Search Results (22)

Supercapacitors (SCs) have garnered significant attention due to their high power density and long cycle life. Among the various electrode materials, carbon materials have emerged as a focal point of research owing to their superior conductivity, stability, and reproducibility. However, the relatively low specific capacitance and specific surface area of carbon materials result in suboptimal electrochemical performance, which seriously hinders their practical applications. This work introduces a straightforward yet effective strategy for constructing hollow nano-cage structures by tannic acid etching of ZIF-8. In this process, tannic acid releases protons that selectively etch the MOF structure, while the residual large molecules adhere to the ZIF-8 surface, stabilizing its framework and preventing structural collapse. Following high-temperature heat treatment, novel hollow nitrogen-doped carbon nano-cage structures (HNCs) are successfully synthesized. Electrochemical tests reveal that the material has a capacity of 349.3 F g⁻¹ at a current density of 0.5 A g⁻¹, and still has a coulombic efficiency of 97.61% as well as a capacity retention of 97.86% after cycling for 10,000 cycles at a current density of 3 A g⁻¹. Therefore, this study provides a novel way to explore the application of carbon materials with excellent electrochemical performance for energy storage. Full article

The present study investigated the ¹H Nuclear Magnetic Resonance (NMR) spectra of hydrogen-rich water (HRW) produced using the EVObooster device. The analyzed HRW has pH = 7.1 ± 0.11, oxidation–reduction potential (ORP) of (−450 ± 11) mV, and a dissolved hydrogen concentration of 1.2 ppm. The control sample was tap water filtered by patented technology. A 600 NMR spectrometer was used to measure NMR spectra. Isotropic 1H nuclear magnetic shielding constants of the most stable clusters (H₂O)_n with n from 3 to 28 have been calculated by employing the gauge-including-atomic-orbital (GIAO) method at the MPW1PW91/6-311+G(2d,p) density function level of theory (DFT). The HRW chemical shift is downfield (higher chemical shifts) due to increased hydrogen bonding. More extensive formations were formed in HRW than in control filtered tap water. The exchange of protons between water molecules is rapid in HRW, and the ¹H NMR spectra are in fast exchange mode. Therefore, we averaged the calculated chemical shifts of the investigated water clusters. As the size of the clusters increases, the number of hydrogen bonds increases, which leads to an increase in the chemical shift. The dependence is an exponential saturation that occurs at about N = 10. The modeled clusters in HRW are structurally stabilized, suggesting well-ordered hydrogen bonds. In the article, different processes are described for the transport of water molecules and clusters. These processes are with aquaporins, fusion pores, gap-junction channels, and WAT FOUR model. The exponential trend of saturation shows the dynamics of water molecules in clusters. In our research, the chemical shift of 4.257 ppm indicates stable water clusters of 4–5 water molecules. The pentagonal rings in dodecahedron cage H₃O⁺(H₂O)₂₀ allow for an optimal arrangement of hydrogen bonds that minimizes the potential energy. Full article

Confining protons into an enclosed carbon cage is expected to give rise to unique electronic properties for both the inner proton and the outer cage. In this work, we systematically investigated the geometric and electronic structures of cationic X⁺@C₆₀ (X⁺ = H⁺, H₃O⁺, and NH₄⁺), and their corresponding neutral species (X = H₂O, NH₃), by quantum chemical density functional theory calculations. We show that C₆₀ can trap H₂O, NH₃, H₃O⁺ and NH₄⁺ at the cage center and only slightly influence their geometries. The single proton clings to the inner wall of C₆₀, forming a C-H chemical bond. The encapsulated neutral species almost do not change the electronic structure of the C₆₀, while the internal cations have obvious effects. The charge transfer effect from the inner species to the C₆₀ cage was found for all X@C₆₀ (X = H₂O, NH₃) (about 0.0 e), X⁺@C₆₀ (X⁺ = H₃O⁺, NH₄⁺) (about 0.5 e) and H⁺@C₆₀ (about 1.0 e) systems. Encapsulating different forms of protons also regulates the fundamental physico-chemical properties of the hollow C₆₀, such as the HOMO-LUMO gaps, infrared spectra, and electrostatic potential, etc., which are discussed in detail. These findings provide a theoretical insight into protons’ applications, especially in energy. Full article

