Comparison of distribution and toxicity following repeated oral dosing of different vanadium oxide nanoparticles in mice

Influence of Oxygen Vacancies Introduced via Acceptor (Gadolinium) Doping to the Pseudocapacitive Properties of Nano-Sized Cerium Oxide

The voluntary introduction of defects can be considered an effective strategy for enhancing the electrochemical properties of metal oxide electrodes. In this study, the enhanced pseudocapacitive properties of an acceptor (Gd) doped cerium oxide nanoparticle-a sustainable metal oxide with low environmental and human toxicity-are investigated in depth using ex situ X-ray photoemission spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Interestingly, with 15 at% Gd doping (15GDC), the specific capacitance of the nanoparticles measured at 1 A g-1 enhanced to 547.8 F g-1, which is fivefold higher than undoped CeO2 (98.7 F g-1 at 1 A g-1). The rate-dependent capacitance is also improved for 15GDC, which showed a 31.0% decrease in the specific capacitance upon a tenfold increase in the current density, while CeO2 showed a 49.9% decrease. The enhanced electrochemical properties are studied in depth via ex situ XPS and EIS analysis, which revealed that the oxygen vacancies at the surface of the nanoparticles played important roles in enhancing both the specific capacitance and the high-rate performance of 15GDC by acting as the active site for pseudocapacitive redox reaction and allowing fast diffusion of oxygen ions at the surface of 15GDC nanoparticles.

A Redox Modulatory SOD Mimetic Nanozyme Prevents the Formation of Cytotoxic Peroxynitrite and Improves Nitric Oxide Bioavailability in Human Endothelial Cells

The endothelium-derived signalling molecule nitric oxide (NO) in addition to controlling multifarious servo-regulatory functions, suppresses key processes in vascular lesion formation and prevents atherogenesis and other vascular abnormalities. The conversion of NO into cytotoxic and powerful oxidant peroxynitrite (ONOO- ) in a superoxide (O2 .- )-rich environment has emerged as a major reason for reduced NO levels in vascular walls, leading to endothelial dysfunction and cardiovascular complications. So, designing superoxide dismutase (SOD) mimetics that can selectively catalyze the dismutation of O2 .- in the presence of NO, considering their rapid reaction is challenging and is of therapeutic relevance. Herein, the authors report that SOD mimetic cerium vanadate (CeVO4 ) nanozymes effectively regulate the bioavailability of both NO and O2 .- , the two vital constitutive molecules of vascular endothelium, even in the absence of cellular SOD enzyme. The nanozymes optimally modulate the O2 .- level in endothelial cells under oxidative stress conditions and improve endogenously generated NO levels by preventing the formation of ONOO- . Furthermore, nanoparticles exhibit size- and morphology-dependent uptake into the cells and internalize via the clathrin-mediated endocytosis pathway. Intravenous administration of CeVO4 nanoparticles in mice caused no definite organ toxicity and unaltered haematological and biochemical parameters, indicating their biosafety and potential use in biological applications.

Biodistribution of Vanadium Dioxide Particles in Mice by Consecutive Gavage Administration: Effects of Particle Size, Dosage, and Health Condition of Mice

The newly developed vanadium dioxide (VO₂), a material with excellent reversible and multi-stimuli responsible phase transition property, has been widely used in high-performance and energy-saving smart devices. The rapid growth of the VO₂-based emerging technologies and the complex biological effect of vanadium to organisms urge a better understanding of the behavior of VO₂ in vivo for safety purpose. Herein, we study the absorption, distribution, and excretion of two commercial VO₂ (nanoscale SVO₂ and bulk MVO₂) in mice after consecutive gavage administration for up to 28 days. The absorption of both types of VO₂ is as low as less than 1.5% of the injected dose within 28 days, while MVO₂ is several times more difficult to be absorbed than SVO₂. Almost all unabsorbed VO₂ is excreted through feces. For the absorbed vanadium, bone is the organ with the largest accumulation, followed by liver, kidney, and spleen. The vanadium content in organs shows a size-, dosage-, and animal health condition-dependent manner, and increases gradually to a saturation value along with the consecutive administration. Generally, smaller particle size and higher dosage lead to higher vanadium contents in organs, and more vanadium accumulates in bone and liver in diabetic mice than in normal mice. After the treatment is stopped, the accumulated vanadium in organs decreases a lot within 14 days, even reaches to the background level in some organs, but the content of vanadium in the bone remains high after 14 days post-exposure. These findings provide basic information for the safety assessment and safe applications of VO₂-based materials.

