Nanoparticle Exposure Research Articles

Multiple stressor effects on a model soil nematode, Caenorhabditis elegans: Combined effects of the pathogen Klebsiella pneumoniae and zinc oxide nanoparticles

Research utilizing the model soil nematode Caenorhabditis elegans has revealed that agriculturally relevant nanoparticles (NP), such as zinc oxide NP (ZnONP), cause toxicity at low concentrations and disrupt molecular pathways of pathogen resistance. However, in most nanotoxicity assessments, model organisms are exposed to a single stressor but in nature organisms are affected by multiple sources of stress, including infections, which might exacerbate or mitigate negative effects of NP exposure. Thus, to expand our understanding of the environmental consequences of released NP, this project examined the synergistic/antagonistic effects of ZnONP on C. elegans infected with a common pathogen, Klebsiella pneumoniae. Individual exposures of C. elegans to ZnONP, zinc sulfate (Zn2+ ions) or K. pneumoniae significantly decreased nematode reproduction compared to controls. To assess the combined stress of ZnONP and K. pneumoniae, C. elegans were exposed to equitoxic EC30 concentrations of ZnONP (or Zn ions) and K. pneumoniae. After the combined exposure there was no decrease in reproduction. This complete elimination of reproductive toxicity was unexpected because exposures were conducted at EC30 Zn concentrations and reproductive toxicity due to Zn should have occurred. Amelioration of the pathogen effects by Zn are partially explained by the Zn impact on the K. pneumoniae biofilm. Quantitative assessments showed that external biofilm production and estimated colony forming units (CFU) of K. pneumoniae within the nematodes were significantly decreased. Taken together, our results suggest that during the combined exposure of C. elegans to both stressors Zn in ionic or particulate form inhibits K. pneumoniae ability to colonize nematode's intestine through decreasing pathogen biofilm formation. This highlights the unpredictable nature of combined stressor effects, calling into question the utility of exposures in simplified laboratory media.

SiO2 Nanoparticles Suspension Exposures with Marine Invertebrates: Genotoxicity Response

The volume of nanoparticles (NPs) used in various sectors of human life is steadily increasing. Due to their unique properties, silicon dioxide nanoparticles (SiO2 NPs) are widely used in industrial production. However, their ecotoxicological effect on marine biota is extremely poorly understood. To highlight this problem, experiments were conducted with short-term SiO2 NPs exposure to the sand dollar Scaphechinus mirabilis sperm, and a 6-day exposure to the adult bivalve mollusk Mytilus trossulus. SiO2 NPs exposure caused an increase in the concentration of Si in the digestive gland of the mollusk, resulting in DNA damage increase. Exposure to all NPs concentrations caused DNA damage to increase but did not affect the sperm fertilization ability. It was found that the DNA is a target in both chronic and acute SiO2 NPs exposure.

Macrophages Release Extracellular Vesicles of Different Properties and Composition Following Exposure to Nanoparticles

Extracellular vesicles are membrane-bound carriers with complex cargoes, which play a major role in intercellular communication, for instance, in the context of the immune response. Macrophages are known to release extracellular vesicles in response to different stimuli, and changes in their size, number, and composition may provide important insights into the responses induced. Macrophages are also known to be highly efficient in clearing nanoparticles, when in contact with them, and in triggering the immune system. However, little is known about how the nature and composition of the vesicles released by these cells may vary upon nanoparticle exposure. In order to study this, in this work, alveolar-like macrophages were exposed to a panel of nanoparticles with varying surface and composition, including amino-modified and carboxylated polystyrene and plain silica. We previously showed that these nanoparticles induced very different responses in these cells. Here, experimental conditions were carefully tuned in order to separate the extracellular vesicles released by the macrophages several hours after exposure to sub-toxic concentrations of the same nanoparticles. After separation, different methods, including high-sensitivity flow cytometry, TEM imaging, Western blotting, and nanoparticle tracking analysis, were combined in order to characterize the extracellular vesicles. Finally, proteomics was used to determine their composition and how it varied upon exposure to the different nanoparticles. Our results show that depending on the nanoparticles' properties. The macrophages produced extracellular vesicles of varying number, size, and protein composition. This indicates that macrophages release specific signals in response to nanoparticles and overall suggests that extracellular vesicles can reflect subtle responses to nanoparticles and nanoparticle impact on intercellular communication.

