Evaluation of Long-Term Toxicity of Oral Zinc Oxide Nanoparticles and Zinc Sulfate in Mice

The toxicological effects of zinc oxide nanoparticles (nano-ZnOs) are related to their dissolution and interference with zinc ion homeostasis. High-soluble zinc sources may produce more severe and acute toxicity; however, the evaluation of potential toxicity of long-term exposure to nano-ZnOs and high-soluble sources of zinc remains obscure. This study aimed at evaluating effects of nano-ZnOs and zinc sulfate on development, serum and hematological parameters, and mineral concentrations in selected tissues and intestinal microbiota in mice via gastrointestinal administration for 7 weeks. Results indicated that 250 mg/kg nano-ZnOs reduced the body weight from weeks 8 to 11, increased serum glutamic-pyruvic transaminase activity, and increased the zinc concentrations of the serum, liver, and kidney while did not affect the relative organ weight, intestinal microbiota, and other mineral concentrations (Fe, Cu, and Mn) in the kidney, liver, and thigh muscle. Oral administration with 250 mg/kg zinc sulfate seemed to show more severe and acute toxicity since mice in zinc sulfate group exhibited reduced body weight from weeks 5 to 11, decreased relative pancreas weight, and increased serum glutamic-oxalacetic transaminase activity and intestinal enteric group.     

Effect of Maternal Exposure to Zinc Oxide Nanoparticles on Reflexive Motor Behaviors in Mice Offspring

International Journal of Peptide Research and Therapeutics - Zinc oxide may influence central nervous system development in offspring but there is no information on role of the zinc oxide...     

Zinc Oxide Nanoparticles Promote the Aggregation of Concanavalin A

The ability of nanoparticles to influence protein folding and aggregation is interesting, not only because of the potential beneficial applications, but also the potential risks to human health and the environment. The interactions of concanavalin A (Con A) with zinc oxide nanoparticles (ZnO-NPs) were investigated by using fluorescence, fourier transform infrared spectroscopy, circular dichroism (CD) and dynamic light scattering techniques. ANS fluorescence and CD spectroscopy authenticated the formation of molten globule state of Con A after its incubation with ZnO-NPs for 36 h. Further incubation of 48 h resulted in the aggregation of unadsorbed Con A, proved by decrease in ANS fluorescence while an increase in thioflavin T fluorescence, characteristic of an aggregates. Moreover, Fourier transform-infrared spectroscopy confirmed the aggregation of unadsorbed Con A. The aggregated products were negligible genotoxic as analyzed by pUC19 plasmid degradation and comet assay. It is clear that ZnO-NPs morphology affect unadsorbed proteins structure. A better understanding of these differences will be essential to engineer fully functional nanobioconjugates and NPs which do not damage the proteins present in the biological system.     

Comparative Study of Antidiabetic Activity and Oxidative Stress Induced by Zinc Oxide Nanoparticles and Zinc Sulfate in Diabetic Rats

In the current study, antidiabetic activity and toxic effects of zinc oxide nanoparticles (ZnO) were investigated in diabetic rats compared to zinc sulfate (ZnSO₄) with particular emphasis on oxidative stress parameters. One hundred and twenty male Wistar rats were divided into two healthy and diabetic groups, randomly. Each major group was further subdivided into five subgroups and then orally supplemented with various doses of ZnO (1, 3, and 10 mg/kg) and ZnSO₄ (30 mg/kg) for 56 consecutive days. ZnO showed greater antidiabetic activity compared to ZnSO₄ evidenced by improved glucose disposal, insulin levels, and zinc status. The altered activities of erythrocyte antioxidant enzymes as well as raised levels of lipid peroxidation and a marked reduction of total antioxidant capacity were observed in rats receiving ZnO. ZnO nanoparticles acted as a potent antidiabetic agent, however, severely elicited oxidative stress particularly at higher doses.     

