ChemSystemsChem最新文献

We previously reported collective behavior in colloidal aggregates of silver phosphate in H₂O₂ and under UV light. Diffusiophoretic interactions between aggregates lead to non-linear behavior such as oscillations and synchronization, in which oscillation frequencies increase with H₂O₂ concentration. The aggregates transition between schooling and dispersed behaviors with incipient spatiotemporal correlations. We identified a kinetic model that maps the chemical species that are thought to underlie non-linear phenomena in the colloidal aggregates, i. e. adsorbed oxygen species *OOH⁻ and *O. We investigate the emergent dynamics for the simplest case, the coupling of two otherwise bistable clusters. Two coupling schemes are proposed and we find that – depending on whether the coupling is excitatory or inhibitory – the clusters may oscillate with zero or π phase shift.

In supramolecular chemistry, photostimulants are generally combined with a static solution under thermodynamic equilibrium with no time progression. After reaching the thermodynamic state, self-assembly events contain various species–a mixture of component molecules, intermediate species, and completed assemblies–which light reaches uniformly. In this study, snapshot control of supramolecular polymerization was first combined with pinpoint photoirradiation using a microflow system. Employing the azobenzene derivative trans-C3NO as a monomer, a snapshot moment of supramolecular polymerization along a microflow channel was selectively irradiated with UV light at 365 nm in a space-resolved manner, so that the monomers, intermediates (oligomers), or extended supramolecular polymers were selectively exposed to light stimuli. We found that a pinpoint photostimulus to each snapshot moment had a pronounced effect on the kinetic pathway by tuning the timing at which the snapshot moment of cis-C3NO was generated. Upon irradiation in the upstream region, in the very early stages before initiating polymerization, supramolecular polymerization was suppressed by generating a less reactive cis-C3NO monomer. However, photoirradiation does not affect the supramolecular polymers in the downstream region because of their stiff nature. Remarkably, when irradiating the middle stream region involving a soft-natured intermediate species, supramolecular copolymerization occurred through in situ conversion from trans- and cis-C3NO inside the primitive supramolecular polymer. Loose monomer stacking in the primitive aggregate endows it with mechanoresponsiveness. Under the influence of shear force in a Hagen–Poiseuille flow, the resultant supramolecular copolymers containing geometrically different cis-isomers were rolled up and transformed into a micrometer-sized disk-like structure. During the in situ supramolecular copolymerization and transformation to the disk structure, a liquid–liquid interface generated in the laminar flow acted as a template to fix the orientation of the monomers and supramolecular polymers, leading to the uniform disk formation. Furthermore, monomers’ orientation in the aligned supramolecular polymers are fixed on the interface, on which light is always irradiated in an anisotropic manner. This results in both complexity at the molecular level and long-range structural order such as regular rolling up at the micrometer range over the molecular scale. By incorporating the photostimulus system, microflow extends its potential for supramolecular chemistry.

An E. coli cell contains ~2500 different chemicals which combine into an ordered biochemical reaction network out of which emerges a living system. A chemist taking 2500 different chemicals from a laboratory chemical cabinet and combining them together will likely cause an explosive disaster and produce an intractable chemical sludge. Systems Chemistry aspires to construct systems whose complexity rivals that of life. However, to do this we will need to learn how to combine hundreds or thousands of different chemicals together to form a functional system without descending into a disordered chemical sludge. This is the Many-Chemicals Problem of Systems Chemistry. I explore a key strategy life employs to overcome this challenge. Namely, the combination of kinetically stable and thermodynamically activated molecules (e. g. ATP) with enzyme catalysts (e. g. histidine kinases). I suggest how the strategy could have begun at the origin of life. Finally, I assess the implications of this strategy for Systems Chemistry and how it will enable systems chemists to construct systems whose complexity rivals that of life.

The creation of large information molecules may have played an essential role in the origins of life. In this study, we conducted slow freeze-thaw (F/T) experiments to test the possibility of enhanced hybridization between the complementary sticky ends attached to kilobase-sized DNA fragments at sub-nanomolar concentrations. DNA fragments of 2- and 3-kilobase pairs (kbp) with 50-base complementary sticky ends that can form 5 kbp-sized hybridization products were mixed. While simple incubation provided little hybridization product, significantly effective hybridization was observed after freezing and thawing at a controlled time rate (<0.3 K min⁻¹), even with small DNA concentrations (<1 nM). Furthermore, slow thawing had a more effect on hybridization than slow freezing. The reaction efficiency was reduced by rapid thawing instead of slow thawing, suggesting that the eutectic phase concentration played an important role in hybridization. A slow F/T cycle was effective even for the hybridization reaction between two 10 kbp DNA fragments, which yielded a 20 kbp product at sub-nanomolar concentrations. Repeating the slow F/T cycle significantly improved the reaction efficiency. The possible role of the F/T cycles in early Earth environments is discussed here.

