Interaction Of Molecules Research Articles

Structural and some Mechanical Properties of Parquetina Nigrescens Pod Nanoparticles Reinforced Mixed Matrix Membrane for Dental Applications

Polylactic acid (PLA) is a biocompatible, and biodegradable thermoplastic. It is renewable being produced by bacterial fermentation of potatoes, sugarcane, or corn starch. PLA has been attempted in many applications to replace petroleum-based polymers because some of its mechanical properties are excellent and it can be processed easily but low toughness and thermal stability are setbacks from one application to another. To improve on mechanical properties of the PLA to be suitable as biomaterials for dental and other applications, this study focuses on synthesis of Parquetinanigrescens pod nanoparticles (PNPNP) as reinforcements in the PLA to engineer new nanocomposites for biomedical applications. Chemical, structural and some mechanical properties were investigated. TEM result indicates an average size of 14.14 nm of the PNPNP used for reinforcing the PLA. Fourier Transform Infrared Spectrograph establishes a reduction in the amount of light transmitted by the PLA. This is due to PNPNP additions with changes in the wavenumbers of the observed peaks affirming formation of new compounds due to interactions of the PLA molecules and PNPNP. X-ray diffractograms reaffirms new compound formations. Moreover, there are enhancements in mechanical properties up to 3% by weight of PNPNP addition to the PLA with about 92% improvement in the impact toughness.

Placental extracellular vesicles from severe preeclamptic women alter calcium homeostasis in cardiomyocytes: An ex vivo study.

Women with severe preeclampsia (sPE) exhibit a heightened risk of postpartum cardiovascular disease compared to those with normotensive pregnancies (NTP). While placental extracellular vesicles (EV) play a crucial role in feto-maternal communication, their impact on cardiomyocytes, particularly in the context of sPE, remains unclear. This study investigated the effect of sPE-associated placental EV (sPE-Plex EV) on cardiomyocyte calcium dynamics. We hypothesized that sPE-Plex EV mediates cardiomyocyte dysfunction by disrupting calcium signaling. EV were isolated from plasma and placental explant culture (Plex) using precipitation methods, and confirmed as Plex EV by PLAP activity and electron microscopy. Moreover, confocal microscopy confirmed the uptake of plasma EV in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) and Plex EV by human AC-16 cardiomyocytes (hAC-16CM) cells. hiPSC-CM cells treated with sPE-EV and hAC-16CM cells treated with sPE-Plex EV exhibited significantly lower levels of Stromal interaction molecule 1 (STIM1) and Phospholamban (PLN) proteins compared to those treated with normotensive controls EV, as confirmed by western blot analysis. Treatment with sPE-Plex EV also resulted in the downregulation of STIM1 and PLN proteins in murine cardiomyocyte (mCM) cells compared to treatment with NTP-Plex EV. Our findings suggest that both plasma EV and Plex EV from sPE may alter calcium signaling in cardiac cells by downregulating calcium sensor proteins (STIM1 and PLN). Therefore, plasma EV and Plex EV from sPE pregnancies have adverse effects by altering calcium dynamics in hiPSC-CM, hAC-16CM, and mCM compared to normotensive control and potential impairment of cardiomyocyte function ex vivo.

STIM1 and lipid interactions at ER-PM contact sites

Store-operated calcium (Ca2+) entry (SOCE) represents a major route of Ca2+ permeation across the plasma membrane (PM) in non-excitable cells, which plays an indispensable role in maintaining intracellular Ca2+ homeostasis. This process is orchestrated through the dynamic coupling between the endoplasmic reticulum (ER)-localized Ca2+ sensor stromal interaction molecule 1 (STIM1) and the PM-resident ORAI1 channel. Upon depletion of ER Ca2+ stores, STIM1 undergoes conformational rearrangements and oligomerization, leading to translocation of STIM1-containing ER membrane towards the PM. This movement is facilitated by the physical interaction between positively charged cytosolic domains within STIM1 and negatively charged phospholipids embedded in the PM, ultimately enabling its binding to and activation of the PM-embedded ORAI1 channel. In this mini-review, we provide an overview of STIM1-mediated Ca2+ signaling at ER-PM contact sites, highlighting the regulatory roles of phospholipids in the inner leaflet and sphingolipids in the outer leaflet of the PM. We also discuss the development of molecular tools that enable real-time visualization and manipulation of membrane contact sites (MCSs) at ER-PM junctions. Lastly, we highlight recent progress in developing targeted therapies for human diseases linked to STIM1 mutations and dysregulated Ca2+ signaling at ER-PM MCSs.

