Toxicity Of Zinc Oxide And Cerium Oxide Nanoparticles To Mesquite

The impact of metal nanoparticles (NPs) in biological systems is still not well understood. Little is known about the response of plants, the first trophic level, to NP exposure; consequently, their possible role on the fate and transport of NPs in ecosystems is unknown. The aim of this research was to determine the response of mesquite (Prosopis juliflora-velutina), a native desert plant, to ZnO and CeO2 (nanoceria) NPs. Mesquite seedlings were grown for 15 days in hydroponics with of ZnO (10 nm) and CeO2 NPs (10 nm) at concentrations varying from 500 to 4000 mg L-1. In the present study, cerium and zinc concentrations as well as the concentration of some macro and micro elements in plant tissues were determined by inductively coupled plasma optical emission spectroscopy (ICP OES). Structural and morphological modification in tissues, deposition of Ce and Zn, and plant stress were examined by infra red microspectroscopy (IMS), electron probe micro-analyzer (EPMA), and specific activity of catalase (CAT) and ascorbate peroxidase (APOX), respectively. In addition, the biotransformation of CeO2 and ZnO NPs was determined by using x-ray absorption spectroscopy (XAS). Results showed that none of the NPs reduced plants growth. In addition, at all concentrations the nanoceria increased CAT and APOX in leaves, while ZnO NPs increased CAT in roots stems and leaves, while APOX was increased in stems and leaves. The ICP-OES data showed that mesquite plants differentially absorbed Zn and Ce from the NPs. In the case of Zn, the bioconcentration factors (metal in tissues/metal in medium) were 11, 4, 2, and 0.9 for the 500, 1000, 2000, and 4000 mg L-1 treatments, respectively. While for the nanoceria the bioconcentration factors were 53, 30, 26, 30, and 12 for the 500, 1000, 2000, and 4000 mg L-1 treatments, respectively. However, in all cases the translocation factors were higher for the ZnO NPs. ZnO NPs reduced the accumulation of some micronutrients, mainly in roots and in some cases in stems; but very few changes were observed in leaves. On the other hand, the nanoceria reduced the concentration of Cu, Mn, and Fe, but increased Mo concentration in roots. The IMS analysis of roots treated with the nanoceria at 4000 mg L-1 showed changes in the peaks associated with proteins (1150-1100 cm-1) and lipids (2900-2850 cm-1), whereas in the ZnO NPs treated plants, only the band of aromatic phenolic compounds (845 cm-1) showed changes. The EPMA analysis confirmed the presence of Zn in the vascular system of the ZnO NP treated plants, but the nanoceria treated plants showed Ce only in cortex and epidermis. However the x-ray mapping did not showed evidence of nanoceria agglomeration in the vascular tissue. The XAS study showed clear evidence of the presence of CeO2 NPs within tissues but ZnO NPs were not observed. The data also showed that at the concentration used and the growth stage studied, the nanoceria and ZnO NPs exerted low toxicity on mesquite, suggesting that this desert plant may display some resistance to both the nanoceria and ZnO NPs

Toxicity of zinc oxide and cerium oxide nanoparticles to mesquite (Prosopis juliflora-velutina)