The crystalline sponge method has proven invaluable in the preparation and analysis of supramolecular host/guest complexes if the host can be obtained in a suitable crystalline form, allowing the analysis of guest binding modes inside host cavities which can inform other studies into processes such as catalysis. Here, we report the structures of a set of ten host/guest complexes using an octanuclear coordination cage host with a range of small-molecule neutral organic guests including four aromatic aldehydes and ketones, three cyclic lactams, and three epoxides. In all cases, the cavity-bound guests are anchored by a collection of CH•••O hydrogen-bonding interactions between an O atom on the guest and a convergent set of CH protons at a pocket on the cage interior surface. Depending on guest size and the presence of solvent molecules as additional guests, there may be one or two cavity-bound guests, with small aromatic guests forming π-stacked pairs. Some guests (the lactams) participate in additional NH•••F H-bonding interactions with surface-bound fluoroborate anions, which indicate the type of anion/guest interactions thought to be responsible for solution-phase catalytic reactions of bound guests. Full article

Lateral transport and release of protons at the water–membrane interface play crucial roles in cell bioenergetics. Therefore, versatile techniques need to be developed for investigating as well as clarifying the main features of these processes at the molecular level. Here, we experimentally measured the kinetics of binding of protons released from the photoactivated compound sodium 2-methoxy-5-nitrophenyl sulfate (MNPS) at the surface of a bilayer lipid membrane (BLM). We developed a theoretical model of this process describing the damage of MNPS coupled with the release of the protons at the membrane surface, as well as the exchange of MNPS molecules and protons between the membrane and solution. We found that the total change in the boundary potential difference across the membrane, ∆ϕ_b, is the sum of opposing effects of adsorption of MNPS anions and release of protons at the membrane–water interface. Steady-state change in the ∆ϕ_b due to protons decreased with the concentration of the buffer and increased with the pH of the solution. The change in the concentration of protons evaluated from measurements of ∆ϕ_b was close to that in the unstirred water layer near the BLM. This result, as well as rate constants of the proton exchange between the membrane and the bulk solution, indicated that the rate-limiting step of the proton surface to bulk release is the change in the concentration of protons in the unstirred layer. This means that the protons released from MNPS remain in equilibrium between the BLM surface and an adjacent water layer. Full article

Baculovirus (Autographa californica multiple nucleopolyhedrovirus, AcMNPV) is an envelope virus possessing a fusogenic protein, GP64, which can be activated under weak acidic conditions close to those in endosomes. When the budded viruses (BVs) are bathed at pH 4.0 to 5.5, they can bind to liposome membranes with acidic phospholipids, and this results in membrane fusion. In the present study, using the caged-proton reagent 1-(2-nitrophenyl)ethyl sulfate, sodium salt (NPE-caged-proton), which can be uncaged by irradiation with ultraviolet light, we triggered the activation of GP64 by lowering the pH and observed membrane fusion on giant liposomes (giant unilamellar vesicles, GUVs) by visualizing the lateral diffusion of fluorescence emitted from a lipophilic fluorochrome (octadecyl rhodamine B chloride, R18) that stained viral envelopes of BVs. In this fusion, entrapped calcein did not leak from the target GUVs. The behavior of BVs prior to the triggering of membrane fusion by the uncaging reaction was closely monitored. BVs appeared to accumulate around a GUV with DOPS, implying that BVs preferred phosphatidylserine. The monitoring of viral fusion triggered by the uncaging reaction could be a valuable tool for revealing the delicate behavior of viruses affected by various chemical and biochemical environments. Full article