Characterization of the soybean oil body interface: revealing the mechanism of changes in the interfacial protein composition, structure, and function of oil bodies extracted under different denaturation conditions

We investigated the stability and rheological properties of extracts from soybean oil bodies (OB) obtained under different denaturing conditions (heating, guanidine hydrochloride, urea, and sodium dodecyl sulfate (SDS)). Differences in the interfacial and antioxidant properties exhibited by the different compositions of interfacial proteins in the extracted OB were also assessed. SDS disrupted the interfacial structure of OB, whereas the treatments under the other three denaturing conditions effectively increased the ability of the OB proteins to form a network structure. The analysis of the secondary and tertiary structures of proteins showed that all denaturation conditions affected both hydrogen bonding and hydrophobic interactions of the protein molecules, with urea leading to the most pronounced structural unfolding and rearrangement of the OB proteins. The microstructure results of the protein indicated that the protein treated with GuHCl and urea exhibited a 'shell-like' structure and structural decomposition, which can promote the pre-encapsulation of active substances through hydrogen bonding or hydrophobic interactions. The electrophoretic results further confirmed that SDS could displace 24-kDa proteins and disrupt the original membrane structure of OB, whereas urea removed most of the extrinsic proteins. The interfacial proteins extracted from OB using the four denaturing methods were different but all had enhanced interfacial and antioxidant properties compared to the control. Therefore, the extraction of OB under different denaturation conditions facilitated the hierarchical extraction of its interfacial proteins, thereby broadening its application in the food industry.

Colorimetric and fluorimtric microenvironment responsivity of oxazolidine in solvatochromic latex nanoparticles: Versatile intelligent polymeric materials with advanced applications

Oxazolidine, a new category of stimuli-chromic dyes, has displayed a wide range of responsivities, such as halochromism, solvatochromism, ionochromism, and hydrochromism. The optical properties of oxazolidine molecules can be influenced notably by the polarity of solvent, media, and polymer nanoparticles. In this study, multi-functionalized acrylic latex nanoparticles containing different polar functional groups such as amide, amine, acid, hydroxyl, epoxide, and long-chain ester were synthesized by one-pot emulsion copolymerization. Prepared latex nanoparticles have a mean particle size in the range of 45–170 nm and spherical or non-spherical (anisotropic) morphologies depending on the polarity of functional groups. To prepare multi-color photoluminescent latex nanoparticles and investigation of solvatochromism in both colloidal solution and solid phase, as prepared multi-functionalized latex nanoparticles were modified physically with an oxazolidine derivative (5 wt%). Investigation of the solvatochromism of the oxazolidine in colloidal solution and solid phase indicated that the media is the main effective parameter for solvatochromism in colloidal solution. In the case of solid-state solvatochromism, the optical properties of oxazolidine were influenced significantly by the polarity of functional groups, because the interactions of oxazolidine molecules with functional groups of latex nanoparticles is the main parameter that influenced the solvatochromism. The solvatochromic properties of oxazolidine in solid polymer powders are useful for developing multi-color photoluminescent materials with advanced applications in the dual-mode visualization of latent fingerprints (LFPs), anticounterfeiting solid inks, and organic light-emitting diodes (OLEDs). Results displayed potential applications of multi-color polymer powders for the detection of LFPs under visible light and UV-light irradiation, for printing of optical security tags, and construction of OLEDs. The presented study introduces a new category of multi-color solid photoluminescent nanomaterials with multiple applications using solvatochromic properties.

Theoretical study based on molecular docking to investigate the potential interaction of known antiviral food components with SARS-CoV-2 proteins

Many food components have antiviral activity, but in most cases, studies in the literature do not report detailed investigations of molecular mechanisms. We performed a comprehensive molecular docking study to investigate the potential interaction of several food molecules, selected for their known antiviral activity, with twelve SARS-CoV-2 target proteins (NSP3, NSP5, NSP7, NSP8, NSP9, NSP10, NSP12, NSP15, NSP16, ORF7A, protein N, and Spike protein). The results suggest that some molecules, particularly β-carotene, all-trans-retinoic acid (ATRA), epigallocatechin 3-gallate and kaempferol, can interact with SARS-CoV-2 protein targets. The study opens new insights into the molecular mechanisms underlying the antiviral properties of food components.

