Toxicity of inorganic vanadium compounds

Accelerating Computation of Acidity Constants and Redox Potentials for Aqueous Organic Redox Flow Batteries by Machine Learning Potential-Based Molecular Dynamics

Due to the increased concern about energy and environmental issues, significant attention has been paid to the development of large-scale energy storage devices to facilitate the utilization of clean energy sources. The redox flow battery (RFB) is one of the most promising systems. Recently, the high cost of transition-metal complex-based RFB has promoted the development of aqueous RFBs with redox-active organic molecules. To expand the working voltage, computational chemistry has been applied to search for organic molecules with lower or higher redox potentials. However, redox potential computation based on implicit solvation models would be challenging due to difficulty in parametrization when considering the complex solvation of supporting electrolytes. Besides, although ab initio molecular dynamics (AIMD) describes the supporting electrolytes with the same level of electronic structure theory as the redox couple, the application is impeded by the high computation costs. Recently, machine learning molecular dynamics (MLMD) has been illustrated to accelerate AIMD by several orders of magnitude without sacrificing the accuracy. It has been established that redox potentials can be computed by MLMD with two separated machine learning potentials (MLPs) for reactant and product states, which is redundant and inefficient. In this work, an automated workflow is developed to construct a universal MLP for both states, which can compute the redox potentials or acidity constants of redox-active organic molecules more efficiently. Furthermore, the predicted redox potentials can be evaluated at the hybrid functional level with much lower costs, which would facilitate the design of aqueous organic RFBs.

A Non-Toxic Binuclear Vanadium(IV) Complex as Insulin Adjuvant Improves the Glycemic Control in Streptozotocin-Induced Diabetic Rats

Diabetes mellitus (DM) complications are a burden to health care systems due to the associated consequences of poor glycemic control and the side effects of insulin therapy. Recently. adjuvant therapies, such as vanadium compounds, have gained attention due to their potential to improve glucose homeostasis in patients with diabetes. In order to determine the anti-diabetic and antioxidant effects of the oxidovanadium(IV) complex (Et3NH)2[{VO(OH}2)(ox)2(µ-ox)] or Vox2), rats with streptozotocin (STZ)-induced diabetes were treated with 30 and 100 mg/kg of Vox2, orally administered for 12 days. Vox2 at 100 mg/kg in association with insulin caused a 3.4 times decrease in blood glucose in STZ rats (424 mg/dL), reaching concentrations similar to those in the normoglycemic animals (126 mg/dL). Compared to insulin alone, the association with Vox2 caused an additional decrease in blood glucose of 39% and 65% at 30 and 100 mg/kg, respectively, and an increased pancreatic GSH levels 2.5 times. Vox2 alone did not cause gastrointestinal discomfort, diarrhea, and hepatic or renal toxicity and was not associated with changes in blood glucose level, lipid profile, or kidney or liver function. Our results highlight the potential of Vox2 in association with insulin in treating diabetes.

Cytotoxicity of vanadium dioxide nanoparticles to human embryonic kidney cell line: Compared with vanadium(IV/V) ions

Vanadium dioxide (VO2) is a class of thermochromic material with potential applications in various fields. Massive production and wide application of VO2 raise the concern of its potential toxicity to human, which has not been fully understood. Herein, a commercial VO2 nanomaterial (S-VO2) was studied for its potential toxicity to human embryonic kidney cell line HEK293, and two most common vanadium ions, V(IV) and V(V), were used for comparison to reveal the related mechanism. Our results indicate that S-VO2 induces dose-dependent cellular viability loss mainly through the dissolved V ions of S-VO2 outside the cell rather than S-VO2 particles inside the cell. The dissolved V ions of S-VO2 overproduce reactive oxygen species to trigger apoptosis and proliferation inhibition via several signaling pathways of cell physiology, such as MAPK and PI3K-Akt, among others. All bioassays indicate that the differences in toxicity between S-VO2, V(IV), and V(V) in HEK293 cells are very small, supporting that the toxicity is mainly due to the dissolved V ions, in the form of V(V) and/or V(IV), but the V(V)'s behavior is more similar to S-VO2 according to the gene expression analysis. This study reveals the toxicity mechanism of nanosized VO2 at the molecular level and the role of dissolution of VO2, providing valuable information for safe applications of vanadium oxides.

Vanadium Compounds with Antidiabetic Potential

Over the last four decades, vanadium compounds have been extensively studied as potential antidiabetic drugs. With the present review, we aim at presenting a general overview of the most promising compounds and the main results obtained with in vivo studies, reported from 1899-2023. The chemistry of vanadium is explored, discussing the importance of the structure and biochemistry of vanadate and the impact of its similarity with phosphate on the antidiabetic effect. The spectroscopic characterization of vanadium compounds is discussed, particularly magnetic resonance methodologies, emphasizing its relevance for understanding species activity, speciation, and interaction with biological membranes. Finally, the most relevant studies regarding the use of vanadium compounds to treat diabetes are summarized, considering both animal models and human clinical trials. An overview of the main hypotheses explaining the biological activity of these compounds is presented, particularly the most accepted pathway involving vanadium interaction with phosphatase and kinase enzymes involved in the insulin signaling cascade. From our point of view, the major discoveries regarding the pharmacological action of this family of compounds are not yet fully understood. Thus, we still believe that vanadium presents the potential to help in metabolic control and the clinical management of diabetes, either as an insulin-like drug or as an insulin adjuvant. We look forward to the next forty years of research in this field, aiming to discover a vanadium compound with the desired therapeutic properties.

