ChemSystemsChem最新文献

Spatiotemporal patterns, such as spiral waves, can be formed on membranes and are coupled with membrane deformation. The membrane can exhibit no-thermal fluctuations owing to active protein interactions. The Review by Hiroshi Noguchi describes the latest developments in theoretical analyses and simulations on nonequilibrium dynamics of biomembranes under active protein interactions and chemical reactions.

In the Research Article by Munenori Numata and co-workers a dissipative self-assembly system powered by flow and light is demonstrated. Supramolecular co-polymerization and rolling-up from the forward polymer's end led to the creation of discrete micrometer-sized supramolecular architecture featuring both molecular-level inner complexity and long-range order over molecular scale.

Giant membrane vesicles (GUVs) and Giant plasma membrane vesicles (GPMVs) are used as models to study membrane properties. We conducted a comparative study to examine how reducing the volume of vesicles with different lipid compositions, solution symmetries, solution asymmetries, and membrane charges affects their morphology. We used three-dimensional visualization techniques to study the shape of the vesicles. Although the vesicles may not be perfectly spherical, they exhibit some fluctuations in their shape. To understand these variations, we used confocal image stacks for visualization. Our experimental observations show that the membrane′s charge influences the deflation of the GUVs in the presence of trans-bilayer sugar asymmetries. The lipid bilayers of our GUVs have a uniform distribution of lipids in both leaflets, indicating no asymmetry in lipid composition. We induce trans-bilayer asymmetries by exposing each leaflet of the bilayer to different solution compositions. We also estimated and compared the deformation of GPMV extracted from HEK-293 cells with trans-bilayer buffer asymmetries and inherent leaflet compositional asymmetry with biomimetic membranes.

Chemical gradients provide spatiotemporal signaling fields in various cellular processes, driving complex dynamic behaviours such as differentiation and spatial organization. Here we employ opposing gradients of two artificial morphogens (sodium dodecyl sulfate (SDS) and sodium phosphotungstate (polyoxometalate; POM)) to systematically investigate morphological differentiation in organized populations of coacervate microdroplet-based protocells. Using a matrix of 16 sets of counter-diffusive gradients, we classify the differentiated protocells into five phenotypes and encode their spontaneous organization into different spatially patterned protocell consortia using a 3-bit binary information system. We show that a predominant SDS gradient produces a diversity of differentiated phenotypes to generate complex spatially coded 2D protocell organizations. In contrast, a prevailing POM gradient decreases morphological differentiation, resulting in population homogenization. Our results improve our understanding of gradient concentration-dependent collective responses in synthetic microscale agents and provide a step to a new spatially resolved information encoding method with 3-bit binary outputs.

Biomolecular condensates, formed through liquid-liquid phase separation (LLPS), serve as enzymatic reaction centers in cells by increasing local concentrations of enzymes and substrates, thereby facilitating reaction kinetics and regulatory mechanisms. Inspired by these natural systems, synthetic condensates are being developed for diverse applications, including payload delivery, sensing, and as microreactors where enzymatic reaction kinetics can be modulated by factors like pH, viscosity, and enzyme-substrate co-localization. Here, we investigate how the physicochemical properties of enzymes and substrates influence condensate formation and function as microreactors. Focusing on cellulase and alkaline phosphatase, which differ in molecular weight and isoelectric point, we employed a minimalistic complex coacervation system of oppositely charged LLPS-promoting peptides. Our findings show how electrostatic forces within condensates influence their role as microreactors. Specifically, the ability of condensates to encapsulate or exclude phosphatase, cellulase, and their substrates, which is pivotal for the regulation of reaction kinetics, is determined by the enzyme surface charge, substrate charge, and condensate charge stoichiometry. These results highlight the potential of utilizing electrostatic forces within condensates to modulate enzymatic reactions, providing critical insights for developing synthetic condensates as microreactors in biotechnology and materials science.

This work presents some ambitious perspectives on how Systems Chemistry can contribute to developing the quite new research line of Chemical Artificial Intelligence (CAI). CAI refers to the efforts of devising liquid chemical systems mimicking some performances of biological and human intelligence, which ultimately emerge from wetware. The CAI systems implemented so far assist humans in making decisions. However, such CAI systems lack autonomy and cannot substitute humans. The development of autonomous chemical systems will allow the colonization of the molecular world with remarkable repercussions on human well-being. As a beneficial side effect, this research line will help establish a deeper comprehension of the mesmerizing phenomenon of the origin of life on Earth and how cognitive capabilities emerge at a basic physico-chemical level.

Iron-sulfur clusters are ancient cofactors that could have played a role in the prebiotic chemistry leading to the emergence of protometabolism. Previous research has shown that certain iron-sulfur clusters can form from prebiotically plausible components, such as cysteine-containing oligopeptides. However, it is unclear if these iron-sulfur clusters could have survived in prebiotically plausible environments. To begin exploring this possibility, we tested the stability of iron-sulfur clusters coordinated to a tripeptide and to N-acetyl-L-cysteine methyl ester in a variety of solutions meant to mimic prebiotically plausible environments. We also assessed the impact of individual chemical components on stability. We find that iron-sulfur clusters form over a wide variety of conditions but that the type of iron-sulfur cluster formed is strongly impacted by the chemical environment and the coordinating scaffold. These findings support the general hypothesis that iron-sulfur clusters were present on the prebiotic Earth and that different types of iron-sulfur cluster predominated in different environments.

The cover picture shows a scanning electron micrograph of self-organized chemical garden tubes. These calcium-based hollow structures are composed of porous walls separating an alkaline exterior liquid and acidic, metal salt interior solution. Natural analogs to this classic chemistry experiment are hydrothermal vents found at the base of the ocean. Their structures are composed of mineral walls which separate two disparate chemical environments maintaining a far-from-equilibrium setting. More in theResearch Article by Pamela Knoll and Corentin C. Loron.

Asymmetric chemical reactions on the surfaces of colloidal particles are known to propel them into directional motion. The dynamics of such chemical micromotors are sensitive to their local chemical environments, which also continually evolve with the reactions on motor surfaces. This two-way coupling between the motor dynamics and the local environment may result in complex nonlinear behaviors. As an example, we report that Janus Ag microspheres, which self-propel in hydrogen peroxide (H₂O₂), spontaneously reverse their direction of motion two or more times. We hypothesize that two distinct chemical reactions between Ag and H₂O₂ drive the micromotor in opposite directions, and which reaction dominates depends on the local pH. Interestingly, the local pH near a Ag micromotor oscillates spontaneously in H₂O₂, likely due to a complex interplay between the kinetics of the reaction between Ag and H₂O₂ and the diffusion of chemical species. Consequently, the pH-sensitive Ag micromotor reverses its direction of motion in response to these pH oscillations. This study introduces a new mechanism for regulating the speed and directionality of micromotors, highlights the potential of Ag micromotors in chemical sensing, and sheds new light on the interplay between chemical kinetics and micromotor dynamics.

The injection of rare-earth metal salt solutions into sodium silicate solution results in vertically growing tubular precipitate structures. At low input concentrations reaction kinetics is the rate-detemining process, leading to linear growth rates independent of injection rates. At higher concentrations, flow drives the precipitate growth, characterized by jetting mechanism. Among the studied rare-earth metal silicates, dysprosium silicate is found to have the most rigid structure with visible growth even at higher injection rates. The outer surface of the hollow tubes is smooth, on which rare-earth hydroxide – based on the result of the energy dispersive X-ray spectroscopy measurements – aggregates into globules.