Physisorption of benzene on cation/silica clusters via cation-π interactions: Theoretical study

Interactions of a benzene molecule with four different silica clusters decorated with mono- and divalent cations (Li+, Na+, Mg2+) have been theoretically studied. By means of SAPT0 calculations, we have analyzed the changes in the energy components in dependence of hydrophobic or hydrophilic positions of adsorption, the size of the cluster studied or the cation used for the ’decoration’. It was found that adsorption of benzene on pristine silica clusters is mainly driven by electrostatic (∼37–43 %) and dispersion (∼37–55 %) forces. At the same time, cation-π interactions can be accounted for by significant electrostatic (∼20–50 %) and induction (∼24–54 %) energy terms. IGM analysis reveals the existence of cation-π and van der Waals interactions. The significant binding of benzene to the decorated silica surface (up to ∼ − 19.97, −29.63, − 93.82 kcal/mol for Na+, Li+, Mg2+, respectively) can pave a way for the sorption of a typical organic contaminant.

Impact of food additives (sodium carbonate and ammonium bicarbonate) on interactions between astringent compounds and an oral cell model

Many foods contain additives like sodium carbonate and ammonium bicarbonate to ensure safety, preserve quality, or extend shelf life. Recent studies suggest these additives may influence interactions between astringent compounds and oral cells. Using a tongue epithelium cell model, we investigated how these salts affect interactions between astringent compounds (phenolic and non-phenolic) and oral constituents. The salts reduced the interaction of green tea flavanol-rich extract (GTE) with salivary proteins and altered interactions with tannic acid and alum. The effects varied depending on the specific astringent compound, salt, and oral constituents, with ionic strength playing a role. The reduced adsorption of flavanols from GTE may be due to oxidation induced by these additives, raising concerns about their use. However, sodium carbonate and ammonium bicarbonate can modify astringent molecule interactions, potentially influencing the astringency of certain products.

3,3′-Diindolylmethane promotes bone formation – A assessment in MC3T3-E1 cells and zebrafish

Osteoporosis is a common degenerative bone disease in middle-aged and elderly people. The current drugs used to treat osteoporosis have many side effects and low patient compliance. Phytochemotherapy may be safer and more effective. 3,3′-diindolemethane (DIM) is the digestive product of indole-3-methanol in cruciferous vegetables in the stomach, which is a kind of anti-tumor and anti-oxidation phytochemical. However, the effects of DIM on osteoblasts and the mechanism by which DIM regulates bone formation are not fully understood. The aim of this study was to investigate the effects of DIM on the bone formation of mouse preosteoblasts MC3T3-E1 and zebrafish. DIM promotes proliferation and osteogenic differentiation of MC3T3-E1 cells in vitro, and also plays a bone promoting role by increasing the interaction between BRCA1-Associated Protein 1(BAP1) and Inositol 1,4,5-Trisphosphate Receptor(IP3R), up-regulating the expression of BAP1 and IP3R and downstream storage operation calcium entry (SOCE) related protein Recombinant Stromal Interaction Molecule 1(STIM1). The effect of DIM on osteoporosis was confirmed in zebrafish osteoporosis model, and its molecular mechanism may be related to BAP1/IP3R/SOCE signaling pathway. These findings highlight the potential therapeutic value of DIM in the prevention and treatment of osteoporosis.

Renshen (Radix Ginseng) polysaccharide promotes repair of the mice intestinal mucosa through regulatory mechanisms based on polyamine and human antigen R.

