Formation Of Supramolecular Structures Research Articles

Aromatic Difluoroboron β-Ketoiminate Complexes: Effect of Substituents on Mechanofluorochromism and Polymorphic Behavior.

Aromatic difluoroboron β-ketoiminate complexes (ketimBF2) are structural nitrogen-containing analogues of aromatic difluoroboron β-diketonates (diketBF2). Aggregation-induced emission (AIE) and polymorphic behavior allow ketimBF2 to exhibit mechanofluorochromic (MFC) properties. A detailed comparative study of the luminescence of a wide range of ketimBF2 with H- and CH3-substituents of nitrogen atom and diketBF2 with various substituents of the chelate ring (methyl, phenyl, toluoyl, anisoyl, biphenyl, naphthyl, anthracyl) in the solid state was carried out. As a result, regularities of the influence of substituents on the luminescent and MFC properties for 21 dyes have been established. Replacing one oxygen atom in diketBF2 with nitrogen atom in the chelate ring (H-substituted ketimBF2) changes the nature of the molecular stacking in crystals, which is manifested in different MFC properties. The introduction of a methyl group into the chelate ring (CH3-substituted ketimBF2) induces steric hindrance, which prevents the efficient formation of supramolecular structures and, consequently, leads to the shortest-wavelength monomeric emission in the solid state in comparison with oxygen and H-substituted nitrogen analogues. Methoxy derivative of H-substituted ketimBF2 exhibits non-reversible fluorochromic switching after annealing and can be used as temperature indicator to control unauthorized heating of temperature-sensitive substances during transportation and storage.

Construction of Cobalt-Containing Polyoxovanadate-Based Inorganic-Organic Hybrids as Heterogeneous Catalysts for the Selective Oxidation of Sulfides.

In order to develop efficient catalysts for the selective oxidation of sulfides, in this work, two polyoxovanadate-based inorganic-organic hybrids, [Co(H2O)3(3-bpfb)0.5(V2O6)]·(3-bpfb)0.5 (1) and [Co(H2O)2(4-bpfb)0.5(V2O6)] (2) [3-bpfb = N, N'-bis(3-pyridylformamide)-1, 4-benzenediamine, 4-bpfb = N, N'-bis(4-pyridylformamide)-1, 4-benzenediamine], were isolated under hydrothermal conditions. The structures of 1 and 2 embodied two kinds of different cobalt-containing polyoxovanadate-based inorganic chains. Compound 1 contained a one-dimensional inorganic zigzag chain created by the aggregation of {V2O6} clusters with each other, on which Co (II) ions were fixed. But it was an inorganic dimeric chain constructed from two linear {V2O6} cluster-based chains gathered by Co (II) ions in 2. The 3-bpfb and 4-bpfb ligands, as the bidentate linkers, coordinated with two Co (II) ions from adjacent chains to organize them into two-dimensional layers. The hydrogen bonds made important contributions to the formation of supramolecular structures of the two compounds. The two compounds served as heterogeneous catalysts and exhibited efficient activity for the selective oxidation of sulfide to sulfoxide and could be reused at least six times without loss of catalytic activity and stability.

Close Packing in Trans Conformers Promotes the Formation of Supramolecular Structures with C1 Symmetry.

Assemblies with C1 symmetry exhibit important applications in many fields such as enantioselective catalysis. However, their formation is challenging due to their large entropic disadvantage, and molecular information on their formation dynamics is limited because of the lack of effective characterization techniques. Here, using achiral amphiphilic molecules such as N-oleoyl ethanolamide (OEA) and its analogues as modeling assembly units, we demonstrated that the sss polarization signals, generated by femtosecond sum frequency generation vibrational spectroscopy (SFG-VS), provide a powerful tool to monitor the formation dynamics of the C1 symmetric supramolecular structures at the interfaces. The trans conformation of the assembly units can provide strong π-π interactions and thus produce enough enthalpy to drive the formation of C1 symmetric supramolecular structures. However, the cis conformation impedes the assembly of C1 symmetric structures and cannot generate sss and chiral polarization SFG signals. These findings may aid in rationally constructing ordered and functional superstructures and understanding the mechanism of chirality formation.

