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Ultrafine particles (UFP) are the smallest atmospheric particulate matter linked to air pollution-related diseases. The extent to which UFP's physical and chemical properties contribute to its toxicity remains unclear. It is hypothesized that UFP act as carriers for chemicals that drive biological responses. This study explores robust methods for generating reference UFP to understand these mechanisms and perform toxicological tests. Two types of combustion-related UFP with similar elemental carbon cores and physical properties but different organic loads were generated and characterized. Human alveolar epithelial cells were exposed to these UFP at the air-liquid interface, and several toxicological endpoints were measured. UFP were generated using a miniCAST under fuel-rich conditions and immediately diluted to minimize agglomeration. A catalytic stripper and charcoal denuder removed volatile gases and semi-volatile particles from the surface. By adjusting the temperature of the catalytic stripper, UFP with high and low organic content was produced. These reference particles exhibited fractal structures with high reproducibility and stability over a year, maintaining similar mass and number concentrations (100⯵g/m3, 2.0·105 #/cm3) and a mean particle diameter of about 40â¯nm. High organic content UFP had significant PAH levels, with benzo[a]pyrene at 0.2â¯% (m/m). Toxicological evaluations revealed that both UFP types similarly affected cytotoxicity and cell viability, regardless of organic load. Higher xenobiotic metabolism was noted for PAH-rich UFP, while reactive oxidation markers increased when semi-volatiles were stripped off. Both UFP types caused DNA strand breaks, but only the high organic content UFP induced DNA oxidation. This methodology allows modification of UFP's chemical properties while maintaining comparable physical properties, linking these variations to biological responses.
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This study presents an oxalic acid-assisted method for synthesizing spinel-structured lithium titanate (Li4Ti5O12; LTO)/carbon composite materials. The Ag-doped LTO nanoparticles (NPs) are synthesized via flame spray pyrolysis (FSP). The synthesized material is used as a precursor for synthesizing the LTO-NP/C composite material with chitosan as a carbon source and oxalic acid as an additive. Oxalic acid improves the dissolution of chitosan in water as well as changes the composition and physical and chemical properties of the synthesized LTO-NP/C composite material. The oxalic acid/chitosan ratio can be optimized to improve the electrochemical performance of the LTO-NP/C composite material, and the electrode synthesized with a high mass loading ratio (5.44 mg cm-2) exhibits specific discharge capacities of 156.5 and 136 mAh g-1at 0.05 C- and 10 C-rate currents, respectively. Moreover, the synthesized composite LTO-NP/C composite material exhibits good cycling stability, and only 1.7% decrease in its specific capacity was observed after 200 charging-discharging cycles at 10 C-rate discharging current.
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Effective density (ρeff) is an important property describing particle transportation in the atmosphere and in the human respiratory tract. In this study, the particle size dependency of ρeff was determined for fresh and photochemically aged particles from residential combustion of wood logs and brown coal, as well as from an aerosol standard (CAST) burner. ρeff increased considerably due to photochemical aging, especially for soot agglomerates larger than 100 nm in mobility diameter. The increase depends on the presence of condensable vapors and agglomerate size and can be explained by collapsing of chain-like agglomerates and filling of their voids and formation of secondary coating. The measured and modeled particle optical properties suggest that while light absorption, scattering, and the single-scattering albedo of soot particle increase during photochemical processing, their radiative forcing remains positive until the amount of nonabsorbing coating exceeds approximately 90% of the particle mass.