To investigate the mechanism and effect of Renshen (Radix Ginseng) polysaccharide on the migration of intestinal epithelial cell line 6 (IEC-6), as well as the repair mechanism of Renshen (Radix Ginseng) polysaccharide on colonic injury induced by dextran sulfate sodium (DSS) in mice. Mice were fed 3% (w/v) DSS for 6 d to create colonic lesions. A cell-migration model was created using cell scratching. mRNA expression, protein expression, translation efficiency of mRNA, and nucleoplasmic distribution of human antigen R (HuR) were determined by real-time reverse transcription-quantitative polymerase chain reaction, western blotting, a dual luciferase reporter system, and immunofluorescence staining, respectively. Renshen (Radix Ginseng) polysaccharide promoted the migration of IEC-6 cells and affected expression of stromal interaction molecule 1 (STIM1) and cell division cycle 42 (Cdc42) at transcriptional and post-transcriptional levels. Renshen (Radix Ginseng) polysaccharide-induced repair of intestinal mucosal injury may be mediated by increased cell migration via polyamine-based regulatory mechanisms. In vitro and in vivo experiments suggest that Renshen (Radix Ginseng) polysaccharide-induced post-transcriptional regulation of STIM1 and Cdc42 may be related to differences in the regulation of different target genes by HuR. Taken together, these data provide a reference for further exploration of the protective effect of Renshen (Radix Ginseng) on the intestinal mucosa.

H3K27 trimethylation-mediated downregulation of miR-216a-3p in sensory neurons regulates neuropathic pain behaviors via targeting STIM1.

Although the therapeutic potential of miRNA-mediated gene regulation has been investigated, its precise functional regulatory mechanism in neuropathic pain remains incompletely understood. In this study, we elucidate that miR-216a-3p serves as a critical non-coding RNA involved in the modulation of trigeminal-mediated neuropathic pain. By conducting RNA-seq and qPCR analysis, we observed a notable decrease of miR-216a-3p in the injured trigeminal ganglia (TG) of male rats. Intra-TG administration of miR-216a-3p agomir or lentiviral-mediated overexpression of miR-216a-3p specifically in sensory neurons of injured TGs alleviated established neuropathic pain behaviors, while downregulation of miR-216a-3p (pharmacologically or genetically) in naïve rats induced pain behaviors. Moreover, nerve injury significantly elevated the H3K27 trimethylation (H3K27me3) levels in the ipsilateral TG, thereby suppressing the SRY-box transcription factor 10 (SOX10) binding to the miR-216a-3p promoter and resulting in the reduction of miR-216a-3p. Inhibiting the enzymes that responsible for catalyzing H3K27me3 restored the nerve injury-induced reduction in miR-216a-3p expression and markedly ameliorated neuropathic pain behaviors. Furthermore, miR-216a-3p targeted stromal interaction molecule 1 (STIM1), and the decreased miR-216a-3p associated with neuropathic pain caused a significant upregulation in the protein abundance of STIM1. Conversely, overexpression of miR-216a-3p in the injured TG suppressed the upregulation of STIM1 expression and reversed the mechanical allodynia. Together, the mechanistic understanding of H3K27me3-dependent SOX10/miR-216a-3p/STIM1 signaling axial in sensory neurons may facilitate the discovery of innovative therapeutic strategies for neuropathic pain management.Significance Statement miRNAs are posttranscriptional regulators of gene expression that play critical roles in the pathogenesis of neuropathic pain. However, the detailed mechanisms by which most pain-associated miRNAs operate and their therapeutic potential are incompletely understood. Our present study revealed that nerve injury-induced trimethylation of lysine 27 on histone H3 (H3K27me3) reduces the binding of SOX10, a transcription factor, to the promoter region of the miR-216a-3p gene, leading to decreased expression of the microRNA, miR-216a-3p. This reduction subsequently promotes neuropathic pain by regulating STIM1. Given that miRNA-mediated gene regulation is a proposed therapeutic approach for treating neuropathic pain, our findings suggest that replenishing miR-216a-3p could serve as a novel strategy for treating chronic neuropathic pain.

Synthesis, Structures, and Physical Properties of ExTTF Substituted with Aryl Groups Through Sulfur Bridges and the Electron Transfers with C60

ExTTF derivatixes (1‐4) bearing aryl groups attached through sulfur bridges have been synthesized. The peripheral aryl groups have a certain influence on both the electronic and crystallographic properties of the exTTFs. Compounds 1‐4 show two bands typical of exTTF derivatives near 360 and 430 nm. Compound 1 and 4 exhibit the characteristic electrochemical exTTF behavior, with one reversible two‐electron process ranging depending on their substitutionthe electron‐withdrawing ability. But 2 and 3 exhibit a similar single two‐electron oxidation wave but electrochemically irreversible redox with peak‐to‐peak potential separation. And 3 has a low redox potential, which is significantly inconsistent with the electron absorption of pyridine substituents. The crystal structures of 1‐4 exhibit the characteristic butterfly shape. Moreover, the peripheral aryl groups exhibit multiple alignment modes with respect to the central exTTF core, caused by their rotation about the two C‐S bonds of the sulfur bridges. Under the interaction of multiple molecules, exTTF shows different molecular packing structures. Compounds 1‐4 have good intermolecular interaction with C60 due to their good electron‐donating ability, butterfly configuration, and free rotation of peripheral aryl groups. These results indicate that 1‐4 organic electronic materials have potential applications in the field of supramolecular assembly.