Cooking Particulate Matter: A Systematic Review on Nanoparticle Exposure in the Indoor Cooking Environment

Background: Cooking and fuel combustion in the indoor environment are major sources of respirable suspended particulate matter (RSPM), which is an excellent carrier of potentially harmful absorbed inorganic and organic compounds. Chronic exposure to RSPM can lead to acute pulmonary illness, asthma, cardiovascular disease, and lung cancer in people involved in cooking. Despite this, questions remain about the harmfulness of different particulate matter (PM) sources generated during cooking, and the factors influencing PM physico-chemical properties. The most reliable methods for sampling and analyzing cooking emissions remain only partially understood. Objectives: This review aims to comprehensively assess the risks of PM generated during cooking, considering the main sources of PM, PM chemical composition, and strategies for PM physico-chemical analysis. We present the first systematic analysis of PM sources and chemical composition related to cooking. We highlight significant differences between studies using different experimental conditions, with a lack of a standard methodology. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement rules and the Patient, Intervention, Comparison, and Outcome (PICO) strategy for scientific research, three different scientific databases (PubMed, Scopus, and Web of Science) were screened to find scientific articles that measure, collect, and analyze the chemical composition of nanometer- and micrometer-sized PM generated during cooking activities under different conditions. Data are summarized to assess risk, evaluating the main sources and factors influencing PM generation, their chemical composition, and how they have been collected and analyzed in changing experimental conditions. Results: From 2474 search results, there were 55 studies that met our criteria. Overall, the main variable sources of PM in cooking activities relate to the stove and fuel type. The concentration and chemical–physical properties of PM are also strongly influenced by the food and food additive type, food processing type, cooking duration, temperature, and utensils. The most important factor influencing indoor PM concentration is ventilation. The PM generated during cooking activities is composed mainly of elemental carbon (EC) and its derivatives, and the porous structure of PM with high surface-to-volume ratio is a perfect carrier of inorganic and organic matter. Conclusions: This review reveals a growing interest in PM exposure during cooking activities and highlights significant variability in the chemical–physical properties of particles, and thus variable exposure risks. Precise risk characterization improves possible preventive strategies to reduce the risk of indoor pollutant exposure. However, comprehensive PM analysis needs proper sampling and analysis methods which consider all factors influencing the physico-chemical properties of PM in an additive and synergistic way. Our analysis highlights the need for method standardization in PM environmental analyses, to ensure accuracy and allow deeper comparisons between future studies.

Structural, metagenomic and metabolic shifts in multispecies freshwater biofilm models exposed to silver nanoparticles

The prevalence of silver nanoparticles (AgNPs) in freshwater environments has long been the subject of concern due to their negative impacts on macro-organisms in general. Nevertheless, it is still not well established how freshwater biofilm microbial communities respond to AgNP exposure. This study employed modelled freshwater biofilms to study their response and interaction with AgNPs by applying metagenomic and metabolomic approaches and high-resolution microscopy. Metagenomic 16 S rRNA sequencing analyses revealed that biofilm microbial diversity did not alter following AgNP exposure (p > 0.05). Further genotype investigation highlighted two key taxa, namely Alphaproteobacteria and Betaproteobacteria, as the backbone of the multispecies biofilm when exposed to AgNPs, which also explained increased extracellular polymeric substance (EPS) production. LS-MS/MS-based untargeted metabolomics demonstrated the role of glycerophospholipid metabolism in maintaining biofilm. Scanning electron microscopic analysis revealed distinct biofilm structural phenotypes characterized by smoother biofilm features exposed to AgNPs. Overall, the study presents a unique view of how multispecies biofilms respond to single environmental stress in the form of silver nanoparticle exposure.

Effects of titanium dioxide (TiO2)/activated carbon (AC) nanoparticle on the growth and immunity of the giant freshwater prawn, Macrobrachium rosenbergii: potential toxicological risks to the aquatic crustaceans.

