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Despite the progress in the area of food safety, foodborne diseases still represent a massive challenge to the public health systems worldwide, mainly due to the substantial inefficiencies across the farm-to-fork continuum. Here, we report the development of a nano-carrier platform, for the targeted and precise delivery of antimicrobials for the inactivation of microorganisms on surfaces using Engineered Water Nanostructures (EWNS). An aqueous suspension of an active ingredient (AI) was used to synthesize iEWNS, with the ‘i’ denoting the AI used in their synthesis, using a combined electrospray and ionization process. The iEWNS possess unique, active-ingredient-dependent physicochemical properties: i) they are engineered to have a tunable size in the nanoscale; ii) they have excessive electric surface charge, and iii) they contain both the reactive oxygen species (ROS) formed due to the ionization of deionized (DI) water, and the AI used in their synthesis. Their charge can be used in combination with an electric field to target them onto a surface of interest. In this approach, a number of nature-inspired antimicrobials, such as H2O2, lysozyme, citric acid, and their combination, were used to synthesize a variety of iEWNS-based nano-sanitizers. It was demonstrated through foodborne-pathogen-inactivation experiments that due to the targeted and precise delivery, and synergistic effects of AI and ROS incorporated in the iEWNS structure, a pico-to nanogram-level dose of the AI delivered to the surface using this nano-carrier platform is capable of achieving 5-log reductions in minutes of exposure time. This aerosol-based, yet ‘dry’ intervention approach using iEWNS nano-carrier platform offers advantages over current ‘wet’ techniques that are prevalent commercially, which require grams of the AI to achieve similar inactivation, leading to increased chemical risks and chemical waste byproducts. Such a targeted nano-carrier approach has the potential to revolutionize the delivery of antimicrobials for sterilization in the food industry.

Nano-enabled coatings (NECs) are a growing class of nanomaterials used in architectural applications that are likely to be thermally decomposed at their end-of-life via commercial waste incineration or accidental fires in buildings, thereby increasing concern over the potential release of engineered nanomaterials (ENMs) used as nanofillers. This is especially important for NECs as they have a larger surface-to-volume ratio compared to more traditional nano-enabled products (NEPs). In addition, questions remain about effects of nanofiller and NEC matrix properties and incineration operational conditions on NECs' thermal decomposition (TD) behavior and the physicochemical and morphological (PCM) properties of associated byproducts. In this study, the recently developed Integrated Exposure Generation System (INEXS) platform was used to identify important factors governing TD of NECs and assess potential environmental health implications. Findings confirm that nanofiller chemical composition, size and mass loading in the matrix, as well as incineration conditions, influence nanofiller release into the aerosol. Conversely, the morphology, mass-size distribution and the overall elemental and organic carbon content of the released aerosol are primarily governed by the host NEC matrix properties. The remaining residual ash properties are strongly dependent on the physicochemical composition of the nanofiller. Overall, the study highlights important byproduct release dynamics and exposure profiles during TD of NECs and warrants further studies on understanding the synergistic interactions between the released byproducts, their fate and transformations, and their toxicological and environmental health implications.

Engineered water nanostructures (EWNS) were utilized to deliver a cocktail of nature derived antimicrobials, to assess their efficacy as a solution to the problem of wound infections. The wound related microorganism Acinetobacter baumannii was inoculated on stainless steel and porcine skin and treated with EWNS. EWNS were able to reduce A. baumannii on stainless steel by 4.79 logs in 15 min, and 2 logs in 30 min on porcine skin. The EWNS were able to reduce the strength of A. baumannii biofilm on stainless steel by 87.31% as measured with the XTT assay (P .001) and 86.27% in cellular counts (P .001), after two EWNS interventions of 30 min each. Total antimicrobial dose delivered to the surface was 1.42 ng. SEM of biofilms after EWNS treatment showed reduced biomass. These results indicate that the EWNS technology has potential for application in field of wound disinfection and healing.

