Engineered Nanomaterials Research Articles

Cadmium Sulfide Quantum Dots, Mitochondrial Function and Environmental Stress: A Mechanistic Reconstruction through In Vivo Cellular Approaches in Saccharomyces cerevisiae

Research on the effects of engineered nanomaterials (ENMs) on mitochondria, which represent one of the main actors in cell function, highlighted effects on ROS production, gametogenesis and organellar genome replication. Specifically, the mitochondrial effects of cadmium sulfide quantum dots (CdS QDs) exposure can be observed through the variation in enzymatic kinetics at the level of the respiratory chain and also by analyzing modifications of reagent and products in term of the bonds created and disrupted during the reactions through Fourier-transform infrared spectroscopy (FTIR). This study investigated both in intact cells and in isolated mitochondria to observe the response to CdS QDs treatment at the level of electron transport chain in the wild-type yeast Saccharomyces cerevisiae and in the deletion mutant Δtom5, whose function is implicated in nucleo–mitochondrial protein trafficking. The changes observed in wild type and Δtom5 strains in terms of an increase or decrease in enzymatic activity (ranging between 1 and 2 folds) also differed according to the genetic background of the strains and the respiratory chain functionality during the CdS QDs treatment performed. Results were confirmed by FTIR, where a clear difference between the QD effects in the wild type and in the mutant strain, Δtom5, was observed. The utilization of these genetic and biochemical approaches is instrumental to clarify the mitochondrial mechanisms implicated in response to these types of ENMs and to the stress response that follows the exposure.

Approaches to Nanoparticle Labeling: A Review of Fluorescent, Radiological, and Metallic Techniques.

Nanomaterials are widely used in commercial products, resulting in the release of nanoscale particles into the environment. This raises concerns about their potential exposure risks in complex biological matrices. Most attempts use engineered nanomaterials (ENMs) to mimic the biological behavior of nanoparticles in the environment, and labeling of ENMs by sensors is a commonly used approach for sensitive detection and tracking of ENMs in organisms. However, due to the distinct physicochemical properties of nanoparticles, different labeling approaches have been developed, each with varying applicability. In this Review, we summarize the three main types of labeling methods used for nanoparticles: fluorescent, radiological, and metallic labeling. We discuss their labeling mechanisms, efficiency, stability, target nanoparticles, and applicability in different organism models. Finally, we propose a labeling scheme for specific nanoparticles. Overall, this Review provides a comprehensive overview of the advances in nanoparticle labeling techniques and their potential applications in environmental and health studies.

Nutrient strengthening of winter wheat by foliar ZnO and Fe3O4 NPs: Food safety, quality, elemental distribution and effects on soil bacteria

With the anticipated application of engineered nanomaterials (ENMs) as foliar fertilizers in agriculture, there is a particular need to accurately assess crop intensification capacity, potential hazards, and effects on the soil environment when ENMs are applied alone or in combination. In this study, the joint analysis of scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) showed that ZnO NPs transformed on the leaf surface or within the leaf, and Fe3O4 NPs were able to translocate from the leaf (~ 25 memu/g) into the stem (~ 4 memu/g), but were unable to enter the grain (below 1 memu/g), guaranteeing food safety. Spray application of ZnO NPs significantly improved grain Zn content of wheat (40.34 mg/kg), whereas Fe3O4 NPs treatment and Zn + Fe NPs treatment did not significantly improve grain Fe content. According to the micro X-ray fluorescence of wheat grains(μ- XRF) and physiological structure in situ analysis showed that ZnO NPs treatment and Fe3O4 NPs treatment could increase the elemental contents of Zn and Fe in the crease tissue and endosperm components, respectively, while antagonism was observed in the grain treated with Zn + Fe NPs. The 16S rRNA gene sequencing results showed that the Fe3O4 NPs treatment had the greatest negative effect on soil bacterial community, followed by Zn + Fe NPs, and ZnO NPs showed some promotion effect. This may be caused by the significantly higher elemental contents of Zn/Fe in the treated roots and soils. This study critically evaluates the application potential and environmental risks of nanomaterials as foliar fertilizers and is instructive for agricultural applications of nanomaterials alone and in combination.

