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Journal of the American Chemical Society Nov 2023The oxygen-tolerant and molybdenum-dependent formate dehydrogenase FdsDABG from is capable of catalyzing both formate oxidation to CO and the reverse reaction (CO...
The oxygen-tolerant and molybdenum-dependent formate dehydrogenase FdsDABG from is capable of catalyzing both formate oxidation to CO and the reverse reaction (CO reduction to formate) at neutral pH, which are both reactions of great importance to energy production and carbon capture. FdsDABG is replete with redox cofactors comprising seven Fe/S clusters, flavin mononucleotide, and a molybdenum ion coordinated by two pyranopterin dithiolene ligands. The redox potentials of these centers are described herein and assigned to specific cofactors using combinations of potential-dependent continuous wave and pulse EPR spectroscopy and UV/visible spectroelectrochemistry on both the FdsDABG holoenzyme and the FdsBG subcomplex. These data represent the first redox characterization of a complex metal dependent formate dehydrogenase and provide an understanding of the highly efficient catalytic formate oxidation and CO reduction activity that are associated with the enzyme.
Topics: Molybdenum; Formate Dehydrogenases; Cupriavidus necator; Carbon Dioxide; Oxidation-Reduction; Formates
PubMed: 37967365
DOI: 10.1021/jacs.3c10199 -
Materials (Basel, Switzerland) Nov 2023High-molybdenum-vanadium high-speed steel is a new type of high-hardenability tool steel with excellent wear resistance, castability, and high-temperature red hardness....
High-molybdenum-vanadium high-speed steel is a new type of high-hardenability tool steel with excellent wear resistance, castability, and high-temperature red hardness. This paper proposes a composition design of high-molybdenum-vanadium high-speed steel for rolls, and its specific chemical composition is as follows (wt.%): C2%, Mo7.0%, V7.0%, Si0.3%, Mn0.3%, Ni0.4%, Cr3.0%, and the rest of the iron. This design is characterized by the increase in molybdenum and vanadium in high-speed steel to replace traditional high-speed steel rolls with the tungsten element in order to reduce the heavy elements' tungsten-specific gravity segregation caused by centrifugal casting so that the roll performance is uniform and the stability of use is improved. JMatPro (version 7.0) simulation software is used for the composition design of high-molybdenum-vanadium high-speed steel. The phase composition diagram is analyzed under different temperatures. The content of different phases of the organization in different temperatures is also studied. The martensitic transformation temperature and different tempering temperatures with the different types of compounds and grain sizes are calculated. The process parameters of heat treatment of high-molybdenum-vanadium high-speed steel are optimized. The selection of carbon content and the temperature of M50 are calculated and optimized, and the results show that the range of pouring temperatures, quenching temperatures, annealing temperatures, and tempering temperatures are 1360~1410 °C, 1190~1200 °C, 818~838 °C, and 550~600 °C, respectively. Scanning electron microscope (SEM) analysis of the samples obtained by using the above heat treatment parameters is consistent with the simulation results, which indicates that the simulation has important reference significance for guiding the actual production.
PubMed: 38005033
DOI: 10.3390/ma16227103 -
Nanotechnology Mar 2024Low-cost, small-sized, and easy integrated high-performance photodetectors for photonics are still the bottleneck of photonic integrated circuits applications and have...
Low-cost, small-sized, and easy integrated high-performance photodetectors for photonics are still the bottleneck of photonic integrated circuits applications and have attracted increasing attention. The tunable narrow bandgap of two-dimensional (2D) layered molybdenum ditelluride (MoTe) from ∼0.83 to ∼1.1 eV makes it one of the ideal candidates for near-infrared (NIR) photodetectors. Herein, we demonstrate an excellent waveguide-integrated NIR photodetector by transferring mechanically exfoliated 2D MoTeonto a silicon nitride (SiN) waveguide. The photoconductive photodetector exhibits excellent responsivity (), detectivity (*), and external quantum efficiency at 1550 nm and 50 mV, which are 41.9 A W, 16.2 × 10Jones, and 3360%, respectively. These optoelectronic performances are 10.2 times higher than those of the free-space device, revealing that the photoresponse of photodetectors can be enhanced due to the presence of waveguide. Moreover, the photodetector also exhibits competitive performances over a broad wavelength range from 800 to 1000 nm with a highof 15.4 A Wand a large* of 59.6 × 10Jones. Overall, these results provide an alternative and prospective strategy for high-performance on-chip broadband NIR photodetectors.