Influence of Solvent Dielectric Constant on the Complex Coacervation Phase Behavior of Polymerized Ionic Liquids.

Complex coacervation is an associative phase separation process of oppositely charged polyelectrolyte solutions, resulting in a coacervate phase enriched with charged polymers and a polymer-lean phase. To date, studies on the phase behavior of complex coacervation have been largely restricted to aqueous systems with relatively high dielectric constants due to the limited solubility of most polyelectrolytes, hindering the exploration of the effects of electrostatic interactions from differences in solvent permittivity. Herein, we prepare two symmetric but oppositely charged polymerized ionic liquids (PILs), consisting of poly[1-[2-acryloyloxyethyl]-3-butylimidazolium bis(trifluoromethane)sulfonimide] (PAT) and poly[1-ethyl-3-methylimidazolium 3-[[[(trifluoromethyl)sulfonyl]amino]sulfonyl]propyl acrylate] (PEA). Due to the delocalized ionic charges and their chemical structure similarity, both PAT and PEA are soluble in various organic solvents with a wide range of dielectric constants, ranging from 16.7 (hexafluoro-2-propanol (HFIP)) to 66.1 (propylene carbonate (PC)). Notably, no significant correlation is observed between the solvent dielectric constant and the phase diagram of the complex coacervation of PILs. Most organic solvents lead to similar phase diagrams and salt resistances regardless of their dielectric constants, except two protic solvents (HFIP and 2,2,2-trifluoroethanol (TFE)) showing significantly low salt resistances compared to the others. The low salt resistance in these protic solvents primarily arises from strong hydrogen bonding between PILs and solvents as evidenced by 1H NMR and small-angle neutron scattering (SANS) experiments. Our finding suggests that for the coacervation of PILs, particularly those with delocalized and weak charge interactions, entropy from the counterion release and polymer-solvent interaction χ parameter play a more important role than the electrostatic interactions of charged molecules, rendered by the dielectric constant of the solvent medium.

Effect of bioactive compounds of Mucuna pruriens on proteins of Wnt/β catenin pathway in pulmonary hypertension by in silico approach.

Modulation of theWnt/β-catenin signaling pathway may aid in discovering new medications for the effective management of pulmonary artery hypertension (PAH). Given the therapeutic potential of Mucuna pruriens in several diseases, the present study aimed toanalyze interactions of different bioactive compounds of Mucuna pruriens plant seeds with Wnt/β-catenin pathway targeting its various components like Wnt 3a, Frizzled 1, LRP 5/6, β-catenin, Disheveled, cyclin D1 by in silico analysis. The proposed work is based on computational analysis including ADME/T properties, by a Swiss ADME server. To understand the molecular interaction pattern Schrodinger, suit a stand-alone software was used to predict the interaction of bioactive molecules of Mucuna Pruriens with target proteins that are involved in Wnt/ β catenin pathway. Further, the simulation pattern of the top docked complex was subjected to MD simulation in Desmond for 100ns. Bioactive molecules from Mucuna Pruriens have drug-like properties and minimal toxicity. Further, the docking study revealed that among the nine compounds, three compounds (Gallic acid, L-dopa, and β-sitosterol) showed good interaction with target proteins. As gallic acid showed good interaction with all target proteins, the docked complex was subjected to MD simulation which was stable throughout the simulation time in terms of RMSD and RMSF. These findings suggest that the bioactive molecules of Mucuna pruriens compounds have potential therapeutic value in the treatment of pulmonary vascular disease. Further, in vivo and in vitro studies are necessary to determine its efficacy and validate its pharmacological activity conclusively.

Gut Microbiota and Tryptophan Metabolism in Pathogenesis of Ischemic Stroke: A Potential Role for Food Homologous Plants.