Comparison of toxicity of silver nanomaterials and silver nitrate on developing zebrafish embryos: Bioavailability, osmoregulatory and oxidative stress

The mechanisms of toxicity of engineered nanomaterials (ENMs) to the early life stages of freshwater fish, and the relative hazard compared to dissolved metals, is only partially understood. In the present study, zebrafish (Danio rerio) embryos were exposed to lethal concentrations of silver nitrate (AgNO3) or silver (Ag) ENMs (primary size 42.5 ± 10.2 nm). The 96 h-LC50 for AgNO3 was 32.8 ± 0.72 μg Ag L−1 (mean ± 95% CI) compared to 6.5 ± 0.4 mg L−1 of the whole material for Ag ENMs; with the ENMs being orders of magnitude less toxic than the metal salt. The EC50 for hatching success was 30.5 ± 1.4 μg Ag L−1 and 6.04 ± 0.4 mg L−1 for AgNO3 and Ag ENMs, respectively. Further sub-lethal exposures were performed with the estimated LC10 concentrations for both AgNO3 or Ag ENMs over 96 h, where about 3.7% of the total Ag as AgNO3 was internalised, as measured by Ag accumulation in the dechorionated embryos. However, for the ENM exposures, nearly all (99.8%) of the total Ag was associated with chorion; indicating the chorion as an effective barrier to protect the embryo in the short term. Calcium (Ca2+) and sodium (Na+) depletion was induced in embryos by both forms of Ag, but hyponatremia was more pronounced in the nano form. Total glutathione (tGSH) levels declined in embryos exposed to both Ag forms, but a superior depletion occurred with the nano form. Nevertheless, oxidative stress was mild as superoxide dismutase (SOD) activity stayed uniform and the sodium pump (Na+/K+-ATPase) activity had no appreciable inhibition compared to the control. In conclusion, AgNO3 was more toxic to the early life stage zebrafish than the Ag ENMs, still differences were found in the exposure and toxic mechanisms of both Ag forms.

A Nano-QSTR model to predict nano-cytotoxicity: an approach using human lung cells data

BackgroundThe widespread use of new engineered nanomaterials (ENMs) in industries such as cosmetics, electronics, and diagnostic nanodevices, has been revolutionizing our society. However, emerging studies suggest that ENMs present potentially toxic effects on the human lung. In this regard, we developed a machine learning (ML) nano-quantitative-structure-toxicity relationship (QSTR) model to predict the potential human lung nano-cytotoxicity induced by exposure to ENMs based on metal oxide nanoparticles.ResultsTree-based learning algorithms (e.g., decision tree (DT), random forest (RF), and extra-trees (ET)) were able to predict ENMs’ cytotoxic risk in an efficient, robust, and interpretable way. The best-ranked ET nano-QSTR model showed excellent statistical performance with R2 and Q2-based metrics of 0.95, 0.80, and 0.79 for training, internal validation, and external validation subsets, respectively. Several nano-descriptors linked to the core-type and surface coating reactivity properties were identified as the most relevant characteristics to predict human lung nano-cytotoxicity.ConclusionsThe proposed model suggests that a decrease in the ENMs diameter could significantly increase their potential ability to access lung subcellular compartments (e.g., mitochondria and nuclei), promoting strong nano-cytotoxicity and epithelial barrier dysfunction. Additionally, the presence of polyethylene glycol (PEG) as a surface coating could prevent the potential release of cytotoxic metal ions, promoting lung cytoprotection. Overall, the current work could pave the way for efficient decision-making, prediction, and mitigation of the potential occupational and environmental ENMs risks.

95 Local Scale Exposure and Fate of Engineered Nanomaterials

Abstract Nanotechnology is a growing megatrend in industrial production and innovations. Many applications utilize engineered nanomaterials (ENMs) that are potentially released into the atmospheric environment, e.g., via direct stack emissions from production facilities, and may have adverse effects on human health and the environment. Previous modeling approaches have focused on large regional compartments, into which the released ENMs are evenly mixed. However, due to the localization of the ENM release and removal processes, potentially higher airborne concentrations and deposition fluxes are obtained around the production facilities. Therefore, we compare the ENM concentrations from a dispersion model to those from the uniformly mixed compartment approach. For realistic release scenarios, we based the modeling on the case study measurement data from two ENM handling facilities. In addition, we calculated the distances, at which 50% of the ENMs are deposited, serving as a physically relevant metric to separate the local scale from the regional scale, thus indicating the size of the high exposure and risk region near the facility. As a result, we suggest a local scale compartment to be implemented in the multicompartment nanomaterial exposure models. We also present a computational tool for local exposure assessment that could be included to regulatory guidance and existing risk governance networks. A related research article is currently under peer-review (Poikkimäki et al. 2022, submitted).