Pyrobacteriopheophorbide-a derivatives possessing various hydrophilic esterifying groups at the C17-propionate residues for photodynamic therapy.

Aiming at the application to photodynamic therapy, natural bacteriochlorophyll-a was converted to chemically stable free-base derivatives possessing different kinds of hydrophilic C17-propionate residues. These semi-synthetic bacteriochlorins were found to have self-assembling ability in an aqueous environment and formed stable J-type aggregates in a cell culture medium containing 0.2% DMSO. The electronic absorption spectra of all the sensitizers showed Qy absorption maxima at 754 nm in DMSO as their monomeric states, while a drastic shift of the red-most bands to ca. 880 nm was observed in the aqueous medium. The circular dichroism spectra in the medium showed much intense signals compared to those measured in DMSO, supporting the formation of well-ordered supramolecular structures. By introducing hydrophilic side chains, the bacteriochlorin sensitizers could be dispersed in the aqueous medium as their J-aggregates without the use of any surfactants. Cellular uptake efficiencies as well as photodynamic activities were evaluated using human cervical adenocarcinoma HeLa cells. Among the 11 photosensitizers investigated, the best result was obtained for a charged derivative possessing trimethylammonium terminal (17-CH2CH2COOCH2CH2N+(CH3)3I-) and photocytotoxicity of EC50 = 0.09 μM was achieved by far-red light illumination of 35 J/cm2 from an LED panel (730 nm).

Understanding self-assembly mechanisms in supramolecular fiber materials through multiscale simulation

Supramolecular materials, assembled through non-covalent interactions, have emerged as a versatile and tunable platform for the development of advanced functional materials with tailored properties and applications. However, comprehending the interactions between self-assembled monomers at the molecular level, particularly when organized into fibrous structures, remains a considerable challenge. In this study, we discovered that solely relying on all-atomistic molecular dynamics simulations is insufficient to reproduce the self-assembly process and the formation of fibrous supramolecular structures. Thus, we combined dissipative particle dynamics (DPD) and all-atomistic molecular dynamic simulations to accurately simulate the fibrous supramolecular structures previously observed in experiments. These structures consist of benzene-1,3,5-tricarboxamide (BTA-EG4), 2-ureido-4 [1H]-pyrimidinone-ethylene glycol molecules (UPy-EG), and glycyrrhizic acid (GA) molecules, each exhibiting varying degrees of topology and planarity. Our analyses focused on elucidating the stability mechanism of these fibrous structures. Notably, we found that hydrogen bonds, π-π interactions and nonbonded interactions, especially Coulomb interaction between monomers and water molecules, play pivotal roles in stabilizing these fibrous structures. This study significantly contributes to our understanding of self-assembly mechanism in supramolecular fiber materials and opens avenues for extending this knowledge to other fibrous supramolecular architectures.

Synthesis, Crystal Growth, Structural Characterization, Supramolecular Chemistry, and Theoretical Calculations of Methylenium Salts of Benzenesulfonates

