Concentrations Of nZnO Research Articles

Performance enhancement of Sb2Se3 solar cell with IGZO and n-ZnO as electron transport layers

A prototype of an antimony (III) selenide (Sb2Se3) solar cell with different electron transport layers (ETLs) was simulated using the Solar Cell Capacitance Simulator (SCAPS) software. The impact of two individual ETLs – namely, indium gallium zinc oxide (IGZO) and n-type zinc oxide (n-ZnO) – was analyzed, and it was found out that n-ZnO was best for the ETL. The n-ZnO, antimony (III) selenide and Indium gallium zinc oxide (IGZO) layers in the newly proposed structure have respective thicknesses of 50, 300 and 20 nm. To achieve the optimum performance of this prototype, the acceptor concentration of copper (II) oxide is taken as 1018 cm−2 and the donor concentration of n-ZnO is taken as 1020 cm−2. The defect densities at antimony (III) selenide and antimony (III) selenide/n-ZnO are taken as 1013 and 1010 cm−2, respectively. They play a crucial part in device performance. With the optimized structure, a maximum power conversion efficiency of up to 31.72% (V OC = 1.148 V, J SC = 48.30 mA/cm2 and fill factor = 88.50%) is obtained with n-ZnO as the ETL. For effective results, the defect densities at both interfaces are taken as 109 cm−2, and maximum efficiency is achieved. Numerical analysis of the proposed structure and study of various parameters such as thickness variation at the absorber layer, series resistance and temperature variation, defect density, metal function and interface density variation were done.

Reducing Gut Dissolution of Zinc Oxide Nanoparticles by Secondary Microplastics with Consequent Impacts on Barnacle Larvae.

The environmental impact of sunscreen is a growing concern, yet the combined effects of its components on marine animals are poorly understood. In this study, we investigated the combined effects of sunscreen-extracted zinc oxide nanoparticles (nZnO) and microplastics (MPs) on the development of barnacle larvae, focusing on the different roles played by primary microplastics (PMPs) and secondary microplastics (SMPs) generated through the phototransformation of PMPs. Our findings revealed that a lower concentration of nZnO (50 μg/L) enhanced molting and eye development in barnacle larvae, while a higher concentration (500 μg/L) inhibited larval growth. Co-exposure to PMPs had no significant effect on larval development, whereas SMPs mitigated the impact of nZnO by restricting the in vivo transformation to ionic Zn. Accumulated SMPs reduced gut dissolution of nZnO by up to 40%, lowering gut acidity by 85% and buffering the in vivo dissolution of nZnO. We further identified a rough-surfaced Si-5 fragment in SMPs that damaged larval guts, resulting in decreased acidity. Another Si-32 resisted phototransformation and had no discernible effects. Our study presented compelling evidence of the impacts of SMPs on the bioeffect of nZnO, highlighting the complex interactions between sunscreen components and their combined effects on marine organisms.

Biochemical and behavioral effects of zinc oxide nanorods on the freshwater mussel Potomida littoralis

ABSTRACT Our study aimed to investigate the impact of nano-zinc oxide (nZnO), a widely used pollutant in industry, pharmaceuticals, and personal care products, on the behavior and oxidative stress of freshwater mussels (Potomida littoralis) an indicator species and also a model non-target organism in ecotoxicology. To this end mussels were exposed to nZnO (50 and 100 µg/L) and Zn2+ from ZnSO4 (50 and 100 µg/L) for 7 days. ZnSO4 was used for comparison purposes and to determine if the toxicity of nZnO was due to the release of ions into the aquatic environment. We evaluated changes in oxidative stress markers, including catalase (CAT), glutathione-S-transferase (GST), acetylcholinesterase (AChE), and malondialdehyde (MDA) levels, on the mussel gills and digestive glands. Additionally, the effect of nZnO on the filtration rate of bivalves was studied. The findings showed that the mussel tissue’s different parameters were significantly affected by exposure to various concentrations of nZnO, causing changes in their behavior that led to a decrease in filtration rate. Additionally, noteworthy increments were observed in CAT activity, AChE activity, and MDA levels, whereas GST activity displayed a decreasing trend, implying that oxidative stress contributes to the toxicity of nZnO. The purpose of this review is to present a framework for comprehending the toxicological impacts of nanoparticles from an environmental standpoint. Additionally, it includes novel information about the connections between nanoparticles (NPs) and bivalve species.