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Atmósfera , Hollín , Humanos , Anciano , Hollín/análisis , Hollín/química , Tamaño de la Partícula , Carbón Mineral , Aerosoles/análisisRESUMEN
In this study, spray pyrolysis; an aerosol processing technique was utilized to produce a mixed-phase copper on carbon (Cu/CuxO@C) catalyst. The catalyst production was performed via chemical reduction of copper nitrate by a reducing sugar, i.e. glucose, using aqueous solution. The physical and chemical properties of the produced particles was assessed using various characterization techniques. The synthesis temperature had pronounced effect on the final particles. Since CO2adsorption onto the catalyst is an important step in catalytic CO2reduction processes, it was studied using thermogravimetric and temperature programmed desorption techniques. Additionally, photocatalytic activity of the particles was evaluated by gas-phase oxidation of acetylene gas which revealed excellent activity under both UV and visible light irradiation indicating the possible use of wider range of the solar spectrum.
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The health effects of exposure to secondary organic aerosols (SOAs) are still limited. Here, we investigated and compared the toxicities of soot particles (SP) coated with ß-pinene SOA (SOAßPin-SP) and SP coated with naphthalene SOA (SOANap-SP) in a human bronchial epithelial cell line (BEAS-2B) residing at the air-liquid interface. SOAßPin-SP mostly contained oxygenated aliphatic compounds from ß-pinene photooxidation, whereas SOANap-SP contained a significant fraction of oxygenated aromatic products under similar conditions. Following exposure, genome-wide transcriptome responses showed an Nrf2 oxidative stress response, particularly for SOANap-SP. Other signaling pathways, such as redox signaling, inflammatory signaling, and the involvement of matrix metalloproteinase, were identified to have a stronger impact following exposure to SOANap-SP. SOANap-SP also induced a stronger genotoxicity response than that of SOAßPin-SP. This study elucidated the mechanisms that govern SOA toxicity and showed that, compared to SOAs derived from a typical biogenic precursor, SOAs from a typical anthropogenic precursor have higher toxicological potency, which was accompanied with the activation of varied cellular mechanisms, such as aryl hydrocarbon receptor. This can be attributed to the difference in chemical composition; specifically, the aromatic compounds in the naphthalene-derived SOA had higher cytotoxic potential than that of the ß-pinene-derived SOA.
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BACKGROUND: Secondary organic aerosols (SOAs) formed from anthropogenic or biogenic gaseous precursors in the atmosphere substantially contribute to the ambient fine particulate matter [PM ≤2.5µm in aerodynamic diameter (PM2.5)] burden, which has been associated with adverse human health effects. However, there is only limited evidence on their differential toxicological impact. OBJECTIVES: We aimed to discriminate toxicological effects of aerosols generated by atmospheric aging on combustion soot particles (SPs) of gaseous biogenic (ß-pinene) or anthropogenic (naphthalene) precursors in two different lung cell models exposed at the air-liquid interface (ALI). METHODS: Mono- or cocultures of lung epithelial cells (A549) and endothelial cells (EA.hy926) were exposed at the ALI for 4 h to different aerosol concentrations of a photochemically aged mixture of primary combustion SP and ß-pinene (SOAßPIN-SP) or naphthalene (SOANAP-SP). The internally mixed soot/SOA particles were comprehensively characterized in terms of their physical and chemical properties. We conducted toxicity tests to determine cytotoxicity, intracellular oxidative stress, primary and secondary genotoxicity, as well as inflammatory and angiogenic effects. RESULTS: We observed considerable toxicity-related outcomes in cells treated with either SOA type. Greater adverse effects were measured for SOANAP-SP compared with SOAßPIN-SP in both cell models, whereas the nano-sized soot cores alone showed only minor effects. At the functional level, we found that SOANAP-SP augmented the secretion of malondialdehyde and interleukin-8 and may have induced the activation of endothelial cells in the coculture system. This activation was confirmed by comet assay, suggesting secondary genotoxicity and greater angiogenic potential. Chemical characterization of PM revealed distinct qualitative differences in the composition of the two secondary aerosol types. DISCUSSION: In this study using A549 and EA.hy926 cells exposed at ALI, SOA compounds had greater toxicity than primary SPs. Photochemical aging of naphthalene was associated with the formation of more oxidized, more aromatic SOAs with a higher oxidative potential and toxicity compared with ß-pinene. Thus, we conclude that the influence of atmospheric chemistry on the chemical PM composition plays a crucial role for the adverse health outcome of emissions. https://doi.org/10.1289/EHP9413.