AbstractThe current investigation describes the synthesis of four novel methylene blue (MB) salts of benzene sulfonate derivatives, featuring bulky anionic groups. The process involves treating chloride salt of MB with sodium salts of 4‐aminobenzene sulfonate, 4‐styrenebenzene sulfonate, 3,7‐naphthalene disulfonate, and anthraquinone‐1,5‐naphthalene disulfonate to substitute the chloride ion with benzoate sulfonate anion in MB‐chloride. The synthesis includes quaternizing MB‐chloride with the corresponding benzene sulfonate in minimal aqueous solvent to promote precipitation. The resultant precipitates were subsequently dissolved in an appropriate solvent to enable the crystallization of the ultimate product. The dissolution occurs either at ambient temperature or with heat. The crystals of the resultant salts were characterized using various analytical techniques like UV‐visible, and FT‐IR spectroscopy, TGA, single crystal X‐ray diffraction and powder X‐ray diffraction analysis. The UV‐visible spectroscopic results, frontier molecular orbital, density of states, molecular electrostatic potentials, and HOMO‐LUMO energy gaps were estimated by DFT. Structural analysis revealed that supramolecular structure of compounds achieved stabilization through electrostatic interactions, a diverse range of both conventional and non‐conventional hydrogen bonds, π–π stacking interactions, and other short‐range interactions. The investigation delves into intricate details and offers a thorough discussion of the fundamental principles that contribute to the formation and stabilization of supramolecular structures.

In situ captured antibacterial action of membrane-incising peptide lamellae

Developing unique mechanisms of action are essential to combat the growing issue of antimicrobial resistance. Supramolecular assemblies combining the improved biostability of non-natural compounds with the complex membrane-attacking mechanisms of natural peptides are promising alternatives to conventional antibiotics. However, for such compounds the direct visual insight on antibacterial action is still lacking. Here we employ a design strategy focusing on an inducible assembly mechanism and utilized electron microscopy (EM) to follow the formation of supramolecular structures of lysine-rich heterochiral β3-peptides, termed lamellin-2K and lamellin-3K, triggered by bacterial cell surface lipopolysaccharides. Combined molecular dynamics simulations, EM and bacterial assays confirmed that the phosphate-induced conformational change on these lamellins led to the formation of striped lamellae capable of incising the cell envelope of Gram-negative bacteria thereby exerting antibacterial activity. Our findings also provide a mechanistic link for membrane-targeting agents depicting the antibiotic mechanism derived from the in-situ formation of active supramolecules.

A Halogen-Bond-Driven Artificial Chloride-Selective Channel Constructed from 5-Iodoisophthalamide-based Molecules.

Despite considerable emphasis on advancing artificial ion channels, progress is constrained by the limited availability of small molecules with the necessary attributes of self-assembly and ion selectivity. In this study, a library of small molecules based on 5-haloisophthalamide and a non-halogenated isophthalamide were examined for their ion transport properties across the lipid bilayer membranes, and the finding demonstrates that the di-hexyl-substituted 5-iodoisophthalamide derivative exhibits the highest level of activity. Furthermore, it was established that the highest active compound facilitates the selective chloride transport that occurs via an antiport-mediated mechanism. The crystal structure of the compound unveils a distinctive self-assembly of molecules, forming a zig-zag channel pore that is well-suited for the permeation of anions. Planar bilayer conductance measurements proved the formation of chloride selective channels. A molecular dynamics simulation study, relying on the self-assembled component derived from the crystal structure, affirmed the paramount significance of intermolecular hydrogen bonding in the formation of supramolecular barrel-rosette structures that span the bilayer. Furthermore, it was demonstrated that the transport of chloride across the lipid bilayer membrane is facilitated by the synergistic effects of halogen bonding and hydrogen bonding within the channel.

Double hydrogen bonding-induced compact H-type π-π stacking enhancing rapid carrier transfer in perylene diimide supramolecules achieving high oxygen evolution performance

Perylene diimides (PDI) are widely used in photocatalytic oxygen evolution due to their deep valence band potentials. Here, we report the synthesis of a unique supramolecular photocatalyst (designated s-PDI-P1) by introducing hydroxyl and carboxyl groups at the imide position of PDI. This modification allows the formation of intermolecular double hydrogen bond structures between the hydroxyl groups, oxygen atoms on the perylene cores and the carboxyl groups. The resulting double hydrogen bonding structures reduce lateral slip and promote the formation of supramolecular structures with H-type π-π stacking. In addition, the intermolecular hydrogen bonding interactions between the hydroxyl groups and the oxygen atoms on the perylene cores bring the PDI molecules closer together, enhancing the conjugation of the PDI supramolecules and facilitating the formation of ultrathin nanosheet-like structures. In this study, we successfully constructed ultrathin nanosheets of the supramolecular photocatalyst s-PDI-P1 with a compact H-type π-π stacking structure, which exhibited enhanced charge transfer capability, shorter charge migration distance, and achieved a high photocatalytic oxygen evolution rate of 3.23 mmolg-1h−1. These results highlight the potential of intermolecular double hydrogen bond structures to improve the separation and migration driving force of photogenerated charges, thus providing a novel design strategy for organic photocatalysts.