A theoretical modelling of the interaction process between a protonated complex of carboxonium derivative [2,6-B₁₀H₈O₂CCH₃*H^fac]⁰ and acetonitrile molecule CH₃CN was carried out. As a result of the process, a trisubstituted [B₁₀H₇O₂CCH₃(NCCH₃)]⁰ derivative was formed. This reaction has an electrophile-induced nucleophilic substitution (EINS) mechanism. The main intermediates and transition states of the substitution process were established. As in the case of all previously investigated EINS processes, the key intermediate was an anion with a dihydrogen H₂ fragment attached to one boron atom (B(H₂) structure motif). The process of nucleophilic substitution can proceed on a different position of the cluster cage. The main potential pathways were assessed. It was established that substitution on the B₄ position of the cluster cage was the most energetically favourable, and the [2,4,6-B₁₀H₇O₂CCH₃(NCCH₃)]⁰ isomer was formed. Full article

Proton relay between interfacial water molecules allows rapid two-dimensional diffusion. An energy barrier, $\Delta G_{\mathrm{r}}^{‡}$, opposes proton-surface-to-bulk release. The $\Delta G_{\mathrm{r}}^{‡}$-regulating mechanism thus far has remained unknown. Here, we explored the effect interfacial charges have on $\Delta G_{\mathrm{r}}^{‡}$’s enthalpic and entropic constituents, $\Delta G_{\mathrm{H}}^{‡}$ and $\Delta G_{\mathrm{S}}^{‡}$, respectively. A light flash illuminating a micrometer-sized membrane patch of a free-standing planar lipid bilayer released protons from an adsorbed hydrophobic caged compound. A lipid-anchored pH-sensitive dye reported protons’ arrival at a distant membrane patch. Introducing net-negative charges to the bilayer doubled $\Delta G_{\mathrm{H}}^{‡}$, while positive net charges decreased $\Delta G_{\mathrm{H}}^{‡}$. The accompanying variations in $\Delta G_{\mathrm{S}}^{‡}$ compensated for the $\Delta G_{\mathrm{H}}^{‡}$ modifications so that $\Delta G_{\mathrm{r}}^{‡}$ was nearly constant. The increase in the entropic component of the barrier is most likely due to the lower number and strength of hydrogen bonds known to be formed by positively charged residues as compared to negatively charged moieties. The resulting high $\Delta G_{\mathrm{r}}^{‡}$ ensured interfacial proton diffusion for all measured membranes. The observation indicates that the variation in membrane surface charge alone is a poor regulator of proton traffic along the membrane surface. Full article

Mitochondrial dysfunction and immune cell dysfunction are commonplace in sepsis and are associated with increased mortality risk. The short chain fatty acid, butyrate, is known to have anti-inflammatory effects and promote mitochondrial biogenesis. We therefore explored the immunometabolic effects of butyrate in an animal model of sepsis. Isolated healthy human volunteer peripheral mononuclear cells were stimulated with LPS in the presence of absence of butyrate, and released cytokines measured. Male Wistar rats housed in metabolic cages received either intravenous butyrate infusion or placebo commencing 6 h following faecal peritonitis induction. At 24 h, splenocytes were isolated for high-resolution respirometry, and measurement of mitochondrial membrane potential (MMP), reactive oxygen species (mtROS), and intracellular cytokines (TNF alpha, IL-10) using flow cytometry. Isolated splenocytes from septic and septic butyrate treated rats were stimulated with LPS for 18 h and the effects of butyrate on cytokine release assessed. Ex vivo, butyrate (1.8 mM) reduced LPS-induced TNF alpha (p = 0.019) and IL-10 (p = 0.001) release by human PBMCs. In septic animals butyrate infusion reduced the respiratory exchange ratio (p < 0.001), consistent with increased fat metabolism. This was associated with a reduction in cardiac output (p = 0.001), and increased lactate (p = 0.031) compared to placebo-treated septic animals (p < 0.05). Butyrate treatment was associated with a reduction in splenocyte basal respiration (p = 0.077), proton leak (p = 0.022), and non-mitochondrial respiration (p = 0.055), and an increase in MMP (p = 0.007) and mtROS (p = 0.027) compared to untreated septic animals. Splenocyte intracellular cytokines were unaffected by butyrate, although LPS-induced IL-10 release was impaired (p = 0.039). In summary, butyrate supplementation exacerbates myocardial and immune cell mitochondrial dysfunction in a rat model of faecal peritonitis. Full article