Due to their unique physicochemical characteristics, nanomaterials exhibit many excellent properties and functions, leading to their applications in numerous fields. The large-scale production and widespread application of nanomaterials have inevitably resulted in their release into the environment, especially the water environment. Several studies have confirmed that exposure to nanomaterials can be toxic to aquatic organisms. However, few studies have focused on the effects of nanomaterial exposure on growth and immunity in crustaceans. In the present study, juvenile Macrobrachium rosenbergii were exposed to different concentrations of titanium dioxide (TiO2)/activated carbon (AC) composite nanomaterial (0.1 and 0.5mg/L) for 45days. The effects of nanoparticle exposure on digestion and antioxidant-related enzyme activities, as well as the expression of growth and immunity-related genes and signaling pathway, were evaluated. Our results show that in response to low concentration of TiO2/AC nanoparticle (0.1mg/L), most of the enzyme activities related to digestion and antioxidation (TPS, LPS, AMS, SOD, and CAT) were diminished. On the contrary, the GSH-Px activity increased under the 0.1mg/L group of TiO2/AC nanoparticle concentration. Additionally, the level of digestive and antioxidant enzyme activities we detected was increased when exposed to 0.5mg/L TiO2/AC nanoparticle. By comparison to the expression level of growth-related genes in the control group, MSTN, CaBP, E75, Raptor, EcR, and EGF were significantly inhibited at 0.1 and 0.5mg/L concentrations of TiO2/AC nanoparticle, whereas the expression level of genes (TLR, JAK, STAT, PPAF, ACP, and AKP) related to immunity was increased when exposed to different concentrations of TiO2/AC nanoparticle. Compared with the control group (0mg/L concentration), 5166 DEGs were identified in the TiO2/AC nanoparticle group, and a large number of DEGs were involved in molting, energy metabolism, stress tolerance, and germ cell development. Moreover, KEGG analysis revealed that many DEGs were assigned into signaling pathways related to metabolic growth and immune stress. These results showed that exposure to TiO2/AC nanoparticle will result in the changes of enzyme activity and routine mRNA expression, suggesting that TiO2/AC nanoparticle which existed in aquatic environment might affect the physiology of M. rosenbergii. This study will provide significant information for the evaluation of nanomaterial toxicity on aquatic crustaceans.

In Vitro Transcriptome Analysis of Cobalt Boride Nanoparticles on Human Pulmonary Alveolar Cells.

Nanobiotechnology influences many different areas, including the medical, food, energy, clothing, and cosmetics industries. Considering the wide usage of nanomaterials, it is necessary to investigate the toxicity potentials of specific nanosized molecules. Boron-containing nanoparticles (NPs) are attracting much interest from scientists due to their unique physicochemical properties. However, there is limited information concerning the toxicity of boron-containing NPs, including cobalt boride (Co2B) NPs. Therefore, in this study, Co2B NPs were characterized using X-ray crystallography (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) techniques. Then, we performed 3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH) release, and neutral red (NR) assays for assessing cell viability against Co2B NP exposure on cultured human pulmonary alveolar epithelial cells (HPAEpiC). In addition, whole-genome microarray analysis was carried out to reveal the global gene expression differentiation of HPAEpiC cells after Co2B NP application. The cell viability tests unveiled an IC50 value for Co2B NPs of 310.353 mg/L. The results of our microarray analysis displayed 719 gene expression differentiations (FC ≥ 2) among the analyzed 40,000 genes. The performed visualization and integrated discovery (DAVID) analysis revealed that there were interactions between various gene pathways and administration of the NPs. Based on gene ontology biological processes analysis, we found that the P53 signaling pathway, cell cycle, and cancer-affecting genes were mostly affected by the Co2B NPs. In conclusion, we suggested that Co2B NPs would be a safe and effective nanomolecule for industrial applications, particularly for medical purposes.

