A novel TEM grid sampler for airborne particles to measure the cell culture surface dose

Mülhopt, S.; Schlager, Christoph; Berger, Markus; Murugadoss, Sivakumar; Hoet, Peter; Krebs, Tobias; Paur, Hanns‐Rudolf; Stapf, Dieter

doi:10.1038/s41598-020-65427-w

Cited by 7 publications

(9 citation statements)

References 22 publications

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“…For both types of agglomerates, the relative increase in deposition becomes less with the increase of the electrostatic field strength. This saturation behavior has been also shown earlier [40] and occurs when all charged agglomerates are deposited. In the TEM images of 17 nm-SA and 117 nm-LA individual particles could not be unambiguously identified due to a strong background signal, (Supplementary Material Figure S3), the doses listed in the summary table were calculated on the basis of the QCM data (measured at 0 V) multiplied by the enhancement factors derived at the different voltages for the corresponding particle types 17 nm-LA and 117 nm-SA.…”

Section: Aerosol Characterization and Determination Of Deposited Dosesupporting

confidence: 81%

“…The deposited cell culture surface dose is reflected by the deposited fraction of the TiO 2 agglomerates exposed as aerosol towards the cells and not easy to determine. For this reason, three different methods were applied: the online monitoring of mass dose using the quartz crystal microbalance QCM (Vitrocell Systems GmbH, Waldkirch, Germany) [29], the image analysis of exposed TEM grids as presented in [40] and the calculation from the SMPS measured number size distribution as shown in [30]. The effective density of all TiO 2 agglomerates were used as determined and reported in [35], and did not differ much between the dispersions ((17nm-SA: 1.55 g/cm 3 ), (17nm-LA: 1.48 g/cm 3 ), (117nm-SA: 1.78 g/cm 3 ), and (17nm-LA: 1.78 g/cm 3 )).…”

Section: Determination Of the Deposited Dosementioning

confidence: 99%

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Agglomeration State of Titanium-Dioxide (TiO2) Nanomaterials Influences the Dose Deposition and Cytotoxic Responses in Human Bronchial Epithelial Cells at the Air-Liquid Interface

et al. 2021

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Extensive production and use of nanomaterials (NMs), such as titanium dioxide (TiO2), raises concern regarding their potential adverse effects to humans. While considerable efforts have been made to assess the safety of TiO2 NMs using in vitro and in vivo studies, results obtained to date are unreliable, possibly due to the dynamic agglomeration behavior of TiO2 NMs. Moreover, agglomerates are of prime importance in occupational exposure scenarios, but their toxicological relevance remains poorly understood. Therefore, the aim of this study was to investigate the potential pulmonary effects induced by TiO2 agglomerates of different sizes at the air–liquid interface (ALI), which is more realistic in terms of inhalation exposure, and compare it to results previously obtained under submerged conditions. A nano-TiO2 (17 nm) and a non-nano TiO2 (117 nm) was selected for this study. Stable stock dispersions of small agglomerates and their respective larger counterparts of each TiO2 particles were prepared, and human bronchial epithelial (HBE) cells were exposed to different doses of aerosolized TiO2 agglomerates at the ALI. At the end of 4h exposure, cytotoxicity, glutathione depletion, and DNA damage were evaluated. Our results indicate that dose deposition and the toxic potential in HBE cells are influenced by agglomeration and exposure via the ALI induces different cellular responses than in submerged systems. We conclude that the agglomeration state is crucial in the assessment of pulmonary effects of NMs.

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Section: Aerosol Characterization and Determination Of Deposited Dosesupporting

confidence: 81%

Section: Determination Of the Deposited Dosementioning

confidence: 99%

Agglomeration State of Titanium-Dioxide (TiO2) Nanomaterials Influences the Dose Deposition and Cytotoxic Responses in Human Bronchial Epithelial Cells at the Air-Liquid Interface

et al. 2021

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“…This deposition efficiency was determined experimentally [ 39 ], but for another aerosol, and therefore the result cannot necessarily be transferred to all investigated aerosols. The increase in deposition rate due to the application of an electric field was also determined experimentally [ 19 , 40 ]. However, the aerosol used for this purpose contained significantly larger particles than those used in this study.…”