Iron Oxide Nanoparticles Affects Behaviour and Monoamine Levels in Mice

Iron oxide (Fe₂O₃) nanoparticles (NPs) attract the attention of clinicians for its unique magnetic and paramagnetic properties, which are exclusively used in neurodiagnostics and therapeutics among the other biomedical applications. Despite numerous research findings has already proved neurotoxicity of Fe₂O₃-NPs, factors affecting neurobehaviour has not been elucidated. In this study, mice were exposed to Fe₂O₃-NPs (25 and 50 mg/kg body weight) by oral intubation daily for 30 days. It was observed that Fe₂O₃-NPs remarkably impair motor coordination and memory. In the treated brain regions, mitochondrial damage, depleted energy level and decreased ATPase (Mg²⁺, Ca²⁺ and Na⁺/K⁺) activities were observed. Disturbed ion homeostasis and axonal demyelination in the treated brain regions contributes to poor motor coordination. Increased intracellular calcium ([Ca²⁺]_i) and decreased expression of growth associated protein 43 (GAP43) impairs vesicular exocytosis could result in insufficient signal between neurons. In addition, levels of dopamine (DA), norepinephrine (NE) and epinephrine (EP) were found to be altered in the subjected brain regions in correspondence to the expression of monoamine oxidases (MAO). Along with all these factors, over expression of glial fibrillary acidic protein (GFAP) confirms the neuronal damage, suggesting the evidences for behavioural changes.

     

Effect of Zinc Oxide Nanoparticles on the Function of MC3T3-E1 Osteoblastic Cells

Zinc oxide nanoparticles (ZnO NPs) can be ingested directly when used in food, food packaging, drug delivery, and cosmetics. This study evaluated the cellular effects of ZnO NPs (50 and 100 nm diameter particle sizes) on the function of osteoblastic MC3T3-E1 cells. ZnO NPs showed cytotoxicity at concentrations of above 50 μg/ml, and there was no significant effect of the size on the cytotoxicity of ZnO NPs. Within the testing concentrations of 0.01～1 μg/ml, which did not cause a marked drop in cell viability, ZnO NPs (0.1 μg/ml) caused a significant elevation of alkaline phosphatase activity, collagen synthesis, mineralization, and osteocalcin content in the cells (P?<?0.05). Moreover, pretreatment with ZnO NPs (0.01～1 μg/ml) significantly reduced antimycin A-induced cell damage by preventing mitochondrial membrane potential dissipation, complex IV inactivation, and ATP loss. Measurement of reactive oxygen species (ROS) indicated decrease in ROS level upon exposure to ZnO nanoparticles (0.01 μg/ml). Hence, our study indicated that ZnO nanoparticles can have protective effects on osteoblasts at low concentrations where there are little or no observable cytotoxic effects.     

Exposure to Zinc Oxide Nanoparticles Induces Neurotoxicity and Proinflammatory Response: Amelioration by Hesperidin

Zinc oxide nanoparticles (ZnONPs) are widely used in food packaging and may enter the body directly if exposed. Hereby, in this study, the oral administration was selected as the route of exposure for rats to nanoparticles and the effect of hesperidin (HSP, 100 mg/kg bwt) was evaluated on ZnONP (600 mg/kg bwt)-induced neurotoxicity in rats. ZnONPs were characterized using transmission electron microscopy. Neurotoxicity was observed as seen by elevation in serum inflammatory markers including tumor necrosis factor alpha (TNF-α), interleukin 1 (IL-1β), interleukin-6 (IL-6), C-reactive protein (CRP), and activities of catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione (GSH) content in rat brains. Pretreatment of rats with HSP in ZnONP-treated group elevated activities of antioxidant enzymes. HSP also caused decrease in TNF-α, IL-1β, IL-6, and CRP levels which was higher in the ZnONP-treated group. The results suggest that HSP augments antioxidant defense with anti-inflammatory response against ZnONP-induced neurotoxicity. The increased antioxidant enzymes enhance the antioxidant potential to reduce oxidative stress.     

Cerium Oxide Nanoparticles Attenuate Oxidative Stress and Inflammation in the Liver of Diethylnitrosamine-Treated Mice

Biological Trace Element Research - The catalytic activity of cerium oxide nanoparticles (CeO2NPs) is responsible for its application as an antitumor agent. This activity may be due to its ability...     

Green Synthesized Zinc Oxide Nanoparticles as Feed Additives to Improve Growth,Biochemical, and Hematological Parameters in Freshwater Fish Labeo rohita

Biological Trace Element Research - Zinc deficiency in aquatic animals affects the biological processes and physiological functions. Thus, the supplement of ZnONPs can be used as an alternative...     

