-
Chemistry, An Asian Journal Jan 2024In recent years, the field of organometallic chemistry has made a great progress and diverse types of metallaaromatics have successively been reported. In those studies,... (Review)
Review
In recent years, the field of organometallic chemistry has made a great progress and diverse types of metallaaromatics have successively been reported. In those studies, incorporation of ligated osmium centers into metallaaromatic systems played a prominent role. The reviewed literature documents that certain metallaaromatics with unconventional photophysical properties, redox and electronic transport properties and magnetism, have potential to be widely used in diverse practical applications, with selected examples of amino acid and fluoride anion identification, photothermal effects, functional materials, photodynamic therapy (PDT) in biomedicine, single-molecule junction conductors, and electron-transport layer materials (ETLs) in solar cells.
PubMed: 37997007
DOI: 10.1002/asia.202300860 -
ACS Sensors Nov 2023Diabetes is a chronic disease caused by a decrease in insulin level or insulin resistance. Diabetes also has detrimental effects on the brain, which can lead to the...
Diabetes is a chronic disease caused by a decrease in insulin level or insulin resistance. Diabetes also has detrimental effects on the brain, which can lead to the injury of the blood-brain barrier and influence the glucose transport. In this study, we use in vivo electrochemical measurement to explore the glucose variation in the brain of early diabetic mice. The glucose level in mice brain is measured using a carbon fiber microelectrode modified with the osmium-derivatized polymer and glucose oxidase. The electrode shows an excellent electrochemical performance, antibiofouling ability, and high stability, which can work stably in the mice brain for 2 h. By monitoring the glucose level in the brain of normal and diabetic mice after injection of concentrated glucose solution into the abdominal cavity, it is found that the variation of cerebral glucose decreases by ∼2 fold for diabetic mice. It is proposed that diabetes can downregulate the activity of glucose transporter in the brain and finally inhibit the brain glucose uptake.
Topics: Mice; Animals; Glucose; Diabetes Mellitus, Experimental; Brain; Glucose Oxidase; Microelectrodes
PubMed: 37950693
DOI: 10.1021/acssensors.3c01165 -
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 -
Data in Brief Dec 2023This paper presents a dataset offering profound insights into the formation and physical properties of two-dimensional (2D) noble metals under various configurations,...
This paper presents a dataset offering profound insights into the formation and physical properties of two-dimensional (2D) noble metals under various configurations, with a primary focus on their role as catalysts for the hydrogen evolution reaction (HER). These data are of significant value to catalysis researchers, materials scientists, and computational chemists, providing them with a detailed understanding of 2D noble metals' behavior as catalysts and enabling advancements in their respective studies. The dataset, thoughtfully structured and meticulously documented, comprises five primary sections, each housing distinct content and analyses. It offers a comprehensive view of the substrate-mediated stabilization and physical properties of 2D noble metals, including silver (Ag), gold (Au), iridium (Ir), osmium (Os), palladium (Pd), platinum (Pt), rhodium (Rh), and ruthenium (Ru). The substrates utilized include bare Si-face 4H-SiC, buffer layer (BuL), and monolayer epitaxial graphene (MEG). The data collection process involves the use of the SIESTA code for density functional theory (DFT) calculations. The vdW-BH functional is consistently applied in conjunction with a double-ζ polarized (DZP) basis set, known for its reliability in capturing nuanced interactions with noble metals. Parameters such as an energy shift of 200 meV and a force tolerance of 0.02 eV/Å are meticulously configured for accurate results. In-depth structural information, including optimized structures in top and side views and Cartesian coordinates for various substrate-metal configurations, is a central component of the dataset. These structural details are pivotal for comprehending the physical properties of 2D noble metals. Furthermore, the dataset encompasses results from charge density difference (CDD) analyses, including cube files, planar-averaged CDD curves, and 3D CDD maps. These analyses provide essential data for understanding the electronic properties of these materials. The dataset also includes outcomes from charge population analyses utilizing Hirshfeld and Voronoi schemes. These analyses offer insights into structural parameters, Hirshfeld charge magnitudes on 2D metal layers, and various energy-related metrics, further enhancing the dataset's richness. In addition to structural data, the dataset presents atomic structures in top and side views of free-standing and substrate-supported 2D noble metals after hydrogen adsorption, along with corresponding Cartesian coordinates. Gibbs free energy (Δ) data for hydrogen adsorption on both free-standing and substrate-supported 2D noble metals contribute to the dataset's depth. This meticulously curated dataset not only serves as a valuable resource for researchers exploring the properties and behaviors of 2D noble metals but also holds significant reuse potential. Researchers can employ this dataset to validate their computational methods and models in catalysis research, enhancing the quality and reliability of their simulations. Furthermore, it serves as a possible educational tool, fostering hands-on learning for students and emerging researchers in the field of computational materials science and catalysis, thereby promoting methodological consistency within the scientific community.
PubMed: 38053595
DOI: 10.1016/j.dib.2023.109801 -
Scientific Reports Oct 2023We have successfully synthesized three osmium-based hexagonal Laves compounds ROs (R = Sc, Y, Lu), and discussed their physical properties. LeBail refinement of pXRD...
