ACS Omega最新文献

FtrABCD is a four-component iron transporter found in several Gram-negative bacteria. Previous data confirm that FtrABCD can only utilize Fe²⁺ and the inner membrane permease, FtrC, from this system, like its eukaryotic homologue, Ftr1p, is predicted to utilize the free energy released during Fe²⁺ oxidation for the transport. Periplasmic FtrB from this system is coancestral with known copper oxidases, and the conserved D118 and H121 are predicted to bind to Cu²⁺, forming an active enzyme. In this work, we report structural data for recombinant wild-type and D118A and H121A mutants from Brucella abortus 2308 which confirm a β-sheet-rich structure which is distinct from known cupredoxins. Calorimetric studies on the wild-type protein show μM affinities for Cu²⁺ and an Fe²⁺ mimic (Mn²⁺), which facilitate the formation of the active enzyme and the enzyme–substrate complex, respectively. In contrast, the D118A mutant failed to bind Cu²⁺. Finally, the electrochemical data reported here revealed biologically accessible reduction potentials for the Cu²⁺ ion in the active enzyme which also showed a pseudozero-order rate of Fe²⁺ oxidation at pH 6.5 and could oxidize Fe²⁺ 3.5-times faster than its rate of autoxidation. Taken together, this report provides experimental data that support structural and functional predictions of FtrB under in vitro conditions.

Nanophotonics has attracted wide attention in photonic devices and biotechnology. Interaction of visible and near-infrared lights with metal nanoparticles (NPs) is already well explored, leading to a mount of applications, especially in high-sensitivity biodetection. However, the effects of metal NPs on mid-infrared (MIR) light are still lacking because the light cannot resonantly excite the surface electron oscillation of the NPs. Recently, gold NP (AuNP)-assisted experiments indicate that AuNPs can be used in the detection of MIR biophotons, but the underlying mechanism remains unclear. Here, constructing a cavity by two AuNPs and performing finite difference time domain simulations based on Maxwell equations, we demonstrate that even if the AuNP dimension is significantly smaller than the MIR wavelength, the AuNP-formed cavity (AuNP-cavity) still can confine the light. The confinement effect increases with an increase in the wavelength or the cavity length when the cavity length and wavelength are fixed, respectively, while it vanishes only when the AuNP dimension is less than 1000th of the light wavelength. These results can be attributed to the resonance of MIR light with the two AuNPs, and in this view, it can be said that this nanocavity overcomes the diffraction limitation of the optical system. Our findings provide an understanding of the biophoton detection mentioned above, potentially promoting the applications of metal NPs in biotechnology and even in MIR-related imaging and wave-guiding circuits.

Fast reconstruction of the pulpal vasculature is crucial for effective pulp regeneration. Dental pulp stem cells (DPSCs) are promising candidates for pulp regeneration because of their potential for multilineage differentiation and vasculogenic properties. Deferoxamine (DFO) has been shown to stimulate angiogenesis during wound healing and bone regeneration; however, the effects of DFO on the angiogenic potential of DPSCs remain unknown. Moreover, its usefulness is restricted by a limited half-life and challenges in achieving localized tissue enrichment. This study aimed to develop a sustained-release injectable hydrogel composite as a drug delivery system and to investigate its influence on DPSCs. Herein, gelatin-based microspheres (GMSs) were loaded with DFO, and temperature-sensitive injectable hydrogels incorporating collagen and chitosan were synthesized to enable controlled DFO release. The experimental findings demonstrated that the DFO-loaded GMSs (DFO-GMSs) hydrogel composite possessed favorable physical properties and biocompatibility, enabling sustained DFO delivery for up to 15 days. DFO effectively stimulated DPSC migration, promoted the secretion of angiogenesis-related factors, and induced tube formation in vitro. These results suggest that the DFO-GMSs hydrogel composite significantly increased the migration and angiogenic potential of DPSCs, highlighting its promise for tissue regeneration applications.

The selective chemical control of wild grasses in wheat is primarily determined by the relative rates of herbicide metabolism, with the superfamily of cytochromes P450 (CYPs) playing a major role in catalyzing phase 1 detoxification reactions. This selectivity is enhanced by herbicide safeners, which induce CYP expression in cereals, or challenged by the evolution of nontarget site resistance (NTSR) in weeds such as blackgrass. Using transcriptomics, proteomics, and functional expression in recombinant yeast, CYPs linked to safener treatment and NTSR have been characterized in wheat and blackgrass. Safener treatment resulted in the induction of 13 families of CYPs in wheat and 5 in blackgrass, with CYP71, CYP72, CYP76, and CYP81 members active toward selective herbicides in the crop. Based on their expression and functional activities, three inducible TaCYP81s were shown to have major roles in safening in wheat. In contrast, a single AmCYP81 that was enhanced by NTSR, but not by safening, was found to dominate herbicide detoxification in blackgrass.