Quantification histopathological analysis in the gills of carp fish exposed to sub lethal concentration of nano zinc oxide

Nano-zinc oxide ranks third in the world in production, as it is used in many industries, enters the aquatic environment directly or indirectly, and is considered one of the most toxic substances for aquatic organisms. Therefore, these studies aimed to determine the toxic effect of the sublethal concentration of N-ZnO on the gills of carp fish that were treated for 7, 14, 21, 28, 35, and 42 days and using a semi-quantitative evaluation protocol for histopathological alteration. The histopathological alteration involved circulatory changes, cell growth disturbances, and morphological changes, the most severe lesion occurred on day 35 of treatment, and the occurrence of necrosis and death of the gill tissue at day 42 of the treatment, which was more significant for morphological changes when compared with the other lesion and period. The results showed that the histopathological changes on the seventh day of treatment were severe lesions, while in the rest of the treatments, they were irreversible lesions. It is concluded from this study that the gills are a good bio-indicator for evaluating the pollution status of the aquatic environment and that the sub-lethal concentration of N-ZnO leads to pathological changes in the gills and the possibility of using semi-quantitative assessment and statistical analysis to give significance for the most severe pathological lesions.

Metabolomics-based assessment of nanoparticles (nZnO) toxicity in an infaunal marine annelid, the lugworm Arenicola marina (Annelida: Sedentaria)

Nanopollutants such as nZnO gain importance as contaminants of emerging concern due to their high production volume and potential toxicity. Coastal sediments serve as sinks for nanoparticles but the impacts and the toxicity mechanisms of nZnO in sediment-dwelling organisms are not well understood. We used metabolomics to assess the effects of nZnO-contaminated sediments on a benthic ecosystem engineer, an infaunal polychaete Arenicola marina. The worms were exposed to unpolluted (control) sediment or to the sediment spiked with 100 or 1000 μg Zn kg−1 of nZnO. Oxidative lesions (lipid peroxidation and protein carbonyls) were measured in the body wall as traditional biomarkers of nanopollutant toxicity. Metabolite profiles (including amino acids, tricarboxylic acid (TCA) cycle and urea cycle intermediates) were determined in the body wall and the coelomic fluid. Exposure to nZnO altered metabolism of the lugworms via suppression of the metabolism of gluconeogenic and aromatic amino acids, and altered the TCA cycle likely via suppression of fumarase activity. These metabolic changes may negatively affect carbohydrate metabolism and energy storage, and impair hormonal signaling in the worms. The total pool of free amino acids was depleted in nZnO exposures with potentially negative consequences for osmoregulation and protein synthesis. Exposure to nZnO led to accumulation of the lipid peroxidation products demonstrating high susceptibility of the cellular membranes to nZnO-induced oxidative stress. The nZnO-induced shifts in the metabolite profiles were more pronounced in the coelomic fluid than the body wall. This finding emphasizes the important metabolic role of the coelomic fluid as well as its suitability for assessing the toxic impacts of nZnO and other metabolic disruptors. The metabolic disruptions caused by environmentally relevant concentrations of nZnO can have negative effects on the organisms' fitness impairing growth and reproduction of the populations of marine bioturbators like the lugworms in nanoparticle-polluted sediments.