Impact of petroleum industry on goats in Saudi Arabia: heavy metal accumulation, oxidative stress, and tissue injury

Heavy metals (HMs) constitute a group of persistent toxic pollutants, and the petroleum industry is one of the sources of these metals. This study aimed to evaluate the levels of lead (Pb), cadmium (Cd), nickel (Ni), and vanadium (V) in Plantago ovata and milk and tissues of domestic goats in the eastern region of Saudi Arabia. Plant samples and blood, milk, muscle, liver, and kidney samples were collected from domestic goats and the levels of Pb, Cd, V, and Ni were determined. Liver and kidney tissue injury, oxidative stress, and expression of pro-inflammatory and apoptosis markers were evaluated. Pb, Cd, V, and Ni were increased in Plantago ovata as well as in milk, blood, muscle, liver, and kidney of goats collected from the polluted site. Aminotransferases, creatinine, and urea were increased in serum, and histopathological changes were observed in the liver and kidney of goats at the oil extraction site. Malondialdehyde and the expression levels of pro-inflammatory cytokines, Bax, and caspase-3 were increased, whereas cellular antioxidants and Bcl-2 were decreased in liver and kidney of goats at the polluted site. In conclusion, petroleum industry caused liver and kidney injury, oxidative stress, and upregulated pro-inflammatory and apoptosis markers in goats. These findings highlight the negative impact of petroleum industry on the environment and call attention to the assessment of its effect on the health of nearby communities.

Phytotoxicity of VO2 nanoparticles with different sizes to pea seedlings

Vanadium dioxide nanoparticles (VO2 NPs) have been massively produced due to their excellent metal-insulator transition characteristics for various applications. Pilot studies indicated the toxicity of VO2 NPs to bacteria and mammalian cells, but the environmental hazards of VO2 NPs to plants have been unrevealed to date. In this study, we reported the inhibitive effects of VO2 NPs to the growth and photosynthesis of pea seedlings. Laboratory synthesized monoclinic VO2 NPs (N-VO2), commercial nanosized VO2 NPs (S-VO2), and commercial microsized VO2 particles (M-VO2) were carefully characterized for environmental toxicity evaluations. VO2 particles were supplemented to culture medium for seed germination and seedling growth. All three VO2 samples did not affect the germination rates of pee seeds, while serious growth inhibition of pea seedlings was observed at 10 mg/L for S-VO2 and N-VO2, and 100 mg/L for M-VO2. VO2 particles had no impact on the chlorophyll contents, but the photosynthesis of leaf was significantly decreased following the consequence of N-VO2 > S-VO2 > M-VO2. The inhibition of photosynthesis was attributed to the damage of acceptor side of photosystem II by VO2 particles at high concentrations. Abundant bioaccumulations of vanadium in roots aroused oxidative damage and changed the root structure. Our results collectively indicated that the phytotoxicity of VO2 NPs was related to the concentration, size and crystalline degree.

Heavy Metal Accumulation, Tissue Injury, Oxidative Stress, and Inflammation in Dromedary Camels Living near Petroleum Industry Sites in Saudi Arabia

The petroleum industry can impact the environment and human health. Heavy metals (HMs), including lead (Pb), cadmium (Cd), nickel (Ni), and vanadium (V), are toxic pollutants found in petroleum that can cause several severe diseases. This study investigated the impact of the oil industry on the Arabian camel (Camelus dromedarius) in the eastern region of Saudi Arabia, pointing to HMs accumulation, tissue injury, redox imbalance, inflammation, and apoptosis. Soil and camel samples (milk, blood, muscle, liver, and kidney) were collected from a site near an oil industry field and another two sites to analyze HMs. Pb, Cd, Ni, and V were increased in the soil and in the camel’s milk, blood, muscle, liver, and kidney at the polluted site. Serum aminotransferases, urea, and creatinine were elevated, and histopathological alterations were observed in the liver and kidney of camels at the oil industry site. Hepatic and renal lipid peroxidation, pro-inflammatory cytokines, Bax, and caspase-3 were increased, whereas cellular antioxidants and Bcl-2 declined in camels at the oil extraction site. In conclusion, the oil industry caused soil and tissue accumulation of HMs, liver and kidney injury, oxidative stress, and apoptosis in camels living close to the oil extraction site. These findings pinpoint the negative impact of the oil industry on the environment, animal, and human health.

