Search Results (297)

A brief summary of the effect of nonspecific interactions upon chemical equilibria in solutions containing a high total concentration of macromolecular solutes comparable to that found in biological fluid media is presented. Analyses of experimental measurements permitting relatively direct quantitation of the free energy of nonspecific intermolecular interaction in solutions of one or two macrosolutes are described, and a table listing published experimental studies of both homo- and hetero-interactions is provided. Methods for calculating the free energy of nonspecific interaction via theory and computer simulation are described. Recommendations for further progress in both measurement and calculation of interaction free energies are presented. Full article

HSP110 is a ubiquitous chaperone contributing to proteostasis. It has a disaggregation activity and can refold denatured proteins. It can regulate fundamental signaling pathways involved in oncogenesis, such as Wnt/β-catenin, NF-κB and STAT3 signaling pathways. In gastric and colorectal cancer, HSP110 has been detected in the nucleus, and nuclear expression has been associated with the resistance of cells to 5-FU chemotherapy. Nuclear translocation of HSP110 is promoted by the exposure of cells to DNA-damaging agents. In a previous work, we demonstrated that nuclear HSP110 participates in the NHEJ DNA repair pathway by facilitating the recruitment of DNA-PKcs to Ku70/80 heterodimers at the site of DNA double-strand breaks. In the present work, analysis of HSP110s’ nuclear interactome revealed an enrichment of components from SWI/SNF chromatin remodeling complexes. We demonstrate that HSP110 is strongly associated with chromatin in temozolomide- and oxaliplatin-treated cells and directly interacts with the core subunit SMARCC2, thereby facilitating the assembly of SWI/SNF complexes. This work expands upon the role of HSP110, which regulates not only proteostasis but also the assembly of critical nuclear macromolecular complexes involved in the adaptive stress response. Full article

The development of eco-friendly surfactants is pivotal for enhanced oil recovery (EOR). In this study, a novel lignin-derived zwitterionic surfactant (DMS) was synthesized through a two-step chemical process involving esterification and free radical polymerization, utilizing renewable alkali lignin, maleic anhydride, dimethylamino propyl methacrylamide (DMAPMA), and sulfobetaine methacrylate (SBMA) as precursors. Comprehensive characterization via ¹H NMR, FTIR, and XPS validated the successful integration of amphiphilic functionalities. Hydrophilic–lipophilic balance (HLB) analysis showed a strong tendency to form stable oil-in-water (O/W) emulsions. The experimental results showed a remarkable 91.6% viscosity reduction in Xinjiang heavy crude oil emulsions at an optimum dosage of 1000 mg/L. Notably, DMS retained an 84.8% viscosity reduction efficiency under hypersaline conditions (total dissolved solids, TDS = 200,460 mg/L), demonstrating exceptional salt tolerance. Mechanistic insights derived from zeta potential measurements and molecular dynamics simulations revealed dual functionalities: interfacial modification by DMS-induced O/W phase inversion and electrostatic repulsion (zeta potential: −30.89 mV) stabilized the emulsion while disrupting π–π interactions between asphaltenes and resins, thereby mitigating macromolecular aggregation in the oil phase. As a green, bio-based viscosity suppressor, DMS exhibits significant potential for heavy oil recovery in high-salinity reservoirs, addressing the persistent challenge of salinity-induced inefficacy in conventional chemical solutions and offering a sustainable pathway for enhanced oil recovery. Full article

Recent advances in molecular dynamics (MD) simulations and the introduction of artificial intelligence (AI) have resulted in a significant increase in accuracy for structure prediction. However, the cell is a highly crowded environment consisting of various macromolecules, such as proteins and nucleic acids. The macromolecular crowding and solution conditions, such as temperature, ion concentration, and the presence of crowders, significantly influence the molecular interactions between and structural changes in proteins and nucleic acids. In this study, we investigate the presence of crowders and their effect on the melting of DNA molecules by analyzing melting profiles of short and long heterogeneous DNA duplexes. In particular, we examine how multiple inert crowders, randomly distributed along long DNA chains, influence DNA melting. We find that the presence of crowders stabilizes double-stranded DNA (dsDNA), with this effect being more pronounced in short DNA duplexes. These findings complement in vitro observations and improve our understanding of dsDNA in cell-like environments. Full article