The impact of metal nanoparticles (NPs) in biological systems is still not well understood. Little is known about the response of plants, the first trophic level, to NP exposure; consequently, their possible role on the fate and transport of NPs in ecosystems is unknown. The aim of this research was to determine the response of mesquite (Prosopis juliflora-velutina ), a native desert plant, to ZnO and CeO2 (nanoceria) NPs. Mesquite seedlings were grown for 15 days in hydroponics with of ZnO (10 nm) and CeO2 NPs (10 nm) at concentrations varying from 500 to 4000 mg L-1. In the present study, cerium and zinc concentrations as well as the concentration of some macro and micro elements in plant tissues were determined by inductively coupled plasma optical emission spectroscopy (ICP OES). Structural and morphological modification in tissues, deposition of Ce and Zn, and plant stress were examined by infra red microspectroscopy (IMS), electron probe micro-analyzer (EPMA), and specific activity of catalase (CAT) and ascorbate peroxidase (APOX), respectively. In addition, the biotransformation of CeO2 and ZnO NPs was determined by using x-ray absorption spectroscopy (XAS). Results showed that none of the NPs reduced plants growth. In addition, at all concentrations the nanoceria increased CAT and APOX in leaves, while ZnO NPs increased CAT in roots stems and leaves, while APOX was increased in stems and leaves. The ICP-OES data showed that mesquite plants differentially absorbed Zn and Ce from the NPs. In the case of Zn, the bioconcentration factors (metal in tissues/metal in medium) were 11, 4, 2, and 0.9 for the 500, 1000, 2000, and 4000 mg L-1 treatments, respectively. While for the nanoceria the bioconcentration factors were 53, 30, 26, 30, and 12 for the 500, 1000, 2000, and 4000 mg L-1 treatments, respectively. However, in all cases the translocation factors were higher for the ZnO NPs. ZnO NPs reduced the accumulation of some micronutrients, mainly in roots and in some cases in stems; but very few changes were observed in leaves. On the other hand, the nanoceria reduced the concentration of Cu, Mn, and Fe, but increased Mo concentration in roots. The IMS analysis of roots treated with the nanoceria at 4000 mg L-1 showed changes in the peaks associated with proteins (1150-1100 cm-1) and lipids (2900-2850 cm -1), whereas in the ZnO NPs treated plants, only the band of aromatic phenolic compounds (845 cm-1) showed changes. The EPMA analysis confirmed the presence of Zn in the vascular system of the ZnO NP treated plants, but the nanoceria treated plants showed Ce only in cortex and epidermis. However the x-ray mapping did not showed evidence of nanoceria agglomeration in the vascular tissue. The XAS study showed clear evidence of the presence of CeO2 NPs within tissues but ZnO NPs were not observed. The data also showed that at the concentration used and the growth stage studied, the nanoceria and ZnO NPs exerted low toxicity on mesquite, suggesting that this desert plant may display some resistance to both the nanoceria and ZnO NPs

Determination Of The Effects Of ZnO And CeO2 Nanoparticles In Mesquite (Prosopis Juliflora) And Soybean (Glycine Max): Synchrotron And Spectroscopic Approaches

The rapid growth of nanotechnology is exposing the environment to abnormal concentrations of engineered nanoparticles (NPs). There is concern about the unknown consequences of NPs on the environment and human health. This Dissertation has relied significantly on Synchrotron and other spectroscopic techniques to give insights on the effects, speciation and distribution of two metal oxide nanoparticles (ZnO, CeO2) on two plant species (Mesquite and Soybean). We evaluated the effects of ZnO (10 nm) and CeO2 (8 nm) NPs on a plant species native to the semi-arid regions of North America, Mesquite (Prosopis juliflora velutina). Mesquite plants grown in hydroponic culture with ZnO NPs presented an increased uptake of Zn when compared to control plants. Zn synchrotron μXRF from root transversal sections (30 μm) showed Zn accumulated mainly in the vascular region. Zn μXRF maps obtained from the leaves showed that Zn is mainly concentrated in the veins. Combined Bulk and μXANES synchrotron analysis showed that Zn has different coordination environments compared to the ZnO NPs, and corroborated that ZnO NPs were transformed on/in the root surface and transported as Zn (II) from roots to leaves. Exposure to ZnO NPs increased the specific activity of stress enzymes catalase in root, stem and leaves and ascorbate peroxidase only in stem and leaves. The concentration of Ce in mesquite plants exposed to CeO2 NPs was higher when compared to the control; however Ce μXRF maps showed most of the cerium was adsorbed in the root. Bulk XANES showed that Ce maintained the same coordination as the CeO2 NPs. Few reports thus far have addressed the entire life cycle of plants grown in NP-contaminated soil. We performed a lifecycle study of ZnO and CeO2 NPs with the fifth largest crop produced in the world and second in the USA, Soybean (Glycine max).We determined the effects of NPs exposure and the potential storage of NPs or their biotransformed products in edible/reproductive organs of the plants in order to study the possible transfer of NPs into the food chain and potentially into the next plant generation. Soybean (Glycine max) seeds were germinated and grown to full maturity in organic farm soil amended with either ZnO NPs or CeO2 NPs at different concentrations. At harvest, synchrotron μ-XRF and μ-XANES analyses were performed on soybean tissues, including pods, to determine the forms of Ce and Zn in NP-treated plants. The X-ray absorption spectroscopy studies showed no presence of ZnO NPs within tissues. However, μ-XANES data showed O-bound Zn, in a form resembling Zn-citrate, which could be an important Zn complex in the soybean grains. On the other hand, the synchrotron μ-XANES results showed that Ce remained mostly as CeO2 NPs within the plant. Our results also showed that a small percentage of Ce(IV), the oxidation state of Ce in CeO2 NPs, was biotransformed to Ce(III). Our results also showed that the plants exposed to CeO2 diminished in growth but most importantly, nitrogen fixation was stopped at higher exposure concentrations. To our knowledge, this is the first report on the presence and effects of CeO2 and Zn compounds in the reproductive/edible portion of the soybean plant grown in farm soil with CeO2 and ZnO NPs