PubMed: 38387089
DOI: 10.1088/1361-6528/ad2c56 -
Angewandte Chemie (International Ed. in... Aug 2023It is known that extracellular free radical reactive oxygen species (ROS) rather than intracellular ROS plays a non-substitutable role in regulation of tumor-suppressing...
It is known that extracellular free radical reactive oxygen species (ROS) rather than intracellular ROS plays a non-substitutable role in regulation of tumor-suppressing (M1) tumor-associated macrophages (TAMs) polarization. However, most therapeutic nanoplatforms mainly provide intracellular ROS and exhibit insufficient accumulation near TAMs, which strongly limits the macrophage-based immunotherapeutic effects. Here we design and synthesize chiral MoS /CoS nanozymes with peroxidase (POD)-like and catalase (CAT)-like activities to efficiently modulate TAMs polarization and reverse tumor immunosuppression by harnessing their chirality-specific interactions with biological systems. MoS /CoS nanoparticles coordinated with d-chirality (d-NPs, right-handed) show improved pharmacokinetics with longer circulating half-life and higher tumor accumulation compared with their l (left-handed)- and dl (racemate)-counterparts. Further, d-NPs can escape from macrophage uptake in the tumor microenvironment (TME) with the aid of cell-unpreferred opposite chirality and act as extracellular hydroxyl radicals (⋅OH) and oxygen (O ) generators to efficiently repolarize TAMs into M1 phenotype. On the contrary, l-NPs showed high cellular uptake due to chirality-driven homologous adhesion between l-NPs and macrophage membrane, leading to limited M1 polarization performance. As the first example for developing chiral nanozymes as extracellular-localized ROS generators to reprogram TAMs for cancer immunotherapy, this study opens an avenue for applications of chiral nanozymes in immunomodulation.
Topics: Humans; Reactive Oxygen Species; Molybdenum; Macrophages; Neoplasms; Nanoparticles; Tumor Microenvironment
PubMed: 37309708
DOI: 10.1002/anie.202307076 -
International Journal of Nanomedicine 2023Bone defects in diabetes mellitus (DM) remain a major challenge for clinical treatment. Fluctuating glucose levels in DM patients lead to excessive production of...
INTRODUCTION
Bone defects in diabetes mellitus (DM) remain a major challenge for clinical treatment. Fluctuating glucose levels in DM patients lead to excessive production of reactive oxygen species (ROS), which disrupt bone repair homeostasis. Bone filler materials have been widely used in the clinical treatment of DM-related bone defects, but overall they lack efficacy in improving the bone microenvironment and inducing osteogenesis. We utilized a gelatine methacrylate (GelMA) hydrogel with excellent biological properties in combination with molybdenum (Mo)-based polyoxometalate nanoclusters (POM) to scavenge ROS and promote osteoblast proliferation and osteogenic differentiation through the slow-release effect of POM, providing a feasible strategy for the application of biologically useful bone fillers in bone regeneration.
METHODS
We synthesized an injectable hydrogel by gelatine methacrylate (GelMA) and POM. The antioxidant capacity and biological properties of the synthesized GelMA/POM hydrogel were tested.
RESULTS
In vitro, studies showed that hydrogels can inhibit excessive reactive oxygen species (ROS) and reduce oxidative stress in cells through the beneficial effects of pH-sensitive POM. Osteogenic differentiation assays showed that GelMA/POM had good osteogenic properties with upregulated expression of osteogenic genes (BMP2, RUNX2, Osterix, ALP). Furthermore, RNA-sequencing revealed that activation of the PI3K/Akt signalling pathway in MC3T3-E1 cells with GelMA/POM may be a potential mechanism to promote osteogenesis. In an in vivo study, radiological and histological analyses showed enhanced bone regeneration in diabetic mice, after the application of GelMA/POM.