Enhancement of antifouling properties, metal ions and protein separation of poly(ether-ether-sulfone) ultrafiltration membranes by incorporation of poly ethylene glycol and n-ZnO

Composite polymeric membranes with enhanced anti-fouling properties, antimicrobial activities and flux were produced via the phase inversion technique using poly (ether-ether-sulfone) (PEES)/polyethylene glycol (PEG) and n-ZnO. SEM and ATR-FTIR spectroscopy were used to study the morphological and chemical properties of the resulting ultrafiltration membranes. PEG and n-ZnO concentration has an effect on membrane morphologies, ultrafiltration performance, thermal characteristics, metal ion separation studies, surface hydrophilicity and anti-fouling capabilities. The permeate flux increased when the PEG concentration was raised. This results revealed that adding PEG and n-ZnO to membranes increased their surface hydrophilicity and anti-fouling properties. The inclusion of 1.5 wt % n-ZnO and 5 wt % PEG to the pristine PEES membrane resulted in a higher flux of 233.76 L m-2 h−1, 70.09 % of water content, 47.46° of contact angle, the porosity of 30.20 %, and hydraulic resistance of 0.22 kPa/Lm−2h−1. Anti-fouling properties of the fabricated membrane were assessed using a model foulant BSA, which revealed a high flux recovery ratio value. As a result, the PEG and n-ZnO incorporated membrane is more hydrophilic than the virgin membrane. In addition, the prepared PEES/PEG/n-ZnO membrane showed a significant increase in metal ions and protein rejection. Furthermore, an antibacterial test of the membrane revealed that the PEG and n-ZnO composite membrane outperformed the bare PEES membrane in terms of antibacterial capabilities. Overall, the findings reveal that combining n-ZnO and PEG resulted in a membrane with improved anti-fouling capabilities and hydrophilicity, making it suitable for water purification.

Aerially Applied Zinc Oxide Nanoparticle Affects Reproductive Components and Seed Quality in Fully Grown Bean Plants (Phaseolus vulgaris L.).

The development of reproductive components in plant species is susceptible to environmental stresses. The extensive application of zinc oxide nanoparticles (nZnO) in various agro-industrial processes has jeopardized the performance and functionality of plants. To understand the response of the developmental (gametogenesis and sporogenesis) processes to nanoparticles (NPs) exposure, the aerial application of nZnO and their ionic counterpart of ZnSO4 at four different levels were examined on bean plants (Phaseolus vulgaris) before the flowering stage. To evaluate the mentioned processes, briefly, flowers in multiple sizes were fixed in paraffin, followed by sectioning and optical analysis. The possibility of alteration in reproductive cells was thoroughly analyzed using both light and electron microscopes. Overall, our results revealed the histological defects in male and female reproductive systems of mature plants depend on NPs levels. Furthermore, NPs caused tapetum abnormalities, aberrations in carbohydrate accumulation, and apoptosis. The nZnO induced abnormal alterations right after meiosis and partly hindered the microspore development, leading to infertile pollens. The seed yield and dry weight were reduced to 70 and 82% at 2,000 mg L–1 nZnO foliar exposure, respectively. The sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis pattern showed the increased expression of two proteins at the molecular weight of 28 and 42 kDa at various concentrations of nZnO and ZnSO4. Overall, our results provided novel insights into the negative effect of nano-scaled Zn on the differential mechanism involved in the reproductive stage of the plants compared with salt form.

Re-evaluation of the environmental hazards of nZnO to denitrification: Performance and mechanism

Numerous studies have shown that zinc oxide nanoparticles (nZnO) have an inhibitory effect on wastewater biotreatment, where doses exceeding ambient concentrations are used. However, the effect of ambient concentrations of ZnO (<1 mg/L) on anaerobic digestion processes is not clear. Herein, this study comprehensively explored the impact of nZnO on the denitrification performance and core microbial community of activated sludge under ambient concentrations. Results showed that only 0.075 mg/L nZnO had shown a beneficial effect on nitrogen removal by activated sludge. When nZnO concentration reached 0.75 mg/L, significant enhancement of nitrate reduction and mitigation of nitrite accumulation were observed, indicating a remarkable stimulatory effect on nitrogen removal. Simultaneously, nZnO could weaken the sludge surface charge and improve the secretion of extracellular polymeric substances, thus enhancing sludge flocculation for denitrification. Microbial community analysis revealed that nZnO exposure increased the relative abundance of denitrifying bacteria, which could contribute to the reinforcement of traditional denitrification. Furthermore, exogenous addition of NH4+ significantly inhibited the accumulation of nitrite, implying that nZnO had a potential to improve the denitrification process via a partial denitrification-anammox pathway. Considering current ambient concentration, the stimulatory effect shown in our work may better represent the actual behavior of ZnO in wastewater biotreatment.