The need and demand for energy are ever increasing with the rapid urbanization of the global population. Near-future economic development and consequent expected industrialization are the strongest indicators of the rising energy requirement. Though fossil fuel and coal are catering toward a major chunk of energy demand, their negative or adverse impact in terms of emission of greenhouse gases (GHGs) and carbon dioxide (CO₂) is causing global warming and imbalance in environmental conditions, leading to a search for commercially viable alternate energy types. As renewable energies like solar and wind are weather-dependent, the search for an alternate energy supply needs to be done even more urgently. Hydrogen (H₂), being a carrier of alternate energy and not an energy source, can deliver or store a significant amount of energy. The stored energy can be utilized for the generation of power, electricity, and heat. Further, hydrogen is very pure in nature and therefore is widely useful from a flexibility and efficiency standpoint. It represents the predominant constituent within the natural environment, totaling about three-fourths of the universe. Storage of hydrogen has gained significance in recent times, and subsurface storage is being looked upon as a viable alternative. However, the successful storage of hydrogen in the subsurface is a function of critical parameters like wettability, capillary pressure, relative permeability, diffusion, microbial activities, etc., which themselves are dependent upon rock types with their corresponding mineralogical compositions, along with associated pressures and temperatures. This work critically reviews the impact that these parameters would have on the storability of hydrogen in the subsurface, evaluates the best possible solution, and recommends a future course of action through insights derived, which need to be considered while considering underground hydrogen storage.

Administration of drugs, especially antibiotics, via intravenous injections with different types of solutions is a common and widely applied treatment method in human and veterinary medicine. One of these antibiotics is oxytetracycline, which is a tetracycline. The aim of this article is to study the effect of temperature (5 °C, 40 °C) and light on the stability of oxytetracycline injections after dissolving different types of reconstitution solutions (sodium chloride 0.9%, dextrose 5%, sodium chloride 0.9% with dextrose 5%, Ringer). After 24 h, the concentration of the oxytetracycline was determined by the HPLC method. The results showed a decrease in the concentration of oxytetracycline due to the effect of high temperature (40 °C) and light in all solutions. On the other hand, the decrease in the concentration of oxytetracycline was less than on low temperature (5 °C) and light protection. The effect of the solution reconstitution solution was also evaluated where the stability of oxytetracycline was best in dextrose 5% solution, followed by sodium chloride 0.9%, Ringer’s solution, and mixed (dextrose with sodium chloride 0.9%). This paper recommends reconstituting oxytetracycline with 5% dextrose and storage under refrigeration away from light to maintain a better stability of oxytetracycline.

The environmental stability of 2D monolayers is critical for their applications across various technology-related fields. These monolayers can degrade when exposed to gaseous components in the environment, so minimizing these degrading effects is essential. In this paper, chlorine exposure to the 2D monolayers, specifically graphene, silicene, phosphorene, and h-BN monolayer, is investigated using van der Waals corrected density functional theory. The results find that atomic chlorine chemisorbs on graphene, h-BN, silicene, and phosphorene with adsorption energies of −1.09, −0.65, −3.10, and −1.74 eV/atom, and bond distances of 3.0, 2.6, 2.2, and 2.1 Å, respectively. In contrast, molecular Cl₂ exhibits physisorption with adsorption energies around −0.22 eV and bond distances ranging from 3.3 to 3.6 Å. NEB calculations show that Cl₂ dissociative chemisorption is exothermic on buckled monolayers (silicene and phosphorene) and endothermic on planar monolayers (graphene and h-BN). On buckled surfaces, Cl₂ dissociates after overcoming energy barriers of 2.0 eV for silicene and 3.2 eV for phosphorene, forming a stable chemisorbed state that is 0.9 eV lower than the physisorbed state. However, on planar monolayers, Cl₂ remains in the physisorbed state because the dissociated chemisorbed state is ≈ 1.5 eV higher in energy. These differences are due to the weaker π-bonds in buckled monolayers, which make dissociation easier, while planar monolayers stabilize the molecular form.

