-
ACS Nano Apr 2024Highly efficient, cost-effective, and durable electrocatalysts, capable of accelerating sluggish reaction kinetics and attaining high performance, are essential for...
Highly efficient, cost-effective, and durable electrocatalysts, capable of accelerating sluggish reaction kinetics and attaining high performance, are essential for developing sustainable energy technologies but remain a great challenge. Here, we leverage a facile heterostructure design strategy to construct atomically thin Os@Pd metallenes, with atomic-scale Os nanoclusters of varying geometries confined on the surface layer of the Pd lattice, which exhibit excellent bifunctional properties for catalyzing both hydrogen evolution (HER) and oxygen reduction reactions (ORR). Importantly, Os@Pd metallenes manifest a low η overpotential of only 11 mV in 1.0 M KOH electrolyte (HER) as well as a highly positive potential of 0.92 V in 0.1 M KOH (ORR), along with superior mass activities and electrochemical durability. Theoretical investigations reveal that the strong electron redistribution between Os and Pd elements renders a precise fine-tuning of respective d-band centers, thereby guiding adsorption of hydrogen and oxygen intermediates with an appropriate binding energy for the optimal HER and ORR.
PubMed: 38552006
DOI: 10.1021/acsnano.3c10219 -
Angewandte Chemie (International Ed. in... May 2024The photocatalytic reduction of carbon dioxide (CO) represents an attractive approach for solar-energy storage and leads to the production of renewable fuels and...
The photocatalytic reduction of carbon dioxide (CO) represents an attractive approach for solar-energy storage and leads to the production of renewable fuels and valuable chemicals. Although some osmium (Os) photosensitizers absorb long wavelengths in the visible-light region, a self-photosensitized, mononuclear Os catalyst for red-light-driven CO reduction has not yet been exploited. Here, we discovered that the introduction of an Os metal to a PNNP-type tetradentate ligand resulted in the absorption of light with longer-wavelength (350-700 nm) and that can be applied to a panchromatic self-photosensitized catalyst for CO reduction to give mainly carbon monoxide (CO) with a total turnover number (TON) of 625 under photoirradiation (λ≥400 nm). CO photoreduction also proceeded under irradiation with blue (λ=405 nm), green (λ=525 nm), or red (λ=630 nm) light to give CO with >90 % selectivity. The quantum efficiency using red light was determined to be 12 % for the generation of CO. A catalytic mechanism is proposed based on the detection of intermediates using various spectroscopic techniques, including transient absorption, electron paramagnetic resonance, and UV/Vis spectroscopy.
PubMed: 38545689
DOI: 10.1002/anie.202403886 -
Methods in Molecular Biology (Clifton,... 2024The study of the localization of secondary metabolites in both plants and the cell cultures on the intravital sections is hampered by the difficulty of obtaining thin,...
The study of the localization of secondary metabolites in both plants and the cell cultures on the intravital sections is hampered by the difficulty of obtaining thin, correctly oriented sections. Techniques for fixing tissues in resins allow these difficulties to be overcome. Properly selected tissue fixation techniques allow using different dyes to identify the compound of interest. In addition, some components of tissue fixation can act as fixatives and as a dye for identifying secondary metabolites. For example, osmium tetroxide, which fixes lipids in tissues, stains phenolic compounds black. This paper describes methods for the detection of phenolic compounds in morphogenic callus culture of buckwheat using osmium tetroxide, Toluidine Blue O dye, and ferric chloride as dyes in epoxy resin-embedded cell culture with double fixation of the material and when material fixed in Karnovsky's fixative.
Topics: Coloring Agents; Osmium Tetroxide; Chlorides; Tolonium Chloride; Fagopyrum; Fixatives; Tissue Fixation; Cell Culture Techniques; Iron; Osmium; Ferric Compounds
PubMed: 38532090
DOI: 10.1007/978-1-0716-3794-4_4 -
FLEX: genetically encodable enzymatic fluorescence signal amplification using engineered peroxidase.Cell Chemical Biology Mar 2024Fluorescent tagging of biomolecules enables their sensitive detection during separation and determining their subcellular location. In this context, peroxidase-based...
Fluorescent tagging of biomolecules enables their sensitive detection during separation and determining their subcellular location. In this context, peroxidase-based reactions are actively utilized for signal amplification. To harness this potential, we developed a genetically encodable enzymatic fluorescence signal amplification method using APEX (FLEX). We synthesized a fluorescent probe, Jenfluor triazole (JFT1), which effectively amplifies and restricts fluorescence signals under fixed conditions, enabling fluorescence-based detection of subcellularly localized electron-rich metabolites. Moreover, JFT1 exhibited stable fluorescence signals even under osmium-treated and polymer-embedded conditions, which supported findings from correlative light and electron microscopy (CLEM) using APEX. Using various APEX-conjugated proteins of interest (POIs) targeted to different organelles, we successfully visualized their localization through FLEX imaging while effectively preserving organelle ultrastructures. FLEX provides insights into dynamic lysosome-mitochondria interactions upon exposure to chemical stressors. Overall, FLEX holds significant promise as a sensitive and versatile system for fluorescently detecting APEX2-POIs in multiscale biological samples.