In Vitro, Oral Acute, and Repeated 28-Day Oral Dose Toxicity of a Mixed-Valence Polyoxovanadate Cluster

Polyoxovanadates (POV) are a subgroup of polyoxometalates (POM), which are nanosized clusters with reported biological activities. This manuscript describes the first toxicity evaluation of a mixed-valence polyoxovanadate, pentadecavanadate, (Me4N)6[V15O36Cl], abbreviated as V15. Cytotoxicity experiments using peripheral blood mononuclear cells (PBMC), larvae of Artemia salina Leach, and in vivo oral acute and repeated 28-day doses in mice was carried out. The LC50 values in PBMC cells and A. salina were 17.5 ± 5.8 μmol L-1, and 17.9 µg L-1, respectively, which indicates high cytotoxic activity. The toxicity in mice was not observed upon acute exposure in a single dose, however, the V15 repeated 28-day oral administration demonstrated high toxicity using 25 mg/kg, 50 mg/kg and, 300 mg/kg doses. The biochemical and hematological analyses during the 28-day administration of V15 showed significant alteration of the metabolic parameters related to the kidney and liver, suggesting moderate toxicity. The V15 toxicity was attributed to the oxidative stress and lipid peroxidation, once thiobarbituric acid (TBAR) levels significantly increased in both males and females treated with high doses of the POV and also in males treated with a lower dose of the POV. This is the first study reporting a treatment-related mortality in animals acutely administrated with a mixed-valence POV, contrasting with the well-known, less toxic decavanadate. These results document the toxicity of this mixed-valence POV, which may not be suitable for biomedical applications.

Adsorptive Stripping Voltammetry for Determination of Vanadium: A Review

The main purpose of this review is to present methods of adsorptive stripping voltammetry that can be used to determine trace amounts of VO₂⁽⁺⁾ in various types of samples. The detection limits achieved using different working electrodes are presented. The factors influencing the obtained signal, including the selection of the complexing agent and the selection of the working electrode, are shown. For some methods, in order to increase the range of applied concentrations in which vanadium can be detected, a catalytic effect is introduced to adsorptive stripping voltammetry. The influence of the foreign ions and organic matter contained in natural samples on the vanadium signal is analyzed. This paper presents methods of elimination associated with the presence of surfactants in the samples. The methods of adsorptive stripping voltammetry for the simultaneous determination of vanadium with other metal ions are also characterized below. Finally, the practical use of the developed procedures, mainly for the analysis of food and environmental samples, is summarized in a tabular version.

Silicon-mediated metabolic upregulation of ascorbate glutathione (AsA-GSH) and glyoxalase reduces the toxic effects of vanadium in rice

Although beneficial metalloid silicon (Si) has been proven to reduce the toxicity of several heavy metals, there is a lack of understanding regarding Si potential function in mitigating phytotoxicity induced by vanadium (V). In this study, effect of Si (1.5 mM) on growth, biomass production, V uptake, reactive oxygen species (ROS), methylglyoxal (MG) formation, selected antioxidants enzymes activities, glyoxalase enzymes under V stress (35 mg L^-1) was investigated in hydroponic experiment. The results showed that V stress reduced rice growth, caused V accumulation in rice. Addition of Si to the nutritional medium increased plant growth, biomass yield, root length, root diameter, chlorophyll parameters, photosynthetic assimilation, ion leakage, antioxidant enzymes activities under V stress. Notably, Si sustained V-homeostasis and alleviated V caused oxidative stress by boosting ascorbate (AsA) levels and the activity of antioxidant enzymes in V stressed rice plants. Furthermore, Si protected rice seedlings against the harmful effects of methylglyoxal by increasing the activity of glyoxalase enzymes. Additionally, Si increased the expression of numerous genes involved in the detoxification of reactive oxygen species (e.g., OsCuZnSOD1, OsCaTB, OsGPX1, OsAPX1, OsGR2, and OsGSTU37) and methylglyoxal (e.g., OsGLYI-1 and OsGLYII-2). The findings supported that Si can be applied to plants to minimize the V availability to plant, and also induced V stress tolerance.

A Study of Vanadate Group Substitution into Nanosized Hydroxyapatite Doped with Eu3+ Ions as a Potential Tissue Replacement Material

In this study, nanosized vanadate-substituted hydroxyapatites doped with 1 mol% and 2 mol% Eu3+ ions were obtained via the precipitation method. To evaluate the structure and morphology of the obtained compounds, the XRPD (X-ray powder diffraction) technique, Rietveld refinement, SEM-EDS (scanning electron microscopy-energy-dispersive spectrometry) and TEM (transmission electron microscopy) techniques as well as FTIR (Fourier transform infrared) spectroscopy were performed. Moreover, the chemical formula was confirmed using the ICP-OES (Inductively coupled plasma optical emission spectroscopy spectroscopy). The calculated average grain size for powders was in the range of 25 to 90 nm. The luminescence properties of vanadium-substituted hydroxyapatite were evaluated by recording emission spectra and excitation spectra as well as luminescence kinetics. The crucial step of this research was the evaluation of the biocompatibility of the synthesized nanomaterials. Therefore, the obtained compounds were tested toward sheep red blood cells and normal human dermal fibroblast to confirm the nontoxicity and biocompatibility of new nanosized Eu3+ ion-doped vanadate-hydroxyapatite. Moreover, the final step of the research allowed us to determine the time dependent ion release to the simulated body fluid environment. The study confirmed cytocompatibility of vanadium hydroxyapatite doped with Eu3+ ions.