APPLICATION OF VISCOELASTIC SYSTEMS IN OIL PRODUCTION INTENSIFICATION PROCESSES

This paper provides an overview of viscoelastic behavior and the use of viscoelastic fluids (VBLs) in various oil production intensification processes. The first part provides basic models describing viscoelastic behavior and corresponding equations of state. Describes the method of testing under the action of harmonic vibrations (method of dynamic tests), possible options for its implementation and the determined rheological properties of the viscoelastic sample. To interpret the results of dynamic tests, a complex module is most often introduced, which consists of two components — the elastic modulus (G’) and the loss modulus (G’’). These dynamic modules and their relationship describe the behavior of the viscoelastic sample. It is shown that with respect to modules, it is possible to conclude on the type of sample - viscoelastic liquid or viscoelastic body. It is also noted that dynamic tests should be carried out in the area of low amplitudes of oscillating loads, in which the rheological properties do not depend on the applied stress or strain. The second part provides examples of viscoelastic systems used in operations such as water flow isolation, hydraulic fracturing, and modified acid treatments. The most common viscoelastic systems used in various technologies are solutions of surfactants and polymers of different structures. It is noted that in order to obtain a viscoelastic gel, polymer solutions are used with a crosslinker, while the rheological properties of surfactant solutions are controlled by external factors — pH, temperature, water mineralization. Viscoelastic surfactant solutions have an advantage over polymer solutions ‑ they are able to recover their properties after mechanical or thermal exposure due to the formation of supramolecular structures as a result of selforganization of surfactant molecules. The surfactant-based HLT property of reversibly collapsing and recovering is used, in particular, to reduce pressure losses to overcome friction. In flow-deflecting acid compositions, viscoelastic surfactants are mainly used, the most common of which are given in the second part of the article.

Antioxidant functions of caffeic acid and allylpyrocatechol in supramolecular oxidation of bulk oil: Role of acidic group in the mass transfer network.

Antioxidant activities of caffeic acid (CFA) and allylpyrocatechol (APC) were measured in bulk oil and in emulsion (oil/water) to evaluate the effects of the carboxylic group on the antioxidant function. As an emulsifier, polyglycerol polyricinoleate (PGPR) was added to the bulk oil to assist in promoting the interfacial activity of antioxidants. The antioxidant activity of CFA in the bulk oil was 186.5% higher than that of APC. In the emulsion, however, APC showed 150.3% higher antioxidant activity. PGPR showed a synergistic effect on CFA (>31%) and APC (<18%) which arose from organizing and supporting the formation of oxidation-microreactors. Water molecules were generated as an oxidation byproduct throughout the oxidation course, and they facilitated the formation of supramolecular structures. Polar imbalance became more prominent in the molecular structure of CFA, due to the presence of the carboxyl group, thereby increasing the effective collisions between the antioxidant molecules and free radicals.

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.

Noncovalent Dualism in Perylene-Diimide-Based Keggin Anion Complexes: Theoretical and Experimental studies.

