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The likelihood of environmental and health impacts of silicon dioxide nanoparticles (SiNPs) has risen, due to their increased use in products and applications. The biological potency of a set of similarly-sized amorphous SiNPs was investigated in a variety of cells to examine the influence of physico-chemical and biological factors on their toxicity. Cellular LDH and ATP, BrdU incorporation, resazurin reduction and cytokine release were measured in human epithelial A549, human THP-1 and mouse J774A.1 macrophage cells exposed for 24 h to suspensions of 5–15, 10–20 and 12 nm SiNPs and reference particles. The SiNPs were characterized in dry state and in suspension to determine their physico-chemical properties. The dose-response data were simplified into particle potency estimates to facilitate the comparison of multiple endpoints of biological effects in cells. Mouse macrophages were the most sensitive to SiNP exposures. Cytotoxicity of the individual cell lines was correlated while the cytokine responses differed, supported by cell type-specific differences in inflammation-associated pathways. SiNP (12 nm), the most cytotoxic and inflammogenic nanoparticle had the highest surface acidity, dry-state agglomerate size, the lowest trace metal and organics content, the smallest surface area and agglomerate size in suspension. Particle surface acidity appeared to be the most significant determinant of the overall biological activity of this set of nanoparticles. Combined with the nanoparticle characterization, integration of the biological potency estimates enabled a comprehensive determination of the cellular reactivity of the SiNPs. The approach shows promise as a useful tool for first-tier screening of SiNP toxicity. [ABSTRACT FROM PUBLISHER]

In vitro cytotoxicity assays are essential tools in the screening of engineered nanomaterials (NM) for cellular toxicity. The resazurin live cell assay is widely used because it is non-destructive and is well suited for high-throughput platforms. However, NMs, in particular carbon nanotubes (CNT) can interfere in assays through quenching of transmitted light or fluorescence. We show that using the resazurin assay with time-point reading of clarified supernatants resolves this problem. Human lung epithelial (A549) and murine macrophage (J774A.1) cell lines were exposed to NMs in 96-well plates in 200 μL of media/well. After 24 h incubation, 100 μL of supernatant was removed, replaced with resazurin reagent in culture media and aliquots at 10 min and 120 min were transferred to black-wall 96-well plates. The plates were quick-spun to sediment the residual CNTs and fluorescence was top-read ( λ Ex = 540 nm, λ Em = 600 nm). The procedure was validated for CNTs as well as silica nanoparticles (SiNP). There was no indication of reduction of resazurin by the CNTs. Stability of resorufin, the fluorescent product of the resazurin reduction was then assessed. We found that polar CNTs could decrease the fluorescence signal for resorufin, possibly through oxidation to resazurin or hyper-reduction to hydroxyresorufin. This effect can be easily quantified for elimination of the bias. We recommend that careful consideration must be given to fluorimetric/colorimetric in vitro toxicological assessments of optically/chemically active NMs in order to relieve any potential artifacts due to the NMs themselves. [ABSTRACT FROM AUTHOR]

There exists a knowledge gap in understanding potential toxicity of mesoporous silica nanoparticles. A critical step in assessing toxicity of these particles is to have a wide size range with different chemistries and physicochemical properties. There are several challenges when synthesizing mesoporous silica nanoparticles over a wide range of sizes including (1) nonuniform synthesis protocols using the same starting materials, (2) the low material yield in a single batch synthesis (especially for particles below 60- 70 nm), and (3)morphological instability during surfactant removal process and surface modifications. In this study, we synthesized a library of mesoporous silica nanoparticles with approximate particle sizes of 25, 70, 100, 170, and 600 nm. Surfaces of the silica nanoparticles were modified with hydrophilic-CH2-(CH2)2-COOH and relatively hydrophobic-CH2-(CH2)10-COOH functional groups. All silica nanoparticles were analysed for morphology, surface functionality, surface area/pore volume, surface organic content, and dispersion characteristics in liquid media. Our analysis revealed the synthesis of a spectrum of monodisperse bare and surface modified mesoporous silica nanoparticles with a narrow particle size distribution and devoid of cocontaminants critical for toxicity studies. Complete physicochemical characterization of these synthetic mesoporous silica nanoparticles will permit systematic toxicology studies for investigation of structure-activity relationships. [ABSTRACT FROM AUTHOR]

Abstract: Our earlier investigations on the chemical composition of biooils derived by the fast pyrolysis of chicken manure revealed the presence of more than 500 compounds. In order to simplify this heterogeneous and complex chemical system, we produced four biooil fractions namely strongly acidic fraction A, weakly acidic fraction B, basic fraction C and neutral fraction D on the basis of their solubilities in aqueous solutions at different pHs. The yield (wt/wt.%) for fraction A was 3%, for fraction B 21.3%, for fraction C 2.4% and for fraction D 32.4%, respectively. The four fractions were analyzed by elemental analyses, Fourier Transform infrared spectrophotometry (FTIR), 1H and 13C nuclear magnetic spectroscopy (NMR), and electrospray ionization mass spectrometry (ESI-MS). The major components of the four fractions were saturated and unsaturated fatty acids, N-heterocyclics, phenols, sterols, diols and alkylbenzenes. The pH separation system produced fractions of enhanced chemical homogeneity. [Copyright &y& Elsevier]