CONCLUSION
In summary, GelMA/POM hydrogels can enhance bone regeneration by directly scavenging ROS and activating the PI3K/Akt signalling pathway.
Topics: Humans; Mice; Animals; Osteogenesis; Hydrogels; Reactive Oxygen Species; Molybdenum; Proto-Oncogene Proteins c-akt; Gelatin; Methacrylates; Phosphatidylinositol 3-Kinases; Diabetes Mellitus, Experimental; Bone Regeneration
PubMed: 37881608
DOI: 10.2147/IJN.S428429 -
The Science of the Total Environment Jan 2024Immunoglobulin E (IgE) is a diagnostic biomarker for allergic diseases. While some metal exposure has been found to be associated with allergic diseases, there are still...
BACKGROUND
Immunoglobulin E (IgE) is a diagnostic biomarker for allergic diseases. While some metal exposure has been found to be associated with allergic diseases, there are still a lot of knowledge gaps regarding the relationship between metal exposure and allergen-specific IgE antibodies, particularly in adults.
METHODS
We included a total of 1433 adult participants from the 2005-2006 National Health and Nutrition Examination Survey (NHANES), all of whom had concentrations of 10 metals (including Barium (Ba), Cadmium (Cd), Cobalt (Co), Cesium (Cs), Molybdenum (Mo), Lead (Pb), Antimony (Sb), Thallium (Tl), Tungsten (Tu), and Uranium (Ur)) in urine, as well as measurements of 19 allergen-specific IgE and total IgE antibodies. Linear regression, logistic regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) were used to estimate associations between metals and total and allergen-specific IgE.
RESULTS
Linear regression models revealed a positive correlation between Pb and Cd levels and the total IgE levels. Furthermore, the WQS and BKMR models suggested a positive association between mixed metals and total IgE levels, with the WQS model highlighting Pb and Cd as the major contributors. Logistic regression models showed positive correlations between Pb and food sensitization, Ur and plant sensitization, negative correlations between Cs and plant sensitization, Co and dust mite and pet sensitization, Mo and dust mite and cockroach sensitization, and Tl and mold sensitization. Moreover, the BKMR results indicated a statistically significant negative correlation between mixed metals and mold sensitization.
CONCLUSION
According to the research findings, exposure to metals is associated with total and allergen-specific IgE in American adults. Further assessment of these relationships is necessary in representative populations of other countries.
Topics: Adult; Humans; Nutrition Surveys; Cadmium; Bayes Theorem; Lead; Allergens; Hypersensitivity; Cobalt; Molybdenum; Thallium; Fungi; Cesium; Uranium; Immunoglobulin E
PubMed: 37777136
DOI: 10.1016/j.scitotenv.2023.167385 -
Biochemical and Biophysical Research... Nov 2023Klebsiella pneumoniae, a facultative anaerobe, relies on acquiring molybdenum to sustain growth in anaerobic conditions, a crucial factor for the pathogen to establish...
Klebsiella pneumoniae, a facultative anaerobe, relies on acquiring molybdenum to sustain growth in anaerobic conditions, a crucial factor for the pathogen to establish infections within host environments. Molybdenum plays a critical role in pathogenesis as it forms an essential component of cofactors for molybdoenzymes. K. pneumoniae utilizes the ABC (ATP-Binding-Cassette) transporter encoded by the modABC operon for uptake of the group VI elements molybdenum and tungsten. In this study, we determined the X-ray crystal structures of both the molybdenum-free and molybdenum-bound substrate-binding protein (SBP) ModA from Klebsiella pneumoniae to 2.00 Å and 1.77 Å resolution respectively. ModA crystallizes in the space group P222 with a single monomer in one asymmetric unit. The purified protein remained soluble and specifically bound molybdate and tungstate with K values of 6.3 nM and 5.2 nM, respectively. Tungstate competes with molybdate by binding to ModA, resulting in enhanced antimicrobial activity. These data provide a starting point for structural and functional analyses of molybdate transport in K. pneumoniae.