The zero-point energies (ZPEs) of paramagnetic molecules, free and compressed in a C₅₉N paramagnetic cage, were computed. The excess of energy acquired by molecules under compression depended on the deuterium and tritium isotopes which ranged from 6–8 kcal/mol for H₂⁺ to 1.0–1.5 kcal/mol for HO^• and HO₂. The differences in the ZPEs of compressed isotopic molecules resulted in large deuterium and tritium isotope effects which differed for singlet and triplet spin states. The hyperfine coupling (HFC) constants for protons and ¹⁷O nuclei decreased under compression, confirming the leakage of the unpaired π-electron from the central oxygen atom of guest molecules into the system of π-electrons of the cage, and its distribution over 60 atoms of the C₅₉N. The latter seems to be the reason why the nitrogen-14 HFCs for C₅₉N remain almost unchanged upon encapsulation of guest molecules. The singlet-triplet splitting is shown to depend on the Coulomb interaction, which controls the sign of the exchange potential. The importance of compression effects on the functioning of enzymes as molecular compressing devices is discussed. Full article

The persistency of COVID-19 in the world and the continuous rise of its variants demand new treatments to complement vaccines. Computational chemistry can assist in the identification of moieties able to lead to new drugs to fight the disease. Fullerenes and carbon nanomaterials can interact with proteins and are considered promising antiviral agents. Here, we propose the possibility to repurpose fullerenes to clog the active site of the SARS-CoV-2 protease, M^pro. Through the use of docking, molecular dynamics, and energy decomposition techniques, it is shown that C₆₀ has a substantial binding energy to the main protease of the SARS-CoV-2 virus, M^pro, higher than masitinib, a known inhibitor of the protein. Furthermore, we suggest the use of C₇₀ as an innovative scaffold for the inhibition of SARS-CoV-2 M^pro. At odds with masitinib, both C₆₀ and C₇₀ interact more strongly with SARS-CoV-2 M^pro when different protonation states of the catalytic dyad are considered. The binding of fullerenes to M^pro is due to shape complementarity, i.e., vdW interactions, and is aspecific. As such, it is not sensitive to mutations that can eliminate or invert the charges of the amino acids composing the binding pocket. Fullerenic cages should therefore be more effective against the SARS-CoV-2 virus than the available inhibitors such as masinitib, where the electrostatic term plays a crucial role in the binding. Full article