Toxicity of boron and vanadium nanoparticles on Danio rerio embryos - Phenotypical, biochemical, and behavioral alterations

Engineered nanoparticles (NPs) are emerging contaminants of concern and it is important to understand their environmental behavior and ecological risks to exposed organisms. Despite their ubiquitous presence in the environment, there is little information about the hazards of certain NPs, such as boron (BNPs) and vanadium (VNPs). The aim of the present research was to investigate the effects of commercial BNPs and VNPs (80 to 100 nm) to zebrafish embryos, at different levels of biological organization. A range of nominal concentrations for both NPs (0, 0.01, 0.1, 1, and 10 mg/L) was tested. Due to the presence of triton X-100 in the NPs' stock dispersions, an additional control group was included (0.001% triton X-100). Survival, hatching, and malformations of embryos were assessed for 96 hours (h) exposure. Locomotor behavior was evaluated at 120 h. Furthermore, embryos were exposed to 0, 1, and 10 mg/L of NPs to evaluate a set of biomarker responses after 96 h: cholinesterase (ChE) and glutathione S-transferase (GST) activities, total glutathione (TG) and energy budgets levels. VNPs induced malformations (10 mg/L), hyperactivity (10 mg/L), erratic swimming (0.01 mg/L), altered swimming pattern (>0.01 mg/L), delayed hatching (10 mg/L) and altered biochemical responses involved in antioxidant defense (GST and TG at >1 mg/L), neurotransmission (ChE at 10 mg/L) and energy metabolism (lipids at >1 mg/L and carbohydrates at 10 mg/L). BNPs caused malformations (10 mg/L), affected swimming pattern (>0.01 mg/L), induced erratic swimming (10 mg/L) and decreased TG content and GST activity (>1 mg/L). At the same concentrations, VNPs affected a greater number of endpoints than BNPs, demonstrating a greater toxicity to zebrafish embryos. The present study shows that BNPs and VNPs may affect aquatic organisms, albeit at relatively great non-environmentally relevant concentrations, reinforcing the importance of the risk assessment of different NPs.

A global systematic review, meta-analysis, and risk assessment of the concentration of vanadium in drinking water resources

The presence of toxic metals such as vanadium in water resources has attracted considerable attention as a new concern in international health. Systematic review and meta-analysis were performed to assess the concentration of vanadium in water resources along with the relevant ecological risk assessment. Databases of Scopus, PubMed, and Embase were investigated to retrieve the related articles from January 01, 1974 to December 25, 2019. Twenty-eight articles containing 152 samples from 24 countries were included. Furthermore, the meta-analysis was conducted by the approach of z-score to estimate differences in the effect size. In addition, the mean of concentrations of vanadium was applied to calculate the risk assessment only to the water surface and choose the maximum environmental concentration (MEC) for demonstrate a worst-case scenario. Here, the risk assessment approach was used to show that the MEC of vanadium confirm the risk it for aquatic ecosystems, being fish (e.g., Danio rerio) our model organism due to their sensibility. According to findings, the MEC of vanadium in surface water varied from 0.010 μg L^-1 (USA) and 68 μg L^-1 (China), with an overall mean of 6.21 ± 13.3 μg L^-1 (mean ± standard deviation). The ecological risk assessment demonstrated that people living in some countries such as China and Japan were at an adverse ecological risk of vanadium in the water resources. Hence, essential control plans besides adequate removal techniques must be implemented for significant deracination of heavy metals like vanadium.

Anti-oxidant and hepatoprotective effects of Salvia officinalis essential oil against vanadium-induced oxidative stress and histological changes in the rat liver

The present study was designed to evaluate the protective effects of Salvia officinalis essential oil (SOEO) against vanadium-induced hepatotoxicity in Wistar rats. Animals were divided into three groups: the first group served as the control (C), where rats received daily 0.5 mL of saline solution (0.9%) given by intraperitoneal (i.p.) way. Rats in the second group (V) received daily by i.p. way 5 mg/kg BW of NH₄VO₃ (V). Rats in the third group (SV) received daily V (5 mg/kg BW) by i.p. way and SOEO (15 mg/kg BW) by gavage. Animals were sacrificed after 4 or 10 days of treatment. Administration of V increased plasma ALT, AST, ALP, and LDH activities, and cholesterol, bilirubin, triglyceride, and NO levels in rats and reduced anti-oxidant enzyme activities in the liver. Treatment with SOEO significantly attenuated these changes. Moreover, the histopathological changes and the overexpression of Hsp72/73 proteins induced by V were significantly improved by SOEO. Therefore, our results suggested that SOEO could protect against V-induced oxidative damage in rat livers. The hepatoprotective effect of SOEO might be attributed to its modulation of detoxification enzymes and/or to its anti-oxidant and free radical scavenging effects.

Tuning the Performance of Aqueous Organic Redox Flow Batteries via First-Principles Calculations

Aqueous organic redox flow batteries have many appealing properties in the application of large-scale energy storage. The large chemical tunability of organic electrolytes shows great potential to improve the performance of flow batteries. Computational studies at the quantum-mechanics level are very useful for guiding experiments, but in previous studies, explicit water interactions and thermodynamic effects were ignored. Here, we applied the computational electrochemistry method based on ab initio molecular dynamics and thermodynamic integration to calculate redox potentials of quinones and their derivatives. The calculated results are in excellent agreement with experimental data. We mixed side chains to tune their reduction potentials and found that solvation interactions and entropy effects play a significant role in side-chain engineering. On the basis of our calculations, we proposed several high-performance negative and positive electrolytes. Our first-principles study paves the way toward the development of large-scale and sustainable electrical energy storage.