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Contaminantes Atmosféricos , Hollín , Aerosoles/análisis , Anciano , Envejecimiento , Contaminantes Atmosféricos/análisis , Contaminantes Atmosféricos/toxicidad , Células Endoteliales/química , Células Endoteliales/metabolismo , Humanos , Pulmón/metabolismo , Material Particulado/análisisRESUMEN
Silicon, a material with high theoretical energy density, holds great promise as a candidate material for anodes in lithium-ion batteries. However, due to an alloying mechanism the material undergoes volume expansion of up to 300%, which results in rapid capacity fading. The coating of silicon with carbon is done by using a biomass-based carbon precursor. The effects of annealing temperature on the morphology of the silicon-carbon structures is presented herein. The mechanically and chemically treated barley straw is mixed with silicon particles and induction annealed in argon atmosphere under different temperatures. The material transformation from carbon-coated silicon (Si@C) to graphite-coated silicon carbide (SiC@graphite) is studied. The Si@C displayed initial specific capacity of 1200 mAh g-1 at 0.1 A g-1, while the capacity retention analysis of Si@C revealed improved cycling stability compared to bare silicon.
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Herein, we present an aerosol filtration method for the fabrication of carbon nanoflower (CNF) thin films. The method was based on generation, evaporation and filtration of solvent encapsulated CNF droplets. The particles were collected on polytetrafluoroethylene membranes and roll-transferred at room temperature onto flexible polyethylene terephthalate substrates. Suspensions for spraying were made in low vapor pressure mixtures of EtOH/Hex (50/50 v/v%). Doping of starter suspensions was made by the addition of organometallic 1-dodecanethiol-coated gold nanoparticles (AuNPs). The produced films displayed substrate surface coverage of up to 83.3% ± 13.9% and a film thickness of up to 2.4 µm. The deposition of doped suspensions resulted in uniform distribution of AuNPs in the volume of the CNF film, which enables film application for flexible photovoltaics.
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Nano-sized metal oxides are currently the most manufactured nanomaterials (NMs), and are increasingly used in consumer products. Recent exposure data reveal a genuine potential for adverse health outcomes for a vast array of NMs, however the underlying mechanisms are not fully understood. To elucidate size-related molecular effects, differentiated THP-1 cells were exposed to nano-sized materials (n-TiO2, n-ZnO and n-Ag), or their bulk-sized (b-ZnO and b-TiO2) or ionic (i-Ag) counterparts, and genome-wide gene expression changes were studied at low-toxic concentrations (<15% cytotoxicity). TiO2 materials were nontoxic in MTT assay, inducing only minor transcriptional changes. ZnO and Ag elicited dose-dependent cytotoxicity, wherein ionic and particulate effects were synergistic with respect to n-ZnO-induced cytotoxicity. In gene expression analyzes, 6 h and 24 h samples formed two separate hierarchical clusters. N-ZnO and n-Ag shared only 3.1% and 24.6% differentially expressed genes (DEGs) when compared to corresponding control. All particles, except TiO2, activated various metallothioneins. At 6 h, n-Zn, b-Zn and n-Ag induced various immunity related genes associating to pattern recognition (including toll-like receptor), macrophage maturation, inflammatory response (TNF and IL-1beta), chemotaxis (CXCL8) and leucocyte migration (CXCL2-3 and CXCL14). After 24 h exposure, especially n-Ag induced the expression of genes related to virus recognition and type I interferon responses. These results strongly suggest that in addition to ionic effects mediated by metallothioneins, n-Zn and n-Ag induce expression of genes involved in several innate and adaptive immunity associated pathways, which are known to play crucial role in immuno-regulation. This raises the concern of safe use of metal oxide and metal nanoparticle products, and their biological effects.