Littérature scientifique sur le sujet « Dynamic hierarchical self-Assembly »

The self-assembly of lipid molecules in aqueous solution under shear flows was investigated using the dissipative particle dynamics simulation method. Three cases were considered: zero shear flow, weak shear flow and strong shear flow. Various self-assembled structures, such as double layers, perforated double layers, hierarchical discs, micelles, and vesicles, were observed. The self-assembly behavior was investigated in equilibrium by constructing phase diagrams based on chain lengths. Results showed the remarkable influence of chain length, shear flow and solution concentration on the self-assembly process. Furthermore, the self-assembly behavior of lipid molecules was analyzed using the system energy, particle number and shape factor during the dynamic processes, where the self-assembly pathways were observed and analyzed for the typical structures. The results enhance our understanding of biomacromolecule self-assembly in a solution and hold the potential for applications in biomedicine.

Soft structures in nature, such as protein assemblies, can organize reversibly into functional and often hierarchical architectures through noncovalent interactions. Molecularly encoding this dynamic capability in synthetic materials has remained an elusive goal. We report on hydrogels of peptide-DNA conjugates and peptides that organize into superstructures of intertwined filaments that disassemble upon the addition of molecules or changes in charge density. Experiments and simulations demonstrate that this response requires large-scale spatial redistribution of molecules directed by strong noncovalent interactions among them. Simulations also suggest that the chemically reversible structures can only occur within a limited range of supramolecular cohesive energies. Storage moduli of the hydrogels change reversibly as superstructures form and disappear, as does the phenotype of neural cells in contact with these materials.

Laser irradiation is used to induce CsPbBr3 NPLs reshaping and morphology control. A hierarchical self-assembly process occurs in the CsPbBr3 NPLs. The crystal growth relies on seeking dynamic balance between heat dissipation and accumulation.

Programming hierarchical graphene nanosheets by two-step exfoliation of graphite combined with an adenine-functionalized telechelic polymer in o-dichlorobenzene can achieve highly stable graphene nanosheets with wide-range tunable layer thickness.

In this paper, hierarchical CuO/MnO2 composite hollow nanospheres have been successfully fabricated by water evaporation-induced self-assembly through a redox transformation reaction between Cu2O nanospheres and KMnO4 solution at 120[Formula: see text]C for 6[Formula: see text]h, followed by removing the residual Cu2O cores with ammonia hydroxide solution. The outstanding feature of this method is that the reaction system is in a dynamic environment due to the evaporation of the solvent water, which benefits the self-assembly of nanostructures to form hierarchical structures. Both Kirkendall effect and Ostwald ripening mechanism are suggested to be responsible for the formation of the hierarchical CuO/MnO2 nanocomposites according to the characterization results. The electrochemical properties of the products were studied, and the results show that the hierarchical CuO/MnO2 hollow nanospheres exhibit high capacity and good rate performance (a stable capacity of about 480[Formula: see text]mAh[Formula: see text]g[Formula: see text] after 80 cycles of variable charging rate), which is probably attributed to the hierarchical hollow nanostructures.

In this work, we further developed a new approach for modeling the processes of the self-assembly of complex molecular nanostructures using molecular dynamics methods; in particular, using a molecular dynamics manipulator. Previously, this approach was considered using the example of the self-assembly of a phenylalanine helical nanotube. Now, a new application of the algorithm has been developed for implementing a similar molecular dynamic self-assembly into helical structures of peptide nanotubes (PNTs) based on other peptide molecules—namely diphenylalanine (FF) molecules of different chirality L-FF and D-FF. In this work, helical nanotubes were assembled from linear sequences of FF molecules with these initially different chiralities. The chirality of the obtained nanotubes was calculated by various methods, including calculation by dipole moments. In addition, a statistical analysis of the results obtained was performed. A comparative analysis of the structures of nanotubes was also performed using the method of visual differential analysis. It was found that FF PNTs obtained by the MD self-assembly method form helical nanotubes of different chirality. The regimes that form nanotubes of right chirality D from initial L-FF dipeptides and nanotubes of left chirality L from D-FF dipeptides are revealed. This corresponds to the law of changing the sign of the chirality of molecular helical structures as the level of their hierarchical organization becomes more complicated.

The dynamic combination of aromatics and peptides yields functional supramolecular biopolymers which self-assemble hierarchically and adapt through non-covalent interactions and/or reversible covalent reactions.

