light. Here we show that electrochemistry can enable concurrent oxidative and reductive reactions relevant to protometabolism within a single environment. Using constant current and constant potential experiments, we promoted the reduction of oxaloacetate (OXA) to malate (MAL) and the oxidation of dihydroorotate (DHO) to orotate (ORO) and uracil (URA). Statistical modeling revealed that lower current densities favored ORO production from DHO, while higher densities promoted the oxidative decarboxylation of DHO to URA as well as the reduction of OXA to MAL. Additionally, we combine the oxidation of DHO to the reduction of other alpha-keto acids (pyruvate and alpha-ketoglutarate) and fumarate. Although the potentials used in this study exceed those presently known to occur in natural environments, the results nonetheless underscore the potential role of geological electromotive forces in enabling early metabolic networks.
Autocatalytic reaction-diffusion fronts are known to exhibit cellular patterns when the reactant of an autocatalytic reaction diffuses sufficiently faster than the autocatalyst . In this study, we analyze the effect of curvature on these patterns through a combined numerical and experimental approach. Experiments using the chlorite-tetrathionate reaction show earlier onset and cellular patterns of larger amplitude on radially propagating fronts than on rectilinear ones, when the autocatalyst invades the reactant . Numerical results corroborate these findings, indicating that the curvature affects the transport of the chemical species and enhances the diffusive instability of an autocatalytic front. As a consequence, there exists a range of diffusion coefficient ratios in which fronts are unstable in the radial geometry but remain stable in the rectilinear configuration. Our results underline the importance of curvature in the dynamics of autocatalytic reaction-diffusion systems.
Tetrazines are heterocyclic aromatic molecules with notable properties, such as elevated electron affinity, yet their supramolecular self-assembly properties are scarcely investigated. In this work, a novel family of compounds featuring a central tetrazine core is presented, where structure-property relations are established upon introducing linear or branched chiral side chains. Different non-covalent interactions enable self-assembly in the system, where H bonding emerges as the main driving force responsible for the aggregation process, leading to the formation of supramolecular gel networks that are characterized by rheology. Additionally, in the solid state, the presence of liquid crystals is explored, highlighting the formation of columnar mesophases, reported here for the first time in tetrazine-bearing species. This study provides fundamental structure-self-assembly properties in the liquid and solid state, highlighting the relevance of non-covalent interactions.
The interplay between biomolecular condensates and cellular membranes is central to understanding dynamic intracellular organization and membrane repair. Here, we present a minimal synthetic system to examine how membrane composition and curvature govern condensate-membrane interactions within this model platform. We demonstrate that the exposure of either lipid or polymer-lipid hybrid giant vesicles with encapsulated bovine serum albumin to a resilin-inspired intrinsically disordered protein (IDP), which undergoes liquid-liquid phase separation, results in in situ formation of transmembrane condensates. This observation of cargo-triggered condensation across giant vesicle membranes directly links encapsulated protein crowding to condensate nucleation and insertion. The condensation morphology was tunable by vesicle size and membrane elasticity where smaller vesicles and stiffer hybrid membranes favored transmembrane condensation, whereas larger or softer membranes promoted membrane wetting and deformation. Condensate formation locally reorganized lipids and facilitated leaflet coupling without compromising overall membrane integrity or cargo retention. This mechanistic understanding offers a unique opportunity to gain insight into the complex cell biological process of membrane repair using a minimal system.
Active compartmentalization is a fundamental property of life, as well as a key element in cell regulation. In order to build synthetic systems with emergent cell-like properties, we need to develop active compartments that form, disappear, and change properties autonomously over time. Here, we report a new strategy to induce temporal changes in coacervates using the urea-urease reaction. This reaction triggers the dissolution of complex coacervates after a controllable delay, as it increases ionic strength through the production of ammonium carbonate. This delayed dissolution can be directly used for a broad range of complex coacervates without any synthetic effort. Furthermore, ammonium carbonate can also decompose over time, evaporating from the solution. This combination of enzymatic synthesis and spontaneous decomposition of salt leads to transient coacervate dissolution, which can be used for the controlled release of cargo and for the modulation of a compartmentalized reaction. Cycles of dissolution/reformation can be repeated multiple times without any waste generation, although the number of cycles is limited by the denaturation of urease. Finally, by combining polyelectrolytes with a protected dipeptide, ureolysis can trigger the formation of multiphase coacervates, as well as the sequential formation, dissolution, and aggregation of simple and complex coacervates.