Silica-based mesoporous systems have gained great interest in drug delivery applications due to their excellent biocompatibility and high loading capability. However, these materials face challenges in terms of pore-size limitations since they are characterized by nanopores ranging between 6–8 nm and thus unsuitable to host large molecular weight molecules such as proteins, enzymes and growth factors (GFs). In this work, for an application in the field of bone regeneration, large-pore mesoporous silicas (LPMSs) were developed to vehicle large biomolecules and release them under a pH stimulus. Considering bone remodeling, the proposed pH-triggered mechanism aims to mimic the release of GFs encased in the bone matrix due to bone resorption by osteoclasts (OCs) and the associated pH drop. To this aim, LPMSs were prepared by using 1,3,5-trimethyl benzene (TMB) as a swelling agent and the synthesis solution was hydrothermally treated and the influence of different process temperatures and durations on the resulting mesostructure was investigated. The synthesized particles exhibited a cage-like mesoporous structure with accessible pores of diameter up to 23 nm. LPMSs produced at 140 °C for 24 h showed the best compromise in terms of specific surface area, pores size and shape and hence, were selected for further experiments. Horseradish peroxidase (HRP) was used as model protein to evaluate the ability of the LPMSs to adsorb and release large biomolecules. After HRP-loading, LPMSs were coated with a pH-responsive polymer, poly(ethylene glycol) (PEG), allowing the release of the incorporated biomolecules in response to a pH decrease, in an attempt to mimic GFs release in bone under the acidic pH generated by the resorption activity of OCs. The reported results proved that PEG-coated carriers released HRP more quickly in an acidic environment, due to the protonation of PEG at low pH that catalyzes polymer hydrolysis reaction. Our findings indicate that LPMSs could be used as carriers to deliver large biomolecules and prove the effectiveness of PEG as pH-responsive coating. Finally, as proof of concept, a collagen-based suspension was obtained by incorporating PEG-coated LPMS carriers into a type I collagen matrix with the aim of designing a hybrid formulation for 3D-printing of bone scaffolds. Full article

The self-association of phosphonic acids with general formula RP(O)(OH)₂ in solution state remains largely unexplored. The general understanding is that such molecules form multiple intermolecular hydrogen bonds, but the stoichiometry of self-associates and the bonding motifs are unclear. In this work, we report the results of the study of self-association of tert-butylphosphonic acid using low temperature liquid-state ¹H and ³¹P NMR spectroscopy (100 K; CDF₃/CDF₂Cl) and density functional theory (DFT) calculations. For the first time, we demonstrate conclusively that polar aprotic medium tert-butylphosphonic acid forms highly symmetric cage-like tetramers held by eight OHO hydrogen bonds, which makes the complex quite stable. In these associates. each phosphonic acid molecule is bonded to three other molecules by forming two hydrogen bonds as proton donor and two hydrogen bonds as proton acceptor. Though the structure of such cage-like tetramers is close to tetrahedral, the formal symmetry of the self-associate is C₂. Full article

Metal engineering structures are commonly covered and protected by coatings. However, the early local corrosion under the coatings and at defects is difficult to detect and discover. Visibility to the naked eye means that corrosion has already developed and expanded. Therefore, it is practical significant to detect the early corrosion of coated metal. Based on the formation of iron ions and anodic acidification in the local corrosion process, iron ions and proton responsive fluorescent rhodamine B acylhydrazone on-off probes are prepared by newly improved methods and denoted as RBA. RBA are loaded on the surface and in the lattice cage of zeolite (ZEO) to protect RBA from premature exposure to the corrosive environment and fluorescence quenching. In corrosive environments, the RBA loaded on the surface are released and complex with iron ions in the environment to activate fluorescence characteristics. Simultaneously, due to the cation exchange of ZEO, iron ions enter the lattice cage of ZEO and combine with RBA in the lattice cage to turn on fluorescence. When applied in epoxy coatings, the RBA/ZEO effectively indicate the occurrence of corrosion under the coatings and at defects, and accurately locate the corrosion site. Nano-scale ZEO (or RBA/ZEO) fill the micropores such as pinholes and defects of the coatings, and increase the difficulty of diffusion and penetration of corrosive media into the coatings. The application of RBA/ZEO functional filler not only do not weaken the main anti-corrosion performance of the coatings, but also significantly improve it. Full article

The intra-cage behaviour of guest H₂ and D₂ molecules in doubly occupied 5¹²6⁴ cages in structure-II (sII) clathrate hydrates were investigated using classical and path-integral molecular dynamics at 100 K. We probed the structure of tetrahedral sites, proton vibrations, localised molecular rattling timescales at sites, and the jump-diffusion travel of H₂ and D₂ molecules between sites. The site-diffusion model was correlated with experimental neutron scattering data, and the cage occupancies were then discussed in light of recent state-of-the-art experimental and theoretical findings in the literature. Full article