Determination of the effects of ZnO and CeO2 nanoparticles in mesquite (Prosopis juliflora) and soybean (Glycine max): Synchrotron and spectroscopic studies

The rapid growth of nanotechnology is exposing the environment to abnormal concentrations of engineered nanoparticles (NPs). There is concern about the unknown consequences of NPs on the environment and human health. This dissertation has relied significantly on Synchrotron and other spectroscopic techniques to give insights on the effects, speciation and distribution of two metal oxide nanoparticles (ZnO, CeO2) on two plant species (Mesquite and Soybean). We evaluated the effects of ZnO (10 nm) and CeO2 (8 nm) NPs on a plant species native to the semi-arid regions of North America, Mesquite (Prosopis juliflora velutina). Mesquite plants grown in hydroponic culture with ZnO NPs presented an increased uptake of Zn when compared to control plants. Zn synchrotron μXRF from root transversal sections (30 μm) showed Zn accumulated mainly in the vascular region. Zn μXRF maps obtained from the leaves showed that Zn is mainly concentrated in the veins. Combined Bulk and μXANES synchrotron analysis showed that Zn has different coordination environments compared to the ZnO NPs, and corroborated that ZnO NPs were transformed on/in the root surface and transported as Zn (II) from roots to leaves. Exposure to ZnO NPs increased the specific activity of stress enzymes catalase in root, stem and leaves and ascorbate peroxidase only in stem and leaves. The concentration of Ce in mesquite plants exposed to CeO2 NPs was higher when compared to the control; however Ce μXRF maps showed most of the cerium was adsorbed in the root. Bulk XANES showed that Ce maintained the same coordination as the CeO2 NPs. Few reports thus far have addressed the entire life cycle of plants grown in NP-contaminated soil. We performed a lifecycle study of ZnO and CeO 2 NPs with the fifth largest crop produced in the world and second in the USA, Soybean (Glycine max).We determined the effects of NPs exposure and the potential storage of NPs or their biotransformed products in edible/reproductive organs of the plants in order to study the possible transfer of NPs into the food chain and potentially into the next plant generation. Soybean (Glycine max) seeds were germinated and grown to full maturity in organic farm soil amended with either ZnO NPs or CeO2 NPs at different concentrations. At harvest, synchrotron μ-XRF and μ-XANES analyses were performed on soybean tissues, including pods, to determine the forms of Ce and Zn in NP-treated plants. The X-ray absorption spectroscopy studies showed no presence of ZnO NPs within tissues. However, μ-XANES data showed O-bound Zn, in a form resembling Zn-citrate, which could be an important Zn complex in the soybean grains. On the other hand, the synchrotron μ-XANES results showed that Ce remained mostly as CeO2 NPs within the plant. Our results also showed that a small percentage of Ce(IV), the oxidation state of Ce in CeO2 NPs, was biotransformed to Ce(III). Our results also showed that the plants exposed to CeO2 diminished in growth but most importantly, nitrogen fixation was stopped at higher exposure concentrations. To our knowledge, this is the first report on the presence and effects of CeO2 and Zn compounds in the reproductive/edible portion of the soybean plant grown in farm soil with CeO2 and ZnO NPs