There is a growing need to develop and characterize reference metal and metal oxide engineered nanomaterials (ENMs) of high purity and tunable intrinsic properties suitable for nanotoxicology research. Here a high throughput (volume) and precision flame spray pyrolysis (FSP) approach coupled with state-of-the-art characterization techniques are utilized to generate such reference ENMs. The lab-based and industrially relevant FSP system, termed as Versatile Engineered Nanomaterials Generation System (VENGES), synthesizes the metals and metal oxides, at high throughput manner with controlled properties, such as primary particle size, aggregate diameter, shape, crystallinity, stoichiometry and surface chemistry. A nanopanel of nine reference ENMs (silica, silver, silver supported on silica, alumina, ceria and iron oxide) was synthesized and characterized using combined electron microscopy, advanced spectroscopic techniques and physical analyses (e.g., BET, XRD, TEM, pycnometry, XPS, ICP-MS and FTIR). ENMs show a high degree of chemical purity and stoichiometry, and low content of carbon residuals, and are sterile and free of bacteria and endotoxins. Further, their colloidal properties and their implication in in-vitro dosimetry have been also investigated in both environmental and test biological media. The suitability of reference ENMs and protocols developed in this study brings forth new arenas to generate reliable and reproducible toxicological data in an effort to reduce conflicting and contradicting inter-laboratory data on relative toxic effects of ENMs.

Electronic cigarettes (e-cigs) have fast increased in popularity but the physico-chemical properties and toxicity of the generated emission remain unclear. Reactive oxygen species (ROS) are likely present in e-cig emission and can play an important role in e-cig toxicity. However, e-cig ROS generation is poorly documented. Here, we generated e-cig exposures using a recently developed versatile exposure platform and performed systematic ROS characterization on e-cig emissions using complementary acellular and cellular techniques: 1) a novel acellular Trolox-based mass spectrometry method for total ROS and hydrogen peroxide (H2O2) detection, 2) electron spin resonance (ESR) for hydroxyl radical detection in an acellular and cellular systems and 3) in vitro ROS detection in small airway epithelial cells (SAEC) using the dihydroethidium (DHE) assay. Findings confirm ROS generation in cellular and acellular systems and is highly dependent on the e-cig brand, flavor, puffing pattern and voltage. Trolox method detected a total of 1.2–8.9 nmol H2O2 eq./puff; H2O2 accounted for 12–68 % of total ROS. SAEC cells exposed to e-cig emissions generated up to eight times more ROS compared to control. The dependency of e-cig emission profile on e-cig features and operational parameters should be taken into consideration in toxicological studies.

Despite mounting evidence of increasing micro- and nanoplastics (MNPs) in natural environments, food, and drinking water, little is known of the potential health hazards of MNPs ingestion. We assessed toxicity and uptake of environmentally relevant MNPs in an in vitro small intestinal epithelium (SIE). Test MNPs included 25 and 1000 nm polystyrene (PS) microspheres (PS25 and PS1K); 25, 100, and 1000 nm carboxyl modified PS spheres (PS25C, PS100C, and PS1KC), and secondary MNPs from incinerated polyethylene (PEI). MNPs were subjected to 3-phase digestion to mimic transformations in the gastrointestinal tract (GIT) and digestas applied to the SIE. Carboxylated MNPs significantly reduced viability and increased permeability to 3 kD dextran. Uptake of carboxyl PS materials was size dependent, with significantly greater uptake of PS25C. Fluorescence confocal imaging showed some PS25C agglomerates entering cells independent of endosomes (suggesting diffusion), others within actin shells (suggesting phagocytosis), and many free within the epithelial cells, including agglomerates within nuclei. Pre-treatment with the dynamin inhibitor Dyngo partially reduced PS25 translocation, suggesting a potential role for endocytosis. These findings suggest that ingestion exposures to MNPs could have serious health consequences and underscore the urgent need for additional detailed studies of the potential hazards of ingested MNPs.