Role of Nitric Oxide in the Pathogenesis of Encephalomyocarditis Virus-Induced Diabetes in Mice

The D variant of encephalomyocarditis virus (EMC-D virus) causes diabetes in mice by destroying pancreatic β cells. In mice infected with a low dose of EMC-D virus, macrophages play an important role in β-cell destruction by producing soluble mediators such as interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), and nitric oxide (NO). To investigate the role of NO and inducible NO synthase (iNOS) in the development of diabetes in EMC-D virus-infected mice, we infected iNOS-deficient DBA/2 mice with EMC-D virus (2 × 10² PFU/mouse). Mean blood glucose levels in EMC-D virus-infected iNOS-deficient mice and wild-type mice were 205.5 and 466.7 mg/dl, respectively. Insulitis and macrophage infiltration were reduced in islets of iNOS-deficient mice compared with wild-type mice at 3 days after EMC-D virus infection. Apoptosis of β cells was decreased in iNOS-deficient mice, as evidenced by reduced numbers of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells. There were no differences in mRNA expression of antiapoptotic molecules Bcl-2, Bcl-xL, Bcl-w, Mcl-1, cIAP-1, and cIAP-2 between wild-type and iNOS-deficient mice, whereas expression of proapoptotic Bax and Bak mRNAs was significantly decreased in iNOS-deficient mice. Expression of IL-1β and TNF-α mRNAs was significantly decreased in both islets and macrophages of iNOS-deficient mice compared with wild-type mice after EMC-D virus infection. Nuclear factor κB was less activated in macrophages of iNOS-deficient mice after virus infection. We conclude that NO plays an important role in the activation of macrophages and apoptosis of pancreatic β cells in EMC-D virus-infected mice and that deficient iNOS gene expression inhibits macrophage activation and β-cell apoptosis, contributing to prevention of EMC-D virus-induced diabetes.Type 1 diabetes results from absolute insulin deficiency caused by destruction of insulin-producing pancreatic β cells. The D variant of encephalomyocarditis virus (EMC-D virus) induces diabetes in genetically susceptible strains of mice by infecting and destroying β cells (13-18). In mice infected with a low dose (1 × 10² PFU/mouse) of EMC-D virus, macrophages play a central role in the destruction of pancreatic β cells (4, 5, 13-15), as evidenced by a significant increase in the incidence of diabetes if macrophages are activated prior to viral infection and complete prevention of EMC-D virus-induced diabetes if macrophages are inactivated prior to viral infection (4). Additional studies found that selective EMC-D viral infection of pancreatic β cells results in an initial recruitment of macrophages into the islets, followed by infiltration of other immunocytes, including T cells, natural killer cells, and B cells (5).EMC-D virus infects and activates macrophages without replication (13) and induces the production of soluble mediators such as interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), and inducible nitric oxide synthase (iNOS), which play important roles in the destruction of β cells (14). These infected macrophages express significantly more iNOS than either IL-1β or TNF-α (13). Treatment of EMC-D virus-infected mice with the tyrosine kinase inhibitor AG126, which inhibits nitric oxide (NO) production in EMC-D virus-infected macrophages, decreases the expression of IL-1β and TNF-α in the pancreatic islets and the incidence of diabetes and insulitis compared with those in vehicle-treated control mice (13). As well, treatment of EMC-D virus-infected mice with an iNOS inhibitor decreases the incidence of diabetes (14). These results suggest that iNOS and NO significantly contribute to the destruction of pancreatic β cells in mice infected with a low dose of EMC-D virus, although their roles are not fully understood.To directly test whether iNOS and NO play a critical role in the pathogenesis of EMC-D virus-induced diabetes in mice, we used iNOS knockout (KO) DBA/2 mice. We found that iNOS-deficient mice infected with EMC-D virus (2 × 10² PFU/mouse) showed a significantly lower incidence of diabetes. There was reduced expression of IL-1β and TNF-α in macrophages and decreased infiltration of immunocytes in the islets of iNOS-deficient mice, resulting in reduced apoptosis of β cells compared with that in EMC-D virus-infected wild-type mice. This study provides direct evidence of a role of NO in the activation of macrophages by EMC-D viral infection and in the pathogenesis of low-dose (2 × 10² PFU/mouse) EMC-D virus-induced diabetes.     