Silica nanoparticles aggravated the metabolic associated fatty liver disease through disturbed amino acid and lipid metabolisms-mediated oxidative stress

The metabolic associated fatty liver disease (MAFLD) is a public health challenge, leading to a global increase in chronic liver disease. The respiratory exposure of silica nanoparticles (SiNPs) has revealed to induce hepatotoxicity. However, its role in the pathogenesis and progression of MAFLD was severely under-studied. In this context, the hepatic impacts of SiNPs were investigated in vivo and in vitro through using ApoE−/− mice and free fatty acid (FFA)-treated L02 hepatocytes. Histopathological examinations and biochemical analysis showed SiNPs exposure via intratracheal instillation aggravated hepatic steatosis, lipid vacuolation, inflammatory infiltration and even collagen deposition in ApoE−/− mice, companied with increased hepatic ALT, AST and LDH levels. The enhanced fatty acid synthesis and inhibited fatty acid β-oxidation and lipid efflux may account for the increased hepatic TC/TG by SiNPs. Consistently, SiNPs induced lipid deposition and elevated TC in FFA-treated L02 cells. Further, the activation of hepatic oxidative stress was detected in vivo and in vitro, as evidenced by ROS accumulation, elevated MDA, declined GSH/GSSG and down-regulated Nrf2 signaling. Endoplasmic reticulum (ER) stress was also triggered in response to SiNPs-induced lipid accumulation, as reflecting by the remarkable ER expansion and increased BIP expression. More importantly, an UPLC-MS-based metabolomics analysis revealed that SiNPs disturbed the hepatic metabolic profile in ApoE−/− mice, prominently on amino acids and lipid metabolisms. In particular, the identified differential metabolites were strongly correlated to the activation of oxidative stress and ensuing hepatic TC/TG accumulation and liver injuries, contributing to the progression of liver diseases. Taken together, our study showed SiNPs promoted hepatic steatosis and liver damage, resulting in the aggravation of MAFLD progression. More importantly, the disturbed amino acids and lipid metabolisms-mediated oxidative stress was a key contributor to this phenomenon from a metabolic perspective.

Tailoring Lipid-Based Drug Delivery Nanosystems by Synchrotron Small Angle X-ray Scattering.

Thanks to specific physico-chemical properties, drug delivery systems based on nanoparticles have proven to effectively transport delicate molecules for therapeutic purposes, protecting them from degradation, increasing their stability in the blood circulation and allowing to convey and release the transported substances in specific areas of the body. Nanoparticles obtained from biopolymers for applications in medicine and pharmaceutics have become particularly popular in recent years due to the enormous research effort in the field of vaccines to respond to the pandemic emergency. Among the various types of biopolymers used to produce nanoparticles for therapeutics, lipids have characteristics that make them biocompatible, with low toxicity and ease of clearance. They can be synthesized by designing their characteristics according to the foreseen administration path, or to the target of the transported drug. The analytical methods mostly used to evaluate the characteristics of lipid nanosytems for drug delivery involve studying their effects on cells, in vitro and in vivo. Although it is often considered a "niche technique" for research in the bio-related sciences, Small Angle X-ray Scattering (SAXS) is a versatile tool to study the structure of nanosystems based on lipids, both ex situ and in situ. Therefore, it allows to evaluate both the effect of the different synthesis parameters and of the exposure of lipid nanoparticles to physiological conditions, which is of fundamental importance to design efficient drug delivery systems. In this mini-review, we will report some recent examples of characterization and design of nanoparticles based on lipids, where SAXS has been a fundamental step both to guide the synthesis of nanomaterials with tailored characteristics, and to understand the interaction between nanomaterials and cells.

Air pollution nanoparticle exposure reduces neurotrophin signaling and causes hippocampal neural stem cell quiescence in mouse brain