Topics: Molybdenum; Klebsiella pneumoniae; Bacterial Proteins; Periplasmic Binding Proteins; ATP-Binding Cassette Transporters; Protein Binding
PubMed: 37751633
DOI: 10.1016/j.bbrc.2023.09.055 -
ACS Applied Materials & Interfaces Jul 2023The synthesis, characterization, and thermogravimetric analysis of tris(,'-di-isopropylacetamidinate)molybdenum(III), Mo(iPr-AMD), are reported. Mo(iPr-AMD) is a rare...
The synthesis, characterization, and thermogravimetric analysis of tris(,'-di-isopropylacetamidinate)molybdenum(III), Mo(iPr-AMD), are reported. Mo(iPr-AMD) is a rare example of a homoleptic mononuclear complex of molybdenum(III) and fills a longstanding gap in the literature of transition metal(III) trisamidinate complexes. Thermogravimetric analysis (TGA) reveals excellent volatilization at elevated temperatures, pointing to potential applications as a vapor phase precursor for higher temperature atomic layer deposition (ALD), or chemical vapor deposition (CVD) growth of Mo-based materials. The measured TGA temperature window was 200-314 °C for samples in the 3-20 mg range. To validate the utility of Mo(iPr-AMD), we demonstrate aerosol-assisted CVD growth of MoO from benzonitrile solutions of Mo(iPr-AMD) at 500 °C using compressed air as the carrier gas. The resulting films are characterized by X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy. We further demonstrate the potential for ALD growth at 200 °C with a Mo(iPr-AMD)/Ar purge/300 W O plasma/Ar purge sequence, yielding ultrathin films which retain a nitride/oxynitride component. Our results highlight the broad scope utility and potential of Mo(iPr-AMD) as a stable, high-temperature precursor for both CVD and ALD processes.
PubMed: 37450887
DOI: 10.1021/acsami.3c04074 -
Journal of Materials Chemistry. B Jun 2024With the advancement in the field of biomedical research, there is a growing demand for biodegradable electronic devices. Biodegradable supercapacitors (SCs) have...
With the advancement in the field of biomedical research, there is a growing demand for biodegradable electronic devices. Biodegradable supercapacitors (SCs) have emerged as an ideal solution for mitigating the risks associated with secondary surgeries, reducing patient discomfort, and promoting environmental sustainability. In this study, MoN@Mo-foil was prepared as an active material for biodegradable supercapacitors through high-temperature and nitridation processes. The composite electrode exhibited superior electrochemical performance in both aqueous and solid-state electrolytes. In the case of the solid-state electrolyte, the MoN@Mo-foil composite electrode-based device demonstrated excellent cycling stability and electrochemical performance. Additionally, the composite electrode exhibited rapid and complete biodegradability in a 3% HO solution. Through detailed experimental analysis and performance testing, we verified the potential application of the MoN@Mo-foil composite electrode in biodegradable supercapacitors. This work provides a new choice of degradable material for developing biomedical electronic devices.
Topics: Electrodes; Electric Capacitance; Humans; Molybdenum; Electrochemical Techniques; Biocompatible Materials; Particle Size; Surface Properties
PubMed: 38771646
DOI: 10.1039/d4tb00649f -
Molecules (Basel, Switzerland) Oct 2023In prokaryotes, the role of Mo/W enzymes in physiology and bioenergetics is widely recognized. It is worth noting that the most diverse family of Mo/W enzymes is... (Review)
Review
In prokaryotes, the role of Mo/W enzymes in physiology and bioenergetics is widely recognized. It is worth noting that the most diverse family of Mo/W enzymes is exclusive to prokaryotes, with the probable existence of several of them from the earliest forms of life on Earth. The structural organization of these enzymes, which often include additional redox centers, is as diverse as ever, as is their cellular localization. The most notable observation is the involvement of dedicated chaperones assisting with the assembly and acquisition of the metal centers, including Mo/W-bisPGD, one of the largest organic cofactors in nature. This review seeks to provide a new understanding and a unified model of Mo/W enzyme maturation.
Topics: Metalloproteins; Prokaryotic Cells; Oxidation-Reduction; Energy Metabolism; Molecular Chaperones; Molybdenum
PubMed: 37894674
DOI: 10.3390/molecules28207195