Reducible Fraction Dominates the Mobility of Vanadium in Soil Around an Iron Smelter

Soil samples were collected to determine the pollution status, spatial distribution and mobility of Vanadium (V) in soil around an iron smelter in Panzhihua. The results showed that the topsoils and deep soils were unpolluted to moderately polluted and the subsurface soils was unpolluted with V. V concentrations in the topsoils decreased with the increase of the altitudes and the distances to the smelter. There was a great potential mobility of V in soil and the reductive dissolution of reducible V in the topsoils was responsible for the high concentration of V in the deep soils. Therefore, more attention should be paid to the reducible V when evaluating the mobility of V in soil.

Mechanism of vanadium(IV) resistance of the strains isolated from a vanadium titanomagnetite mining region

Microbial treatment for vanadium contamination of soils is a favorable and environment-friendly method. However, information of the resistant mechanism of the strains in soils to vanadium, especially to tetravalent vanadium [vanadium(IV)], is still limited. Herein, potential of the vanadium(IV) biosorption and biotransformation of the strains (4K1, 4K2, 4K3 and 4K4) which were capable of tolerating vanadium(IV) was determined. For biosorption, the bioadsorption and the bioabsorption of vanadium(IV) occur on the bacterial cell wall and within the cell, respectively, were taken into consideration. Comparison of the vanadium(IV) adsorbed on the bacterial cell walls and remained in the cells after sorption indicated the major bacterial vanadium(IV) sorption role of the bioadsorption which was at least one order of magnitude higher than the bioabsorption amount. Isotherm study using various isotherm models revealed a monolayer and a multilayer vanadium(IV) biosorption by 4K2 and the others (4K1, 4K3 and 4K4), respectively. Higher biosorption was observed in acidic conditions than in alkaline conditions, and the maximum biosorption was 2.41, 9.35, 7.76 and 8.44 mg g^-1 observed at pH 6 for 4K1, at pH 3 for 4K2, and at pH 4 for 4K3 and 4K4, respectively. At the present experimental range of the initial vanadium(IV) concentration, optimal biosorption capacity of the bacteria was observed at the vanadium(IV) level of 100-250 mg L^-1. Different biotransformation level of vanadium(IV) in soils by the stains was observed during a 28-d pot incubation of the soils mixed with the strains, which can be attributed to the discrepancy of both soil properties and bacterial species. Present study can help to fill up the gaps of the insufficient knowledge of the vanadium(IV) resistant mechanism of the strains in soils.

Characteristic of adsorption, desorption, and co-transport of vanadium on humic acid colloid

Understanding the interactions between humic acid colloid (HAC) and vanadium (V) in soils is of great importance in forecasting the behaviors and fates of V in the soil and groundwater systems. This study investigated the characteristics and factors that affect V adsorption-desorption by the HAC; meanwhile, we also explored the co-transport of the HAC and V in a saturated porous media. Scanning Electronic Microscopy micrographs showed the variation of morphological features on the surface of the HAC before and after V adsorption. Fourier transform infrared spectroscopy spectra revealed that the presence of hydroxyl, carboxyl, carbonyl, carbon-carbon double bond, amino, and aromatic ring on the HAC participated in V adsorption. The adsorption isotherms were well described by the Langmuir model, and the adsorption kinetics of the HAC was better described by the pseudo-first-order kinetic models. The adsorption-desorption was strongly dependent on the initial V concentration, solution pH, and temperature. The maximum adsorption amount was 861.17 mg g^-1 by 200 mg L^-1 HAC at the initial V concentration of 500 mg L^-1, and the corresponding desorption amount was 15.13 mg g^-1. These results showed that the HAC had high fixation capacity of V in soil. In addition, the HAC sped up the mobility of V; however, it decreased mass of migration of V in the saturated quartz sand column. These results are expected to provide insight into the potential impact of HAC on geochemical behaviours of V in vulnerable ecosystems.

Protective Effects of Dietary Antioxidants against Vanadium-Induced Toxicity: A Review

Vanadium (V) in its inorganic forms is a toxic metal and a potent environmental and occupational pollutant and has been reported to induce toxic effects in animals and people. In vivo and in vitro data show that high levels of reactive oxygen species are often implicated in vanadium deleterious effects. Since many dietary (exogenous) antioxidants are known to upregulate the intrinsic antioxidant system and ameliorate oxidative stress-related disorders, this review evaluates their effectiveness in the treatment of vanadium-induced toxicity. Collected data, mostly from animal studies, suggest that dietary antioxidants including ascorbic acid, vitamin E, polyphenols, phytosterols, and extracts from medicinal plants can bring a beneficial effect in vanadium toxicity. These findings show potential preventive effects of dietary antioxidants on vanadium-induced oxidative stress, DNA damage, neurotoxicity, testicular toxicity, and kidney damage. The relevant mechanistic insights of these events are discussed. In summary, the results of studies on the role of dietary antioxidants in vanadium toxicology appear encouraging enough to merit further investigations.