Feeding nano particles of vitamin C and zinc oxide: Effect on growth performance, immune response, intestinal morphology and blood constituents in heat stressed broiler chickens

A total of 360 male broiler chickens (Ross 308) were used in a 3 × 3 factorial arrangement of treatments consisting of 3 concentrations of NVC (0, 50 and 100 mg/kg of diet) and 3 concentrations of NZnO (0, 30 and 60 mg/kg of diet) with 4 replicates of 10 broiler chickens each. Broiler chickens were reared under normal condition until d 25 and after that the heat stress (34 ± 2°C) was applied for eight hours (0900 to 1700 h) from d 25 to 42. Body weight gain (BWG) and feed intake (FI) were measured weekly and feed conversion ratio (FCR) was calculated on pen basis. At d 42, all broiler chickens of each pen were individually weighed and the mean value of the pen weight was recorded then one broiler chicken weighing close to the mean weight of the pen was randomly selected, blood sampled and slaughtered for carcass measurements. There was an interaction (P≤0.01) between NVC and NZnO on BWG, FCR and relative weight of liver with the greatest BWG (P≤0.001), improvement in FCR (P≤0.01) and relative weight of spleen (P≤0.001) in broiler chickens fed the diet containing 100 mg NVC/kg diet with 60 mg NZnO/kg diet. Supplementation of diet with NVC linearly increased (P≤0.01) BWG. NZnO had a quadratic effect (P≤0.001) on BWG. Inclusion of NVC and NZnO had a quadratic effect (P≤0.01 and P≤0.05 respectively) on FCR. Vitamin C nano particles and NZnO linearly and quadratically (P≤0.001) increased the relative weight of liver. There was an interaction effect of NVC and NZnO on relative weight of thigh (P≤0.05), spleen, bursa and jejunum (P≤0.001). NVC linearly increased relative weight of carcass and spleen (P≤0.05) and had a quadratic effect on relative weight of bursa (P≤0.01). Supplementation of the diet with 50 mg NVC/kg diet and 60 mg NZnO/kg diet had the greatest effect on villus height and width, and on crypt depth (P≤0.05). Nanoparticles of NVC and NZnO linearly and quaratically (P≤0.01) increased villus height, crypt depth, and villus height: crypt depth. The interaction of NVC and NZnO on red blood cell (RBC) count was significant with broiler chickens receiving the diet supplying 100 mg NVC//kg diet with 30 or 60 mg NZnO/kg diet having the greatest number of RBC(P≤0.001). Nano zinc oxide linearly (P≤0.001) increased glutathion peroxidase concentration. It was concluded that supplementation of the diet with 100 mg of NVC/kg diet plus 60 mg of NZnO/kg diet can improve growth performance, glutathione peroxidase activity, immune function and carcass characteristics in broiler chickens under heat stress conditions.

Metal Nanoparticles-Mediated Changes on Gene Expressions and Physiological Parameters of Capsicum annuum L.

Objective: The uptake and accumulation of nanoparticles by plants create a potential threat for human health in cases where humans consume the plants. The aim of the study was to analyze the potential beneficial or inhibitory effects of nAl2O3 and nZnO on Capsicum annuum L. (pepper)'s germination, root growth, and expression levels of aquaporin and dehydrin genes. Material and Method: Different concentrations (0.5, 2.5, or 5.0 mM) of nAl2O3 and nZnO were used for the germination of pepper seeds. ICP-MS analysis was performed to determine ion contents in nanoparticle-treated pepper plants. Levels of aquaporin and dehydrin gene expressions were analyzed by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Results: The pepper germination was not affected by nanoparticle applications. While nAl2O3 treatments did not change root growth, higher concentrations of nZnO negatively affected root length and root number. In particular, the application of 0.5 mM nZnO significantly upregulated aquaporin and dehydrin gene expressions in roots. Downregulation of dehydrin gene expression occurred in stems and roots after exposure to nAl2O3 treatments. Conclusion: The gene expression alterations and changes of growth parameters showed especially nZnO have potentially phytotoxic for pepper plants. Moreover, expression analysis suggested that the tested genes may play roles in response to the nanoparticle-based abiotic stress.

