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Molecules (Basel, Switzerland) Mar 2021The synthesis of cyclometalated osmium complexes is usually more complicated than of other transition metals such as Ni, Pd, Pt, Rh, where cyclometalation reactions... (Review)
Review
The synthesis of cyclometalated osmium complexes is usually more complicated than of other transition metals such as Ni, Pd, Pt, Rh, where cyclometalation reactions readily occur via direct activation of C-H bonds. It differs also from their ruthenium analogs. Cyclometalation for osmium usually occurs under more severe conditions, in polar solvents, using specific precursors, stronger acids, or bases. Such requirements expand reaction mechanisms to electrophilic activation, transmetalation, and oxidative addition, often involving C-H bond activations. Osmacycles exhibit specific applications in homogeneous catalysis, photophysics, bioelectrocatalysis and are studied as anticancer agents. This review describes major synthetic pathways to osmacycles and related compounds and discusses their practical applications.
PubMed: 33809231
DOI: 10.3390/molecules26061563 -
Frontiers in Cellular and Infection... 2021Accumulating evidence indicates that high-fat diet (HFD) is a controllable risk factor for osteoporosis, but the underlying mechanism remains to be elucidated. As a...
BACKGROUND
Accumulating evidence indicates that high-fat diet (HFD) is a controllable risk factor for osteoporosis, but the underlying mechanism remains to be elucidated. As a primary biological barrier for nutrient entry into the human body, the composition and function of gut microbiota (GM) can be altered rapidly by HFD, which may trigger abnormal bone metabolism. In the current study, we analyzed the signatures of GM and serum metabolomics in HFD-induced bone loss and explored the potential correlations of GM and serum metabolites on HFD-related bone loss.
METHODS
We conducted a mouse model with HFD-induced bone loss through a 12-week diet intervention. Micro-CT, Osmium-μCT, and histological analyses were used to observe bone microstructure and bone marrow adipose tissue. Quantitative Real-Time PCR was applied to analyze gene expression related to osteogenesis, adipogenesis, and osteoclastogenesis. Enzyme-linked immunosorbent assay was used to measure the biochemical markers of bone turnover. 16s rDNA sequencing was employed to analyze the abundance of GM, and UHPLC-MS/MS was used to identify serum metabolites. Correlation analysis was performed to explore the relationships among bone phenotypes, GM, and the metabolome.
RESULTS
HFD induced bone loss accompanied by bone marrow adipose tissue expansion and bone formation inhibition. In the HFD group, the relative abundance of was increased significantly, while , , , and were decreased compared with the ND group. Association analysis showed that thirty-two bacterial genera were significantly related to bone volume per tissue volume (BV/TV). One hundred and forty-five serum metabolites were identified as differential metabolites associated with HFD intervention, which were significantly enriched in five pathways, such as purine metabolism, regulation of lipolysis in adipocyte and cGMP-PKG signaling pathway. Sixty-four diffiential metabolites were matched to the MS2 spectra; and ten of them were positively correlated with BV/TV and five were negatively correlated with BV/TV.
CONCLUSIONS
These findings indicated that the alternations of GM and serum metabolites were related to HFD-induced bone loss, which might provide new insights into explain the occurrence and development of HFD-related osteoporosis. The regulatory effects of GM and metabolites associated with HFD on bone homeostasis required further exploration.
Topics: Adipose Tissue; Animals; Diet, High-Fat; Gastrointestinal Microbiome; Mice; Mice, Inbred C57BL; Tandem Mass Spectrometry
PubMed: 35004355
DOI: 10.3389/fcimb.2021.788576 -
Methods in Molecular Biology (Clifton,... 2019Immuno-EM is a method that can determine the localization of a protein in a tissue at the ultrastructural level. Generally, membrane structures in immuno-EM specimens...
Immuno-EM is a method that can determine the localization of a protein in a tissue at the ultrastructural level. Generally, membrane structures in immuno-EM specimens have very low contrast because fixation is performed without osmium. Here, by using high-angle annular dark field (HAADF)-scanning transmission electron microscopy (STEM) instead of transmission electron microscopy (TEM) for observation of immuno-EM samples, we demonstrate that photoreceptor disk membranes are clearly visible and that the procedures described in this article can be extended to visualize other membrane structures.
Topics: Biomarkers; Microscopy, Electron, Scanning Transmission; Microscopy, Immunoelectron; Retina
PubMed: 30324452
DOI: 10.1007/978-1-4939-8669-9_20 -
Scientific Reports Apr 2017Nanodiamonds containing fluorescent nitrogen-vacancy centers are increasingly attracting interest for use as a probe in biological microscopy. This interest stems from...