50 Human Hazard Assessment of Nanomaterials: Supporting Risk Decision Making Through Interlaboratory Trial Data

Abstract The prevalent application of engineered nanomaterials (ENMs) has led to an extensive effort to develop tools facilitating their risk assessment and management. This interlaboratory trial (encompassing two laboratories) sought to investigate the genotoxic impact of ENMs using the hypoxanthine phosphoribosyltransferase (HPRT) forward mutation assay and in vitro cytokinesis-blocked micronucleus (CBMN) assay, utilising harmonised protocols. In the CBMN assay, human lymphoblast (TK6) cells were exposed to zinc oxide (ZnO), titanium dioxide (TiO2) and tungsten carbide-cobalt (WC/Co) for 24-hours after which 1000 binucleated cells were scored for micronuclei (n=2). For the HPRT assay, TK6 and mouse fibroblast (V79) cells were exposed to ZnO, TiO2, WC/Co, CuO and Nanocyl-CNTs for 24-hours after which 600 wells were scored for point mutations (n=2). Significant cytotoxicity and micronuclei frequency was reported following ZnO exposure (20µg/ml). Significant micronuclei induction was reported following WC/Co exposures (2-fold over control, 100µg/ml). No significant mutagenicity was detected with ZnO or TiO2; both laboratories observed significant cytotoxicity following exposure to ZnO (20µg/ml; 37% reduction in cell viability). In the second interlaboratory trial CuO induced significant cytotoxicity (36% reduction in viability: 0.5µg/ml), and a 32-fold increase in mutagenicity. The Nanocyl induced a 6-fold increase in mutagenicity. The data generated here has shown good statistical concordance between laboratories and has highlighted a promising route forward in supporting risk decision making for ENMs. The authors would like to acknowledge this research has received funding from the European Union’s Horizon 2020 research and innovation program for the RiskGONE project, grant agreement #814425.

3 An Introduction to the SbD4Nano Project

Abstract A major challenge for the global nanotechnology sector is the development of safe and functional engineered nanomaterials (ENMs) and nano-enabled products (NEPs). In order to minimise the risks to human and environmental health during the engineering of NEPs the goal of the Safe-by-Design for Nano (SbD4Nano) project is to create a novel e-infrastructure for the definition, performance testing and implementation of Safe-by-Design (SbD) approaches in the nanotechnology supply chains. The project aims to demonstrate how selecting appropriate surface modification of nanomaterials can reduce the hazard and risk to workers, consumers and the environment whilst maintaining its functionality. The presentation will give an introduction to the project and outline the results generated thus far. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 862195

Optimization of Targeted Plant Proteomics Using Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS).

This study was conducted to optimize a targeted plant proteomics approach from signature peptide selection and liquid chromatography with tandem mass spectrometry (LC-MS/MS) analytical method development and optimization to sample preparation method optimization. Three typical protein extraction and precipitation methods, including trichloroacetic acid (TCA)/acetone method, phenol method, and TCA/acetone/phenol method, and two digestion methods, including trypsin digestion and LysC/trypsin digestion, were evaluated for selected proteins related to the impact of engineered nanomaterials (ENMs) on wheat (Triticum aestivum) plant growth. In addition, we compared two plant tissue homogenization methods: grinding freeze-dried tissue and fresh tissue into a fine powder using a mortar and pestle aided with liquid nitrogen. Wheat plants were grown under a 16 h photoperiod (light intensity 150 μmol·m-2·s-1) for 4 weeks at 22 °C with a relative humidity of 60% and were watered daily to maintain a 70-90% water content in the soil. Processed samples were analyzed with an optimized LC-MS/MS method. The concentration of selected signature peptides for the wheat proteins of interest indicated that the phenol extraction method using fresh plant tissue, coupled with trypsin digestion, was the best sample preparation method for the targeted proteomics study. Overall, the optimized approach yielded the highest total peptide concentration (68,831 ng/g, 2.4 times the lowest concentration) as well as higher signature peptide concentrations for most peptides (19 out of 28). In addition, three of the signature peptides could only be detected using the optimized approach. This study provides a workflow for optimizing targeted proteomics studies.