Vanadium Induces Oxidative Stress and Mitochondrial Quality Control Disorder in the Heart of Ducks

Vanadium (V) is an ultra-trace element presenting in humans and animals, but excessive V can cause toxic effects. Mitochondrial quality control (MQC) is an essential process for maintaining mitochondrial functions, but the relationship between V toxicity and MQC is unclear. To investigate the effects of excessive V on oxidative stress and MQC in duck hearts, 72 ducks were randomly divided into two groups, including the control group and the V group (30 mg of V/kg dry matter). The cardiac tissues were collected for the histomorphology observation and oxidative stress status evaluation at 22 and 44 days. In addition, the mRNA and protein levels of MQC-related factors were also analyzed. The results showed that excessive V could trigger vacuolar degeneration, granular degeneration, as well as mitochondrial vacuolization and swelling in myocardial cells. In addition, CAT activity was elevated in two time points, while T-SOD activity was increased in 22 days but decreased in 44 days after V treatment. Meanwhile, excessive V intake could also increase the number of Drp1 puncta, the mRNA levels of mitochondrial fission–related factors (Drp1and MFF), and protein (MFF) level, but decrease the number of Parkin puncta and the mitochondrial biogenesis (PGC-1α, NRF-1, and TFAM), mitochondrial fusion (OPA1, Mfn1, and Mfn2), and mitophagy (Parkin, PINK1, P62, and LC3B) related mRNA levels and protein (PGC-1α, Mfn1, Mfn2, PINK1) levels. Collectively, our results suggested that excessive V could induce oxidative stress and MQC disorder in the heart of ducks.

Effects of VO2 nanoparticles on human liver HepG2 cells: Cytotoxicity, genotoxicity, and glucose and lipid metabolism disorders

The rapid development of smart materials stimulates the production of vanadium dioxide (VO₂) nanomaterials. This significantly increases the population exposure to VO₂ nanomaterials via different pathways, and thus urges us to pay more attentions to their biosafety. Liver is the primary accumulation organ of nanomaterials in vivo, but the knowledge of effects of VO₂ nanomaterials on the liver is extremely lacking. In this work, we comprehensively evaluated the effects of a commercial VO₂ nanoparticle, S-VO₂, in a liver cell line HepG2 to illuminate the potential hepatic toxicity of VO₂ nanomaterials. The results indicated that S-VO₂ was cytotoxic and genotoxic to HepG2 cells, mainly by inhibiting the cell proliferation. Apoptosis was observed at higher dose of S-VO₂, while DNA damage was detected at all tested concentrations. S-VO₂ particles were internalized by HepG2 cells and kept almost intact inside cells. Both the particle and dissolved species of S-VO₂ contributed to the observed toxicities. They induced the overproduction of ROS, and then caused the mitochondrial dysfunction, ATP synthesis interruption, and DNA damages, consequently arrested the cell cycle in G2/M phase and inhibited the proliferation of HepG2 cells. The S-VO₂ exposure also resulted in the upregulations of glucose uptake and lipid content in HepG2 cells, which were attributed to the ROS production and autophagy flux block, respectively. Our findings offer valuable insights into the liver toxicity of VO₂ nanomaterials, benefiting their safely practical applications.