Nanodiamonds containing fluorescent nitrogen-vacancy centers are increasingly attracting interest for use as a probe in biological microscopy. This interest stems from (i) strong resistance to photobleaching allowing prolonged fluorescence observation times; (ii) the possibility to excite fluorescence using a focused electron beam (cathodoluminescence; CL) for high-resolution localization; and (iii) the potential use for nanoscale sensing. For all these schemes, the development of versatile molecular labeling using relatively small diamonds is essential. Here, we show the direct targeting of a biological molecule with nanodiamonds as small as 70 nm using a streptavidin conjugation and standard antibody labelling approach. We also show internalization of 40 nm sized nanodiamonds. The fluorescence from the nanodiamonds survives osmium-fixation and plastic embedding making them suited for correlative light and electron microscopy. We show that CL can be observed from epon-embedded nanodiamonds, while surface-exposed nanoparticles also stand out in secondary electron (SE) signal due to the exceptionally high diamond SE yield. Finally, we demonstrate the magnetic read-out using fluorescence from diamonds prior to embedding. Thus, our results firmly establish nanodiamonds containing nitrogen-vacancy centers as unique, versatile probes for combining and correlating different types of microscopy, from fluorescence imaging and magnetometry to ultrastructural investigation using electron microscopy.
PubMed: 28389652
DOI: 10.1038/s41598-017-00797-2 -
International Journal of Molecular... Jul 2021Photodynamic therapy (PDT) has become an alternative to standard cancer treatment methods such as surgery, chemotherapy and radiotherapy. The uniqueness of this method... (Review)
Review
Photodynamic therapy (PDT) has become an alternative to standard cancer treatment methods such as surgery, chemotherapy and radiotherapy. The uniqueness of this method relies on the possibility of using various photosensitizers (PS) that absorb and convert light emission in radical oxygen-derived species (ROS). They can be present alone or in the presence of other compounds such as metal organic frameworks (MOFs), non-tubules or polymers. The interaction between DNA and metal-based complexes plays a key role in the development of new anti-cancer drugs. The use of coordination compounds in PDT has a significant impact on the amount ROS generated, quantum emission efficiency (Φem) and phototoxic index (PI). In this review, we will attempt to systematically review the recent literature and analyze the coordination complexes used as PS in PDT. Finally, we compared the anticancer activities of individual coordination complexes and discuss future perspectives. So far, only a few articles link so many transition metal ion coordination complexes of varying degrees of oxidation, which is why this review is needed by the scientific community to further expand this field worldwide. Additionally, it serves as a convenient collection of important, up-to-date information.
Topics: Cell Line, Tumor; Humans; Metal-Organic Frameworks; Neoplasms; Photochemotherapy; Photosensitizing Agents; Reactive Oxygen Species
PubMed: 34360819
DOI: 10.3390/ijms22158052 -
Philosophical Transactions. Series A,... Mar 2015Platinum compounds are a mainstay of cancer chemotherapy, with over 50% of patients receiving platinum. But there is a great need for improvement. Major features of the... (Review)
Review
Platinum compounds are a mainstay of cancer chemotherapy, with over 50% of patients receiving platinum. But there is a great need for improvement. Major features of the cisplatin mechanism of action involve cancer cell entry, formation mainly of intrastrand cross-links that bend and unwind nuclear DNA, transcription inhibition and induction of cell-death programmes while evading repair. Recently, we discovered that platinum cross-link formation is not essential for activity. Monofunctional Pt compounds such as phenanthriplatin, which make only a single bond to DNA nucleobases, can be far more active and effective against a range of tumour types. Without a cross-link-induced bend, monofunctional complexes can be accommodated in the major groove of DNA. Their biological mechanism of action is similar to that of cisplatin. These discoveries opened the door to a large family of heavy metal-based drug candidates, including those of Os and Re, as will be described.
Topics: Antineoplastic Agents; Cross-Linking Reagents; DNA; DNA Repair; Drug Design; Humans; Models, Chemical; Neoplasms; Platinum; Transition Elements
PubMed: 25666060
DOI: 10.1098/rsta.2014.0185 -
Experimental Eye Research Aug 2022The distal outflow pathway of the human eye consists of the outer wall of Schlemm's canal, collector channels, and the deep-scleral, mid-scleral and episcleral vessels.... (Review)
Review
The distal outflow pathway of the human eye consists of the outer wall of Schlemm's canal, collector channels, and the deep-scleral, mid-scleral and episcleral vessels. It is the last region of transit for aqueous humor before returning to the venous system. While the trabecular meshwork, scleral spur, and inner wall of Schlemm's canal have been extensively analyzed to define their contributions to aqueous outflow, the role of the distal outflow pathway is not completely understood. Collector channels, emanating from Schlemm's canal were previously thought to be passive conduits for aqueous humor. However, recent studies have shown many collector channels contain flap-like appendages which move with changes in pressure. These findings, along with studies demonstrating innervation of episcleral vessels, have led to questions regarding whether other structures in the distal outflow pathway are under neural regulation and how this may influence aqueous humor outflow. This study evaluates the innervation of the outer wall of Schlemm's canal and collector channels, along with the deep-scleral, mid-scleral and episcleral vasculature with microcomputed tomography and 3-dimensional reconstruction, correlative light microscopy, immunohistochemistry, and transmission electron microscopy. Peripheral, autonomic, and sensory nerve fibers were found to be present adjacent to Schlemm's canal outer wall endothelium, collector channel endothelium, and in the different regions of the distal outflow vasculature. Nerves were more commonly identified in regions that contained collector channels when compared to regions without collector channels. These findings regarding the neural anatomy suggest an active neural regulation of aqueous humor outflow throughout the proximal and distal regions of the conventional outflow pathway.