We have successfully synthesized three osmium-based hexagonal Laves compounds ROs (R = Sc, Y, Lu), and discussed their physical properties. LeBail refinement of pXRD data confirms that all compounds crystallize in the hexagonal centrosymmetric MgZn-type structure (P6/mmc, No. 194). The refined lattice parameters are a = b = 5.1791(1) Å and c = 8.4841(2) Å for ScOs, a = b = 5.2571(3) Å and c = 8.6613(2) Å for LuOs and a = b = 5.3067(6) Å and c = 8.7904(1) Å for YOs. ROs Laves phases can be viewed as a stacking of kagome nets interleaved with triangular layers. Temperature-dependent magnetic susceptibility, resistivity and heat capacity measurements confirm bulk superconductivity at critical temperatures, T, of 5.36, 4.55, and 3.47 K for ScOs, YOs, and LuOs, respectively. We have shown that all investigated Laves compounds are weakly-coupled type-II superconductors. DFT calculations revealed that the band structure of ROs is intricate due to multiple interacting d orbitals of Os and R. Nonetheless, the kagome-derived bands maintain their overall shape, and the Fermi level crosses a number of bands that originate from the kagome flat bands, broadened by interlayer interaction. As a result, ROs can be classified as (breathing) kagome metal superconductors.
PubMed: 37794026
DOI: 10.1038/s41598-023-43621-w -
Chemical Science Nov 2023Photodynamic therapy (PDT) is a medical technique for the treatment of cancer. It is based on the use of non-toxic molecules, called photosensitizers (PSs), that become...
Photodynamic therapy (PDT) is a medical technique for the treatment of cancer. It is based on the use of non-toxic molecules, called photosensitizers (PSs), that become toxic when irradiated with light and produce reactive oxygen specious (ROS) such as singlet oxygen (O). This light-induced toxicity is rather selective since the physician only targets a specific area of the body, leading to minimal side effects. Yet, a strategy to improve further the selectivity of this medical technique is to confine the delivery of the PS to cancer cells only instead of spreading it randomly throughout the body prior to light irradiation. To address this problem, we present here novel sulfonamide-based monopodal and dipodal ruthenium and osmium polypyridyl complexes capable of targeting carbonic anhydrases (CAs) that are a major target in cancer therapy. CAs are overexpressed in the membrane or cytoplasm of various cancer cells. We therefore anticipated that the accumulation of our complexes in or outside the cell prior to irradiation would improve the selectivity of the PDT treatment. We show that our complexes have a high affinity for CAs, accumulate in cancer cells overexpressing CA cells and importantly kill cancer cells under both normoxic and hypoxic conditions upon irradiation at 540 nm. More importantly, Os(ii) compounds still exhibit some phototoxicity under 740 nm irradiation under normoxic conditions. To our knowledge, this is the first description of ruthenium/osmium-based PDT PSs that are CA inhibitors for the selective treatment of cancers.
PubMed: 37920359
DOI: 10.1039/d3sc03932c -
Chemistry, An Asian Journal Dec 2023The versatile coordinating nature of N,S bidentate ligands is of great importance in medicinal chemistry imparting stability and enhancing biological properties of the...
The versatile coordinating nature of N,S bidentate ligands is of great importance in medicinal chemistry imparting stability and enhancing biological properties of the metal complexes. Phenylthiocarbamide-based N,S donor Schiff bases converted into Ru /Os (cymene) complexes and characterized by spectroscopic techniques and elemental analysis. The hydrolytic stability of metal complexes to undergo metal-halide ligand exchange reaction was confirmed both by the DFT and NMR experimentation. The ONIOM (QM/MM) study confirmed the histone protein targeting nature of aqua/hydroxido complex 2 aH with an excellent binding energy of -103.19 kcal/mol. The antiproliferative activity against a panel of cancer cells A549, MCF-7, PC-3, and HepG2 revealed that ruthenium complexes 1 a-3 a were more cytotoxic than osmium complexes and their respective ligands 1-3 as well. Among these ruthenium cymene complex bearing sulfonamide moiety 2 a proved a strong cytotoxic agent and showed excellent correlation of cellular accumulation, lipophilicity, and drug-likeness to the anticancer activity. Moreover, the favorable physiochemical properties such as bioavailability and gastrointestinal absorption of ligand 2 also supported the development of Ru complex 2 a as an orally active anticancer metallodrug.
Topics: Coordination Complexes; Cymenes; Ligands; Ruthenium; Schiff Bases; Antineoplastic Agents; Cell Line, Tumor
PubMed: 37737043
DOI: 10.1002/asia.202300804 -
Biological Psychiatry Aug 2023Connectomics allows mapping of cells and their circuits at the nanometer scale in volumes of approximately 1 mm. Given that the human cerebral cortex can be 3 mm in...