Environmental Hazards of Boron and Vanadium Nanoparticles in the Terrestrial Ecosystem-A Case Study with Enchytraeus crypticus

From the start of the 21st century, nanoecotoxicological research has been growing in fast steps due to the need to evaluate the safety of the increasing use of engineered nanomaterials. Boron (B) and vanadium (V) nanoparticles (NPs) generated by anthropogenic activities are subsequently released in the environment; therefore, organisms can be continuously exposed to these NPs for short or long periods. However, the short and long-term effects of BNPs and VNPs on soil organisms are unknown. This work aimed to recognize and describe their potential toxicological effects on the model species Enchytraeus crypticus, assessing survival and reproduction, through a longer-term exposure (56 days (d)-OECD test extension of 28 d), and avoidance behavior, through a short-term exposure (48 hours (h)). After 28 d, BNPs did not induce a significant effect on E. crypticus survival, whereas they decreased the organisms' reproduction at 500 mg/kg. From 10 to 500 mg/kg, VNPs decreased the E. crypticus survival and/or reproduction. After 56 d, 100 to 500 mg/kg BNPs and 50 to 500 mg/kg VNPs, decreased the reproduction output of E. crypticus. The estimated Effect Concentrations (EC_x) based on reproduction, for BNPs, were lower at 56 d compared with 28 d; for VNPs, an opposite pattern was found: EC_x 28 d < EC_x 56 d. BNPs did not induce an avoidance behavior, but organisms avoided the soil contaminated with 10 mg VNPs/kg. The tested NPs showed different E. crypticus apical effects at 28 d from the ones detected at 56 d, dependent on the type of NPs (B vs. V). In general, VNPs showed to be more toxic than BNPs. However, the effects of VNPs were alleviated during the time of exposure, contrarily to BNPs (which became more toxic with extended duration). The present study adds important information about NPs toxicity with ecological significance (at the population level). Including long-term effects, the obtained results contributes to the improvement of NPs risk assessment.

Cytotoxicity and genotoxicity of low-dose vanadium dioxide nanoparticles to lung cells following long-term exposure

Vanadium dioxide nanoparticles (VO₂ NPs) have been massively produced and widely applied due to their excellent metal-insulator transition property, making it extremely urgent to evaluate their safety, especially for low-dose long-term respiratory occupational exposure. Here, we report a comprehensive cytotoxicity and genotoxicity study on VO₂ NPs to lung cell lines A549 and BEAS-2B following a long-term exposure. A commercial VO₂ NP, S-VO₂, was used to treat BEAS-2B (0.15-0.6 μg/mL) and A549 (0.3-1.2 μg/mL) cells for four exposure cycles, and each exposure cycle lasted for 4 consecutive days; then various bioassays were performed after each cycle. Significant proliferation inhibition was observed in both cell lines after long-term exposure of S-VO₂ at low doses that did not cause apparent acute cytotoxicity; however, the genotoxicity of S-VO₂, characterized by DNA damage and micronuclei, was only observed in A549 cells. These adverse effects of S-VO₂ were exposure time-, dose- and cell-dependent, and closely related to the solubility of S-VO₂. The oxidative stress in cells, i.e., enhanced reactive oxygen species (ROS) generation and suppressed reduced glutathione, was the main toxicity mechanism of S-VO₂. The ROS-associated mitochondrial damage and DNA damage led to the genotoxicity, and cell proliferation retard, resulting in the cellular viability loss. Our results highlight the importance and urgent necessity of the investigation on the long-term toxicity of VO₂ NPs.

Incorporation of a Biocompatible Nanozyme in Cellular Antioxidant Enzyme Cascade Reverses Huntington's Like Disorder in Preclinical Model

The potentiality of nano-enzymes in therapeutic use has directed contemporary research to develop a substitute for natural enzymes, which are suffering from several disadvantages including low stability, high cost, and difficulty in storage. However, inherent toxicity, inefficiency in the physiological milieu, and incompatibility to function in cellular enzyme networks limit the therapeutic use of nanozymes in living systems. Here, it is shown that citrate functionalized manganese-based biocompatible nanoscale material (C-Mn₃ O₄ NP) efficiently mimics glutathione peroxidase (GPx) enzyme in the physiological milieu and easily incorporates into the cellular multienzyme cascade for H₂ O₂ scavenging. A detailed computational study reveals the mechanism of the nanozyme action. The in vivo therapeutic efficacy of C-Mn₃ O₄ nanozyme is further established in a preclinical animal model of Huntington's disease (HD), a prevalent progressive neurodegenerative disorder, which has no effective medication to date. Management of HD in preclinical animal trial using a biocompatible (non-toxic) nanozyme as a part of the metabolic network may uncover a new paradigm in nanozyme based therapeutic strategy.