Impacts of Copper Oxide Nanoparticles in Bell Pepper (\u3ci\u3eCapsicum annum\u3c/i\u3e L.) Plants: A Full Life Cycle Study

Several studies have explored the effects of copper nanoparticles (NPs) on different edible plants. However, no studies on bell pepper (Capsicum annum L.) plants have been reported. In this study, plants were grown for a full life-cycle assessment (90 days of exposure) in natural soil amended with nano CuO (nCuO), bulk CuO (bCuO), and ionic copper (CuCl2) at 0, 125, 250, and 500 mg kg−1. Based on our experimental findings, none of the treatments significantly affected stem elongation, plant dry biomass, foliar area, leaf chlorophyll content, and fruit productivity of bell pepper. However, ionic copper significantly decreased the gas exchange parameters, evapotranspiration, stomatal conductance, and photosynthesis by an average of 41%, 59%, and 38%, respectively, compared to the other treatments at select concentrations (p ≤ 0.05). The ICP-OES data showed that, except for bCuO at 500 mg kg−1, at 250 mg kg−1 and above, the three compounds significantly increased root Cu (196%, 184%, and 184%) with respect to the control. Only at 500 mg kg−1, ionic Cu gave significantly higher root Cu compared to the other Cu treatments. Additionally, at 125 mg kg−1, leaf P was 41% lower for nCuO, compared to the bCuO treatment. At 500 mg kg−1, nCuO reduced Zn by 55% in leaves and 47% in fruits, compared to the control (p ≤ 0.05); however, it is premature to assert that the reduction in fruit Zn compromises the nutritional quality of bell pepper. Overall, this investigation showed that, at the concentrations tested, nCuO presented low toxicity to bell pepper, with rare differences between nano and bulk treatment responses

Plant-based green synthesis of metallic nanoparticles: scientific curiosity or a realistic alternative to chemical synthesis?

Currently, thousands of tons of metallic nanoparticles (MNPs) are produced and utilized in nano-enabled devises, personal care, medicinal, food and agricultural products. It is generally accepted that the reaction compounds and the techniques used in industrial production of MNPs are not environmentally friendly. The green synthesis has been proposed as an alternative to reduce the use of hazardous compounds and harsh reaction conditions in the production of MNPs. In this endeavor, investigators have used organic compounds, microbes, plants and plant-derived materials as reducing agents. Research papers are published every year, and each one of them stresses the benefits of the green approach and the advantages over the traditional syntheses. However, after almost two decades since the explosion of the reports about the new approach, the commercial production of green-synthesized nanoparticles does not seem to find a way to scale up commercial production. This review includes descriptions of the traditional and green synthesis and applications of MNPs and highlights the factors limiting the use of plant-based synthesis as a real alternative to the traditional synthesis of MNPs

Zno Nanoparticle Fate In Soil And Zinc Bioaccumulation In Corn Plants (Zea Mays) Influenced By Alginate