Large-amplitude co-conformational motions are a unique characteristic of catenanes and related mechanical interlocked molecules that underlie their applications as molecular switches and machines. Due to the challenging synthesis, precise incorporation of multiple macrocycles of different properties into a single [n]catenane and studies on the dynamics of the interlocked components are, however, scarce. In this work, a water-soluble radial [7]catenane was obtained in one step in high yield (95% formation, 80% isolated yield). Dynamics of the four beta-cyclodextrins (beta-CD) and two cucurbit[6]urils (CB[6]) interlocked on a central macrocycle were also studied by variable temperature NMR. While the motions of the beta-CDs can be modulated by external stimuli, those of the CB[6]s are found to be unaffected.
Controlling product selectivity in complex chemical reaction networks (CRNs) remains a major challenge in rational catalyst design, as multiple competing pathways often yield diverse products. The formose reaction, an autocatalytic process that converts formaldehyde (HCHO) into monosaccharides, represents a prototypical nonenzymatic CRN. It has long been investigated in the context of prebiotic chemistry and, more recently, as a system that transforms a C1 compound into higher-carbon species. In this study, we examined the influence of catalysts on pathway selectivity within this reaction network. Sodium tungstate (Na2WO4), which we have previously investigated, produces a product distribution distinct from that obtained with conventional strong base catalysts. Analysis of the aldopentose (C5a) formation pathway revealed that xylose formation predominates under NaOH catalysis, whereas Na2WO4 selectively promotes ribose production. Mechanistic experimental studies and density functional theory (DFT) calculations indicate that WO4 2- preferentially stabilizes the transition state leading to ribose. These findings demonstrate that understanding catalyst-substrate interactions and identifying the reaction pathways they govern in the formose reaction network enables the prediction of product distributions in complex CRNs.
False knowledge is more misleading than no information, and the rising threats from counterfeitors demand advanced strategies of secure, multilayered encryption. The fluorescence-based routine systems have become recurrent, often requiring complicated synthesis and UV light for decoding. We have countered the common notion that novel applications need newer molecules by employing conventional molecules in unconventional ways. Motivated by nature, we implemented stimuli-responsive organic dyes to develop color-coded encryption-simple, harmless, and UV-free alternatives that preserve crucial security features. pH- or redox-responsive dyes were purposely selected so that time-dependent color changes can be displayed under chemically triggered nonequilibrium conditions. This feature was exploited in designing time-gated, multidimensional, diverse color codes. An alternative decryption method was demonstrated via smart windows-stimuli-sensitive barriers that regulated access across parallel time scales managed by independent triggers. Our strategy affords dual time-locked color codes with hierarchical security operated through orthogonal stimuli, achieving complex encryption with simple, synthesis-free decoding. A highly accurate indigenous decoding strategy is successfully demonstrated.
Catalyst-free dynamic covalent polyureas (DCPUs) have emerged as a promising class of environmentally friendly and sustainable materials that combine the mechanical robustness of traditional polyureas with the stimuli-responsive properties of dynamic urea bonds (DUBs). This review elaborates on the general concepts that have guided important developments of the recent advances in catalyst-free DUBs and DCPUs, focusing on the dynamic mechanisms of well-designed urea bonds, structure-property relationships, and diverse applications. The rational design of DUBs is discussed, highlighting their unique features in terms of DUBs' reversibility and kinetics. Furthermore, the mechanical properties, self-healing efficiency, thermal stability, reprocessability, and recyclability of DCPUs are analyzed, along with their potential applications in self-healing coatings, recyclable composites, shape-memory materials, 3D printing, and so on. Finally, the current challenges and future perspectives in this fast-growing field of DUBs and DCPUs are discussed.
With the extensive use of nuclear energy, the disposal of radioactive iodine waste has become an issue in the energy industry. Herein, we reported a series of quadruple hydrogen-bonded supramolecular polymers combining 2-ureido-4[1H]-pyrimidinone (UPy) with Troger's base (TB) for iodine adsorption: TB-UPys, demonstrated a volatile iodine adsorption capacity of 4 g & centerdot;g(-1), with a second-order kinetic rate constant of 2.8 & times; 10(-4) g & centerdot;min(-1)& centerdot;mg(-1) for aqueous iodine adsorption. This work leverages the unique hydrogen bonding properties to construct stable and robust iodine adsorption materials, paving a new way forward for the future development of iodine adsorbents.
We explore the use of a photoacid in a chemical reaction cycle, which allows for the controlled sol-to-gel transition of a saccharide aldehyde-based self-assembling system. The modulation of the pH with light enables to generate chemical fuels in situ, thus triggering monomer activation and gelation. Our efforts represent a promising step toward dissipative self-assembled systems with a higher degree of spatiotemporal control.