Age-Related Effects of Orthovanadate Nanoparticles Involve Activation of GSH-Dependent Antioxidant System in Liver Mitochondria

Vanadium is an important ultra-trace element nowadays attracting attention with particular emphasis on medical application. But the therapeutic application of vanadium-based drugs is still questionable and restricted due to some toxic side effects. It was found that unique redox properties of vanadium in nanoform provided antioxidant activity and prevented oxidative disturbance in cells in vitro. Though, on the organism level, ambiguous effects of vanadium-based nanoparticles were observed. In this study, the age-related features of prooxidant/antioxidant balance in blood serum and liver mitochondrial and postmitochondrial fractions of 3 and 18-month-old Wistar male rats treated with orthovanadate nanoparticles (GdVO₄/Eu³⁺, 8 × 25 nm) within 2 months have been investigated. Prooxidant potential-related indexes were the content of lipid hydroperoxides as well as aconitase activity. Activity of glutathione peroxidase, glutathione-S-transferase, glutaredoxin, glutathione reductase, glucose-6-phosphate dehydrogenase, and NADPH-dependent isocitrate dehydrogenase designated the tissue antioxidant potential. Based on the obtained values, the integral index of the prooxidant/antioxidant balance-the reliability coefficient (Kr) has been calculated. The data show that due to activation some chain links of GSH-dependent antioxidant system, GdVO₄/Eu³⁺ nanoparticles increase the reliability of the prooxidant-antioxidant balance in tissues and especially in the liver mitochondria of old animals (Kr in mitochondria of young rats was 2.94, and in mitochondria of old ones-9.83 conventional units). Detected in vitro glutathione peroxidase-like activity of the GdVO₄/Eu³⁺ nanoparticles is supposed to be among factors increasing the reliability of the system. So, for the first time, the beneficial effect of the long-term orthovanadate nanoparticle consumption in old males has been discovered.

Effects of vanadium (sodium metavanadate) and aflatoxin-B1 on cytochrome p450 activities, DNA damage and DNA methylation in human liver cell lines

Vanadium is considered as "possibly carcinogenic to humans" (V₂O₅, IARC Group 2B), yet uncertainties persist related to the toxicity mechanisms of the multiple forms of vanadium. Exposure to vanadium often co-occurs with other metals or with organic compounds that can be transformed by cytochrome p450 (CYP) enzymes into DNA-reactive carcinogens. Therefore, effects of a soluble form of vanadium (sodium metavanadate, NaVO₃) and aflatoxin-B1 (AFB1) were tested separately and together, for induction of CYP activities, DNA damage (γH2AX and DNA alkaline unwinding assays), and DNA methylation changes (global genome and DNA repeats) in HepaRG or HepG2 liver cell lines. NaVO₃ (≥ 2.3 μM) reduced CYP1A1 and CYP3A4 activities and induced DNA damage, butcaused important cell proliferation only in HepaRG cells. As a binary mixture, NaVO₃ did not modify the effects of AFB1. There was no reproducible effect of NaVO₃ (<21 μM) on DNA methylation in AluYb8, satellite-α, satellite-2, and by the luminometric methylation assay, but DNA methylation flow-cytometry signals in HepG2 cells (25-50 μM) increased at the G1 and G2 cell cycle phases. In conclusion, cell lines responded differently to NaVO₃ supporting the importance of investigating more than one cell line, and a carcinogenic role of NaVO₃ might reside at low concentrations by stimulating the proliferation of tumorigenic cells.