Exposure to organophosphate-based nerve agents and pesticides poses health and security threats to civilians, soldiers, and first responders. Thus, there is a need to develop effective decontamination agents that are nonhazardous to human health. To address this, we demonstrate that instantaneous hydrolysis of methyl paraoxon (Me-POX), a nerve agent simulant, can be achieved in the presence of aminoguanidine imines at pH 10: ● the pyridine-4-aldehyde aminoguanidine-imine (1) and ● the 2,3-butanedione aminoguanidine-imine (2). The hydrolysis of Me-POX under these conditions is substantially faster than that of the state-of-the-art decontaminating agent, Dekon-139 (2,3-butanedione oxime, potassium salt). Furthermore, Dekon-139 shows adverse effects when applied on skin surfaces, making it of great interest to develop safer but effective decontaminating agents for neutralizing nerve agents and pesticides exposed to skin-surface areas. Our pharmaceutically relevant aminoguanidine derivatives serve as rather nontoxic and safe decontaminating agents for organophosphate-based nerve agents and pesticides. The hydrolytic degradation products of Me-POX by our aminoguanidine-based imines and Dekon-139 are pH dependent. At pH > 10, Me-POX is hydrolyzed to give dimethyl phosphate as the exclusive product, whereas at pH < 9, the major product of hydrolysis is methyl 4-nitrophenyl phosphate (M4NP). We applied Quantum Mechanics calculations to investigate the mechanism of this dramatically accelerated decontamination process. We predict that in the rate-determining transition state, both 1 and 2 stabilize the reaction center through hydrogen bonding. Compared to Dekon-139, the rate constants of the rate-determine steps (RDS) are predicted to be over 9,000 times larger for 1 and over 600 times larger for 2, explaining the improvement. Quantum Mechanics calculations rationalize the pH-dependent hydrolysis products of the Me-POX in the gas phase, and gauge-including atomic orbital (GIAO)-³¹P NMR chemical shift calculations confirm the experimental values.

The growing demand for energy coupled with the need for environmental sustainability underscores the importance of advancing renewable energy technologies. Among these, geothermal energy stands out as a clean and sustainable resource with substantial potential for heating and power generation. However, the corrosion of materials in geothermal facilities presents a significant operational challenge. This study explores the development of a self-healing anticorrosive coating based on microcapsule technology to address this issue. The proposed coating releases corrosion inhibitors from the microcapsules upon damage, enabling autonomous repair. Microcapsules were fabricated with an oil-soluble imidazoline oleate corrosion inhibitor encapsulated in urea-formaldehyde resin and incorporated into an epoxy resin matrix. The resulting composite coating demonstrated enhanced self-healing properties. Key parameters, including the core-to-wall ratio, healing duration, and microcapsule concentration, were systematically examined for their influence on self-healing efficiency. The performance of the composite was rigorously evaluated through simulated geothermal water corrosion tests under conditions representative of geothermal systems. The results indicate that microcapsules with a core-to-wall ratio of 3:1, using OP-10 as an emulsifier at 0.5 wt % of the core material, exhibited optimal structural integrity and encapsulation efficiency (74.6% core content, 85.7% coating efficiency). Additionally, epoxy resin composites with microcapsule concentrations greater than 20 wt % exhibited effective self-healing of artificially induced damage, demonstrating superior anticorrosive properties crucial for geothermal applications. These findings suggest that the developed self-healing composite holds great potential for mitigating corrosion in geothermal energy systems, contributing to the durability and efficiency of geothermal facilities.

The continuous outbreak of various viruses reminds us to prepare broad-spectrum antiviral drugs. Human dihydroorotate dehydrogenase (hDHODH) inhibitor exhibits broad-spectrum antiviral effects. In order to explore the novel type of human dihydroorotate dehydrogenase inhibitor (hDHODHi), we have optimized, designed, and synthesized 17 compounds and conducted biological activity evaluation, molecular docking, and molecular dynamics studies. The results of biological activity evaluation showed that compounds 10 and 16 exhibited submicromolar inhibitory activity, with IC₅₀ values of 0.188 ± 0.004 and 0.593 ± 0.012 μM, respectively. Molecular docking studies showed that compounds 10 and 16 were in good agreement with the hDHODH activity pocket and interacted well with amino acid residues. Compared to the cocrystallized structure of the brequinar analogue complex, inhibitors 10 and 16 increased their direct interaction with Ala55. In addition, molecular dynamics studies showed that inhibitors 10 and 16 have strong affinity for proteins, and their complexes are stable, which confirms the significant inhibitory effect of inhibitors 10 and 16 on hDHODH in vitro. Through analysis, it was found that the carboxyl group and para introduced fluorine atoms in R¹, as well as the naphthalene in R², are key factors in improving activity. This conclusion provides help for further research into hDHODH inhibitors in the future. This study has promoted the significance of the development of broad-spectrum antiviral drugs.