Nanoparticles (NPs) can interact with naturally occurring inorganic and organic substances in soils, which may change their transport behavior in soil and plants. This study was performed in two steps. In the first step, corn (Zea mays) plants were cultivated for one month in soil amended with 10 nm commercial spheroid ZnO NPs at 0–800 mg kg−1 and sodium alginate at 10 mg kg−1. In the second step, the plants were grown with ZnO NPs at 400 mg kg−1 and alginate at 0, 10, 50, and 100 mg kg−1. The dynamics of Zn concentrations in soil solution and Zn accumulation in plant tissues were determined by ICP-OES. Biomass accumulation, chlorophyll concentration, and the activity of antioxidant enzymes in leaves were also quantified. Results indicate that ZnO NPs coexisting with Zn dissolved species were continuously released to the soil solution to replenish the Zn ions or ZnO NPs scavenged by roots. At 400 and 800 mg kg−1, without alginate, ZnO NPs significantly reduced the root and shoot biomass production; however, plants treated with these NP concentrations, plus alginate, had significantly more Zn in tissues with no reduction in biomass production. Alginate significantly reduced the activity of stress enzymes catalase and peroxidase, which could indicate damage in the defense system. The effects of ZnO NPs in a food crop grown in alginate enriched soil, showing an excess of Zn in the aerial parts, are yet to be reported

Transport of Zn in a sandy loam soil treated with ZnO NPs and uptake by corn plants: Electron microprobe and confocal microscopy studies

The manufacture and multiple uses of zinc oxide (ZnO) nanoparticles (NPs) will represent a possible source of soil contamination. Little is known about how these NPs transport in soil and plants. In this research, the transport of Zn/ZnO NPs in sandy loam soil and the uptake by corn plants (Zea mays) was investigated. Results showed that ZnO NPs exhibit low mobility in a soil column at various ionic strengths. Elution curves suggest that some of the adsorbed ZnO NPs/Zn were released in the presence of chemical perturbations. The breakthrough of released Zn coincided with Fe and Al (indicator of soil colloids) suggesting that soil colloids may act as carriers of strongly adsorbed NPs. By using electron microprobe, Zn/ZnO NPs aggregates were visualized associate with soil clay minerals. The uptake (mg/kg) of Zn by one-month old corn plants varied from 69 to 409 in roots and from 100 to 350 in shoots, respectively, in soils contaminated with different concentrations of ZnO NPs (from 100 to 800 mg NPs/kg soil). Confocal microscope images showed that ZnO NPs aggregates penetrated the root epidermis and cortex through the apoplastic pathway; however, the presence of some NP aggregates in xylem vessels suggests that the aggregates passed the endodermis through the symplastic pathway

Tomato Fruit Nutritional Quality Is Altered by the Foliar Application of Various Metal Oxide Nanomaterials

Carbohydrates and phytonutrients play important roles in tomato fruit’s nutritional quality. In the current study, Fe3O4, MnFe2O4, ZnFe2O4, Zn0.5Mn0.5Fe2O4, Mn3O4, and ZnO nanomaterials (NMs) were synthesized, characterized, and applied at 250 mg/L to tomato plants via foliar application to investigate their effects on the nutritional quality of tomato fruits. The plant growth cycle was conducted for a total of 135 days in a greenhouse and the tomato fruits were harvested as they ripened. The lycopene content was initially reduced at 0 stored days by MnFe2O4, ZnFe2O4, and Zn0.5Mn0.5Fe2O4; however, after a 15-day storage, there was no statistical difference between the treatments and the control. Moreover, the β-carotene content was also reduced by Zn0.5Mn0.5Fe2O4, Mn3O4, and ZnO. The effects of the Mn3O4 and ZnO carried over and inhibited the β-carotene after the fruit was stored. However, the total phenolic compounds were increased by ZnFe2O4, Zn0.5Mn0.5Fe2O4, and ZnO after 15 days of storage. Additionally, the sugar content in the fruit was enhanced by 118% and 111% when plants were exposed to Mn3O4 and ZnO, respectively. This study demonstrates both beneficial and detrimental effects of various NMs on tomato fruit quality and highlights the need for caution in such nanoscale applications during crop growth