Mesenchymal stem cell interaction with Ti6Al4V alloy pre-exposed to simulated body fluid

Titanium and its alloys are widely used for substitution of hard tissues, especially in orthopaedic and dental surgery. Despite the benefit of the use of titanium for such applications, there are still questions which must be sorted out. Surface properties are crucial for cell adhesion, proliferation and differentiation. Mainly, micro/nanostructured surfaces positively influence osteogenic differentiation of human mesenchymal stem cells. Ti₆Al₄V is a biocompatible α + β alloy which is widely used in orthopaedics. The aim of this study was to investigate the interaction of the nanostructured and ground Ti₆Al₄V titanium alloys with simulated body fluid complemented by the defined precipitation of hydroxyapatite-like coating and to study the cytotoxicity and differentiation capacity of cells with such a modified titanium alloy. Nanostructures were fabricated using electrochemical oxidation. Human mesenchymal stem cells (hMSC) were used to evaluate cell adhesion, metabolic activity and proliferation on the specimens. The differentiation potential of the samples was investigated using PCR and specific staining of osteogenic markers collagen type I and osteocalcin. Our results demonstrate that both pure Ti₆Al₄V, nanostructured samples, and hydroxyapatite-like coating supported hMSC growth and metabolic activity. Nanostructured samples improved collagen type I synthesis after 14 days, while both nanostructured and hydroxyapatite-like coated samples enhanced collagen synthesis on day 21. Osteocalcin synthesis was the most enhanced by hydroxyapatite-like coating on the nanostructured surfaces. Our results indicate that hydroxyapatite-like coating is a useful tool guiding hMSC osteogenic differentiation.

Titanium and its alloys are widely used for substitution of hard tissues, especially in orthopaedic and dental surgery.

The first pollution investigation of road sediment in Gary, Indiana: Anthropogenic metals and possible health implications for a socioeconomically disadvantaged area

An investigation of road sediment in Gary, Indiana revealed high levels of various trace metals such as Zn, Mn, and Cr, often exceeding those of background reference concentrations as shown through geoaccumulation indices and contamination factors. The hazard index (HI) value for Mn in children was >1 (1.7), suggesting possible long-term non-carcinogenic health risk. Mn HI for children is even higher for the five samples closest to a US Steel facility, with an HI of 2.8. Through SEM-EDS analysis, the prevalence of small particulates (PM_2.5 and PM_2.5-10) containing potentially harmful elements such as Mn and Pb illustrate a health risk through direct inhalation or ingestion. The small nature of particulates in general may also pose an increased health risk for respiratory diseases such as asthma. Mn concentrations in the road sediment were particularly high, with 30 out of 32 samples exceeding 1800 ppm. Mn and V concentrations show a strong spatial trend of decreasing concentration away from a US Steel facility. These spatial trends along with correlation plots of the bulk chemistry suggest that industrial steel manufacturing, particularly US Steel in Gary, is a major contributing source of Mn and V. Fe and Cr show a moderate decrease in concentrations away from the US Steel facility, which suggests some sourcing from the steel facility when coupled with bulk chemistry plots. Zn and Cu do not show much evidence of sourcing from the US Steel facility, likely due to increased mixing from other sources. Further work constraining anthropogenic sources, the bioaccessible fraction of metals, and analysis of direct atmospheric particulates can help with remedial activity and risk assessment.

Field-Enhanced Nanoconvection Accelerated Electrocatalytic Conversion of Water Contaminants and Electricity Generation

The development of high-performance electrocatalytic systems for the extraction of energy from contaminants in wastewater are urgently needed in emerging renewable energy technologies. However, given that most of the contaminants are present in low concentrations, the heterogeneous catalytic reactions often suffer from slow kinetics due to mass transfer limitations. Here, we report that localized free convection induced by enthalpy change of the reaction can enhance interfacial mass transport. This phenomenon can be found around high-curvature nanosized tips. The finite-element numerical simulation shows that the heat of reactions can produce temperature gradients and subsequently lead to fluid motion at the interfaces, which facilitates the rate-limiting step (mass transfer). To demonstrate the effects of localized field-enhanced mass transport in electrocatalytic conversion of aqueous dilute species, a galvanic cell is constructed with a vertically aligned polyaniline array with sharp tips (as cathode) for the detoxification of a low concentration of carcinogenic chromate and synchronous electricity generation, which show lower overpotential (0.17 V decreased), higher reaction rate (increased by 28%), and power density (22.3 W m^-2 in 2 mM chromate). The power output can be scaled up (open voltage of ∼3.7 V and volumetric power density of 840.1 W m^-3) by using a continuous flow-through cell with stacked electrodes for further improve the mass transport.

Vanadium Dioxide Nanocoating Induces Tumor Cell Death through Mitochondrial Electron Transport Chain Interruption

A biomaterials surface enabling the induction of tumor cell death is particularly desirable for implantable biomedical devices that directly contact tumor tissues. However, this specific antitumor feature is rarely found. Consequently, an antitumor-cell nanocoating comprised of vanadium dioxide (VO2) prepared by customized reactive magnetron sputtering has been proposed, and its antitumor-growth capability has been demonstrated using human cholangiocarcinoma cells. The results reveal that the VO2 nanocoating is able to interrupt the mitochondrial electron transport chain and then elevate the intracellular reactive oxygen species levels, leading to the collapse of the mitochondrial membrane potential and the destruction of cell redox homeostasis. Indeed, this chain reaction can effectively trigger oxidative damage in the cholangiocarcinoma cells. Additionally, this study has provided new insights into designing a tumor-cell-inhibited biomaterial surface, which is modulated by the mechanism of mitochondria-targeting tumor cell death.