PubMed: 38513646
DOI: 10.1016/j.chembiol.2024.02.007 -
Advanced Healthcare Materials Jun 2024Diabetic wounds are susceptible to bacterial infections, largely linked to high blood glucose levels (hyperglycemia). To treat such wounds, enzymes like glucose oxidase...
Diabetic wounds are susceptible to bacterial infections, largely linked to high blood glucose levels (hyperglycemia). To treat such wounds, enzymes like glucose oxidase (GOx) can be combined with nanozymes (nanomaterials mimic enzymes) to use glucose effectively for purposes. However, there is still room for improvement in these systems, particularly in terms of process simplification, enzyme activity regulation, and treatment effects. Herein, the approach utilizes GOx to directly facilitate the biomineralized growth of osmium (Os) nanozyme (GOx-OsNCs), leading to dual-active centers and remarkable triple enzyme activities. Initially, GOx-OsNCs use vicinal dual-active centers, enabling a self-cascaded mechanism that significantly enhances glucose sensing performance compared to step-by-step reactions, surpassing the capabilities of other metal sources such as gold and platinum. In addition, GOx-OsNCs are integrated into a glucose-sensing gel, enabling instantaneous visual feedback. In the treatment of infected diabetic wounds, GOx-OsNCs exhibit multifaceted benefits by lowering blood glucose levels and exhibiting antibacterial properties through the generation of hydroxyl free radicals, thereby expediting healing by fostering a favorable microenvironment. Furthermore, the catalase-like activity of GOx-OsNCs aids in reducing oxidative stress, inflammation, and hypoxia, culminating in improved healing outcomes. Overall, this synergistic enzyme-nanozyme blend is user-friendly and holds considerable promise for diverse applications.
Topics: Glucose Oxidase; Animals; Osmium; Anti-Bacterial Agents; Wound Healing; Mice; Blood Glucose; Diabetes Mellitus, Experimental; Humans; Glucose; Wound Infection
PubMed: 38507709
DOI: 10.1002/adhm.202303548 -
Angewandte Chemie (International Ed. in... May 2024Herein, multiple types of chiral Os(II) complexes have been designed to address the appealing yet challenging asymmetric C(sp)-H functionalization, among which the...
Chiral Osmium(II)/Salox Species Enabled Enantioselective γ-C(sp)-H Amidation: Integrated Experimental and Computational Validation For the Ligand Design and Reaction Development.
Herein, multiple types of chiral Os(II) complexes have been designed to address the appealing yet challenging asymmetric C(sp)-H functionalization, among which the Os(II)/Salox species is found to be the most efficient for precise stereocontrol in realizing the asymmetric C(sp)-H amidation. As exemplified by the enantioenriched pyrrolidinone synthesis, such tailored Os(II)/Salox catalyst efficiently enables an intramolecular site-/enantioselective C(sp)-H amidation in the γ-position of dioxazolone substrates, in which benzyl, propargyl and allyl groups bearing various substituted forms are well compatible, affording the corresponding chiral γ-lactam products with good er values (up to 99 : 1) and diverse functionality (>35 examples). The unique performance advantage of the developed chiral Os(II)/Salox system in terms of the catalytic energy profile and the chiral induction has been further clarified by integrated experimental and computational studies.
PubMed: 38499469
DOI: 10.1002/anie.202401498 -
Science Progress 2024Termites cause a serious menace to wooden structures all over the world. They rely mostly on entozoic fauna residing in their hindgut for the digestion of cellulosic and...
Termites cause a serious menace to wooden structures all over the world. They rely mostly on entozoic fauna residing in their hindgut for the digestion of cellulosic and hemicellulosic materials. One of the ways to control termites is through their gut symbionts. The present study was designed to characterize the hindgut bacteria isolated from and . Furthermore, the growth inhibitory effect of eight tropical plant extracts was investigated to find out potential control agents for these bacterial isolates. The characterization of bacteria was carried out based on their morphology, Gram staining, biochemical and amplification of 16SrRNA gene. Amplified products were sequenced to confirm their relationship with bacterial isolates from termites of other regions. The growth inhibitory effect of ethanolic leaf extracts of eight plants was evaluated in an invitro agar well diffusion method. Qualitative and quantitative phytochemical analysis of the most effective plant was carried out to learn about bioactive agents. The results confirmed the presence of five bacteria from each termite species. The , and were common to both termites whereas and were found in only and harbor and in addition to common three ones. Among the plant extracts of , , , and , the > were found to have growth inhibitory effects with increasing concentrations from 100 to 2000 µg/mL. The biodiversity of the bacterial fauna is important for the biological control of termites. Leaf extracts of these medicinal plants can be used to control termite infestation in an environment-friendly manner to save huge economic loss.
Topics: Animals; Isoptera; Bacteria; Plant Extracts; Biodiversity
PubMed: 38490163
DOI: 10.1177/00368504241236026 -
Inorganic Chemistry Apr 2024Deprotonation of the thioamidate group of [OsH{κ-,-[NHC(CH)S]}(≡CPh)(IPr)(PPr)]OTf [; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolylidene; OTf = CFSO] results in the...