AbstractBackgroundExposure to urban air pollution particles is strongly associated with higher risks of accelerated cognitive decline, cerebral atrophy, and dementia in multiple population studies. Among possible mechanisms is the decrease of neurotrophins, shown for BDNF in human exposures, which have critical roles in regulating adult neurogenesis and synaptic plasticity.MethodC57BL/6 mice were exposed to nano‐sized particulate matter (nPM, batch nPM2016a) from urban traffic air pollution for 8 weeks and the mRNAs of neurotrophins and receptors in mouse brain were measured by qPCR assay and neural stem cells measured by immunohistochemistry.ResultnPM exposure altered mRNA levels of neurotrophin genes (Ngf, Bdnf, Ntf‐3 and Ntf‐4/5) with brain region‐specificity. In cerebral cortex (CX), Ngf and Ntf‐3 were decreased (17% and 29% respectively), Ntf‐4/5 increased (78%), and Bdnf unchanged. In hippocampus (HP), Bdnf and Ntf‐4/5 were decreased (40% and 38% respectively) while Ngf and NTF‐3 unchanged. In olfactory bulb (OB), only Bdnf was decreased (10%). The mRNAs of neurotrophin receptors (Trka, Trkb, Trkc and p75Ntr) in CX, HP and OB were less responsive to nPM exposure, and only shown by OB with 22% decrease of p75Ntr and 14% decrease of Vgr (VGF nerve growth factor inducible). Exposure to nPM increased the quiescence of neural stem cells in hippocampal SGZ by IHC assay (Control 69.3% VS nPM 76.6%, P = 0.02), but did not alter the total number of neural stem cells. .ConclusionChronic air pollution exposure altered neurotrophin signaling with factor‐ and brain region‐specificity, and increased neural stem cell quiescence.

Synergetic effect of steam and activated tyre char on the selective production of levoglucosan-rich bio-oil from catalytic pyrolysis of wood chips

The catalysts used in the pyrolytic bio-oil upgrading process are either expensive or not efficient enough. This research aims to investigate and improve the catalytic capability of tyre char (TC), an otherwise low-value waste, as an effective catalyst for upgrading bio-oil derived from the pyrolysis of eucalyptus wood chips. Efforts were specifically made to tailor the TC properties to improve the selectivity of levoglucosan (LGA), a value-added bio-chemical in bio-oil. Experiments were carried out in a two-stage fixed-bed reactor in the absence and presence of steam (30 vol%) at different heating rates (10 °C/min and 110 °C/min). By using 3-Flex, SEM-EDX, XRD, XRF, CHNS, and synchrotron XAS analyses, it was found that zinc and sulphur added during the tyre manufacturing process were mainly present in the form of ZnS nanoparticles with a crystallite size less than 1 nm in the TC matrix. An overall deoxygenation extent of 31.7 wt% was achieved with original TC catalyst and slow heating rate of 10 °C/min. However, this number was increased to 49.2 wt% with steam activated TC and fast heating rate of 110 °C/min, and adding steam to the reactor at the optimum temperature of 500 °C. More specifically, the introduction of steam and activated TC to the pyrolysis reactor enhanced the transformation of heavy hydrocarbons to light species and value-added chemicals such as LGA and furfural, reaching 34.9 wt% and 11.3 wt% on the mass basis of bio-oil, respectively. The high catalytic performance can be attributed to the large porosity and better exposure of ZnS nanoparticles on the surface of the activated TC, and the influence of steam in shifting the reactions toward more selective production of light hydrocarbons.

Biomarkers of oxidative stress in urine and plasma of operators at six Singapore printing centers and their association with several metrics of printer-emitted nanoparticle exposures

Inhalation of nanoparticles emitted from toner-based printing equipment (TPE), such as laser printers and photocopiers, also known as PEPs, has been associated with systemic inflammation, hypertension, cardiovascular disease, respiratory disorders, and genotoxicity. Global serum metabolomics analysis in 19 healthy TPE operators found 52 dysregulated biomolecules involved in upregulation of inflammation, immune, and antioxidant responses and downregulation of cellular energetics and cell proliferation. Here, we build on the metabolomics study by investigating the association of a panel of nine urinary OS biomarkers reflecting DNA/RNA damage (8OHdG, 8OHG, and 5OHMeU), protein/amino acid oxidation (o-tyrosine, 3-chlorotyrosine, and 3-nitrotyrosine), and lipid oxidation (8-isoprostane, 4-hydroxy nonenal, and malondialdehyde [MDA]), as well as plasma total MDA and total protein carbonyl (TPC), with several nanoparticle exposure metrics in the same 19 healthy TPE operators. Plasma total MDA, urinary 5OHMeU, 3-chlorotyrosine, and 3-nitrotyrosine were positively, whereas o-tyrosine inversely and statistically significantly associated with PEPs exposure in multivariate models, after adjusting for age and urinary creatinine. Urinary 8OHdG, 8OHG, 5OHMeU, and total MDA in urine and plasma had group mean values higher than expected in healthy controls without PEPs exposure and comparable to those of workers experiencing low to moderate levels of oxidative stress (OS). The highest exposure group had OS biomarker values, most notably 8OHdG, 8OHG, and total MDA, that compared to workers exposed to welding fumes and titanium dioxide. Particle number concentration was the most sensitive and robust exposure metric. A combination of nanoparticle number concentration and OS potential of fresh aerosols is recommended for larger scale future studies.