Thermosensitive hydrogel, as a smart polymer material, showed great potential for application in the field of wound repair due to its unique external temperature responsiveness and excellent biocompatibility. Chitosan, a natural macromolecular polysaccharide derived from the deacetylation of chitin, possessed not only strong interactions with biomolecules such as DNA, proteins, and lipids, but also unique biocompatibility and degradability. Chitosan-based thermosensitive hydrogels, prepared by compounding chitosan with surfactants, underwent sol–gel phase transitions at varying external temperatures, which provided an ideal healing environment for wounds. This comprehensive review was initiated by elucidating the sol–gel phase transformation mechanism underlying thermosensitive hydrogels and the intricate process of wound repair. In addition, this review provided a detailed overview of the prevalent types of chitosan-based thermosensitive hydrogels, highlighting their unique characteristics and applications in different types of wound repair. Finally, the challenges and development directions of chitosan-based thermosensitive hydrogels in wound repair were discussed, aiming to provide theoretical support and practical guidance for their future applications in wound healing. Full article

Composite catalysts combining absorbers and active metal hold significant potential for improving the efficiency of biomass microwave-assisted pyrolysis (MAP). Compatibility optimization of composite catalysts can be facilitated through comparative analysis for the influential mechanisms of absorbers and catalysts. Therefore, decoupling experiments about the MAP of Sargassum and calculations based on density functional theory (DFT) were conducted in this research, to investigate the influential mechanisms of absorbers and active metal. The results show the introduction of both the absorbers (SiC) and active metal (MgO) increase the yields of high-value components, such as hydrogen and hydrocarbons. However, their influential mechanisms are different. The introduction of SiC enhances the heating rate within the reaction zone, shortening the duration of MAP and inhibiting the condensation of bio-oil and the interaction between bio-oil and bio-char, and thereby increasing the bio-oil yield by 4%. The introduction of MgO lowers the energy barriers for macromolecular decomposition and gas generation, promoting the decomposition of bio-char and bio-oil, and thus leading to a 12% increase in the yield of bio-gas. This research conclusion provides a theoretical basis for the optimization and design of composite catalysts. Full article

This study investigates the stability behavior of blends composed of ethylene-propylene-diene monomer (EPDM) and styrene-butadiene-styrene (SBS), focusing on the effects of γ-irradiation on these materials. FTIR, CL, and DSC analysis indicate that blends with more than 50% SBS demonstrate remarkable resistance to significant radiation doses. This study highlights that at increased γ-irradiation doses, specifically 100 and 150 kGy, structural changes in the polystyrene aromatic rings are detected, providing insights into the modifications induced by radiation exposure. Among the tested formulations, the blend containing 75% SBS demonstrated the best performance against γ-irradiation, showcasing superior mechanical and structural resistance to radiation-induced degradation. The results indicate that γ-irradiation leads to managed degradation within the SBS/EPDM mixtures: while EPDM experiences increased crosslinking, SBS proves resilient against crosslinking, thus bolstering the stability of EPDM under irradiation scenarios. Additionally, thermal analysis underlines the beneficial role of SBS by showing enhanced thermal stability in SBS-rich samples (SBS content higher than 50%) experiencing reduced thermal degradation through repeated heating cycles. This outcome suggests that the inclusion of SBS effectively reduces crosslinking and chain scission impacts, thereby enhancing consistency in thermal properties over multiple cycles. Full article

The investigation of structure–function relationships in enzyme polysaccharide complexes provides a theoretical foundation for modulating enzyme properties and expanding their industrial applications. In this study, the interaction of cysteine proteases—bromelain, ficin, and papain—with a grafted chitosan–poly(N-vinylpyrrolidone) copolymers, Cs-g-PVP, was examined, and its effect on the catalytic and stability properties of the enzymes was assessed. Molecular docking and Fourier-transform infrared spectroscopy were used to analyze the topology of the resulting complexes and identify macromolecular fragments involved in binding. Based on the obtained results, it was hypothesized that complex formation would lead to a slight reduction in the catalytic activity of cysteine proteases. In vitro studies of the complexes confirmed this hypothesis, showing that the enzymes retained more than 63% of their proteolytic activity while their half-inactivation time during storage increased by up to ~12-fold. The investigated Cs-g-PVP copolymers demonstrated high efficiency as supports for the studied enzymes, capable of retaining up to 100% of the added enzymes. Full article