Deprotonation of the thioamidate group of [OsH{κ-,-[NHC(CH)S]}(≡CPh)(IPr)(PPr)]OTf [; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolylidene; OTf = CFSO] results in the release of acetonitrile and formation of the terminal sulfide complex OsH(S)(≡CPh)(IPr)(PPr) (), which has been transformed into the hydrosulfide [OsH(SH)(≡CPh)(IPr)(PPr)]OTf () and the methylsulfide [OsH(SMe)(≡CPh)(IPr)(PPr)]OTf () through protonation and methylation reactions, respectively. The structure, spectroscopic characteristics, and reactivity of these compounds are compared. Reactions of and with 2-hydroxypyridine and 2-mercaptopyridine afford [OsH{κ-,-[X-py]}(≡CPh)(IPr)(PPr)]OTf [X = O (), S()].
PubMed: 38488723
DOI: 10.1021/acs.inorgchem.4c00596 -
Nanoscale Mar 2024Two spherical nanoparticulate materials were prepared by base-catalyzed sol-gel hydrolysis/self-condensation of the bis- alkaloid-phthalazine-based bridged...
Two spherical nanoparticulate materials were prepared by base-catalyzed sol-gel hydrolysis/self-condensation of the bis- alkaloid-phthalazine-based bridged bis(triethoxysilanes). For the purpose of comparing the catalytic properties, two compact materials were also prepared from the same precursors using a fluoride-catalyzed sol-gel process. All materials were characterized by SEM, TEM, solid-state Si NMR and C NMR, TGA, and FTIR. The prepared silsesquioxane-based materials were studied as potential heterogeneous catalysts for selected enantioselective reactions. The spherical material with regularly incorporated bis-quinine-phthalazine chiral units exhibited good to excellent enantioselectivities in osmium-catalyzed dihydroxylations of alkenes. Enantioselectivities observed in dihydroxylations of aromatic -alkenes were as excellent as those observed with the homogeneous catalyst (DHQ)-PHAL. One compact and one nanoparticulate material was successfully recycled and reused five times without loss of enantioselectivity. Furthermore, both quinine-based and cinchonine-based materials were tested as heterogeneous organocatalysts for chlorolactonization of 4-arylpent-4-enoic acids. The materials showed only moderate enantioselectivities; however, these are the first heterogeneous catalysts for enantioselective chlorolactonization published so far.
PubMed: 38487903
DOI: 10.1039/d3nr06234a -
Molecules (Basel, Switzerland) Feb 2024A series of new chelating bidentate (SS) alkylimidazole-2-thione-Ru(II)/Os(II) complexes (, , , /, , ), and the tridentate (SNS)...
A series of new chelating bidentate (SS) alkylimidazole-2-thione-Ru(II)/Os(II) complexes (, , , /, , ), and the tridentate (SNS) pyridine-2,6-diylimidazole-2-thione-Ru(II)/Os(II) complexes (, /, , ) in the forms [M(cym)(L)Cl]PF and [M(cym)(L)]PF (M = Ru or Os, cym = η--cymene, and L = heterocyclic derivatives of thiourea) respectively, were successfully synthesized. Spectroscopic and analytical methods were used to characterize the complexes and their ligands. Solid-state single-crystal X-ray diffraction analyses revealed a "piano-stool" geometry around the Ru(II) or Os(II) centers in the respective complexes. The complexes were investigated for in vitro chemotherapeutic activities against human cervical carcinoma (HeLa) and the non-cancerous cell line (Hek293) using the MTT assay. The compounds , , , , , , and the reference drug, 5-fluorouracil were found to be selective toward the tumor cells; the compounds , , , , , and , which were found not to be selective between normal and tumor cell lines. The IC value of the tridentate half-sandwich complex (86 ± 9 μM) showed comparable anti-proliferative activity with the referenced commercial anti-cancer drug, 5-fluorouracil (87 ± 15 μM). The pincer (SNS) osmium complexes (36 ± 10 μM) and (40 ± 4 μM) were twice as effective as the reference drug 5-fluorouracil at the respective dose concentrations. However, the analogous pincer (SNS) ruthenium complex was ineffective and did not show anti-proliferative activity, even at a higher concentration of 147 ± 1 μM. These findings imply that the higher stability of the chelating (SS) and the pincer (SNS) ligand architectures in the complexes improves the biological (anti-proliferative) activity of the complexes by reducing the chance of ligand dissociation under physiological conditions. In general, the pincer (SNS) osmium complexes were found to be more cytotoxic than their ruthenium analogues, suggesting that the anti-proliferative activity of the imidazole-2-thione-Ru/Os complexes depends on the ligand's spatial coordination, the nature of the metal center, and the charge of the metal complex ions.
Topics: Humans; Ruthenium; Osmium; Ligands; HEK293 Cells; Thiones; Chelating Agents; Antineoplastic Agents; Coordination Complexes; Cell Line, Tumor; Fluorouracil; Cymenes
PubMed: 38474456
DOI: 10.3390/molecules29050944