The response of microphytobenthos to physical disturbance, herbicide, and titanium dioxide nanoparticle exposure

The microphytobenthos that form transient biofilms are important primary producers in intertidal, depositional habitats, yet we have only a limited understanding of how they respond to the cumulative impacts of the growing range of anthropogenic stressors to which they are exposed. We know even less about how the temporal alignment of exposure – such as duration and exposure sequence – may affect the response. Estuarine biofilms were cultured in mesocosms and exposed to the herbicide glyphosate and titanium dioxide (TiO2) nanoparticles in different sequences (glyphosate-first or TiO2-first), as well as in the presence and absence of physical disturbance. We found that at environmentally realistic chemical concentrations, the order of exposure was less important than the total stressor scenario in terms of impacts on key functional attributes and diatom community structure. Physical disturbance did not have an impact on functional attributes, regardless of exposure sequence.

Oxidative damage induced by combined exposure of titanium dioxide nanoparticles and cypermethrin in rats for 90 days.

Titanium dioxide nanoparticles (TiO2NPs) and cypermethrin (CPM) are widely used in various fields, and they can enter the environment in different ways. Combined exposure of TiO2NPs and CPM may increase the accumulation of pollutants in organisms and affect human health. This study was undertaken to evaluate the oxidative and inflammatory parameters associated with the combined exposure of TiO2NPs and CPM in rats. Twenty-four healthy male adult SD rats were randomly divided into four groups. The first group served as the control, while groups 2, 3, and 4 were treated with TiO2NPs (450mg/m3); CPM (6.67mg/m3) or combined exposure of TiO2NPs and CPM by inhalation for 90 days. We investigated the oxidative damage induced through combined exposure of TiO2NPs and CPM in rats by evaluating hematology of the rats and determining the blood biochemical index. Our results demonstrated that inhalation of TiO2NPs and CPM increased the levels of oxidative stress markers such as malondialdehyde and alkaline phosphatase in the serum of rats. These were accompanied by a decreased glutathione peroxidase and total superoxide dismutase levels. Furthermore, the level of glutathione peroxidase was further decreased while malondialdehyde was increased in the combined exposure of TiO2NPs and CPM. Interestingly, pathological sections showed that different degrees of tissue injury could be seen in the liver and lung tissues of each exposure group. In summary, the combined exposure of TiO2NPs and CPM can cause increased oxidative damage in rats and damage the tissue structure of the liver and lung.

Silver nanoparticles potentiate antitumor and oxidant actions of cisplatin via the stimulation of TRPM2 channel in glioblastoma tumor cells

We investigated the effects of silver nanoparticle (AgNP) and cisplatin (CiSP) exposure via the activation of TRPM2 cation channels in glioblastoma (DBTRG-05MG) cell line.The cells were divided into four groups as control, AgNPs (100 μg/ml for 48 h), CiSP (25 μM for 24 h), and CiSP + AgNPs. We found that the cytotoxic, oxidant and apoptotic actions of CiSP were further stimulated through the activation of TRPM2 (via ADP-ribose and H2O2) in the cells by the treatment of AgNPs. The actions were decreased in the cells by the treatments of TRPM2 antagonists (ACA and 2APB). The apoptotic actions of AgNPs were induced by the stimulation of propidium iodide positive DBTRG-05MG rate, caspase −3, caspase −8, and caspase −9 activations, although their oxidant actions were acted by the increase of mitochondrial membrane depolarization, lipid peroxidation, mitochondrial oxygen free radicals (ROS), and cytosolic ROS, but the decrease of total antioxidant status, glutathione, and glutathione peroxidase. The accumulation of cytosolic free Ca2+ and Zn2+ into mitochondria via the activation of TRPM2 current density and activity accelerated oxidant and apoptotic actions of AgNPs in the cells.We found that the combination of AgNPs and CiSP was synergistic via the stimulation of TRPM2 for treatment of DBTRG-05MG cells. The combination of AgNPs and CiSP showed a favorable action via the stimulation of TRPM2 in the treatment of glioblastoma tumor cells.