Promotion effects and mechanisms of molybdenum disulfide on the propagation of antibiotic resistance genes in soil

The rapid development of nanotechnology has aroused considerable attentions toward understanding the effects of engineered nanomaterials (ENMs) on the propagation of antibiotic resistance. Molybdenum disulfide (MoS2) is an extensively used ENM and poses potential risks associated with environmental exposure; nevertheless, the role of MoS2 toward antibiotic resistance genes (ARGs) transfer remains largely unknown. Herein, it was discovered that MoS2 nanosheets accelerated the horizontal transfer of RP4 plasmid across Escherichia coli in a dose-dependent manner (0.5–10 mg/L), with the maximum transfer frequency 2.07-fold higher than that of the control. Integration of physiological, transcriptomics, and metabolomics analyses demonstrated that SOS response in bacteria was activated by MoS2 due to the elevation of oxidative damage, accompanied by cell membrane permeabilization. MoS2 promoted bacterial adhesion and intercellular contact via stimulating the secretion of extracellular polysaccharides. The ATP levels were maximally increased by 305.7 % upon exposure to MoS2, and the expression of plasmid transfer genes was up-regulated, contributing to the accelerated plasmid conjugation and increased ARG abundance in soil. Our findings highlight the roles of emerging ENMs (e.g., MoS2) in ARGs dissemination, which is significant for the safe applications and risk management of ENMs under the development scenarios of nanotechnology.

Critical aspects in occupational exposure assessment with different aerosol metrics in an industrial spray coating process

Engineered Nanomaterials (ENMs) have several uses in various industrial fields and are embedded in a myriad of consumer products. However, there is continued concern over the potential adverse health effects and environmental impacts of ENMs due to their unique physico-chemical characteristics. Currently, there are no specific international regulations for various ENMs. There are also no Occupational Exposure Limits (OEL) regulated by the European Union (EU) for nanomaterials in the form of nano-objects, their aggregates or agglomerates (NOAA). For ENMs the question of which metric to be used (i.e., mass, surface area, number concentrations) to determine the exposure is still not resolved. The aim of this work is to assess the worker exposure by inhalation in an industrial spray coating process by using all three metrics mentioned above. Two target ENMs (N-doped TiO2, TiO2N and AgNPs capped with a quaternized hydroxyethyl-cellulose, AgHEC) generated for industrial-scale spraying processes were considered. Results showed that the averaged particle number concentration (10–100 nm) was below 2.7 104 cm−3 for both materials. The Lung Deposited Surface Area (LDSA) was in the range between 73 and 98 μm2cm−3 and the particle mass concentration (obtained by means of ICP-EOS off-line analysis) resulted below 70 μg m−3 and 0.4 μg m−3 for TiO2 and Ag, respectively. Although, the airborne particles concentration compared well with the NIOSH Recommended Exposure Level (REL) limits the contribution to the background, according to EN 17058 (Annex E) was significant (particularly in the particle number and PM1 mass concentrations). We successfully evaluated the worker exposure by means of the different airborne particles' metrics (number, surface and mass concentrations). We concluded that worker exposure assessment involving ENMs is a complex procedure with requires both real time and off-line measurements and a deep investigation of the background.

Probing emergence of biomolecular coronas around drug‐loaded liposomal nanoparticles in the solution by using nanoparticle tracking analysis

AbstractVarious state‐of‐art analytical methods have played a critical role in understanding the nature of protein coronas. In most cases, the analyses require the biomolecule‐coated engineered nanomaterials (ENMs) to be isolated from the biological environment by energetic processes. This only allows investigation of so‐called “hard” coronas, which are biomolecules tightly bound to the surfaces of ENMs. We examined fluorescence‐nanoparticle tracking analysis (F‐NTA) as a suitable method to study the formation of natural biomolecular coronas in solution, that is, without separation. The formation of coronas of high‐density lipoprotein, immunoglobulin G, and human serum albumin, and also that of the blood serum around fluorescently labeled PEGylated doxorubicin‐loaded liposomes were investigated in terms of the changes in hydrodynamic size as a function of concentration, incubation time, and PEGylation density of liposomes. From the results, this study successfully demonstrates that NTA in the fluorescence mode is indeed suitable to probing intact biomolecular coronas in the native environment.