Tissue-Specific Regulation of the Contents and Correlations of Mineral Elements in Hens by Zinc Oxide Nanoparticles

Due to their small size, zinc oxide (ZnO) nanoparticles (NPs) are readily absorbed and easily cross biological barriers, which make them promising candidates as diet additives. However, some studies have reported that ZnO NPs cause toxicity; therefore, their safety and potency as diet additives for farm animals should be established. This study was the first to fully evaluate the effects of ZnO NPs on the homeostasis of eight elements in seven organs/tissues. The regulation of element homeostasis was found to be organ specific with no influence on oxidation status, anti-oxidation capability, or organ damage. ZnO NPs may specifically regulate the homeostasis of mineral elements and affect the following correlations: (1) between the element content in each organ and the concentration of Zn used in ZnSO₄ or ZnO NP treatments; (2) between ZnO NP and ZnSO₄ treatments for the same element in each organ; and (3) between elements (in each organ in ZnSO₄ or ZnO NP treatments) in layers’ organs/tissues. The use of ZnO NPs as diet additives for animals should be implemented cautiously because, among other uncertainties, they may affect mineral element content.     

Effects of Dietary Zinc Oxide Nanoparticles on Growth Performance and Antioxidative Status in Broilers

Broilers in four groups were fed a basal diet supplemented with 60 mg/kg zinc oxide (60-ZnO; control), or 20, 60, or 100 mg/kg ZnO nanoparticles (20-, 60-, and 100-nano-ZnO, respectively). Compared with the controls, after 14 days, birds in the 20- and 60-nano-ZnO groups had significantly greater weight gains and better feed conversion ratios. However, the body weight of birds in the 100-nano-ZnO group was dramatically reduced after 28 days. Relative to the control group, the total antioxidant capability (T-AOC) in serum and liver tissue was significantly higher in the 20-nano-ZnO group at all time points and also significantly higher in the 60- and 100-nano-ZnO groups in serum on days 28 and 35 and in liver tissues on days 21 and 28. Compared with the controls, the activity of copper-zinc superoxide dismutase (Cu-Zn-SOD) was significantly greater in the 60- and 100-nano-ZnO groups in serum on days 28 and 35 and in liver tissues after 21 days. Catalase activity in serum samples was significantly higher in the 20- and 60-nano-ZnO groups relative to the control and 100-nano-ZnO birds, but catalase activity in liver tissue was not affected by different nano-ZnO levels. Malondialdehyde content in serum and liver tissues was significantly reduced in the 20-, 60-, and 100-nano-ZnO groups compared with that in the control group at all time points except day 42. Taken together, our data indicate that appropriate concentration of dietary ZnO nanoparticles improves growth performance and antioxidative capabilities in broilers, and 20 mg/kg nano-ZnO is the optimal concentration.     

Comparative Hazard Identification by a Single Dose Lung Exposure of Zinc Oxide and Silver Nanomaterials in Mice

Comparative hazard identification of nanomaterials (NMs) can aid in the prioritisation for further toxicity testing. Here, we assessed the acute lung, systemic and liver responses in C57BL/6N mice for three NMs to provide a hazard ranking. A silver (Ag), non-functionalised zinc oxide (ZnO) and a triethoxycaprylylsilane functionalised ZnO NM suspended in water with 2% mouse serum were examined 24 hours following a single intratracheal instillation (I.T.). An acute pulmonary inflammation was noted (marked by a polymorphonuclear neutrophil influx) with cell damage (LDH and total protein) in broncho-alveolar lavage fluid (BALF) after administration of both non-functionalised and functionalised ZnO. The latter also induced systemic inflammation measured as an increase in blood neutrophils and a decrease in blood lymphocytes. Exposure to Ag NM was not accompanied by pulmonary inflammation or cytotoxicity, or by systemic inflammation. A decrease in glutathione levels was demonstrated in the liver following exposure to high doses of all three nanomaterials irrespective of any noticeable inflammatory or cytotoxic effects in the lung. By applying benchmark dose (BMD) modeling statistics to compare potencies of the NMs, we rank functionalised ZnO ranked the highest based on the largest number of affected endpoints, as well as the strongest responses observed after 24 hours. The non-functionalised ZnO NM gave an almost similar response, whereas Ag NM did not cause an acute response at similar doses.     

Biochemical Study of Heterosis for Brain Myelin Content in Mice

Heterosis (hybrid vigor) for brain myelin content has been examined in detail in (C57BL/6J x DBA/2J)F1 hybrid mice at 17 days of age. The amount of myelin isolated from the F1 hybrid brain is greater than that isolated from either parental strain. In addition, the total protein content in the myelin of the three genotypes showed the following trend: F1 greater than DBA greater than C57. However, no discernible differences in myelin protein compositions could be detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Analysis of the whole brain for several myelin-associated constituents such as GM1 ganglioside, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase), 5'-nucleotidase, and carbonic anhydrase indicated that heterosis exists for these components. No heterosis was found for such nonmyelin constituents as gangliosides GD1a, GT, GQ, RNA, DNA, and choline acetyltransferase. A developmental study of the whole brain CNPase indicated that the heterotic effect was greatest during the most active period of myelination (17-30 days). We conclude that the heterotic effect is specific for myelin content and is probably the result of an accelerated myelin synthesis. The heterotic effect should have great potential as a new model for studying aspects of myelinogenesis.     