Melatonin-mediated resistance to copper oxide nanoparticles-induced toxicity by regulating the photosynthetic apparatus, cellular damages and antioxidant defense system in maize seedlings

The pollution of nanoparticles (NPs) has linked with severe negative effects on crop productivity. Thus, effective strategies are needed to mitigate the phytotoxicity of NPs. The aim of present study was to evaluate the efficacy of exogenously applied melatonin (MT) in mitigating the toxic effects of copper oxide nanoparticles (CuO NPs) from maize seedlings. Therefore, we comprehensively investigated the inhibitory effects of MT against CuO NPs-induced toxicity on morpho-physiological, biochemical and ultrastructural levels in maize. Our results show that CuO NPs (300 mg L−1) exposure displayed significantly reduction in all plant growth traits and induced toxicity in maize. Furthermore, 50 μM MT provided maximum plant tolerance against CuO NPs-induced phytotoxicity. It was noticed that MT improved plant growth, biomass, photochemical efficiency (Fv/Fm), chlorophyll contents (Chl a and Chl b), SPAD values and gas exchange attributes (stomatal conductance, net photosynthetic rate, intercellular CO2 concentration and transpiration rate) under CuO NPs stress. In addition, MT enhanced the antioxidant defense system and conferred protection to ultrastructural (mainly chloroplast, thylakoids membrane and plastoglobuli) damages and stomatal closure in maize plants subjected to CuO NPs stress. Together, it can be stated that the exogenous supply of MT improves the resilience of maize plants against the CuO NPs-induced phytotoxicity. Our current findings can be useful for the enhancement of plant growth and yield attributes in CuO NPs-contaminated soils. The reported information can provide insight into the MT pathways that can be used to improve crop stress tolerance in a challenging environment.

Earthworms Drive the Effect of La2O3 Nanoparticles on Radish Taproot Metabolite Profiles and Rhizosphere Microbial Communities.

To promote the sustainable and safe application of nanotechnology employing engineered nanoparticles (NPs) in agroecosystems, it is crucial to pay more attention to the NP-mediated biological response process and environmental impact assessment simultaneously. Herein, 50 mg kg-1 La2O3 NPs were added to soils without and with earthworms for cherry radish growth for 50 days to investigate the response changes of metabolites in radish above- and below-ground organs and rhizosphere bacterial communities. We found that La2O3 NP exposure, especially with earthworms, notably increased the La bioavailability and uptake by taproots and eventually increased radish leaf sucrose content and plant biomass. The La2O3 NP exposure significantly altered metabolite profiles in taproot flesh and peel tissues, and particularly La2O3 NP exposure combined with earthworms was more conducive to La2O3 NPs to promote radish taproot peel to synthesize more secondary antioxidant metabolites. Moreover, compared with the control, the La2O3 NP exposure resulted in weaker and fewer correlations between rhizosphere bacteria and taproot metabolites, but this was recovered somewhat after the inoculation of earthworms. Altogether, our results provide novel insights into the soil-fauna-driven biological and biochemical impact of La2O3 NP exposure on edible root crops and the long-term environmental risks to the rhizosphere microbiota in agroecosystems.