Toxicity of biogenic zinc oxide nanoparticles to soil organic matter cycling and their interaction with rice-straw derived biochar

Given the rapidly increasing use of metal oxide nanoparticles in agriculture as well as their inadvertent addition through sewage sludge application to soils, it is imperative to assess their possible toxic effects on soil functions that are vital for healthy crop production. In this regard, we designed a lab study to investigate the potential toxicity of one of the most produced nanoparticles, i.e. zinc oxide nanoparticles (nZnO), in a calcareous soil. Microcosms of 80 g of dry-equivalent fresh soils were incubated in mason jars for 64 days, after adding 100 or 1000 mg of biogenically produced nZnO kg−1 soil. Moreover, we also added rice-straw derived biochar at 1 or 5% (w: w basis) hypothesizing that the biochar would alleviate nZnO-induced toxicity given that it has been shown to adsorb and detoxify heavy metals in soils. We found that the nZnO decreased microbial biomass carbon by 27.0 to 33.5% in 100 mg nZnO kg−1 soil and by 39.0 to 43.3% in 1000 mg nZnO kg−1 soil treatments across biochar treatments in the short term i.e. 24 days after incubation. However, this decrease disappeared after 64 days of incubation and the microbial biomass in nZnO amended soils were similar to that in control soils. This shows that the toxicity of nZnO in the studied soil was ephemeral and transient which was overcome by the soil itself in a couple of months. This is also supported by the fact that the nZnO induced higher cumulative C mineralization (i.e. soil respiration) at both rates of addition. The treatment 100 mg nZnO kg−1 soil induced 166 to 207%, while 1000 mg nZnO kg−1 soil induced 136 to 171% higher cumulative C mineralization across biochar treatments by the end of the experiment. However, contrary to our hypothesis increasing the nZnO addition from 100 to 1000 mg nZnO kg−1 soil did not cause additional decrease in microbial biomass nor induced higher C mineralization. Moreover, the biochar did not alleviate even the ephemeral toxicity that was observed after 24d of incubation. Based on overall results, we conclude that the studied soil can function without impairment even at 1000 mg kg−1 concentration of nZnO in it.

Toxicity and combined effects of antibiotics and nano ZnO on a phosphorus-removing Shewanella strain in wastewater treatment

Antibiotics and nanoparticles, which are emerging contaminants, can occur simultaneously in biological wastewater treatment systems, potentially resulting in complex interactive effects. This study investigated the effects of individual and complex zinc oxide nanoparticles (nZnO) and antibiotics (quinolone and sulfonamide), on the Shewanella strain used to remove phosphorus (PO43-), metabolic processes, as well as its complexing and toxicity mechanisms. The inhibition of PO43- removal increased from 30.7% to 100.0% with increased nZnO concentrations (half maximal effective concentration (EC50) = 1.1 mg Zn/L) by affecting poly-p and glycogen metabolites. The combined exposure to nZnO and ciprofloxacin/norfloxacin (CIP/NOR) had a significant antagonistic effect on the removal of PO43- and on the metabolism of poly-p and glycogen in phosphate-accumulating organisms (PAOs), whereas the complexing of sulfonamide and nZnO had no significant additional effect. Thus, the complexing of nanoparticles and antibiotics exhibited different toxicity effects from the antibiotic structure-based complex reactions. These results can be used to improve wastewater treatment processes and reduce risks associated with wastewater discharge.

Can Swimming Microalgal Cells be Vehicles for ZnO Nanoparticle Transportation and Thus Lead to Zn Diffusion?