The intestinal flora is involved in the maintenance of human health and the development of diseases, and is closely related to the brain. As an essential amino acid, tryptophan (TRP) participates in a variety of physiological functions in the body and affects the growth and health of the human body. TRP catabolites produced by the gut microbiota are important signaling molecules for microbial communities and host-microbe interactions, and play an important role in maintaining health and disease pathogenesis. The review first demonstrates the evidence of TRP metabolism in stroke and the relationship between gut microbiota and TRP metabolism. Furthermore, the review reveals that food homologous plants (FHP) bioactive compounds have been shown to regulate various metabolic pathways of the gut microbiota, including the biosynthesis of valine, leucine, isoleucine, and vitamin B6 metabolism. The most notable metabolic alteration is in TRP metabolism. The interaction between gut microbiota and TRP metabolism offers a plausible explanation for the notable bioactivities of FHP in the treatment of ischemic stroke (IS). This review enhances the comprehension of the underlying mechanisms associated with the bioactivity of FHP on IS.

Exploring Plasmonic Standalone Surface-Enhanced Raman Scattering Nanoprobes for Multifaceted Applications in Biomedical, Food, and Environmental Fields.

Surface-enhanced Raman scattering (SERS) is an innovative spectroscopic technique that amplifies the Raman signals of molecules adsorbed on rough metal surfaces, making it pivotal for single-molecule detection in complex biological and environmental matrices. This review aims to elucidate the design strategies and recent advancements in the application of standalone SERS nanoprobes, with a special focus on quantifiable SERS tags. We conducted a comprehensive analysis of the recent literature, focusing on the development of SERS nanoprobes that employ novel nanostructuring techniques to enhance signal reliability and quantification. Standalone SERS nanoprobes exhibit significant enhancements in sensitivity and specificity due to optimized hot spot generation and improved reporter molecule interactions. Recent innovations include the development of nanogap and core-satellite structures that enhance electromagnetic fields, which are crucial for SERS applications. Standalone SERS nanoprobes, particularly those utilizing indirect detection mechanisms, represent a significant advancement in the field. They hold potential for wide-ranging applications, from disease diagnostics to environmental monitoring, owing to their enhanced sensitivity and ability to operate under complex sample conditions.

Water in peripheral TM-interfaces of Orai1-channels triggers pore opening

The activation of the Ca2+-channel Orai1 via the physiological activator stromal interaction molecule 1 (STIM1) requires structural rearrangements within the entire channel complex involving a series of gating checkpoints. Focusing on the gating mechanism operating along the peripheral transmembrane domain (TM) 3/TM4-interface, we report here that some charged substitutions close to the center of TM3 or TM4 lead to constitutively active Orai1 variants triggering nuclear factor of activated T-cell (NFAT) translocation into the nucleus. Molecular dynamics simulations unveil that this gain-of-function correlates with enhanced hydration at peripheral TM-interfaces, leading to increased local structural flexibility of the channel periphery and global conformational changes permitting pore opening. Our findings indicate that efficient dehydration of the peripheral TM-interfaces driven by the hydrophobic effect is critical for maintaining the closed state of Orai1. We conclude that a charge close to the center of TM3 or TM4 facilitates concomitant hydration and widening of peripheral TM interfaces to trigger constitutive Orai1 pore opening to a level comparable to or exceeding that of native activated Orai1.

Molecular simulation of asphaltene clustering in toluene and n-heptane: Thermodynamics and dynamics aspects