We report the synthesis and comprehensive characterization of organic-inorganic hybrid salts formed by bis-cationic N,N'-bis(2-(trimethylammonium)ethylene)perylene-3,4,9,10-tetracarboxylic acid bisimide (PTCD2+) and Keggin-type [XW12O40]n- (X = Si, n = 4; X = P, n = 3) polyoxometalates. (PTCD)3[PW12O40]2·3DMSO·2H2O (2) and (PTCD)2[SiW12O40]·DMSO·2H2O (3) were structurally characterized by single crystal X-ray diffraction. The cations in both structures exhibited infinite chainlike arrangements through π-π interactions, contrasting with the previously reported cation-anion stacking observed in naphthalene diimide derivatives. A detailed theoretical study employing topological analysis of the electron density distribution within the quantum theory of atoms in molecules approach provided further insights into this structural dualism. Atomic force microscopy analyses revealed the formation of self-assembled supramolecular structures on graphite from molecular monolayers (3 nm of thick) to submicrometer aggregates for 2. Hyperspectral Raman spectroscopy imaging revealed that such heterostructures are likely formed by an enhanced π-π interactions. Both complexes demonstrated interesting electrochemical behavior, photoluminescence and X-ray-induced luminescence. Electron spin resonance analysis confirmed charge separation in both compounds, with enhanced efficiency observed in compound 2. Our findings of these perylene-based organic-inorganic hybrid salts offer the potential for their application in optoelectronic devices and functional materials.

Cholesterol-Conjugated Supramolecular Multimeric siRNAs: Effect of siRNA Length on Accumulation and Silencing In Vitro and In Vivo.

Conjugation of small interfering RNA (siRNA) with lipophilic molecules is one of the most promising approaches for delivering siRNA in vivo. The rate of molecular weight-dependent siRNA renal clearance is critical for the efficiency of this process. In this study, we prepared cholesterol-containing supramolecular complexes containing from three to eight antisense strands and examined their accumulation and silencing activity in vitro and in vivo. We have shown for the first time that such complexes with 2'F, 2'OMe, and LNA modifications exhibit interfering activity both in carrier-mediated and carrier-free modes. Silencing data from a xenograft tumor model show that 4 days after intravenous injection of cholesterol-containing monomers and supramolecular trimers, the levels of MDR1 mRNA in the tumor decreased by 85% and 68%, respectively. The in vivo accumulation data demonstrated that the formation of supramolecular structures with three or four antisense strands enhanced their accumulation in the liver. After addition of two PS modifications at the ends of antisense strands, 47% and 67% reductions of Ttr mRNA levels in the liver tissue were detected 7 days after administration of monomers and supramolecular trimers, respectively. Thus, we have obtained a new type of RNAi inducer that is convenient for synthesis and provides opportunities for modifications.

Novel polymeric organic gelator as lost circulation material for oil-based drilling fluids

With the exploitation of unconventional oil and gas resources towards deep and ultra-deep formations, oil-based drilling fluids (OBDFs) with white oil as a base oil have been increasingly employed in China to achieve safe, efficient, and fast drilling operations. However, due to the lack of effective lost circulation material (LCM), drilling time and drilling fluids are severely delayed and extra consumed, respectively. Herein, we innovatively propose and successfully develop a polymeric organic gelator using an emulsifier-free emulsion polymerization method and find that it achieves remarkable plugging ability in OBDF, superior to commercial LCMs, including asphalt, fine calcium carbonate, elastic graphite, and rubber particles. In detail, SMHDV with a branched C8 pendant group, benzene ring, isopropyl, and acetate groups is homogeneously dispersed in OBDF after hot rolling and capable of blocking permeable porous formations, resulting in a reduction of the cumulative filtration by 68 % at a concentration as low as 1 wt%. When added at a high concentration above 10 wt%, SMHDV turned into an organogel which can block cracks and prevent severe lost circulations together with other bridging materials. Furthermore, SMHDV maintains considerable plugging capacity in a wide temperature range of 80–150 °C, which meets most requirements of oil wells. The superior performance is attributed to the formation of supramolecular network structure in white oil due to the self-assembly behavior, which originated from the appropriate hierarchical polarities. In addition, the material can maintain stable rheological properties after hot rolling, improving the electrical stability of the drilling fluid. It is expected to form a set of scientific and efficient OBDF plugging technology to solve the leakage problems encountered during drilling.