Abstract: MCM-41 silica whose pores have been expanded by post-synthesis hydrothermal treatment in the presence of N,N-dimethyldecylamine exhibits a unique combination of large pores (up to 20nm), pore volume (up to 3.5cc/g) and surface area (>1000m2/g). It was used to accommodate a large amount of amine groups (2.2mmol/g); thus generating a highly active base catalyst for Knoevenagel condensation. [Copyright &y& Elsevier]

Abstract: MCM-41 silica, whose pores have been expanded by post-synthesis treatment with -dimethyldecylamine, was used as an inexpensive high-surface area, large-pore support for rapid preparation of monodispersed palladium nanoparticles. The nanoparticles, initially prepared at room temperature, showed remarkable thermal stability as their size increased from to only after calcination at 500 °C in air followed by reduction in H2 at the same temperature. These materials were found to be highly active and stable catalysts for the Suzuki coupling reaction with virtually no leaching. [Copyright &y& Elsevier]

Vaping is gaining in popularity. However, there is still much that remains unknown about the potential risk and harms of vaping. Formation of oxidative products is one of such areas that are not well understood. In this study, we used an in-situ thermal desorption GC/MS method to investigate the formation of oxidative products of several monoterpenes at or below typical vaping temperatures. Among the five tested monoterpenes, the unchanged portion of the parent compound in the vapour varied from 97 to 98% for myrcene to 11–28% for terpinolene. The majority of formed oxidative products in the vapour have a molecular weight of 134 (loss of two hydrogens), 150 (insertion of one oxygen and loss of two hydrogen atoms) or 152 (insertion of one oxygen atom). Three products, likely to be p-(1-propenyl)-toluene, β-pinone and fenchol were also observed. This is the first in-situ thermal desorption GC/MS study to investigate the possible formation of oxidative products of monoterpenes, one of the major components in vaping liquids, at temperatures that are relevant to the vaping process. Although the toxicity of inhaling these oxidative products is not clear yet, allergic and irritation reactions associated with oxidized monoterpene oils are well documented. Therefore, potential adverse effects of inhaling these oxidative products during vaping could be investigated to help support human risk assessment. [ABSTRACT FROM AUTHOR]

While production of engineered carbon nanotubes (CNTs) has escalated in recent years, knowledge of risk associated with exposure to these materials remains unclear. We report on the cytotoxicity of four CNT variants in human lung epithelial cells (A549) and murine macrophages (J774). Morphology, metal content, aggregation/agglomeration state, pore volume, surface area and modifications were determined for the pristine and oxidized single-walled (SW) and multi-walled (MW) CNTs. Cytotoxicity was evaluated by cellular ATP content, BrdU incorporation, lactate dehydrogenase (LDH) release, and CellTiter-Blue (CTB) reduction assays. All CNTs were more cytotoxic than respirable TiO2 and SiO2 reference particles. Oxidation of CNTs removed most metallic impurities but introduced surface polar functionalities. Although slopes of fold changes for cytotoxicity endpoints were steeper with J774 compared to A549 cells, CNT cytotoxicity ranking in both cell types was assay-dependent. Based on CTB reduction and BrdU incorporation, the cytotoxicity of the polar oxidized CNTs was higher compared to the pristine CNTs. In contrast, pristine CNTs were more cytotoxic than oxidized CNTs when assessed for cellular ATP and LDH. Correlation analyses between CNTs' physico-chemical properties and average relative potency revealed the impact of metal content and surface area on the potency values estimated using ATP and LDH assays, while surface polarity affected the potency values estimated from CTB and BrdU assays. We show that in order to reliably estimate the risk posed by these materials, in vitro toxicity assessment of CNTs should be conducted with well characterized materials, in multiple cellular models using several cytotoxicity assays that report on distinct cellular processes. [ABSTRACT FROM AUTHOR]