Repeated-oral dose toxicity of polyethylene microplastics and the possible implications on reproduction and development of the next generation

With the increased distribution of microplastics in the environment, the potential for harmful effects on human health and ecosystems have become a global concern. Considering that polyethylene microplastics (PE-MPs) are among the most produced plastics worldwide, we administered PE-MPs (0.125, 0.5, 2 mg/day/mouse) by gavage to mice (10 mice/sex/dose) for 90 days. Compared to control, the body weight gain was significantly reduced in the male mice, and the proportion of neutrophils in the blood stream clearly increased in both sexes of mice. Persistence of a PE-MPs-like material and migration of granules to the mast cell membrane and accumulation of damaged organelles were observed in the stomachs and the spleens from the treated dams, respectively. Additionally, the IgA level in the blood stream was significantly elevated in the dams administered with PE-MPs compared to control, and the subpopulation of lymphocytes within the spleen was altered. Following, we performed an additional study to screen the effects of PE-MPs on reproduction and development (5 mice/sex/dose). Importantly, number of live births per dam, the sex ratio of pups, and body weight of pups was notably altered in groups treated with PE-MPs compared to the control group. Additionally, PE-MPs affected the subpopulation of lymphocytes within the spleen of the offspring, as did in the dams. Therefore, we propose that reproductive and developmental toxicity testing is warranted to evaluate the safety of microplastics. Additionally, we suggest that the IgA level may be used as a biomarker for harmful effects following exposure on microplastics.

Cytotoxicity of vanadium oxide nanoparticles and titanium dioxide-coated vanadium oxide nanoparticles to human lung cells

Due to excellent metal-insulator transition property, vanadium dioxide nanoparticles (VO₂ NPs)-based nanomaterials are extensively studied and applied in various fields, and thus draw safety concerns of VO₂ NPs exposure through various routes. Herein, the cytotoxicity of VO₂ NPs (N-VO₂ ) and titanium dioxide-coated VO₂ NPs (T-VO₂ ) to typical human lung cell lines (A549 and BEAS-2B) was studied by using a series of biological assays. It was found that both VO₂ NPs induced a dose-dependent cytotoxicity, and the two cell lines displayed similar sensitivity to VO₂ NPs. Under the same conditions, T-VO₂ NPs showed slightly lower cytotoxicity than N-VO₂ in both cells, indicating the surface coating of titanium dioxide mitigated the toxicity of VO₂ NPs. Titanium dioxide coating changed the surface property of VO₂ NPs and reduced the vanadium release of particles, and thus helped lowing the toxicity of VO₂ NPs. The induced cell viability loss was attributed to apoptosis and proliferation inhibition, which were supported by the assays of apoptosis, mitochondrial membrane damage, caspase-3 level, and cell cycle arrest. The oxidative stress, i.e., enhanced reactive oxygen species generation and suppressed reduced glutathione , in A549 and BEAS-2B cells was one of the major mechanisms of the cytotoxicity of VO₂ NPs. These findings provide safety guidance for the practical applications of vanadium dioxide-based materials.

Tissue distribution following 28 day repeated oral administration of aluminum-based nanoparticles with different properties and the in vitro toxicity

The tissue distribution and toxicity of nanoparticles (NPs) depend on their physical and chemical properties both in the manufactured condition and within the biological system. We characterized three types of commercially available aluminum-based NPs (Al-NPs), two rod-type aluminum oxide NPs (Al₂ O₃ , AlONPs), with different aspect ratios (short [S]- and long [L]-AlONPs), and spherical aluminum cerium oxide NPs (AlCeO₃ , AlCeONPs). The surface area was in order of the S-AlONPs > L-AlONPs > AlCeONPs. Very importantly, we found that AlCeONPs is Al₂ O₃ -coated CeO₂ NPs, but not AlCeO₃ NPs, and that the Al level in AlCeONPs is approximately 20% of those in S- and L-AlONPs. All three types of Al-NPs were slightly ionized in gastric fluid and rapidly particlized in the intestinal fluid. There were no significant differences in the body weight gain following 28 days of repeated oral administration of the three different types of Al-NPs. All Al-NPs elevated Al level in the heart, spleen, kidney and blood at 24 hours after the final dose, accompanied by the altered tissue level of redox reaction-related trace elements. Subsequently, in four types of cells derived from the organs which Al-NPs are accumulated, H9C2 (heart), HEK-293 (kidney), splenocytes and RAW264.7 (blood), S-AlONPs showed a very low uptake level and did not exert significant cytotoxicity. Meanwhile, cytotoxicity and uptake level were the most remarkable in cells treated with AlCeONPs. In conclusion, we suggest that the physicochemical properties of NPs should be examined in detail before the release into the market to prevent unexpected adverse health effects.