Topics: Aqueous Humor; Humans; Intraocular Pressure; Microscopy, Electron, Transmission; Sclera; Trabecular Meshwork; X-Ray Microtomography
PubMed: 35636488
DOI: 10.1016/j.exer.2022.109132 -
Chemical & Pharmaceutical Bulletin 2022Osmium is defined in the international council for harmonization (ICH-Q3D) guidelines as an element whose concentration can be determined by validated methods including...
Osmium is defined in the international council for harmonization (ICH-Q3D) guidelines as an element whose concentration can be determined by validated methods including microwave-assisted nitric acid digestion and inductively coupled plasma mass spectrometry. However, microwave digestion using nitric acid is known to result in osmium recoveries higher than the theoretical values in spiked tests because of the formation of highly volatile osmium tetroxide in an oxidation reaction. To stabilize osmium, the addition of thiourea as a complexing agent has been tested and proved its utility. It remains unclear whether other compounds can prevent the over-recovery of osmium. In this study, we investigated four compounds, thiourea, ascorbic acid, sodium sulfite, and potassium metabisulfite, that could reduce the overestimation of osmium isotopes. The minimum amounts of thiourea, ascorbic acid, sodium sulfite, and potassium metabisulfite required to stabilize 10 ng/mL osmium in blank matrix were 1.0, 1.0, 2.5, and 2.5 g/L, respectively. The relative standard deviations obtained from 12 analyses for each stabilization solution were less than 3.3% in thiourea, 12.7% in ascorbic acid, 9.0% in sodium sulfite, and 10.6% in potassium metabisulfite. The stabilization solutions were investigated in a digested tablet matrix and were found to be effective. The impact of adding stabilization solutions on the determination of all ICH-Q3D element concentrations was also evaluated. As stabilization solutions had a small or significant impact on the determination of some elements, it was concluded that osmium determination should be conducted independently.
Topics: Hydrogen-Ion Concentration; Isotopes; Mass Spectrometry; Microwaves; Osmium
PubMed: 34980735
DOI: 10.1248/cpb.c21-00739 -
Angewandte Chemie (International Ed. in... Dec 2016We propose the very first "Nernstian biosupercapacitor", a biodevice based on only one redox polymer: poly(vinyl imidazole-co-allylamine)[Os(bpy) Cl], and two...
We propose the very first "Nernstian biosupercapacitor", a biodevice based on only one redox polymer: poly(vinyl imidazole-co-allylamine)[Os(bpy) Cl], and two biocatalysts. At the bioanode PQQ-dependent glucose dehydrogenase reduces the Os moieties at the polymer to Os shifting the Nernst potential of the Os /Os redox couple to negative values. Concomitantly, at the biocathode the reduction of O by means of bilirubin oxidase embedded in the same redox polymer leads to the oxidation of Os to Os shifting the Nernst potential to higher values. Despite the use of just one redox polymer an open circuit voltage of more than 0.45 V was obtained during charging and the charge is stored in the redox polymer at both the bioanode and the biocathode. By connecting both electrodes via a predefined resistor a high power density is obtained for a short time exceeding the steady state power of a corresponding biofuel cell by a factor of 8.
Topics: Glucose 1-Dehydrogenase; Organometallic Compounds; Osmium; Oxidation-Reduction; Oxygen
PubMed: 27805779
DOI: 10.1002/anie.201607144 -
Beilstein Journal of Nanotechnology 2022A surfactant-free synthesis of precious metal nanoparticles (NPs) performed in alkaline low-boiling-point solvents has been recently reported. Monoalcohols are here...
A surfactant-free synthesis of precious metal nanoparticles (NPs) performed in alkaline low-boiling-point solvents has been recently reported. Monoalcohols are here investigated as solvents and reducing agents to obtain colloidal Os nanoparticles by using low-temperature (<100 °C) surfactant-free syntheses. The effect of the precursor (OsCl or HOsCl), precursor concentration (up to 100 mM), solvent (methanol or ethanol), presence or absence of a base (NaOH), and addition of water (0 to 100 vol %) on the resulting nanomaterials is discussed. It is found that no base is required to obtain Os nanoparticles as opposed to the case of Pt or Ir NPs. The robustness of the synthesis for a precursor concentration up to 100 mM allows for the performance of X-ray total scattering with pair distribution function (PDF) analysis, which shows that 1-2 nm hexagonal close packed (hcp) NPs are formed from chain-like [OsO Cl ] complexes.
PubMed: 35281627
DOI: 10.3762/bjnano.13.17