In Ukrainian

Regulation of enterohepatic circulation of bile acids in human body is actual task to overcome cardiovascular diseases. The aim of this work was to create biocompatible sorbents with improved sorption ability in relation to bile acids. Mesoporous organosilicas of MCM‑41 type with chemically grafted 3‑aminopropyl and steroid groups were obtained by sol‑gel condensation of tetraethyl orthosilicate and functional silanes in the presence of template cetyltrimethylammonium bromide. Porous structure of synthesized organosilicas was characterized by low‑temperature nitrogen adsorption–desorption and X‑ray diffraction analysis. Formation of typical for MCM‑41 hexagonal arrangement of cylindrical mesopores was confirmed. Structural parameters of synthesized silica materials were calculated. The influence of surface steroid groups on sorption ability of organosilicas was studied on example of bile salts (sodium cholate and taurocholate) in dependence of duration of contact, acidity of medium, and equilibrium concentration. Analysis of kinetic parameters of sorption estimated by Lagergren and Ho-McKey models confirms the proceeding of pseudo-second order process. The most effective sorption of sodium cholate and taurocholate was observed at pH ~ 5 and pH ~ 2, respectively, where the ovterlapping of pH regions of 3‑aminopropyl groups protonation and bile acids dissociation takes place. Analysis of experimentally obtained isotherms by use of Freundlich, Redlich‑Peterson, and BET models was carried out. It has been found that protonated amino groups are the main sorption centers of bile acids protolytic forms by synthesized aminosilica in pH range from 1 to 8. Introduction of steroid groups in surface layer at sol-gel synthesis leads to the increase of bile salts sorption due to the cooperative interactions with formation of supramolecular structures in the surface layer of organosilica. Obtained results prove prospects of usage of organosilica sorbents with surface steroid groups for regulation of bile acids content in human body.

Leveraging the relative strengths of hydrogen and halogen bonds to control nanostructures

Halogen bonds (XBs) and hydrogen bonds (HBs) present a straightforward yet effective strategy for controlling nanostructure morphology. The self-assembled nanopattern, modulated by the relative strengths of XBs and HBs, has rarely been studied using analogous molecules. This research systematically evaluates the relationship between the strengths of Br···O hetero-XBs and N···H HBs in directing the formation of 2D supramolecular co-assembled structures. In this work, tetracarboxylic acid (PEDA), featuring four carboxyl substitutions, forms a stable hydrogen-bonded Rosette network that can function as a template for trapping guest molecules of complementary shape and size. The star-shaped bromine-substituted 1,3,5-tris(3,5-dibromophenyl)benzene (TDB) and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT) serve as XB donor and HB acceptor respectively, thus capable of acting as guest molecules co-assembly with the PEDA at the heptanoic acid/HOPG interface. Bimolecular co-assembly patterns resulting from these combinations were investigated using scanning tunneling microscopy (STM) and supported by density functional theory (DFT) calculations. The findings indicate that TDB molecules can be accommodated within the triangular cavities of the Rosette network due to the weaker Br···O hetero-XB. Concurrently, the similar star-shaped TPT can co-assemble with PEDA to form an acid–pyridine–acid Ladder-like network based on stronger N···H HBs. Therefore, Br···O hetero-XBs seemingly play no decisive role in the coassembly process of PEDA and TDB. Conversely, N···H HBs hold evident significance in the coassembly of PEDA and TPT. This work potentially holds substantial value for the future design and customization of devices employing the interplay of XBs and HBs.