Silver nanoparticles (AgNPs) are a common antimicrobial additive for a variety of applications, including wound care. However, AgNPs often undergo dissolution resulting in release of silver ions, with subsequent toxicity to mammalian cells. The cornea is a primary exposure site to topically administered AgNPs in and around the eye but their impact on corneal wound healing is understudied. Thus, the purpose of this study was to determine in vitro toxicity of AgNPs on corneal epithelial cells and fibroblasts as well as their effects on corneal epithelial wound healing utilizing an in vivo rabbit model. Non-coated 20 nm sized AgNP (AgNP-20) as well as 1% and 10% silver silica NPs (AgSiO2NPs) were tested at concentrations ranging from 0.05–250 μg/mL. Immortalized human corneal epithelial (hTCEpi) cells and primary rabbit corneal fibroblasts (RCFs) were incubated for 24 h with AgNPs and cell viability was tested. Additionally, a round wound healing assay was performed to determine hTCEpi cell migration. Quantitative real-time PCR and western blot analysis was performed to determine α-smooth muscle actin (α-SMA, a myofibroblast marker) mRNA and protein expression, respectively, in RCFs treated with 50 μg/mL of AgNPs. Corneal epithelial wound healing was evaluated with 1%-AgSiO2NPs (10 and 250 μg/mL) using an in vivo rabbit model. Rabbits were subsequently euthanized, and histologic sections of the enucleated globes were used to determine corneal penetration of 1%-AgSiO2NPs with autometallography and hyperspectral darkfield microscopy. Cell viability of both the hTCEpi cells and fibroblasts was significantly decreased by the three AgNPs in a dose dependent manner. Migration of hTCEpi cells was significantly inhibited by the three AgNPs. Alpha-SMA mRNA expression was significantly inhibited with three AgNPs, but only the 1%-AgSiO2NPs inhibited protein expression of α-SMA. In vivo epithelial wound closure did not significantly differ between groups treated with 10 or 250 μg/mL of 1%-AgSiO2NPs or vehicle control. The 1%-AgSiO2NPs penetrated throughout all corneal layers and into the anterior chamber in all treated eyes with no histopathological changes observed. In conclusion, the 1%-AgSiO2NPs are safe and have potential therapeutic applications through its efficacy of the corneal penetration and reduced scar formation during corneal wound healing.

With rapid development of novel nanotechnologies that incorporate engineered nanomaterials (ENMs) into manufactured products, long-term, low dose ENM exposures in occupational settings is forecasted to occur with potential adverse outcomes to human health. Few ENM human health risk assessment efforts have evaluated tumorigenic potential of ENMs. Two widely used nano-scaled metal oxides (NMOs), cerium oxide (nCeO2) and ferric oxide (nFe2O3) were screened in the current study using a sub-chronic exposure to human primary small airway epithelial cells (pSAECs). Multi-walled carbon nanotubes (MWCNT), a known ENM tumor promoter, was used as a positive control. Advanced dosimetry modeling was employed to ascertain delivered vs. administered dose in all experimental conditions. Cells were continuously exposed in vitro to deposited doses of 0.18 μg/cm2 or 0.06 μg/cm2 of each NMO or MWCNT, respectively, over 6 and 10 weeks, while saline- and dispersant-only exposed cells served as passage controls. Cells were evaluated for changes in several cancer hallmarks, as evidence for neoplastic transformation. At 10 weeks, nFe2O3- and MWCNT-exposed cells displayed a neoplastic-like transformation phenotype with significant increased proliferation, invasion, and soft agar colony formation ability compared to controls. nCeO2-exposed cells showed increased proliferative capacity only. Isolated nFe2O3 and MWCNT clones from soft agar colonies retained their respective neoplastic-like phenotypes. Interestingly, nFe2O3-exposed cells, but not MWCNT cells, exhibited immortalization and retention of the neoplastic phenotype after repeated passaging (12–30 passages) and after cryofreeze and thawing. High content screening and protein expression analyses in acute exposure ENM studies vs. immortalized nFe2O3 cells, and isolated ENM clones, suggested that long-term exposure to the tested ENMs resulted in iron homeostasis disruption, an increased labile ferrous iron pool, and subsequent reactive oxygen species generation, a well-established tumorigenesis promotor. In conclusion, sub-chronic exposure to human pSAECs with a cancer hallmark screening battery identified nFe2O3 as possessing neoplastic-like transformation ability, thus suggesting that further tumorigenic assessment is needed.

© 2020 Elsevier B.V. Emerging, two-dimensional engineered nanomaterials (2DNMs) possess unique and diverse physical and chemical properties, such as extreme aspect ratios, adjustable electronic properties as well as functional lattice defects and surface chemistry which underpin their interactions with biological systems. This perspective highlights the need for structure activity relationship (SAR) studies for key properties of emerging graphene-related and inorganic 2DNMs upon prioritization based on their potential impact and trajectory for large-scale production and applications. Further, it is discussed how a synthesis platform of microbiologically sterile, size-sorted, “model” 2DNMs with precise structure would enable SAR toxicological studies and allow for the sustainable and safe translation of 2D nanotechnology to real-world applications.