The concentration of eco-toxic zinc oxide nanoparticles (nZnO) in aquatic ecosystems is increasing, and an effective method for their removal is needed. We hypothesize that microalgal cells may act as nZnO vehicles-if the nZnO concentration does not affect their swimming ability-enabling Zn diffusion and sedimentation. We conducted experiments using flasks connected via a U-type vessel; the first flask contained nZnO suspensions and second flask contained artificial seawater, respectively. We added microalgae to the first flask and illuminated the second. The microalgae appeared to promote sedimentation. However, only a few microalgal cells passed via phototaxis into the second flask, so the detection of nZnO or Zn ions in the second flask was not possible. Therefore, to confirm whether the microalgae affect Zn transportation, a more accurate method to detect nZnO or Zn ions at very low concentrations is needed.

New Insights into the Transcriptional, Epigenetic, and Physiological Responses to Zinc Oxide Nanoparticles in Datura stramonium; Potential Species for Phytoremediation

This study aimed to explore the physiological, epigenetic, and transcriptional responses of Datura stramonium, a stress-resistant plant, to long-time exposure to zinc oxide nanoparticles (nZnO; 0, 100, and 500 mg l−1). The results of the study illustrate that the nZnO100 promoted biomass accumulation and growth indices, whereas nZnO500 caused severe phytotoxicity. Unlike nZnO500 treatment which reduced leaf K (34.7%) and Fe (16.2%), implying impaired nutrition, the nZnO100-treated seedlings encompassed higher concentrations of K (20.8%) and Fe (21.7%) than the control. Moreover, the nZnO displayed a higher efficacy to improve Zn bioaccumulation than the bulk counterpart, and the supplements induced phenylalanine ammonia-lyase, catalase, and peroxidase activities. Besides, nZnO500 treatment enhanced leaf proline concentration. The nZnO treatments also led to variations in the expression of histone deacetylase (HDA3), indicating an epigenetic modification. The nZnO treatments transcriptionally stimulated the WRKY1 transcription factor by an average of 9.5-fold. With increasing the concentration of nZnO, transcriptions of AREB and bZIP transcription factors were induced by averages of 4.3- and 8.7-fold, respectively. The supplements transcriptionally upregulated proteinase inhibitor II (PI-II). While nZnO500 was associated with a drastic induction (11.28-fold) in hyoscyamine 6 beta-hydroxylase (H6H), the nZnO100 treatment slightly (3.2-fold) induced transcription of H6H. The upregulations in the expression of tropinone reductase I (TRI) resulted from the nZnO treatments. Ultimately, positive correlations were found among transcription factors (AREB, bZIP, and WRKY1), H6H, TRI, and PI-II. This study provides deeper insights into the nZnO-associated molecular responses in transcription factors, epigenetics, secondary metabolism, and defense-related genes in resistant plant species.

Season-dependent effects of ZnO nanoparticles and elevated temperature on bioenergetics of the blue mussel Mytilus edulis

Input of ZnO nanoparticles (nZnO) from multiple sources have raised concerns about the potential toxic effects on estuarine and coastal organisms. The toxicity of nZnO and its interaction with common abiotic stressors (such as elevated temperature) are not well understood in these organisms. Here, we examined the bioenergetics responses of the blue mussel Mytilus edulis exposed for 21 days to different concentrations of nZnO or dissolved zinc (Zn2+) (0, 10, 100 μg l−1) and two temperatures (ambient and 5 °C warmer) in winter and summer. Exposure to nZnO had little effect on the protein and lipid levels, but led to a significant depletion of carbohydrates and a decrease in the electron transport system (ETS) activity. Qualitatively similar but weaker effects were found for dissolved Zn. In winter mussels, elevated temperature (15 °C) led to elevated protein and lipid levels increasing the total energy content of the tissues. In contrast, elevated temperature (20 °C) resulted in a decrease in the lipid and carbohydrate levels and suppressed ETS in summer mussels. These data indicate that moderate warming in winter (but not in summer) might partially compensate for the bioenergetics stress caused by nZnO toxicity in M. edulis from temperate areas such as the Baltic Sea.