Oral bioaccessibility and health risk assessment of vanadium(IV) and vanadium(V) in a vanadium titanomagnetite mining region by a whole digestive system in-vitro method (WDSM)

Oral bioaccessibility of vanadium(IV) and vanadium(V) in soil, dust and concentrate fines from a vanadium titanomagnetite mining region was assessed by a whole digestive system in-vitro scheme. The scheme including the addition of sweat and the large intestinal digestion was used to estimate the oral bioaccessibility of vanadium(IV) and vanadium(V) in the whole digestive system for the first time. Higher oral bioaccessibility of vanadium(IV) and vanadium(V) was determined in gastric and small intestinal phases demonstrating that their major roles for vanadium digestion and absorption. The decreasing order of the oral bioaccessibility of vanadium(IV) and vanadium(V) in each digestive phase was stomach, small intestine, large intestine and mouth. Higher oral bioaccessibility of vanadium(V) in the whole digestion indicated its higher risk potential for human than vanadium(IV). Lower oral bioaccessibility of vanadium(IV) and vanadium(V) determined in bionic digestion illustrated detoxicity potential of human body for ingested vanadium. Compared with soil and dust, higher digestion rate of vanadium in vanadium titanomagnetite concentrate fines indicated its higher risk for human, especially for mining workers. Based on vanadium oral bioaccessibility, hazard quotients of the vanadium were much less than the critical level suggested for no non-carcinogenic risks to the populations surrounding the sampling sites. Indeed, compared with the estimations based on total vanadium content, the incorporation of oral vanadium bioaccessibility into risk assessments could give more realistic information.

Facile Preparation of Iron-Manganese Oxide@Diatomite Composite for Effective Removal of Vanadium from Wastewater

Excess pentavalent vanadium(v) has severely degraded water quality and posed a huge threat to human health over the past several decades. Hence, it’s urgent and significant to explore a novel adsorbent which is low cost and efficient to treat vanadium pollution. In this work, a novel iron-manganese oxide@diatomite (MnFe2O4@DE) adsorbent with superior removal performance for simulated vanadium(v) wastewater was synthesised via a facile hydrothermal method. The as-prepared MnFe2O4@DE composite was characterised through different characterisation techniques. The results indicated that the MnFe2O4 nanoparticles were uniformly deposited on the surface of diatomite, resulting in a larger specific surface area and pore volume of the composite. In addition, the MnFe2O4@DE adsorbent exhibited the highest adsorption capacity for vanadium(v) (18.37mgg−1±0.5%), which was up to around 13.24 and 1.33 times as much as that of pure diatomite and MnFe2O4, respectively. This is mainly attributed to the enhanced specific surface area and pore volume. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis demonstrated vanadium(v) could be reduced to low valence vanadium with low toxicity by the MnFe2O4@DE composite which could exist as VO2+ and VO+ cations in solution. The adsorption process was better fitted with a pseudo-second-order kinetic model and Langmuir model, which is spontaneous and endothermic. Overall, the novel MnFe2O4@DE composite could be applied as a promising adsorbent in addressing vanadium pollution issues due to its properties of low cost, effectiveness, and environmental friendliness.

Efeitos tóxicos de compostos de vanádio sobre os parâmetros biológicos de embriões e adultos de zebrafish ( Danio rerio )

RESUMO Foram avaliados os efeitos tóxicos do metavanadato de sódio (MV), pentóxido de vanádio (PV) e sulfato de oxovanádio (SV), potenciais fármacos antidiabéticos, em embriões e adultos de zebrafish (Danio rerio). Os embriões foram expostos a concentrações de 10-1000µg/mL para avaliação da CL50 96h e seus efeitos teratogênicos. Os adultos foram expostos a 10 e 20µg/mL dos mesmos compostos para se avaliarem alterações comportamentais relacionadas à exposição química e à mortalidade. A CL50 96h foi de 22,48, 53,62 e 74,14µg/mL para MV, SV e PV, respectivamente. Houve 100% de mortalidade nas concentrações de 400-1000µg/mL dos três compostos. Os efeitos teratogênicos mais observados (P<0,05) nos embriões foram edemas de pericárdio e saco vitelínico. Foram constatados, nos animais adultos expostos aos compostos de vanádio, maior batimento opercular e congestão nos arcos branquiais. A exibição dos comportamentos Flutuar e Descansar nos adultos expostos foi significativa (P<0,05), como também a exibição do comportamento Respiração Aérea. Pode-se concluir que a exposição química aos compostos de vanádio causou efeitos tóxicos em embriões e adultos de zebrafish com alta mortalidade. Diante disso, o seu uso como potencial fármaco antidiabético deve ser mais bem estudado em razão do efeito tóxico dessas substâncias.

Comparative study on Ti-Nb binary alloys fabricated through spark plasma sintering and conventional P/M routes for biomedical application

The main purpose of this work is to obtain homogenous, single β phase in binary Ti-xNb (x = 18.75, 25, and 31.25 at.%) alloys by simple mixing of pure elemental powders using different sintering techniques such as spark plasma sintering (pressure-assisted sintering) and conventional powder metallurgy (pressure-less sintering). Synthesis parameters such as sintering temperature and holding time etc. are optimized in both techniques in order to get homogenous microstructure. In spark plasma sintering (SPS), complete homogeneous β phase is achieved in Ti25at.%Nb using 1300 °C sintering temperature with 60 min holding time under 50 MPa pressure. On the other hand, complete β phase is obtained in Ti25at.%Nb through conventional powder metallurgy (P/M) route using sintering temperature of 1400 °C for 120 min holding time which are adopted from the dilatometry studies. Nano-indentation is carried out for mechanical properties such as Young's modulus and nano-hardness. Elastic properties of binary Ti-xNb compositions are fallen within the range of 80-90 GPa. Cytotoxicity as well as cell adhesion studies carried out using MG63, osteoblast-like cells showed excellent biocompatibility of thus developed Ti25at.%Nb surface irrespective of fabrication route.