A recent published study showed that TiO2 (E171) and SiO2 (E551), two widely used nano-enabled food additives, increased the translocation of the commonly used pesticide boscalid by 20% and 30% respectively. Such increased absorption of pesticides due to the presence of engineered nanomaterials (ENMs) in food raises health concerns for these food additives. In this companion study, mRNA expression of genes related to cell junctions in a small intestinal epithelial cellular model after exposure to simulated digestas of fasting food model (phosphate buffer) containing boscalid (150 ppm) with or without either TiO2 or SiO2 (1% w/w) were analyzed. Specific changes in cell barrier function underlying or contributing to the increased translocation of boscalid observed in the previous study were assessed. Results showed that exposure to boscalid alone has no significant effect on cell junction genes, however, co-exposure to boscalid and TiO2 significantly regulated expression of cell-matrix junction focal adhesion-related genes, e.g., downregulating Cav1 (- 1.39-fold, p

Toner-based printing equipment (TPE), including laser printers and photocopiers, utilize several engineered nanomaterials (ENMs) to improve toner performance. Operation of TPE, which rarely employ any exposure controls, generates high exposures to nanoparticles that contain ENMs and complex organics. Epidemiological literature in copier operators documents respiratory effects, including nasal blockage, cough, excessive sputum, and breathing difficulties, cardiovascular effects, oxidative stress, and inflammation. However, epidemiological studies in humans with adequate exposure assessment and dose-response analysis are lacking. We present herein the analysis of the upper airway and systemic inflammation in plasma of 19 healthy copier operators at six Singapore workplaces. We employed a repeated panel design (four biomarker measurements over two weeks) combined with a multi-marker approach (14 inflammatory cytokines in plasma and nasal lavage (NL)), and comprehensive exposure assessment using four distinct exposure metrics. We investigated spatial and temporal patterns of markers of upper airway and systemic inflammation and their association with various exposure metrics. Several inflammatory markers, namely fractalkine, IL-1β, and IL-1α in NL, and fractalkine, IL-1β, TNF-α, and IFN-γ in plasma, were strongly and positively associated with at least one exposure metric, whereas GM-CSF was negatively associated. The inflammation score was also strongly associated with TPE nanoparticle exposures. Exposure to TPE emissions induced moderate upper airway inflammation and stronger systemic inflammation in these healthy operators, characterized by upregulation of at least IL-1β, fractalkine, TNF-α and IFN-γ. Proinflammatory cytokines TNF-α, IFN-γ and IL-1β play an important role in orchestrating inflammatory responses in various clinical conditions, including cardiovascular and autoimmune disease, and likely trigger activation of endothelial cells, leading to overexpression of fractalkine, a chemokine that is involved in and associated with multiple disorders, including atherosclerosis and vascular disease. Future larger-scale epidemiological studies in these workers and consumers exposed chronically to TPE nanoparticle emissions and proactive interventions to reduce or eliminate TPE exposures are recommended.

Background Several recent studies have linked emissions from printing equipment with upper airway inflammation and systemic oxidative stress in healthy humans, lung inflammation in mice, and cytotoxicity, induction of inflammatory markers and epigenetic changes in human cell lines. Acute exposures have lead to upper airway inflammation and systemic oxidative stress, which for certain markers took longer than 24–36 h post-exposure to clear. Objective In this follow-up work, we determined: i) whether chronic exposures to nanoparticles from copiers lead to chronic upper airway inflammation and systemic oxidative stress; and ii) whether expression patterns of biomarkers for such stresses change during transition from acute to chronic exposures. Methods Six permanent employees from three copy centers and eleven controls participated in the study. Nasal lavage and urine samples were collected on Monday morning (pre-shift, Mo-AM) and evening (post-shift, Mo-PM), as well as at the end of the workweek (Fr-PM), over three random weeks. The matched controls were sampled over one week. Nasal lavage samples were analyzed for a panel of 14 pro-inflammatory cytokines/chemokines, inflammatory cells, and total protein. Urine samples were analyzed for 8-OH-dG , a biomarker of systemic oxidative stress. Detailed quantitative exposure assessment to airborne nanoparticles was conducted for a whole week, and included size distribution, size-fractionated aerosol collection, extensive chemical analysis, and lung burden estimates. Results The daily geometric mean total particle number concentration varied between 14,600–21,860 particles/cm 3 , 1.7–12.1 times greater than background, with maxima up to 143,000 particles/cm 3 . Mass concentration of the nanoscale fraction was in the 1–10 μg/m 3 range. Chemical composition of the nanoparticle fraction was comprised mostly of organic compounds, mixed with several engineered nanoparticles, which contributed a metal content ranging from 2 to 8% of the total particulate mass. Five out of the 14 inflammatory cytokines, namely IL-6, IL-8, TNFα, IL-1β and Eotaxin, were significantly elevated in the nasal lavage samples of the chronically exposed copier operators (p 8-OH-dG in (4.3 fold) in urine samples. Conclusion Chronic upper airway inflammation and systemic oxidative stress were documented in photocopier operators chronically exposed to nanoparticles. These findings agree with the recent toxicological literature on printer-emitted particles and medical case reports, and call for an industry-wide study of the health effects resulting from exposure to printer-emitted particles in chronically exposed workers. Inflammatory markers point to possible involvement of toll-like receptors, particularly TLR-4, oxidative stress, and the Nf-kB pathway in mediating airway tissue inflammation.