Synergistic effect of a fluorinated azobenzene for transforming spherical micelles into thread-like micelles with a disk-like cross-section

The free energy in solutions of amphiphilic molecules leads to the formation of supramolecular structures, often making spherical aggregates, worm-like micelles, vesicles, and lamellae. In this work, we add a fluorinated azobenzene, 4-(4-trifluoromethoxy phenyl azo) phenol (Azo-3F) to a solution mainly made of spherical and rodlike micelles of CetylTrimethylAmmonium Bromide (CTAB) and sodium salicylate (NaSal). These structures transform to disk-like micelles, which concatenate through hydrogen bridges to form long thread-like structures highly similar to worm-like micelle structures. This conclusion was reached after observing that NMR results suggest the formation of aggregates in solution with Azo-3F molecules inside them. Viscosity increases by three orders of magnitude at low shear rates when Azo-3F is added, and it shear-thins as the shear rate increases. The viscoelastic spectra show that the fluid changes from viscous to viscoelastic. Cole-Cole plots follow semicircles, typical of Maxwellian behavior below ∼ 35 °C. Cryo-TEM micrographs of the solution with Azo-3F show giant thread-like structures, and cross-sectional analysis of SAXS and WAXS profiles predict oblate ellipsoidal structures. In addition, MD simulations show that the disk-like micelles interact mainly through hydrogen bonds and electrostatics, forming micellar strings. These strings behave similarly to worm-like micelles, explaining why the solution behaves as a Maxwellian fluid at relatively low temperatures. Consequently, when some specific molecules are introduced in supramolecular structures, such as a spherical micelle, they can be transformed into disk-like micelles that assemble into thread-like micelles.

Features of Obtaining and Properties of Fulvic Acid from the Peat of Nizhny Novgorod Region

Properties of fulvic acid (FA) extracted from the peat of the Nizhny Novgorod region of Russia by ultrasonic extraction with alkaline or ethanol solutions and further purification were studied in the paper. The purification of FA by the Lamar method was shown to possibly lead to the formation of FA polymorphs of the same composition but different structure (IR, solid-state 13С NMR, fluorescence, UV, energy-dispersive X-ray spectroscopy, SEM and optical microscopy, concentration of carboxyl and phenol groups). Aggregation of FA polymorphs in water led to the formation of nanoparticles with the average size of 8–10 nm and the zeta potential of –22 to –27 mV. The formation and properties of polymorphic supramolecular structures are greatly influenced by the drying mode. The solubility of the two FA polymorphs varied from freely soluble (3.3 mL of water per gram) after the FA solution freeze-drying to soluble (12 mL of water per gram) after the FA solution vacuum drying. The FA sample extracted by ethanol ultrasonic extraction from the peat, followed by convection drying, had a solubility of 666.7 mL of water per gram (Slightly soluble), a zeta potential of -6 mV, and a particle size of 15–20 nm.

Self-assembly mechanisms of cyclic peptide nanotubes in the presence of water molecules; study of hydrogen bonding, aggregation and Mir-210 gene delivery

Self-assembling cyclic peptides are a type of bioinspired supramolecular building blocks. They have the ability to stack together, forming supramolecular cyclic peptide nanotubes. This stacking is driven by β-sheet-like hydrogen bonding. In general, a single hydrogen bond is not strong enough to form ordered supramolecular structures. However, when multiple hydrogen bonds are aligned and built into arrays, they exhibit increased strength and directionality. This enables the formation of well-defined and organized supramolecular structures. The continuous advancements in understanding cyclic peptides and their unique properties open new doors for their application in functional materials, ion transport channels, and drug delivery systems, including gene therapy. When it comes to gene therapy, which involves introducing genetic material into cells to treat or prevent diseases, delivery systems play a crucial role. The use of cyclic peptides in these delivery systems can enhance the stability, specificity, and cellular uptake of the therapeutic cargo, thereby improving the overall success of gene therapy treatments. Hydrogen bond formation makes the cyclic peptide nanotube more stable and has an important role in its formation. The number of hydrogen bonds between cyclic peptides is 117 on average during the simulation time of 200 ns. Also, hydrogen bonds formation between Mir-210 and cyclic peptide nanotube during the simulation time observed which is an average of 17 bonds.