Transcriptomic Profiling the Effects of Airway Exposure of Zinc Oxide and Silver Nanoparticles in Mouse Lungs

Consumers and manufacturers are exposed to nanosized zinc oxide (nZnO) and silver particles (nAg) via airways, but their biological effects are still not fully elucidated. To understand the immune effects, we exposed mice to 2, 10, or 50 μg of nZnO or nAg by oropharyngeal aspiration and analyzed the global gene expression profiles and immunopathological changes in the lungs after 1, 7, or 28 days. Our results show that the kinetics of responses varied in the lungs. Exposure to nZnO resulted in the highest accumulation of F4/80- and CD3-positive cells, and the largest number of differentially expressed genes (DEGs) were identified after day 1, while exposure to nAg caused peak responses at day 7. Additionally, nZnO mainly activated the innate immune responses leading to acute inflammation, whereas the nAg activated both innate and adaptive immune pathways, with long-lasting effects. This kinetic-profiling study provides an important data source to understand the cellular and molecular processes underlying nZnO- and nAg-induced transcriptomic changes, which lead to the characterization of the corresponding biological and toxicological effects of nZnO and nAg in the lungs. These findings could improve science-based hazard and risk assessment and the development of safe applications of engineered nanomaterials (ENMs), e.g., in biomedical applications.

The contribution shift of ammonia-oxidizing archaea and bacteria to ammoxidation under Ag-NPs/SWCNTs/PS-NPs stressors in constructed wetlands

Ammonia-oxidizing microorganisms (AOMs, archaea (AOA) and bacteria (AOB)) are primarily responsible for the ammoxidation in constructed wetlands (CWs). However, little is known about evaluating the response of AOA and AOB to engineered nanomaterials (ENMs) and quantifying the shift of their contribution to ammoxidation. Herein, we operated a series of CWs exposing to silver nanoparticles (Ag-NPs), single-walled carbon nanotubes (SWCNTs), and polystyrene nano-sized plastics (PS-NPs) with the wastewater-accumulating concentration of ENMs for 180 days. The results showed that the abundance of AOA amoA gene in situ was far lower than that of AOB, while the abundance ratio of AOA to AOB increased by 15 folds after 180-day experiment. Using DNA stable isotope probing (DNA-SIP) experiment, we found that the active AOB microbiota varied substantially but the AOA was more stable across different groups. Furthermore, the co-occurrence analysis proved that ENMs stress increased the negative coexistence pattern of AOA and AOB; predictive functional profiling showed that the ENMs enhanced the functional advantage of AOA by inhibiting AOB (mainly hydroxylamine oxidation process). Finally, the contribution of AOA increased under exposing to SWCNTs (18.35%), PS-NPs (24.92%), and Ag-NPs (32.14%) compared with control group (0.03%) for 180 days. Despite this, AOB was still the primary executant of ammoxidation in CWs. Overall, in our study, the differences in activities and contributions of AOMs were quantified in CWs, and a significantly negative coexistence relationship between AOA and AOB was revealed when exposed to emerging nanomaterials.

Systematic stress persistence and recovery patterns of rice (Oryza sativa L.) roots in response to molybdenum disulfide nanosheets