Connectomics allows mapping of cells and their circuits at the nanometer scale in volumes of approximately 1 mm. Given that the human cerebral cortex can be 3 mm in thickness, larger volumes are required. Larger-volume circuit reconstructions of human brain are limited by 1) the availability of fresh biopsies; 2) the need for excellent preservation of ultrastructure, including extracellular space; and 3) the requirement of uniform staining throughout the sample, among other technical challenges. Cerebral cortical samples from neurosurgical patients are available owing to lead placement for deep brain stimulation. Described here is an immersion fixation, heavy metal staining, and tissue processing method that consistently provides excellent ultrastructure throughout human and rodent surgical brain samples of volumes 2 × 2 × 2 mm and up to 37 mm with one dimension ≤2 mm. This method should allow synapse-level circuit analysis in samples from patients with psychiatric and neurologic disorders.
Topics: Humans; Connectome; Immersion; Microscopy, Electron; Staining and Labeling; Brain; Biopsy
PubMed: 36740206
DOI: 10.1016/j.biopsych.2023.01.025 -
Microscopy Research and Technique Dec 2023Midthermic machine perfusion (MMP) of post-circulatory arrest donor liver grafts has the advantage of preserving the functional ultrastructure of hepatocytes in donor...
Midthermic machine perfusion (MMP) of post-circulatory arrest donor liver grafts has the advantage of preserving the functional ultrastructure of hepatocytes in donor grafts. It was reported that oxygenation during MMP reduces portal venous resistance and increases bile production. The MMP with hemoglobin-based oxygen vesicles (HbV) keeps the lower aspartate aminotransferase level (an indicator of liver injury) and maintains the functional ultrastructure of mitochondria in the hepatocytes. To evaluated differences of ultrastructural damages in donor livers between the MMP with and without HbV, porcine liver grafts after 60 min of warm ischemia were perfused at 22°C for 4 h with or without HbV, and a part of liver grafts were analyzed by transmission electron microscopy (TEM) and osmium-maceration scanning electron microscopy (OM-SEM). The remaining grafts were perfused with autologous blood at 38°C for 2 h in an isolated liver reperfusion model (IRM) that mimics the inside of the body after transplantation, and then analyzed by TEM and OM-SEM. Hepatocytes after MMP had small round mitochondria with rod-shaped cristae and reticulovesicular rough endoplasmic reticulum (rER) in both HbV(+) and HbV(-) livers. After IRM of HbV(+) livers, the well-developed lamellar rER was often found in hepatocytes. Liver sinusoidal endothelial cells (LSECs) after MMP contained some large vacuolar structures containing amorphous garbage in the cytoplasm, and their size along with appearance frequency were smaller and lower, respectively, in HbV(+) livers than HbV(-). Oxygenation during the MMP by using HbV suppressed the ultrastructural damages in donor livers, in particular for the LSECs. RESEARCH HIGHLIGHTS: Liver sinusoidal endothelial cells after midthermic machine perfusion had large vacuolar organelles with amorphous garbage. Oxygenation during the perfusion made them less and smaller, ultrastructurally supporting its utility.
Topics: Swine; Animals; Humans; Liver Transplantation; Oxygen; Endothelial Cells; Organ Preservation; Perfusion; Living Donors; Liver; Death; Hemoglobins
PubMed: 37656974
DOI: 10.1002/jemt.24405 -
Journal of Medical Imaging (Bellingham,... Sep 2023Assessing the complex three-dimensional (3D) structure of the cochlea is crucial to understanding the fundamental aspects of signal transduction in the inner ear and is...
PURPOSE
Assessing the complex three-dimensional (3D) structure of the cochlea is crucial to understanding the fundamental aspects of signal transduction in the inner ear and is a prerequisite for the development of novel cochlear implants. X-ray phase-contrast computed tomography offers destruction-free 3D imaging with little sample preparation, thus preserving the delicate structure of the cochlea. The use of heavy metal stains enables higher contrast and resolution and facilitates segmentation of the cochlea.
APPROACH
For μ-CT of small animal and human cochlea, we explore the heavy metal osmium tetroxide (OTO) as a radiocontrast agent and delineate laboratory from synchrotron CT. We investigate how phase retrieval can be used to improve the image quality of the reconstructions, both for stained and unstained specimens.
RESULTS
Image contrast for soft tissue in an aqueous solution is insufficient under the in-house conditions, whereas the OTO stain increases contrast for lipid-rich tissue components, such as the myelin sheaths in nervous tissue, enabling contrast-based rendering of the different components of the auditory nervous system. The overall morphology of the cochlea with the three scalae and membranes is very well represented. Further, the image quality of the reconstructions improves significantly when a phase retrieval scheme is used, which is also suitable for non-ideal laboratory settings. With highly brilliant synchrotron radiation (SR), we achieve high contrast for unstained whole cochleae at the cellular level.
CONCLUSIONS
The OTO stain is suitable for 3D imaging of small animal and human cochlea with laboratory , and relevant pathologies, such as a loss of sensory cells and neurons, can be visualized. With SR and optimized phase retrieval, the cellular level can be reached even for unstained samples in aqueous solution, as demonstrated by the high visibility of single hair cells and spiral ganglion neurons.
PubMed: 37753271
DOI: 10.1117/1.JMI.10.5.053501