In this work, using small-angle X-ray scattering from synchrotron radiation, the macromolecular structure of chitosan and gelatin polyelectrolytes and their mixtures at various pH values and ratios was studied to determine the size and shape of primary supramolecular (bio)PEC. Analysis of the scattering profiles of the initial solutions of chitosan and gelatin with the building of the pair distance function showed the formation of single-modal distributions with a maximum molecular size of 46 and 32.2 nm, respectively. Ab initio reconstruction of the macromolecule’s shape showed the formation of objects shaped like an oblate spheroid. In mixtures of chitosan and gelatin at a pH below the isoelectric point, it was found that the scattering structures correspond to the initial biopolymers. However, it is observed that values of the aspect ratio at a ratio above 1:10 gradually increase, which indicates a slight elongation of the average particle and indirectly indicates the formation of dissipative structures of (bio)PEC. In mixtures at a pH above the isoelectric point, it was shown that at ratios above 1:5, the formation of primary supramolecular complexes is observed, which is accompanied by an increase in zero-scattering intensity by about three times, maximum molecular size by two to two-and-a-half times relative to the initial polymers, and the formation of elongated structures corresponding to the cylinder (swollen spiral). It may be a consequence of the increased efficiency of the polyelectrolyte associative interaction between chitosan and gelatin. Full article

Hydraulic fracturing is an effective method for enhancing coalbed methane (CBM) recovery. The injected fluids affect the chemical and physical structures of coal, resulting in diverse stimulation effects. While most current research primarily focuses on alterations in pore-fracture structures, few studies have examined or compared the changes in chemical structures during the fracturing process. This study presents a comparative analysis of the effects of five types of pre-fracturing fluids—slick water, acid solutions, and oxidant solutions—on coal, with the aim of identifying the similarities and differences in how these fluids modify the chemical structure of coal. The results indicate that, after being treated by five pre-fracturing fluids, the aromaticity index (I) increased, and the degree of aromatic condensation polymerization (DOC) decreased. The length of the aliphatic chain (L) increased after being treated by PAM but decreased after being treated by acids and oxidizers. Additionally, the graphitization (g) of all coal samples increased. Among the treatments, the combined acid system of hydrochloric acid (HCl) and hydrofluoric acid (HF) demonstrated a more pronounced effect on enhancing aromaticity and graphitization of the microcrystalline structure compared to HCl alone. Sodium hypochlorite (NaClO) had the most significant impact on the ordering of the macromolecular structure, while hydrogen peroxide (H₂O₂) exerted the most pronounced effect on the graphitization of the microcrystalline structure. These findings contribute to a deeper understanding of the interaction mechanisms between fracturing fluids and coal, providing theoretical support for the efficient development of CBM. Full article

This article presents a method for synthesizing a polymer composite based on the interaction of PVA and HNa isolated from coals from the Shubarkol deposit (Karaganda, Kazakhstan). The study focuses on the macromolecular aspects of the formation of the polymer matrix structure and the effect of a natural modifier on the properties of the composite. Taking into account the concept of macromolecular design, the addition of small additives of HNa (2–10%) significantly changes the nature of intermolecular interactions in the solution, promoting the accelerated structuring of the polymer network. This is manifested in a decrease in the gelation time, which is confirmed by a kinetic analysis based on changes in the relative viscosity of the systems. It was found that the greatest increase in viscosity is achieved on the fifth day with a content of 10% HNa and pH = 7, which, on the fifth day, indicates a critical concentration of the modifier necessary for the formation of a stable spatial network of hydrogen bonds and ion-dipole interactions between the functional groups of PVA and HNa. Morphological studies using AFM showed that an increase in the HNa content leads to a significant smoothing of the composite surface, indicating the formation of a more homogeneous and dense structure. These changes are due to the reorganization of the macromolecular architecture under the influence of modifying additives. The adsorption characteristics of the composite were estimated by the maximum sorption capacity, which was 3.40 mmol/g for Cu(II) ions. The results emphasize that the targeted control of the structure at the macromolecular level allows the creation of polymeric materials with specified physicochemical properties that are effective for wastewater treatment from heavy metals. The study demonstrates the potential of macromolecular design as a tool for the development of polymer composites with improved performance characteristics and environmental significance. Full article