This study investigated the thermodynamic and dynamic properties of asphaltene molecules in Toluene and n-Heptane using the OPLS-AA force field in the GROMACS package at 300 K and 1 bar. The results indicate that van der Waals (vdW) interactions have a significant influence on thermodynamics, accounting for around 88–90 % of the total interaction energy between asphaltene molecules, while Coulombic (Coul) interactions contribute approximately 10–12 %. Stable asphaltene aggregates form at concentrations equal to or greater than 8 asphaltene molecules in 4000 molecules of Toluene. The interaction energy between asphaltene chains, which promotes aggregation, is much weaker than the interaction between aromatic rings. Longer chains exhibit more attractive vdW interactions and more repulsive Coul interactions. The presence of heteroatoms (sulfur and oxygen) hinders the parallel and symmetrical interaction of asphaltene molecules. Density profiles and two-dimensional maps were used to analyze the spatial arrangement of asphaltenes. A total interaction energy equal to or more positive than −300 kJ/mol for asphaltene-liquid interactions is introduced as a criterion for classifying a liquid as an asphaltene precipitator. The polarity of the solvent was inferred not to affect asphaltene solubility. In n-Heptane, asphaltene molecules aggregated to form a dense nucleus, while in Toluene, sharp peaks in the density profiles indicated the formation of clusters of varying sizes via asphaltene aggregation. Systems containing 64 and 32 asphaltene molecules had the highest probability of forming clusters comprising 10–16 and 12–16 asphaltene molecules, respectively. In Toluene, the average cluster sizes ranged from 1.4 to 6.1 molecules, depending on asphaltene concentration. Cluster size analysis showed variations in both size and stacking architectures, including face-to-face stacked and T-shaped aggregates. The proportion of face-to-face stacked structures was higher than T-shaped structures in both Toluene and n-Heptane, with the ratio of face-to-face stacked to T-shaped aggregates estimated at ∼2.9. While thermodynamic equilibrium was well attained, simulation times longer than 150 ns are recommended to achieve dynamic equilibrium.

Unleashing the Potential of Tailored ZnO-MgO Nanocomposites for the Enhancement of NO2 Sensing Performance at Room Temperature.

Surface functionalization of semiconducting metal oxides has emerged as a highly effective approach for enhancing their sensing capabilities. In the present work, the surface of randomly oriented zinc oxide (ZnO) nanowires is modified with an optimized thickness (7 nm) of magnesium oxide (MgO), which exhibits an exceptionally sensitive and selective behavior toward NO2 gas, yielding a response of approximately 310 for 10 ppm concentration at room temperature. The synergistic interplay between ZnO and MgO leads to a remarkable 20-fold improvement in sensor response compared to a pristine ZnO film and allows the detection of concentrations as low as 50 ppb. The ZnO-MgO composite was characterized using X-ray diffraction (XRD), XPS, and SEM-EDS to gain structural, compositional, and morphological insights. The interaction of the NO2 molecule with the sensor film was investigated using density functional theory (DFT) simulations, revealing that oxygen vacant sites on the MgO surface are most favorable for NO2 adsorption, with an adsorption energy of -3.97 eV and a charge transfer of 1.74e toward NO2. The XPS, photoluminescence (PL), and EPR measurements experimentally verified the presence of oxygen vacancies in the sensing material. The introduction of localized levels within the band gap by oxygen vacancies significantly promotes the interaction of gas molecules with these sites, which enhances the charge transfer toward NO2 gas molecules. This augmentation has a profound influence on the space charge region at the ZnO-MgO interface, which is pivotal for modulating the charge transport in the ZnO layer, resulting in the substantial improvement of NO2 response at room temperature.

Hydrogen peroxide disrupts the regulatory pathway of saliva secretion in two salivary acinar rat cell lines.

Secretion of saliva is controlled by autonomic nerve signals via regulation of Ca2+-dependent ion transport across acinar cell membranes. Oxidative stress may affect this process, leading to a decrease in saliva production. This study investigates elements of the Ca2+ regulatory pathway and their vulnerability to hydrogen peroxide-induced oxidative stress. Rat parotid and submandibular salivary gland acinar cell lines were exposed to different hydrogen peroxide concentrations to simulate oxidative stress. Cell viability and intracellular reactive oxygen species were measured, mRNA levels were assessed via RT-qPCR, and protein expression was studied using western blot and immunofluorescence microscopy. Elevated concentrations of hydrogen peroxide reduced cell viability and increased intracellular levels of reactive oxygen species and led to a decrease in cholinergic receptor muscarinic 3 and adrenoreceptor alpha 1A mRNA and protein levels in both cell lines. In parotid gland cells, both mRNA and protein levels of stromal interaction molecule 1 and Orai1 decreased with increasing concentrations of hydrogen peroxide. In contrast, in submandibular gland cells stromal interaction molecule 1 and Orai1 displayed differential mRNA and protein expression levels. Our study revealed that hydrogen peroxide exposure alters rat parotid and submandibular acinar cells, increasing reactive oxygen species and reducing autonomic receptor expression. Differential mRNA and protein expression of stromal interaction molecule 1 and Orai1 highlight complex oxidative stress effects on Ca2⁺ signaling. Most likely these effects will be deleterious to salivary secretion, but some effects may be protective.