Accumulation of zinc, copper, or cerium in carrot (Daucus carota) exposed to metal oxide nanoparticles and metal ions

The release of engineered nanoparticles (ENPs) into the environment has raised concerns about the potential risks to food safety and human health. There is a particular need to determine the extent of ENP uptake into plant foods. Belowground vegetables growing in direct contact with the growth substrate are likely accumulate the highest concentration of ENPs. Carrot (Daucus carota) was grown in sand amended with ZnO, CuO, or CeO2 NPs or the same concentrations of Zn2+, Cu2+, or Ce4+. Treatment with ZnO or Zn2+ produced a concentration-dependent decrease in root and total biomass. Ionic Cu2+ and Ce4+ caused a greater reduction in shoot biomass as compared to the corresponding ENP treatments. Accumulation of Zn, Cu, or Ce in the taproot was restricted to the taproot periderm. Metal concentrations in the taproot periderm were higher for the ionic treatments than for the ENP treatments. Radial penetration of the metals into the taproot and subsequent translocation to shoots was also generally greater for plants receiving the ionic treatment than the ENP treatment. The distribution of the metals from the ENP treatments across the periderm, taproot, and shoots differed from that observed for the ionic treatments. Overall, the ENPs were no more toxic than the ionic treatments and showed reduced accumulation in the edible tissues of carrot. The results demonstrate that the understanding of ionic metal transport in plants may not accurately predict ENP transport and that additional comparative study is needed for this and other crop plants

Uptake and accumulation of bulk and nanosized cerium oxide particles and ionic cerium by radish (Raphanus sativus L.).

The potential toxicity and accumulation of engineered nanomaterials (ENMs) in agricultural crops has become an area of great concern and intense investigation. Interestingly, although below-ground vegetables are most likely to accumulate the highest concentrations of ENMs, little work has been done investigating the potential uptake and accumulation of ENMs for this plant group. The overall objective of this study was to evaluate how different forms of cerium (bulk cerium oxide, cerium oxide nanoparticles, and the cerium ion) affected the growth of radish (Raphanus sativus L.) and accumulation of cerium in radish tissues. Ionic cerium (Ce(3+)) had a negative effect on radish growth at 10 mg CeCl3/L, whereas bulk cerium oxide (CeO2) enhanced plant biomass at the same concentration. Treatment with 10 mg/L cerium oxide nanoparticles (CeO2 NPs) had no significant effect on radish growth. Exposure to all forms of cerium resulted in the accumulation of this element in radish tissues, including the edible storage root. However, the accumulation patterns and their effect on plant growth and physiological processes varied with the characteristics of cerium. This study provides a critical frame of reference on the effects of CeO2 NPs versus their bulk and ionic counterparts on radish growth

Bioavailability of cerium oxide nanoparticles to Raphanus sativus L. in two soils.

Cerium oxide nanoparticles (CeO2 NP) are a common component of many commercial products. Due to the general concerns over the potential toxicity of engineered nanoparticles (ENPs), the phytotoxicity and in planta accumulation of CeO2 NPs have been broadly investigated. However, most previous studies were conducted in hydroponic systems and with grain crops. For a few studies performed with soil grown plants, the impact of soil properties on the fate and transport of CeO2 NPs was generally ignored even though numerous previous studies indicate that soil properties play a critical role in the fate and transport of environmental pollutants. The objectives of this study were to evaluate the soil fractionation and bioavailability of CeO2 NPs to Raphanus sativus L (radish) in two soil types. Our results showed that the silty loam contained slightly higher exchangeable fraction (F1) of cerium element than did loamy sand soil, but significantly lower reducible (F2) and oxidizable (F3) fractions as CeO2 NPs concentration increased. CeO2 NPs associated with silicate minerals or the residue fraction (F4) dominated in both soils. The cerium concentration in radish storage root showed linear correlation with the sum of the first three fractions (r(2) = 0.98 and 0.78 for loamy sand and silty loam respectively). However, the cerium content in radish shoots only exhibited strong correlations with F1 (r(2) = 0.97 and 0.89 for loamy sand and silty loam respectively). Overall, the results demonstrated that soil properties are important factors governing the distribution of CeO2 NPs in soil and subsequent bioavailability to plants

Minimal information for studies of extracellular vesicles 2018 (MISEV2018):a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points

Copper, Chromium And Arsenic In Soil And Plants Near Coated And Uncoated CCA Wood

For many years, Chromated Copper Arsenate (CCA) was widely applied as a wood preservative, and though its use for most residential uses has been phased out, concerns about CCA leaching into soil from existing structures remain. In this study, we determined the effects of coating CCA wood on reducing such leaching. Ten boxes were constructed, 6 of which were coated with opaque film forming (FF) or penetrating finishes (PF), filled with soil, and weathered for 2 years. The soil was periodically sampled up to 2 years, and then romaine lettuce, arugula, basil and chives were grown under greenhouse conditions in these boxes. After 2 years, average amounts of arsenic (As) in the soil 2 cm from the CCA wood was 29 mg/kg, dry weight, 27 from wood coated with PF finishes and 6 in those coated with FF finishes. Soil As in all samples 6 cm from the wood were near the background value of 3.4. The average amount of As in arugula grown 2 cm from the edge of the CCA wood was 60 mg/kg, dry weight, 61 in wood coated with PF finishes and 24 in those coated with FF finishes. Similarly, in chives the amounts were 75 in CCA, 75 in PF, 12 in FF, in lettuce they were 5 in CCA, 5 in PF, in 1.4 FF and in basil they were 6 CCA, 10 PF, 3 FF. The amounts of As in plants grown in the control boxes were all \u3c1. Compared to uncoated CCA wood, there was no reduction in As in plants grown along the edge of CCA wood coated with penetrating finishes, while the reduction in plant As ranged from 50-84% in plants grown next to the opaque finished wood. The reduction in arsenic in samples grown 6 cm from the wood compared to 2 cm from the wood ranged from 55-84%. The amounts of arsenic in the arugula and chives exceed the British limit for plant As of 1 mg/kg (fresh weight). As a result, gardeners should avoid growing certain vegetables in soils near CCA wood