An experimental pathway to the spontaneous generation of compositionally diverse synthetic protocells is presented. The pathway is initiated by flat giant unilamellar vesicles (FGUVs) that originate from compositionally different multilamellar lipid reservoirs and undergo spontaneous spreading across solid surfaces. On contact, the spreading FGUVs merge to produce a concentration gradient in membrane lipids across the fusion interface. Subsequent reconstruction through a series of shape transformations produces a network of nanotube-connected lipid vesicles that inherit different ratios of the membrane constituents derived from the bilayers of the parent FGUVs. The fusion process leads to the engulfment of small FGUVs by larger FGUVs, mimicking predator-prey behavior in which the observable characteristics of the prey are lost but the constituents are carried by the predator FGUV to the next generation of lipid vesicles. We speculate that our results could provide a feasible pathway to autonomous protocell diversification in origin of life theories and highlight the possible role of solid surfaces in the development of diversity and rudimentary speciation of natural protocells on the early Earth.

Cells are highly functional and complex molecular systems. Artificially creating such systems remains a challenge, which has been extensively studied in various research fields, including synthetic biology and molecular robotics. DNA nanotechnology is a powerful tool for bottom-up engineering for constructing functional nanostructures or chemical reaction networks which can be utilized as components for artificial molecular systems. Encapsulation of these components into a giant unilamellar vesicle (GUV) composed of a lipid bilayer, the base structure of the cellular membrane, results in a functional cell-sized structure that partially mimics some cellular functions. This review discusses the studies contributing to the construction of GUV-based artificial molecular systems based on DNA nanotechnology. Molecular transport and signal transduction through lipid membranes are essential to uptake molecules from the environment and respond to stimuli. Membrane shaping relates to various functions, including motility and signaling. A chemical reaction network is required to autonomously regulate the system‘s functions. This review describes the functions realized using DNA nanostructures and DNA reaction networks. Given the designability and programmability of DNA nanotechnology, it may be possible that the functionality of artificial molecular systems could be comparable to or even surpass that of natural molecular systems.

Biological translation is a universal process taking place in the ribosome. It involves the synthesis of a protein with a particular sequence from the information encoded in a messenger RNA and the amino acids carried by transfer RNAs with the assistance of specific enzymes. However, the origin of translation in the prebiotic world and, thus, in the absence of enzymes is difficult to envisage. Past and recent studies proposed different prebiotic models, following top-down and bottom-up approaches, for the origin and evolution of a primitive ribosome. The bottom-up models made use of distinct covalent linkages to connect RNA strands with amino acids and peptides. In this review, I focus on the covalent linkages used in these prebiotic models: acyl phosphate mixed anhydrides, phosphoramidates and ureas. I describe their syntheses under prebiotically plausible reaction conditions, as well as include their main conventional preparation methods. I also comment on their properties and chemical stabilities in aqueous solution. Finally, I examine the functions of the described covalent linkages in prebiotic processes involving RNA-templated amino acid transfer and peptide synthesis.

Hydrothermal vents maintain far-from equilibrium conditions that may have provided the necessary settings for the origin of life. To understand reactions under these physicochemical conditions, scientists have turned to the classic demonstration experiment, chemical gardens. The self-organization of precipitate tubes separates high and low pH environments similarly to the naturally occurring geological structures. Here, we report calcium-based chemical gardens forming in solutions containing anions of silicate, carbonate, or a mixture of the two in 100 °C and 23 °C environments. Under high temperature conditions, chemical gardens tend to have faster average growth velocities and form taller structures. We measure the composition of the precipitate tubes using Fourier transform infrared spectroscopy and find the formation of all polymorphs of calcium carbonate along with calcium silicates.

The front cover artwork is provided by the Lerch group at the Stratingh Institute for Chemistry at the University of Groningen, The Netherlands. The cover illustrates a robot communicating with surrounding entities using various (chemical) signals. Not all communication and signal processing are successful, hence the slight confusion on the robot′s face. The cover alludes to the breadth of and future challenges for chemical communication within autonomous materials and robots. Cover design by Dr. Kaja Sitkowska. Read the full text of the Concept at 10.1002/syst.202400005.

The intricate interplay between self-assembly and phase separation orchestrates biomolecular organization inside cells, thereby dictating the formation of vital structures such as protein assemblies and membraneless organelles (MLOs). However, in the context of supramolecular polymerization, these fundamental processes have traditionally been studied separately. This study reevaluates the supramolecular polymerization process to unveil the presence of phase-separated droplet state. Utilizing the well-studied benzene-1,3,5-tricarboxamide (BTA) supramolecular motif, we explore its thermally driven liquid-liquid phase separation (LLPS). Thermodynamic and kinetic analysis, employing temperature-dependent spectroscopic and microscopic techniques, elucidates the distinct BTA states and their evolution towards the thermodynamic fiber state. This research sheds light on the existence of hidden phases of supramolecular monomers, emphasizing the delicate balance of non-covalent interactions among monomers and with solvents in governing self-assembly vs. phase separation. This is particularly important in comprehending phase separation in the biological realm such as in MLOs, and for applications such as condensate-modifying therapeutics.