Synthesis, structure, solution behavior, reactivity and biological evaluation of oxidovanadium(iv/v) thiosemicarbazone complexes

The synthesis and characterization of an oxidovanadium(iv) [VIVO(L)(acac)] (1) and of two dioxidovanadium(v) [VVO2(L')] (2) and [VVO2(L)] (2a) complexes of the Schiff base formed from the reaction of 4-(p-fluorophenyl) thiosemicarbazone with pyridine-2-aldehyde (HL) are described. The oxidovanadium(iv) species [VIVO(L)(acac)] (1) was synthesized by the reaction of VIVO(acac)2 with the thiosemicarbazone HL in refluxing ethanol. The recrystallization of [VIVO(L)(acac)] (1) in DMF, CH3CN or EtOH gave the same product i.e. the dioxidovanadium(v) complex [VVO2(L)] (2a); however, upon recrystallization of 1 in DMSO a distinct compound [VVO2(L')] (2) was formed, wherein the original ligand L- is transformed to a rearranged one, L'-. In the presence of DMSO the ligand in complex 1 is found to undergo methylation at the carbon centre attached to imine nitrogen (aldimine) and transformed to the corresponding VVO2-species through in situ reaction. The synthesized HL and the metal complexes were characterized by elemental analysis, IR, UV-Vis, NMR and EPR spectroscopy. The molecular structure of [VVO2(L')] (2) was determined by single crystal X-ray crystallography. The methylation of various other ligands and complexes prepared from different vanadium precursors under similar reaction conditions was also attempted and it was confirmed that the imine methylation observed is both ligand and metal precursor specific. Complexes 1 and 2 show in vitro insulin-like activity against insulin responsive L6 myoblast cells, higher than VIVO(acac)2, with complex 1 being more potent. In addition, the in vitro cytotoxicity studies of HL, and of complexes 1 and 2 against the MCF-7 and Vero cell lines were also done. The ligand is not cytotoxic and complex 2 is significantly more cytotoxic than 1. DAPI staining experiments indicate that an increase in the time of incubation and an increase of concentration of the complexes lead to the increase in cell death.

Stone quarrying induces organ dysfunction and oxidative stress in Meriones libycus

Exposure to heavy metal-containing dust arising from stone quarrying may cause severe health problems. The aim of this study was to evaluate the impact of stone quarrying in Riyadh (Saudi Arabia) on the Libyan jird Meriones libycus. Soil samples and jirds were collected from four sites located at different distances from the quarrying area. Soil from the first (500 m away from the quarry) and second (1800 m away) sites showed a significant increase in cadmium (Cd), lead (Pb), nickel (Ni), and vanadium (V) when compared with the reference site (38,000 m away). Jirds at these sites exhibited significant increases in liver, kidney, lung, and fur levels of Cd, Pb, Ni, and V. Serum transaminases, creatinine, and malondialdehyde (MDA) levels were significantly increased in jirds, whereas reduced glutathione (GSH) levels decreased. Liver, kidney, and lung tissues of jirds, collected from the first and second sites, showed significantly increased MDA and decreased GSH levels. Additionally, animals at both sites showed altered hematological parameters and several histopathological changes in their liver, kidney, and lung. Soil and animals at the third site (7300 m away) showed no significant changes. Thus, our study showed the impact and hazardous effects of quarrying on the liver, kidney, lung, and hemogram of M. libycus. These findings can provide scientific evaluation for studying the impact of quarrying on the workers and communities living close to the studied area.

Removal of toxic metals from vanadium-contaminated soils using a washing method: Reagent selection and parameter optimization

Vanadium (V) contamination in soils is an increasing worldwide concern facing human health and environmental conservation. The fractionation of a metal influences its mobility and biological toxicity. We analyzed the fractionations of V and several other metals using the BCR three-step sequential extraction procedure. Among methods for removing metal contamination, soil washing is an effective permanent treatment. We conducted experiments to select the proper reagents and to optimize extraction conditions. Citric acid, tartaric acid, oxalic acid, and Na₂EDTA all exhibited high removal rates of the extractable state of V. With a liquid-to-solid ratio of 10, washing with 0.4 mol/L citric acid, 0.4 mol/L tartaric acid, 0.4 mol/L oxalic acid, and 0.12 mol/L Na₂EDTA led to removal rates of 91%, 88%, 88%, and 61%, respectively. The effect of multiple washing on removal rate was also explored. According to the changes observed in metal fractionations, differences in removal rates among reagents is likely associated with their pK_a value, pH in solution, and chemical structure. We concluded that treating with appropriate washing reagents under optimal conditions can greatly enhance the remediation of vanadium-contaminated soils.

Pollution by metals: Is there a relationship in glycemic control?

There are evidences of environmental pollution and health effects. Metals are pollutants implicated in systemic toxicity. One of the least studied effects, but which is currently becoming more important, is the effect of metals on glycemic control. Metals have been implicated as causes of chronic inflammation and oxidative stress and are associated to obesity, hyperglycemia and even diabetes. Arsenic, iron, mercury, lead, cadmium and nickel have been studied as a risk factor for hyperglycemia and diabetes. There is another group of metals that causes hypoglycemia such as vanadium, chromium, zinc and magnesium by different mechanisms. Zinc, magnesium and chromium deficiency is associated with increased risk of diabetes. This review summarizes some metals involved in glycemic control and pretends to alert health professionals about considering environmental metals as an important factor that could explain the poor glycemic control in patients. Further studies are needed to understand this poorly assessed problem.