Human biomonitoring and personal air monitoring. An integrated approach to assess exposure of stainless-steel welders to metal-oxide nanoparticles

In welding, there is a potential risk due to metal-oxide nanoparticles (MONPs) exposure of workers. To investigate this possibility, the diameter and number particles concentration of MONPs were evaluated in different biological matrices and in personal air samples collected from 18 stainless-steel welders and 15 unexposed administrative employees engaged in two Italian mechanical engineering Companies. Exhaled breath condensate (EBC) and urine were sampled at pre-shift on 1st day and post-shift on 5th day of the workweek, while plasma and inhalable particulate matter (IPM) at post-shift on 5th day and analysed using the Single Particle Mass Spectrometry (SP-ICP-MS) technique to assess possible exposure to Cr2O3, Mn3O4 and NiO nanoparticles (NPs) in welders. The NPs in IPM at both Companies presented a multi-oxide composition consisting of Cr2O3 (median, 871,574 particles/m3; 70 nm), Mn3O4 (median, 713,481 particles/m3; 92 nm) and NiO (median, 369,324 particles/m3; 55 nm). The EBC of welders at both Companies showed Cr2O3 NPs median concentration significantly higher at post-shift (64,645 particles/mL; 55 nm) than at pre-shift (15,836 particles/mL; 58 nm). Significantly lower Cr2O3 NPs median concentration and size (7762 particles/mL; 44 nm) were observed in plasma compared to EBC of welders. At one Company, NiO NPs median concentration in EBC (22,000 particles/mL; 65 nm) and plasma (8248 particles/mL; 37 nm) were detected only at post-shift. No particles of Cr2O3, Mn3O4 and NiO were detected in urine of welders at both Companies. The combined analyses of biological matrices and air samples were a valid approach to investigate both internal and external exposure of welding workers to MONPs. Overall, results may inform suitable risk assessment and management procedures in welding operations.

Toxicity of boron nitride nanoparticles influencing bio-physicochemical responses in freshwater green algae.

Boron nanoparticles have emerged as promising nanomaterials with a wide array of applications in the biomedical, industrial, and environmental fields. However, the potential impact of these nanoparticles on aquatic organisms is not yet known. In the present study, the comparative impact of boron nitride nanoparticles and its bulk form is investigated on two freshwater algae. For this purpose, the effect on the physiological index, cellular morphology, and biochemistry profiles are examined. In Chlorella vulgaris, nano form of boron nitride is found to reduce the growth more (40%) than its bulk form (with ~ 25% growth reduction) at 50 mgl-1 treatment level. While in case of Coelastrella terrestris, 40% reduction under nano form and 33.33% reduction under bulk form is observed at 100 mgl-1 of boron nitride. Chlorophyll and carotenoid levels were also reduced under nanoparticles compared to the bulk. Proline, lactate dehydrogenase, and malondialdehyde assay were found significantly high under nanoparticle exposure. Additionally, increased catalase and superoxide dismutase enzyme activity under nanoparticle exposure revealed that the antioxidant system was activated in both the algae to eliminate the adverse influence of reactive oxygen species. The shading effect and aggregation of nanoparticles over the surface of algal cells are also important factors in attributing toxicity which are confirmed through the compound, TEM, and SEM micrographs. The study suggests that the nano form is more toxic than the bulk form and toxicity is concentration-dependent.

Thermal Radiation Energy Performance on Stagnation-Point Flow in the Presence of Base Fluids Ethylene Glycol and Water over Stretching Sheet with Slip Boundary Condition

Nanoparticles are useful in improving the efficiency of convective heat transfer. The current study addresses this gap by making use of an analogy between Al2O3 and γ-Al2O3 nanoparticles in various base fluids across a stretched sheet conjunction with f. Base fluids include ethylene glycol and water. We address, for the first time, the stagnation-point flow of a boundary layer of γ-Al2O3 nanofluid over a stretched sheet with slip boundary condition. Al2O3 nanofluids employ Brinkman viscosity and Maxwell’s thermal conductivity models with thermal radiations, whereas γ-Al2O3 nanofluids use viscosity and thermal conductivity models generated from experimental data. For the boundary layer, the motion equation was solved numerically using the fourth-order Runge–Kutta method and the shooting approach. Plots of the velocity profile, temperature profile, skin friction coefficient and reduced Nusselt number are shown. Simultaneous exposure of the identical nanoparticles to water and ethylene glycol, it is projected, would result in markedly different behaviors with respect to the temperature profile. Therefore, this kind of research instills confidence in us to conduct an analysis of the various nanoparticle decompositions and profile structures with regard to various base fluids.