Fate of Zinc Oxide Nanoparticles Coated onto Macronutrient Fertilizers in an Alkaline Calcareous Soil

Zinc oxide (ZnO) nanoparticles may provide a more soluble and plant available source of Zn in Zn fertilizers due to their greater reactivity compared to equivalent micron- or millimetre-sized (bulk) particles. However, the effect of soil on solubility, spatial distribution and speciation of ZnO nanoparticles has not yet been investigated. In this study, we examined the diffusion and solid phase speciation of Zn in an alkaline calcareous soil following application of nanoparticulate and bulk ZnO coated fertilizer products (monoammonium phosphate (MAP) and urea) using laboratory-based x-ray techniques and synchrotron-based μ-x-ray fluorescence (μ–XRF) mapping and absorption fine structure spectroscopy (μ–XAFS). Mapping of the soil-fertilizer reaction zones revealed that most of the applied Zn for all treatments remained on the coated fertilizer granule or close to the point of application after five weeks of incubation in soil. Zinc precipitated mainly as scholzite (CaZn₂(PO₄)₂.2H₂O) and zinc ammonium phosphate (Zn(NH₄)PO₄) species at the surface of MAP granules. These reactions reduced dissolution and diffusion of Zn from the MAP granules. Although Zn remained as zincite (ZnO) at the surface of urea granules, limited diffusion of Zn from ZnO-coated urea granules was also observed for both bulk and nanoparticulate ZnO treatments. This might be due to either the high pH of urea granules, which reduced solubility of Zn, or aggregation (due to high ionic strength) of released ZnO nanoparticles around the granule/point of application. The relative proportion of Zn(OH)₂ and ZnCO₃ species increased for all Zn treatments with increasing distance from coated MAP and urea granules in the calcareous soil. When coated on macronutrient fertilizers, Zn from ZnO nanoparticles (without surface modifiers) was not more mobile or diffusible compared to bulk forms of ZnO. The results also suggest that risk associated with the presence of ZnO NPs in calcareous soils would be the same as bulk sources of ZnO.     

l-Carnosine and Taurine Supplementation Attenuates the Intensity of Diabetes in Alloxan-Induced Diabetic Male Albino Rats

International Journal of Peptide Research and Therapeutics - Diabetes is a metabolic disorder caused by defects in insulin production and insulin activity. l-Carnosine is a dipeptide containing...     

Role of Zinc Oxide Nanoparticles in Countering Negative Effects Generated by Cadmium in Lycopersicon esculentum

Journal of Plant Growth Regulation - Nanotechnology now plays a revolutionary role in many applications; nanomaterials have experienced significant importance in both basic and applied sciences as...     

Impact of Engineered Zinc Oxide Nanoparticles on the Individual Performance of Mytilus galloprovincialis

The increased use of engineered nanoparticles (ENPs) in consumer products raises the concern of environmental release and subsequent impacts in natural communities. We tested for physiological and demographic impacts of ZnO, a prevalent metal oxide ENP, on the mussel Mytilus galloprovincialis. We exposed mussels of two size classes, <4.5 and ≥4.5 cm shell length, to 0.1–2 mg l⁻¹ ZnO ENPs in seawater for 12 wk, and measured the effect on mussel respiration, accumulation of Zn, growth, and survival. After 12 wk of exposure to ZnO ENPs, respiration rates of mussels increased with ZnO concentration. Mussels had up to three fold more Zn in tissues than control groups after 12 wk of exposure, but patterns of Zn accumulation varied with mussel size and Zn concentrations. Small mussels accumulated Zn 10 times faster than large mussels at 0.5 mg l⁻¹, while large mussels accumulated Zn four times faster than small mussels at 2 mg l⁻¹. Mussels exposed to 2 mg l⁻¹ ZnO grew 40% less than mussels in our control group for both size classes. Survival significantly decreased only in groups exposed to the highest ZnO concentration (2 mg l⁻¹) and was lower for small mussels than large. Our results indicate that ZnO ENPs are toxic to mussels but at levels unlikely to be reached in natural marine waters.