Psoriasis is an immune-related disorder that is marked by abnormal thickening of the skin, the rapid multiplication of keratinocytes, and complex interactions between immune cells and the affected areas. Although psoriasis cannot currently be cured, drugs can alleviate symptoms by regulating immune homeostasis and preventing comorbidities. There are many types of drugs to treat psoriasis: small-molecule drugs, including corticosteroids; retinoids; vitamin D analogs; and immunosuppressants, such as glucocorticoid ointment, tretinoin cream, methotrexate tablets, etc. Macromolecular biological drugs, such as Certolizumab, Secukinumab, Guselkumab, etc., include monoclonal antibodies that target various inflammatory signaling pathways. Compared with traditional small-molecule drugs, biological therapies offer better targeting and lower systemic side effects, but their high costs and invasive administration modes constrict their widespread use. Spesolimab is the latest biological agent used to target the interleukin-36 receptor (IL-36R) to be approved for market use, which significantly reduces the risk of general pustular psoriasis (GPP) flare by 84%. Additionally, there are several biological agents used to target the interleukin-23/T helper 17 cell pathway that have already entered Phase II and III clinical trials. At present, the first-line therapeutic strategy for mild psoriasis is topical administration. Systemic therapy and phototherapy are preferred for treating moderate to severe types. However, the current therapeutic drugs for psoriasis cannot completely meet the clinical needs. More advanced drug delivery systems with optimized target effects and better bioavailability are required. Nanocarriers are emerging for the delivery of proteins, nucleic acids, and cell-based therapies. In this review, we analyze the current status of psoriasis therapeutics and discuss novel delivery systems for diverse psoriasis drugs, as well as emerging cell-based therapies. We also summarize the therapeutic effectiveness of different delivery strategies. Full article

Simulations of the Brownian dynamics of diffusing particles in complex environments provide important information about the characteristics of the medium and the properties of biological processes. Notable examples include the diffusion of ions and macromolecular solutes through channels of varying cross-section, such as pores in biological membranes, living tissues, zeolites, carbon nanotubes, and synthetic porous materials. In these systems, the observed diffusion can exhibit anomalous behavior characterized by a nonlinear increase in the mean squared displacement. In this article, we present a toy model of the diffusion of rod-shaped particles through a narrowing, conical pore with a trapezoidal longitudinal cross-section. Particles of different sizes undergo a random walk due to interactions with the environment (modeled as noise). We study how the diffusion properties change with particle size as a function of pore width. The numerical analysis of diffusion-driven transport through narrowing conical channels reveals its effective subdiffusive, i.e., anomalous, character. Full article

Among the various strategies used to enhance the solvation power of supercritical carbon dioxide (scCO₂), the use of CO₂-philic compounds has been extensively studied over the recent two decades. Given the biocompatibility of this medium, extraction technologies based on scCO₂ are particularly attractive, and a molecular-level understanding of intermolecular interactions is crucial for optimizing processing conditions. Functionalized sugars and cyclic oligosaccharides, such as cyclodextrins, can be rendered soluble in scCO₂, opening new avenues for vectorization strategies and supramolecular chemistry in this medium. To support the exploration of CO₂-philic compounds relevant to these research goals, we conducted a molecular dynamics investigation into the solvation properties of cyclodextrins functionalized with CO₂-philic groups. We thoroughly analyzed the key solute–solvent interactions and their influence on the cavity shape. Additionally, we provided insights into the solvation behavior of peracetylated $\alpha$ and $\beta$-glucose across different regions of the carbon dioxide phase diagram. We were able to confirm the importance of the well-known (acetyl)C–O⋯C(CO₂) interaction, as the most important signature of CO₂-philicity of carbonyl compounds. Depending on the substituent, this interaction can be assisted by a cooperative (methyl)₂HCH⋯O(CO₂) intermolecular bond. In cyclodextrins, conformational flexibility, with a possible change in the conformation of some pyranose units, was observed in the macromolecular structure. On the other hand, these structural modifications were not present for $\alpha$- and $\beta$-glucose. Full article

In order to explore the influence of different pore sizes of anthracite on the methane adsorption characteristics, a low-temperature liquid nitrogen adsorption experiment was carried out. Six types of anthracite with pore sizes ranging from 10 Å to 60 Å were selected as simulation objects. By means of molecular simulation technology and using the Materials Studio 2020 software, a macromolecular model of anthracite was established, and a grand canonical Monte Carlo (GCMC) simulation comparative study was conducted. The variation laws of the interaction energy and diffusion during the process of coal adsorbing CH₄ under different pore size conditions were obtained. The results show that affected by the pore size, under the same temperature condition, the peak value of the interaction energy distribution between coal and CH₄ shows a downward trend with the increase in the pore size under the action of pressure, and the energy gradually decreases. The isothermal adsorption curves all conform to the Langmuir isothermal adsorption model. The Langmuir adsorption constant a shows an obvious upward trend with the increase in the pore size, with an average increase of 16.43%. Moreover, under the same pressure, when the pore size is 60 Å, the adsorption amount of CH₄ is the largest, and as the pore size decreases, the adsorption amount also gradually decreases. The size of the pore size is directly proportional to the diffusion coefficient of CH₄. When the pore size increases to 50 Å, the migration state of CH₄ reaches the critical point of transformation, and the diffusion coefficient rapidly increases to 2.3 times the original value. Full article