Physiological and Molecular Response of <i>Arabidopsis thaliana</i> (L.) to Nanoparticle Cerium and Indium Oxide Exposure

The effects of cerium oxide (CeO₂) and indium oxide (In₂O₃) nanoparticles (NPs) exposure on <i>Arabidopsis thaliana</i> (L.) Heynh. were investigated. After inoculation in half strength MS medium amended with 0–2000 ppm CeO₂ and In₂O₃ NPs for 25 days, both physiological and molecular responses were evaluated. Exposure at 250 ppm CeO₂ NPs significantly increased plant biomass, but at 500–2000 ppm, plant growth was decreased by up to 85% in a dose-dependent fashion. At 1000 and 2000 ppm CeO₂ NPs, chlorophyll production was reduced by nearly 60% and 85%, respectively, and anthocyanin production was increased 3–5-fold. Malondialdehyde (MDA) production, a measure of lipid peroxidation, was unaffected by exposure to 250–500 ppm CeO₂ NPs, but at 1000 ppm, MDA formation was increased by 2.5-fold. Exposure to 25–2000 ppm In₂O₃ NPs had no effect on <i>A. thaliana</i> biomass and only minor effects (15%) on root elongation. Total chlorophyll and MDA production were unaffected by In₂O₃ NPs exposure. Molecular response to NP exposure as measured by qPCR showed that both types of elements altered the expression of genes central to the stress response such as the sulfur assimilation and glutathione (GSH) biosynthesis pathway, a series of genes known to be significant in the detoxification of metal toxicity in plants. Interestingly, In₂O₃ NPs exposure resulted in a 3.8–4.6-fold increase in glutathione synthase (GS) transcript production, whereas CeO₂ NPs yielded only a 2-fold increase. It seems likely that the significantly greater gene regulation response upon In₂O₃ NPs exposure was directly related to the decreased phytotoxicity relative to CeO₂ treatment. The use of NP rare earth oxide elements has increased dramatically, yet knowledge on fate and toxicity has lagged behind. To our knowledge, this is the first report evaluating both physiological and molecular plant response from exposure to these important nanoparticles

Exposure of agricultural crops to nanoparticle CeO2in biochar-amended soil

Biochar is seeing increased usage as an amendment in agricultural soils but the significance of nanoscale interactions between this additive and engineered nanoparticles (ENP) remains unknown. Corn, lettuce, soybean and zucchini were grown for 28 d in two different soils (agricultural, residential) amended with 0â2000 mg engineered nanoparticle (ENP) CeO2 kgâ1and biochar (350 °C or 600 °C) at application rates of 0â5% (w/w). At harvest, plants were analyzed for biomass, Ce content, chlorophyll and lipid peroxidation. Biomass from the four species grown in residential soil varied with species and biochar type. However, biomass in the agricultural soil amended with biochar 600 °C was largely unaffected. Biochar co-exposure had minimal impact on Ce accumulation, with reduced or increased Ce content occurring at the highest (5%) biochar level. Soil-specific and biochar-specific effects on Ce accumulation were observed in the four species. For example, zucchini grown in agricultural soil with 2000 mg CeO2 kgâ1and 350 °C biochar (0.5â5%) accumulated greater Ce than the control. However, for the 600 °C biochar, the opposite effect was evident, with decreased Ce content as biochar increased. A principal component analysis showed that biochar type accounted for 56â99% of the variance in chlorophyll and lipid peroxidation across the plants. SEM and μ-XRF showed Ce association with specific biochar and soil components, while μ-XANES analysis confirmed that after 28 d in soil, the Ce remained largely as CeO2. The current study demonstrates that biochar synthesis conditions significantly impact interactions with ENP, with subsequent effects on particle fate and effects

Analysis of Silver Nanoparticles in Antimicrobial Products Using Surface-Enhanced Raman Spectroscopy (SERS)

Silver nanoparticles (AgNPs) are the most commonly used nanoparticles in consumer products. Concerns over human exposure to and risk from these particles have resulted in increased interest in novel strategies to detect AgNPs. This study investigated the feasibility of surface-enhanced Raman spectroscopy (SERS) as a method for the detection and quantification of AgNPs in antimicrobial products. By using ferbam (ferric dimethyl-dithiocarbamate) as an indicator molecule that binds strongly onto the nanoparticles, AgNPs detection and discrimination were achieved based on the signature SERS response of AgNPs-ferbam complexes. SERS response with ferbam was distinct for silver ions, silver chloride, silver bulk particles, and AgNPs. Two types of AgNPs with different coatings, citrate and polyvinylpirrolidone (PVP), both showed strong interactions with ferbam and induced strong SERS signals. SERS was effectively applicable for detecting Ag particles ranging from 20 to 200 nm, with the highest signal intensity in the 60–100 nm range. A linear relationship (<i>R</i>² = 0.9804) between Raman intensity and citrate-AgNPs concentrations (60 nm; 0–20 mg/L) indicates the potential for particle quantification. We also evaluated SERS detection of AgNPs in four commercially available antimicrobial products. Combined with ICP-MS and TEM data, the results indicated that the SERS response is primarily dependent on size, but also affected by AgNPs concentration. The findings demonstrate that SERS is a promising analytical platform for studying environmentally relevant levels of AgNPs in consumer products and related matrices