Exogenous application and endogenous elevation of salicylic acid levels by overexpressing a salicylic acid-binding protein 2 gene enhance nZnO tolerance of tobacco plants

Salicylic acid (SA) plays vital roles in the stress response of plants. However, the relationship between SA signaling and plant tolerance to nZnO stress has not been reported. The effects of different sizes and concentrations of nZnO on tobacco plants grown in MS medium or soil were evaluated. The effects of exogenous and endogenous SA on the morphological and biochemical parameters of tobacco plants by exogenous application of SA and overexpression of LcSABP2 gene were also investigated in this study. The endogenous SA content and the expression of salicylic acid-binding protein 2 (SABP2) gene increased in tobacco individuals with nZnO treatment. Exogenously applied SA increased the germination rate of tobacco seeds, and enhanced the root length and chlorophyll content of tobacco seedlings. Overexpression of LcSABP2 gene in transgenic tobacco significantly increased SA content in plants with nZnO treatment. Compared to the wild type plants, transgenic tobacco with nZnO treatment showed higher chlorophyll content, net photosynthetic rate, related gene expression, activities of SOD, POD and CAT, and less contents of H2O2, O2− and MDA, which suggested that LcSABP2 might play important regulatory roles in plant resistance to nZnO toxicity by elevating the level of endogenous SA, promoting the action of photosynthetic system, and enhancing the activities of antioxidant enzymes. This study illustrated that exogenous and endogenous SA might all be involved in alleviating the toxicity of nZnO on plants.

Anticancer Effects of Zinc Oxide Nanoparticles Through Altering the Methylation Status of Histone on Bladder Cancer Cells.

PurposeZinc oxide nanoparticles (nZnO) have been widely used in the medicine field. Numerous mechanistic studies for nZnO’s anticancer effects are merely performed under high concentration exposure. However, possible anticancer mechanisms of epigenetic dysregulation induced by low doses of nZnO are unclear.MethodsnZnO were characterized and bladder cancer T24 cells were treated with nZnO for 48 hrs at different exposure concentrations. Cell cycle, apoptosis, cell migration and invasion were determined. We performed qRT-PCR, Western blot and chromatin immunoprecipitation to detect the mRNA and protein levels of signaling pathway cascades for histone modification.ResultsIn this study, we investigated the potential anticancer effects and mechanisms of nZnO on histone modifications in bladder cancer T24 cells upon low-dose exposure. Our findings showed that low concentrations of nZnO resulted in cell cycle arrest at S phase, facilitated cellular late apoptosis, repressed cell invasion and migration after 48 hrs exposure. These anticancer effects could be attributed to increased RUNX3 levels resulting from reduced H3K27me3 occupancy on the RUNX3 promoter, as well as decreased contents of histone methyltransferase EZH2 and the trimethylation of histone H3K27. Our findings reveal that nZnO are able to enter into the cytoplasm and nucleus of T24 cells. Additionally, both particles and ions from nZnO may jointly contribute to the alteration of histone methylation. Moreover, sublethal nZnO-conducted anticancer effects and epigenetic mechanisms were not associated with oxidative stress or DNA damage.ConclusionWe reveal a novel epigenetic mechanism for anticancer effects of nZnO in bladder cancer cells under low-dose exposure. This study will provide experimental basis for the toxicology and cancer therapy of nanomaterials.

Co-transport behavior of nano-ZnO particles in the presence of metal-nanoparticles through saturated porous media