Picolinic Acid Promoted Permanganate Oxidation of D-Mannitol in Micellar Medium

Kinetics of permanganate oxidation of D-mannitol have been investigated spectrophotometrically under pseudo-first-order conditions in aqueous acidic media at 30 °C. The spectral analysis of hydrazone derivative of the product indicates the product to be an aldehyde. The observed rate constant value was found to be relatively slow in the uncatalyzed path, which increases by the presence of four isomeric promoters: 2-picolinic acid (2-PA), 4-picolinic acid (4-PA), 2,3-dipicolinic acid (2,3-diPA) and 2,6-dipicolinic acid (2,6-diPA). The catalytic effect of sodium dodecylbenzene sulfonate (SDBS) surfactant on the permanganate oxidation of D-mannitol has been also studied in the presence of the promoters. The critical micelle concentration (CMC) of SDBS alone and in presence of D-mannitol was determined by conductometry and spectrophotometry. The aggregation and morphological changes during reaction were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The variation of the reaction rates for the different promoters in the presence and absence of SDBS micellar catalyst is discussed qualitatively in the terms of partitioning nature of substrate, charge of surfactant and reactants. 2,3-diPA in association with SDBS as micellar catalyst accelerated the reaction velocity compared to the uncatalyzed path.

Oxidative stress-mediated selective antimicrobial ability of nano-VO2 against Gram-positive bacteria for environmental and biomedical applications

Vanadium dioxide (VO2) is a unique thermochromic material as a result of its semiconductor-metal transition, holding great promise for energy-saving intelligent windows. Herein, pure nano-VO2 from discrete nanoparticles to continuous films were successfully deposited on quartz glass by controlling the sputtering parameters. It was demonstrated that, for Gram-positive S. aureus and S. epidermidis, the nano-VO2 could effectively disrupt bacteria morphology and membrane integrity, and eventually cause death. By contrast, the nano-VO2 did not exhibit significant toxicity towards Gram-negative E. coli and P. aeruginosa. To our knowledge, this is the first report on a selective antimicrobial effect of nano-VO2 materials on Gram-positive bacteria. Based on the experimental results, a plausible mechanism was proposed for the antimicrobial selectivity, which might originate from the different sensitivity of Gram-positive and Gram-negative bacteria to intracellular reactive oxygen species (ROS) level. Elevated intracellular ROS levels exceed the threshold that bacteria can self-regulate to maintain cellular redox homeostasis and thus cause oxidative stress, which can be alleviated by the intervention of glutathione (GSH) antioxidant. In addition, nano-VO2 did not produce significant cytotoxicity (hemolysis) against human erythrocytes within 12 h. Meanwhile, potential cytotoxicity against HIBEpiC revealed a time- and dose-dependent behavior that might be controlled and balanced by careful design. The findings in the present work may contribute to understanding the antimicrobial behavior of nano-VO2, and to expanding the new applications of VO2-based nanomaterials in environmental and biomedical fields.

Tunicate-Inspired Gallic Acid/Metal Ion Complex for Instant and Efficient Treatment of Dentin Hypersensitivity

Dentin hypersensitivity is sharp and unpleasant pains caused by exposed dentinal tubules when enamel outside of the tooth wears away. The occlusion of dentinal tubules via in situ remineralization of hydroxyapatite is the best method to alleviate the symptoms caused by dentin hypersensitivity. Commercially available dental desensitizers are generally effective only on a specific area and are relatively toxic, and their performance usually depends on the skill of the clinician. Here, a facile and efficient dentin hypersensitivity treatment with remarkable aesthetic improvement inspired by the tunicate-self-healing process is reported. As pyrogallol groups in tunicate proteins conjugate with metal ions to heal the torn body armor of a tunicate, the ingenious mechanism by introducing gallic acid (GA) as a cheap, abundant, and edible alternative to the pyrogallol groups of the tunicate combined with a varied daily intake of metal ion sources is mimicked. In particular, the GA/Fe(3+) complex exhibits the most promising results, to the instant ≈52% blockage in tubules within 4 min and ≈87% after 7 d of immersion in artificial saliva. Overall, the GA/metal ion complex-mediated coating is facile, instant, and effective, and is suggested as an aesthetic solution for treating dentin hypersensitivity.

Decavanadate Toxicology and Pharmacological Activities: V10 or V1, Both or None?

This review covers recent advances in the understanding of decavanadate toxicology and pharmacological applications. Toxicological in vivo studies point out that V10 induces several changes in several oxidative stress parameters, different from the ones observed for vanadate (V1). In in vitro studies with mitochondria, a particularly potent V10 effect, in comparison with V1, was observed in the mitochondrial depolarization (IC50 = 40 nM) and oxygen consumption (99 nM). It is suggested that mitochondrial membrane depolarization is a key event in decavanadate induction of necrotic cardiomyocytes death. Furthermore, only decavanadate species and not V1 potently inhibited myosin ATPase activity stimulated by actin (IC50 = 0.75 μM) whereas exhibiting lower inhibition activities for Ca(2+)-ATPase activity (15 μM) and actin polymerization (17 μM). Because both calcium pump and actin decavanadate interactions lead to its stabilization, it is likely that V10 interacts at specific locations with these proteins that protect against hydrolysis but, on the other hand, it may induce V10 reduction to oxidovanadium(IV). Putting it all together, it is suggested that the pharmacological applications of V10 species and compounds whose mechanism of action is still to be clarified might involve besides V10 and V1 also vanadium(IV) species.