Many foods contain appreciable levels of engineered nanomaterials (ENMs) (diameter < 100 nm) that may be either intentionally or unintentionally added. These ENMs vary considerably in their compositions, dimensions, morphologies, physicochemical properties, and biological responses. From a toxicological point of view, it is often convenient to classify ingested ENMs (iENMs) as being either inorganic (such as TiO2, SiO2, Fe2O3, or Ag) or organic (such as lipid, protein, or carbohydrate), since the former tend to be indigestible and the latter are generally digestible. At present there is a relatively poor understanding of how different types of iENMs behave within the human gastrointestinal tract (GIT), and how the food matrix and biopolymers transform their physico-chemical properties and influence their gastrointestinal fate. This lack of knowledge confounds an understanding of their potential harmful effects on human health. The purpose of this article is to review our current understanding of the GIT fate of iENMs, and to highlight gaps where further research is urgently needed in assessing potential risks and toxicological implications of iENMs. In particular, a strong emphasis is given to the development of standardized screening methods that can be used to rapidly and accurately assess the toxicological properties of iENMs.

Increasing use of engineered nanomaterials (ENMs) means increased human exposures. Potential adverse effects include those on the immune system, ranging from direct toxicity to impairment of defenses against environmental pathogens and toxins. Effects on lung macrophages may be especially prominent, because they serve to clear foreign materials like ENMs and bacterial pathogens. We investigated the effects of 4 hour exposures over a range of concentrations, of a panel of industry-relevant ENMs, including SiO2, Fe2O3, ZnO, CeO2, TiO2, and an Ag/SiO2 composite, on human THP-1 macrophages. Effects on phagocytosis of latex beads, and phagocytosis and killing of Francisella tularensis (FT), as well as viability, oxidative stress and mitochondrial integrity, were measured by automated scanning confocal microscopy and image analysis. Results revealed some notable patterns: 1) Phagocytosis of unopsonized beads was increased, whereas that of opsonized beads was decreased, by all ENMs, with the exception of ZnO, which reduced both opsonized and unopsonized uptake; 2) Uptake of opsonized and unopsonized FT was either impaired or unaffected by all ENMs, with the exception of CeO2, which increased phagocytosis of unopsonized FT; 3) Macrophage killing of FT tended to improve with all ENMs; and 4) Viability was unaffected immediately following exposures with all ENMs tested, but was significantly decreased 24 hours after exposures to Ag/SiO2 and ZnO ENMs. The results reveal a complex landscape of ENM effects on macrophage host defenses, including both enhanced and reduced capacities, and underscore the importance of robust hazard assessment, including immunotoxicity assessment, of ENMs.

Cellulose nanofibers (CNF) reduced serum triglyceride levels in rats when co-administered with heavy cream by gavage. Do CNF and other nanomaterials (NMs) alter the tissue distribution and retention of co-administered metal ions? We evaluated whether 5 different NMs affected tissue distribution of co-ingested (65)Zn(++) and (59)Fe(+++) in zinc-replete versus zinc-deficient mice. Male C57BL/6J mice were fed either zinc-replete or zinc-deficient diets for 3 weeks, followed by gavage with NM suspensions in water containing both (65)ZnCl(2) and (59)FeCl(3). Urine and feces were measured for 48 h post-gavage. Mice were euthanized and samples of 22 tissues were collected and analyzed for (65)Zn and (59)Fe in a gamma counter. Our data show that zinc deficiency alters the tissue distribution of (65)Zn but not of (59)Fe, indicating that zinc and iron homeostasis are regulated by distinct mechanisms. Among the tested NMs, soluble starch-coated chitosan nanoparticles, cellulose nanocrystals, and TiO(2) reduced Zn and Fe tissue retention in zinc-deficient but not in zinc-replete animals.