The increasing application of engineered nanomaterials (ENMs) unavoidably leads to environmental release and biological exposure. Understanding the potential hazards of ENMs on crops is essential for appropriate utilization and management. Herein, rice seedlings were hydroponically exposed to molybdenum sulfide (MoS2, a typical ENM) nanosheets at 5−20 mg/L for 7 days and then depurated for another 7 days in a fresh culture medium. Exposure to MoS2 triggered irreversible reductions in root length (by 26.3%–69.9%) and tip number (by 22.2%–66.0%). Integration of biochemical assays, transcriptomic and metabolomics found that oxidative stress induced by MoS2 in roots was persistent, whereas the activation of aquaporins, ionic transportation, and energy synthesis was normalized due to the recovery of nutrient uptake. The down-regulated levels of genes and metabolites associated with peroxidases, hemicellulose synthesis, expansins, and auxins caused persistent structural damages (sclerosis and rupture) of root cell walls. Approximately 64.5%–84.8% of internalized MoS2 nanosheets were degraded, and the successive up-regulation of genes encoding cytochrome P450s and glutathione S-transferases reflected the biotransformation and detoxification of MoS2 in the depuration period. These findings provide novel insights into the persistence and recovery of MoS2 phytotoxicity, which will help advance the risk assessment of MoS2 application on environment.

Differences in toxicity and accumulation of metal from copper oxide nanomaterials compared to copper sulphate in zebrafish embryos: Delayed hatching, the chorion barrier and physiological effects

The mechanisms of toxicity of engineered nanomaterials (ENMs) to the early life stages of freshwater fish, and the relative hazard compared to dissolved metals, is only partially understood. In the present study, zebrafish embryos were exposed to lethal concentrations of copper sulphate (CuSO4) or copper oxide (CuO) ENMs (primary size ∼15 nm), and then the sub-lethal effects investigated at the LC10 concentrations over 96 h. The 96 h-LC50 (mean ± 95% CI) for CuSO4 was 303 ± 14 µg Cu L−1 compared to 53 ± 9.9 mg L−1 of the whole material for CuO ENMs; with the ENMs being orders of magnitude less toxic than the metal salt. The EC50 for hatching success was 76 ± 11 µg Cu L−1 and 0.34 ± 0.78 mg L−1 for CuSO4 and CuO ENMs respectively. Failure to hatch was associated with bubbles and foam-looking perivitelline fluid (CuSO4), or particulate material smothering the chorion (CuO ENMs). In the sub-lethal exposures, about 42% of the total Cu as CuSO4 was internalised, as measured by Cu accumulation in the de-chorionated embryos, but for the ENMs exposures, nearly all (94%) of the total Cu was associated with chorion; indicating the chorion as an effective barrier to protect the embryo from the ENMs in the short term. Both forms of Cu exposure caused sodium (Na+) and calcium (Ca2+), but not magnesium (Mg2+), depletion from the embryos; and CuSO4 caused some inhibition of the sodium pump (Na+/K+-ATPase) activity. Both forms of Cu exposure caused some loss of total glutathione (tGSH) in the embryos, but without induction of superoxide dismutase (SOD) activity. In conclusion, CuSO4 was much more toxic than CuO ENMs to early life stage zebrafish, but there are subtle differences in the exposure and toxic mechanisms for each substance.

Rapid membrane surface functionalization with Ag nanoparticles via coupling electrospray and polymeric solvent bonding for enhanced antifouling and catalytic performance: Deposition and interfacial reaction mechanisms

Electrospray is an effective, fast, and potentially scalable approach for membrane surface functionalization using various engineered nanomaterials (ENMs). However, the lack of fundamental understandings of the deposition process hinders the controlled deposition, efficient utilization, and long-term stabilization of the ENMs, and thus the practical applications of the nanocomposite membranes. To bridge this critical knowledge gap, advanced online characterization techniques (laser diffraction size measurement and laser doppler velocimetry) coupled with mathematical aerosol modeling are utilized to understand the three key process parameters: droplet size, deposition velocity, and evaporation rate. After deposition, polymeric solvent bonding (i.e., interdiffusion and subsequent entanglement of polymers) was found to substantially stabilize the deposited Ag NPs. We further provide a comprehensive description of such interfacial reaction mechanisms. Our results show a consistency between theoretical predication and measurement of the droplet size or deposition velocity, whereas realistic droplet evaporation rate is lower than the theoretical value due to the addition of the polymer. Successful stabilization of Ag NPs via interfacial polymeric bonding occurs under the conditions of large material contact area, high material compatibility, proper temperature (e.g., 22 °C), and polymer-to-solvent ratio (e.g., 3–5%). Our coupled approach achieves superior Ag NP coverage with high stability within minutes. Despite some reduction in water permeance, the resultant membrane shows markedly improved catalytic and antimicrobial (antibiofouling) performance (>90% enhancement) and maintained rejection. Taken together, our findings provide fundamental insights into the coupled process of electrospray deposition and polymeric solvent bonding to enable additive manufacturing of novel nanocomposite membranes with diverse structures and multiple functions.