A novel biomimetic DNA analogue with fluorescence has been synthesized to generate functional supramolecular architectures. Experimental studies show that triaminopyrimidine nucleoside (2) undergoes a sterically controlled self-assembly into hydrogen-bonded linear tapes and hexameric rosettes. Self-association of the hydrogen-bonded triaminopyrimidine–cyanuric acid complex into elongated, rodlike nanostructures was shown by dynamic light scattering and transmission electron microscopy, suggesting hierarchical formation of higher-order, π-stacked assemblies. The hydrogen-bond self-assembly of the DNA analogue decreased the fluorescence of the nucleosides. This guest-induced fluorescence quenching can be used to develop DNA-hybridization probes. MM+ molecular modelling and semi-empirical molecular orbital PM3 calculations (1) predicted the incorporation of triaminopyrimidine nucleoside into new types of artificial DNA strands and triplex formation with natural, complementary DNA strands containing thymine (1).

Incorporation of peptide or mesogenic units into block copolymers enables hierarchical order, whereby an interplay between microphase separation and peptide secondary structure formation or liquid crystal ordering occurs. This thesis concerns the self-assembly process and dynamics in block copolymers with hierarchical order. The second and third chapters discuss peptide-based poly(γ-benzyl-Lglutamate)-poly(ethylene glycol)-poly(γ-benzyl-L-glutamate) triblock copolymers and side-group liquid crystal polystyrene-poly [2-(((3-cholesteryl)-oxy)carbonyl)decyl methacrylate)] diblock copolymers. In the first case, the morphology was revealed and the peptide secondary structure was probed by a combination of scattering and microscopy techniques.