Controlled laboratory and field experiments were performed to collect volatile organic compounds (VOCs) emitted during drying of alfalfa. Laboratory experiments were conducted using a flow reactor method. Three drying temperatures of 60, 150 and 250°C with three drying times (5, 20 and 45min) were used to collect the VOCs. Field experiments were performed to validate the results obtained in the flow reactor method using a small-scale rotary drum dryer (operated at temperatures of 202, 345 and 480°C) and an industrial dehydration plant operated at temperatures of 800 to 1000°C. The exhaust gases collected during the drying process were subjected to a gas chromatography and mass spectrometry (GC–MS) analysis and the presence of a total of 48 VOCs was detected. The most common groups detected during alfalfa drying were alcohols, aldehydes, ketone, ester and unsaturated and saturated hydrocarbons. Drying temperature has a predominant effect on the number of VOCs emissions. The number of VOCs emitted increased with an increase in drying temperature. Drying time had an insignificant effect on the number of VOCs emitted, however, the intensity or concentration of compounds increased with an increase in drying time. The studies of different parts of the alfalfa plant revealed that a large group of the compounds present in one part (either leaf or stem) were absent in the other, although some compounds were present in all cases. Volatile organic compounds such as 1-octen-3-ol, (E)-3-hexen-1-ol and (E)-2-hexanal, were the most common compounds present in all parts of alfalfa plant. Sulphur compounds were present only in stems and may cause a potential problem for human health. The VOCs obtained from flowers are rich in alcohols and aldehydes. [Copyright &y& Elsevier]

Artificial athletic turf containing crumb rubber (CR) from shredded tires is a growing environmental and public health concern. However, the associated health risk is unknown due to the lack of toxicity data for higher vertebrates. We evaluated the toxic effects of CR in a developing amniote vertebrate embryo. CR water leachate was administered to fertilized chicken eggs via different exposure routes, i.e., coating by dropping CR leachate on the eggshell; dipping the eggs into CR leachate; microinjecting CR leachate into the air cell or yolk. After 3 or 7 d of incubation, embryonic morphology, organ development, physiology, and molecular pathways were measured. The results showed that CR leachate injected into the yolk caused mild to severe developmental malformations, reduced growth, and specifically impaired the development of the brain and cardiovascular system, which were associated with gene dysregulation in aryl hydrocarbon receptor, stress-response, and thyroid hormone pathways. The observed systematic effects were probably due to a complex mixture of toxic chemicals leaching from CR, such as metals (e.g., Zn, Cr, Pb) and amines (e.g., benzothiazole). This study points to a need to closely examine the potential regulation of the use of CR on playgrounds and artificial fields. [ABSTRACT FROM AUTHOR]

Background: There is paucity of information on mechanisms constituting adverse birth outcomes. We assessed here the relationship between vascular integrity and adverse birth effects. Methods and results: Third trimester maternal plasma (n = 144) from the Maternal-Infant Research on Environmental Chemicals Study (MIREC) was analysed for vascular, inflammatory and oxidative stress markers by HPLC-fluorescence, protein array and EIA method. Analysis of the <25th and >75th percentile birth weight subgroups revealed markers associated with birth weight (ETs, MMP-9, VEGF, and 8-isoPGF-2α) and gestational age (ET-1, MMP-2, and VEGF). Conclusions: Mechanistic insights into adverse birth outcome pathways can be achieved by integrating information on multiple biomarkers, physiology using systems biology approach. [ABSTRACT FROM PUBLISHER]

Cooked, milled purple-fleshed sweet potato (PFSP) accessions, PM09.812 and PM09.960, underwent digestion in a dynamic human gastrointestinal (GI) model that simulates gut digestive conditions to study the bioaccessibility and biotransformation of anthocyanins. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry showed accession-dependent variations in anthocyanin release and degradation. After 24 h, more anthocyanin species were detected in the small intestinal vessel relative to other vessels for accession PM09.960 whereas more species appeared in the ascending colonic vessel for accession PM09.812. The ferric reducing antioxidant power was increased in the small intestinal vessel for PM09.960 and in the ascending colonic vessel for accession PM09.812, corresponding to the appearance of a majority of anthocyanins for each accession. These results show that intestinal and colonic microbial digestion of PFSP leads to an accession-dependent pattern for anthocyanin bioaccessibility and degradation. [ABSTRACT FROM AUTHOR]

The toxicity of carbon nanotubes (CNTs) has received significant attention due to their usage in a wide range of commercial applications. While numerous studies exist on their impacts in water and soil ecosystems, there is a lack of information on the exposure to CNTs from the atmosphere. The transformation of CNTs in the atmosphere, resulting in their functionalization, may significantly alter their toxicity. In the current study, the chemical modification of single wall carbon nanotubes (SWCNTs) via ozone and OH radical oxidation is investigated through studies that simulate a range of expected tropospheric particulate matter (PM) lifetimes, in order to link their chemical evolution to toxicological changes. The results indicate that the oxidation favors carboxylic acid functionalization, but significantly less than other studies performed under nonatmospheric conditions. Despite evidence of functionalization, neither O3 nor OH radical oxidation resulted in a change in redox activity (potentially giving rise to oxidative stress) or in cytotoxic end points. Conversely, both the redox activity and cytotoxicity of SWCNTs significantly decreased when exposed to ambient urban air, likely due to the adsorption of organic carbon vapors. These results suggest that the effect of gas-particle partitioning of organics in the atmosphere on the toxicity of SWCNTs should be investigated further. [ABSTRACT FROM AUTHOR]