Predicting accidental release of engineered nanomaterials to the environment.

Challenges in distinguishing between natural and engineered nanomaterials (ENMs) and the lack of historical records on ENM accidents have hampered attempts to estimate the accidental release and associated environmental impacts of ENMs. Building on knowledge from the nuclear power industry, we provide an assessment of the likelihood of accidental release rates of ENMs within the next 10 and 30 years. We evaluate risk predictive methodology and compare the results with empirical evidence, which enables us to propose modelling approaches to estimate accidental release risk probabilities. Results from two independent modelling approaches based on either assigning 0.5% of reported accidents to ENM-releasing accidents (M1) or based on an evaluation of expert opinions (M2) correlate well and predict severe accidental release of 7% (M1) in the next 10 years and of 10% and 20% for M2 and M1, respectively, in the next 30 years. We discuss the relevance of these results in a regulatory context.

The interaction of ZnO nanoparticles, Cr(VI), and microorganisms triggers a novel ROS scavenging strategy to inhibit microbial Cr(VI) reduction.

Cr(VI) contaminated water usually contains other contaminants like engineered nanomaterials (ENMs). During the process of microbial treatment, the inevitable interaction of Cr(VI), ENMs, and microorganisms probably determines the efficiency of Cr(VI) biotransformation, however, the corresponding information remains elusive. This study investigated the interaction of ZnO nanoparticles (NPs), Cr(VI), and Pannonibacter phragmitetus BB (hereafter BB), which changed the process of microbial Cr(VI) reduction. ZnO NPs inhibited Cr(VI) reduction, but had no effect on bacterial viability. In particular, Cr(VI) induced BB to produce organic acids and to drive Zn2+ dissolution from ZnO NPs inside and outside of cells. The dissolved Zn2+ not only promoted Cr(VI) reduction to Cr(V)/Cr(IV) by strengthening sugar metabolism and inducing increase in NAD(P)H production, but also hindered Cr(V)/Cr(IV) transformation to Cr(III) through down-regulating Cr(VI) reductase genes. A novel bacterial driven ROS scavenging mechanism leading to the inhibition of Cr(VI) reduction was elucidated. Specifically, the accumulated Cr(VI) and Cr(V)/Cr(IV) formed a redox dynamic equilibrium, which triggered the disproportionation of superoxide radicals mimicking superoxide dismutase through the flip-flop of Cr(VI) and Cr(V)/Cr(IV) in bacterial cells. This study provided a realistic insight into design the applicability of biological remediation technology for Cr(VI) contaminant and evaluating environmental risks of ENMs.

Analytical chemistry of engineered nanomaterials: Part 1. Scope, regulation, legislation, and metrology (IUPAC Technical Report)

Abstract Analytical chemistry is crucial for understanding the complex behavior observed for engineered nanomaterials (ENMs). A variety of analytical chemistry techniques and methodological approaches are used for isolation/purification and determination of the composition of pristine nanomaterials and for the detection, identification, and quantification of nanomaterials in nano-enabled consumer products and the complex matrices found in cosmetics, food, and environmental and biological samples. Adequate characterization of ENMs also requires physicochemical characterization of number of other properties, including size, shape, and structure. The requirement for assessment of a number of ENM properties frequently requires interdisciplinary approaches and multi-modal analysis methods. This technical report starts with an overview of ENMs definitions and classification, their properties, and analytical scenarios encountered with the analysis of both pristine nanomaterials and complex matrices containing different nanomaterials. An evaluation of the current status regarding nanomaterial identification and characterization for regulatory purposes and legislation, including emerging regulations and related scientific opinions, is provided. The technical report also presents a large and critical overview of the metrology of nanomaterials, including available reference materials and the development and validation of standardized methods that are currently available to address characterization and analysis challenges. The report focuses mainly on chemical analysis techniques and thus it is complementary to previous IUPAC technical reports focused on characterizing the physical parameters of ENMs and on nanotoxicology.