Développer des études multi-échelles spatiales (nano/méso/micro-macroscopiques) et temporelles est crucial pour comprendre, maîtriser et piloter les relations liant la structure aux propriétés de transport ionique de matériaux fonctionnels hiérarchiquement auto-assemblés. C’est selon ces lignes de force que ce travail exploratoire se positionne pour relever les défis scientifiques associés. Il vise notamment à rassembler des éléments de compréhension pour générer de familles d'électrolytes à conduction (cat/an)ionique ajustables de par leur conception et pouvant être mises en œuvre par des processus robustes d'élaboration qui autoriseront leur intégration dans des dispositifs de conversion et stockage électrochimique de l’énergie plus efficaces. Les familles modèles de la matière molle (fonctionnelle) électrolytique choisies sont les Cristaux Liquides Ioniques Thermotropes (CLITs) qui combinent synergétiquement l’autoassemblage hiérarchique dynamique à travers différentes échelles à des facultés d’autoréparation pour encoder un transport ionique de dimensionnalité (quasi-1D/quasi-2D/3D) contrôlée. L’ingénierie moléculaire, la synthèse et l’étude de familles modèles de ces conducteurs (an/cat)ioniques (A/C)-CLITs stimuli-sensibles sont ainsi présentés et discutés dans ce travail de recherche.L’étude de l’organisation supramoléculaire d’une famille modèle de C-CLITs conducteurs des cations K+ et Na+ décrit i) une mésophase Cubique bicontinue (Cubbi) à symétrie Ia3d monotrope (c’est-à-dire qui se développe seulement lors de la première montée en température) et ii) une mésophase Colonnaire hexagonale (Colhex), sièges respectifs de processus de transport 3D et quasi-1D. Les parties ioniques polaires constituent le cœur des colonnes et les chaînes aliphatiques la périphérie de celles-ci. L’étude expérimentale et la modélisation du confinement des porteurs de charges au sein d’une famille modèle d’A-CLITs C18C18Im+/X- (X- = Br-, I-, N(CN)2-), formant des mésophases Smectiques A interdigitées (SmAd sièges d’un transport ionique anisotrope quasi-2D), révèlent un régime de nanoconfinement des anions soumis à des interactions électrostatiques au sein des sous-couches polaires (épaisseur de ca. 1 nm) de leur organisation lamellaire. L’étude de ces CLITs aborde ainsi l’impact fonctionnel de la mosaïcité, c’est-à-dire de la coexistence de domaines mésomorphes présentant des orientations et tailles différentes sur le transport ionique.Une première description expérimentale directe a permis de décrire le rôle de cette mosaïcité dynamique à la fois i) sur l’organisation à longue distance de domaines mésomorphes et ii) sur le transport ionique à l’échelle méso-/macro-scopique. Au sein des mésophases formées par le C-CLIT conducteur du cation K+, la mésophase Cubbi présente des valeurs de conductivité deux ordres de grandeur plus importantes que celles liées à la mésophase Colhex. La mésophase Cubbi ne nécessitant pas de stratégies spécifiques de gestion des défauts (faible densité de défauts/d’interfaces homophasiques), les sous-domaines polaires peuvent y percoler efficacement selon un mécanisme intrinsèquement 3D. L’ordre à longue distance des domaines dynamiques mésomorphes SmAd de l’A-CLIT C18C18Im+/N(CN)2-, induit par l’application d’un stimulus externe (un champ magnétique de 1 T), se traduit par une augmentation de ca. 1.6x la taille moyenne des domaines mésomorphes (de 92 à 145 nm) à 80°C. Du fait de la réduction du désordre et du nombre d’interfaces homophasiques (pouvant pénaliser le transport des anions), une augmentation naturelle (attendue) des valeurs de conductivités d’un facteur ca. x2.6 (9 à 25 µS·cm-1) est observée.In fine, les CLITs, matériaux électrolytiques 2.0 encodant propriétés de transport ionique et faculté (bio-inspirée) d’auto-assemblage/réparation dynamique, se positionnent comme une classe originale de matériaux fonctionnels stimuli-sensibles pour le stockage et la conversion électrochimique de l’énergie
Developing multi-scale spatial (nano/meso/micro-macroscopic) and temporal studies is crucial to understand, control, and pilot the relationships linking the structure to the ionic transport properties of hierarchically self-assembled functional materials. It is along these research lines that this exploratory work is positioned to meet their associated scientific challenges. It aims in particular to bring together elements of understanding for designing families of electrolytes with tuneable-by-design (cat/an)ionic conductivity levels and that can be implemented by reliable manufacturing processes to authorize their scalable integration into more efficient electrochemical energy conversion and storage devices. The scrutinized model families of soft-matter electrolytes are Thermotropic Ionic Liquid Crystals (TILCs), which synergistically combine dynamic hierarchical self-assembly with self-healing functionalities to encode dimensionality (quasi-1D/ quasi-2D/3D) controlled ionic transport. This research work presents and discusses the molecular engineering, syntheses and detailed studies of these model stimuli-responsive (An/Cat)ionic (A/C)-TILCs conductors.The study of the supramolecular organization of a model family of K+ and Na+ cation-conducting C-TILCs has unravelled i) a monotropic (i.e. which develops only during of the first heating scan) bicontinuous Cubic mesophase (Cubbi) with an Ia3d symmetry and ii) a hexagonal Columnar mesophase (Colhex), encoding 3D and quasi-1D transport processes, respectively. Polar ionic sub-domains are localized at the heart of the columns decorated at their periphery by aliphatic chains. The experimental study and modelling of the confinement of charge carriers within a model family of C18C18Im+/X- (X= Br-, I-, N(CN)2-) A-TILCs forming interdigitated Smectic A mesophases (SmAd are hosting quasi-2D anisotropic ionic transport) reveals a regime of nanoconfinement of anions subjected to electrostatic interactions within the ca. 1 nm-"thick" polar sub-layers within their lamellar organizations. The study of these TILCs thus addresses the functional impact of mosaicity, i.e. how the coexistence of mesomorphic domains presenting different orientations and sizes is impacting ionic transport.A first direct experimental description allows to describe the role of this dynamic mosaicity both i) on the long-range organization of mesomorphic domains and ii) onto ion transport at the meso-/macro-scopic scale. Within mesophases formed by the K+-cation conducting C-TILC, the Cubbi mesophase presents conductivity values two orders of magnitude greater than those associated to the Colhex mesophase. As the Cubbi mesophase does not require specific defect management strategies (low density of defects/homophasic interfaces), it turns out that polar subdomains can thus percolate efficiently according to an intrinsically 3D mechanism. In contrast, the long-range ordering of the (dynamic) SmAd mesomorphic domains of the C18C18Im+/N(CN)2- A-TILC, induced by the application of an external stimulus (here, a magnetic field of 1 T), results in a ca. x1.6 increase (from 92 to 145 nm) of the average size of mesomorphic domains at 80°C. Due to the reduction of the disorder and of the number of homophasic interfaces (which can penalize the transport of anions), a natural (expected) increase in conductivity values by a factor ca. x2.6 (9 to 25 µS·cm-1) is observed.Ultimately, TILCs, i.e. 2.0 electrolytic materials encoding ionic transport properties and (bioinspired) dynamic self-assembly/repairing functionalities, are consisting in an original class of stimuli-sensitive functional materials for the electrochemical conversion and storage of energy

Abstract Cells are assembled from hierarchically organized macromolecules, forming very complex, crowded, integrated, and self-organized networks of cytomatrix components known as protoplasts or cytoplasm. These assembled, ordered biological macromolecules embody historical aspects of cellular organization. Inherited patterns of structural templating derive from the very first ancient cells as initial forms of templated self-assembly, thereafter continuously reiterating through cell divisions. Clusters of intracellular ordered macromolecules form nano-protoplast units supporting nano-intentionality that represents a kind of subcellular proto-mind. In the evolution of first proto-cells, semi-independent units could have acted as a coacervate stage (small liquid droplets of two immiscible liquid phases) within cellular evolution. Moveable electrons and charged molecules generate a redox code which, together with the bioelectric code, comprise the bioelectricity-based cellular senomic fields. Excitable plasma membrane-generated bioelectric fields and associated dynamic actin filaments are closely integrated via endocytic vesicle recycling, and generate systemic long-distance signals known as bioelectrical action potentials.