The objective of this study is to evaluate the co-transport behavior of nZnO (193.0 nm) along with other metal-based ENPs [i.e., nTiO2 (198.6 nm), nAg (167.9 nm), and nFexOy (178.5 nm)] through saturated porous media in the presence and absence of humic acid (HA) under varying pH (8, 6.5 and 5). To achieve this objective a series of column experiments are performed where the nZnO particles are injected in the porous media in the presence of other metal ENPs. After each column experiment, the column was sectioned, and the retained mass of nZnO and the porosity along the length of the column were measured. The size and surface charge of ENPs were also assessed. The study indicates that negligible amount of nZnO get transported in the absence of HA whether injected as a single entity or along with other ENPs. However, in the presence of HA and at pH 8, significant amounts (C/C0 = 0.57 to 0.68) of nZnO get transported. The surface charge of nZnO or mix-ENPs is positive or close to neutral. While in the presence of HA, surface charge of nZnO or mix-ENPs becomes highly negative (-40.6 ± 0.9 mV), which probably resulted in unfavorable condition for particle deposition in the presence of HA. Presence of nAg and nTiO2 does not influence the transport efficiency of nZnO. However, in the presence of nFexOy and under HA medium a decrease in the eluted concentration of nZnO is observed. With a decrease in pH (within a range of 8 to 5), co-transport efficiency of nZnO particles (α = 0.05-1.00, C/C0 = 0.68-0.0) has reduced drastically even when suspended in HA medium. This is probably controlled by surface charge of ENPs. The study also indicates that the hyper-exponential retention of ENPs has insignificant implication on the alteration of porosity of the media. Overall it could be stated that the presence of HA and the solution pH are mainly controlling the transport behavior of nZnO within the experimental condition adopted in this study.

Phytotoxicity of nano-zinc oxide to tomato plant (Solanum lycopersicum L.): Zn uptake, stress enzymes response and influence on non-enzymatic antioxidants in fruits

Abstract The production of metallic nanoparticles is greatly increasing due to its wide range of applications in agricultural formulations. The present pot experiment investigated the uptake of Zn from nano-zinc oxide (n-ZnO)-amended soil at 300, 600 and 1000 mg n-ZnO/kg concentrations, and its effects on the enzymatic and non-enzymatic antioxidants in tomato tissues and fruits respectively. Results showed that root uptake of Zn increased with increasing n-ZnO concentrations. The enzyme activity showed that n-ZnO, through the generation of H 2 O2 and induction of oxidative stress, significantly reduced the activity of stress-controlling enzymes (APX and SOD) in the root. Conversely in leaves, despite alteration in chlorophylls in the early growing stage, APX activity was only significant at 1000 mg n-ZnO/kg) while SOD activity was enhanced at all treatments. CAT activity was significantly reduced, unlike in the roots where CAT activity was significantly enhanced. Contents of total phenols, flavonoids, β -carotene and lycopene in fruits were significantly reduced by at least 4.8% while ascorbic acid was promoted at low n-ZnO treatments. In conclusion, the toxic effect of n-ZnO on stress enzymes was prominent in tomato roots, and there was also inhibitory effect on induction of non-enzymatic antioxidants in the tomato fruits.

Soil pH effects on the toxicity of zinc oxide nanoparticles to soil microbial community.

We conducted an experiment with two agricultural soils with acidic and alkaline pH levels to assess the effects of zinc oxide nanoparticles (nZnO) on the bacterial community. The effect of the nZnO concentrations (0, 0.1, 1, 10, 100, 1000mgZn/kg soil) and contact time between nanoparticles and soil (180days) was considered. We measured the microbial respiration rate, nitrogen transformation, enzymatic activities (dehydrogenase (DH), acidic phosphatase (ACP), and alkaline phosphatase (ALP)), and the community-level physiological profile (CLPP) soil parameters. Respiration potential and nitrogen transformation were negatively affected only at the highest nZnO concentration. The changes in enzymatic activities were very variable with time and between both soils. A stimulating effect of the nanoparticles on microbial activity was clearly shown at 30days after the nZnO application in both soils, except for the 1000mg/kg in calcareous soil, after which time in the latter, the functional richness of the bacterial community was reduced to virtually zero. However, values of the enzymatic activities demonstrated that there was self-adaptation of microbial communities over the study period (180days). The nZnO 1000mg/kg dose produced an increase in bacterial growth in the acidic soil, without apparent changes in their metabolic profiles over time. A good correlation was found between microbial respiration rates (calcareous and acidic soils) and microbial metabolic activity (acidic soil) based on extracted Zn concentrations. Our findings suggest the necessity of additional studies to examine the effects of nZnO in natural microorganism populations in soil with different pH levels for extended periods of time.