Section: Discussionmentioning

confidence: 99%

“…The particle mass per area deposited via diffusional as well as via electrostatic mechanism for dose enhancement can be monitored online using a quartz crystal microbalance [ 20 , 21 ]. Additionally, a new tool to reproducibly expose sample grids for transmission electron microscopy (TEM) to obtain dose information with respect to the spatial distribution and the agglomeration state of the deposited particles was developed and applied within this study [ 22 ]. The ALI exposure station has already been used to investigate the toxicological impact of environmental atmospheres and technical emission sources like ship diesel exhaust [ 23 , 24 ], biomass combustion emissions [ 25 ], and suspended nanomaterials as metal oxides and silica [ 15 , 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Impact of Nanocomposite Combustion Aerosols on A549 Cells and a 3D Airway Model

et al. 2021

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The use of nanomaterials incorporated into plastic products is increasing steadily. By using nano-scaled filling materials, thermoplastics, such as polyethylene (PE), take advantage of the unique properties of nanomaterials (NM). The life cycle of these so-called nanocomposites (NC) usually ends with energetic recovery. However, the toxicity of these aerosols, which may consist of released NM as well as combustion-generated volatile compounds, is not fully understood. Within this study, model nanocomposites consisting of a PE matrix and nano-scaled filling material (TiO2, CuO, carbon nano tubes (CNT)) were produced and subsequently incinerated using a lab-scale model burner. The combustion-generated aerosols were characterized with regard to particle release as well as compound composition. Subsequently, A549 cells and a reconstituted 3D lung cell culture model (MucilAir™, Epithelix) were exposed for 4 h to the respective aerosols. This approach enabled the parallel application of a complete aerosol, an aerosol under conditions of enhanced particle deposition using high voltage, and a filtered aerosol resulting in the sole gaseous phase. After 20 h post-incubation, cytotoxicity, inflammatory response (IL-8), transcriptional toxicity profiling, and genotoxicity were determined. Only the exposure toward combustion aerosols originated from PE-based materials induced cytotoxicity, genotoxicity, and transcriptional alterations in both cell models. In contrast, an inflammatory response in A549 cells was more evident after exposure toward aerosols of nano-scaled filler combustion, whereas the thermal decomposition of PE-based materials revealed an impaired IL-8 secretion. MucilAir™ tissue showed a pronounced inflammatory response after exposure to either combustion aerosols, except for nanocomposite combustion. In conclusion, this study supports the present knowledge on the release of nanomaterials after incineration of nano-enabled thermoplastics. Since in the case of PE-based combustion aerosols no major differences were evident between exposure to the complete aerosol and to the gaseous phase, adverse cellular effects could be deduced to the volatile organic compounds that are generated during incomplete combustion of NC.

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“…The deposited particle dose was additionally calculated from image analysis of particles deposited on grids for transmission electron microscopy (TEM) placed on the Transwell membranes [ 46 ]. The copper grids with formvar film (Plano GmbH, Wetzlar, Germany) were exposed in parallel to the cell cultures, but without liquid beneath the membrane.…”

Section: Methodsmentioning

confidence: 99%

Air–Liquid Interface Exposure of Lung Epithelial Cells to Low Doses of Nanoparticles to Assess Pulmonary Adverse Effects

et al. 2020

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Reliable and predictive in vitro assays for hazard assessments of manufactured nanomaterials (MNMs) are still limited. Specifically, exposure systems which more realistically recapitulate the physiological conditions in the lung are needed to predict pulmonary toxicity. To this end, air-liquid interface (ALI) systems have been developed in recent years which might be better suited than conventional submerged exposure assays. However, there is still a need for rigorous side-by-side comparisons of the results obtained with the two different exposure methods considering numerous parameters, such as different MNMs, cell culture models and read outs. In this study, human A549 lung epithelial cells and differentiated THP-1 macrophages were exposed under submerged conditions to two abundant types of MNMs i.e., ceria and titania nanoparticles (NPs). Membrane integrity, metabolic activity as well as pro-inflammatory responses were recorded. For comparison, A549 monocultures were also exposed at the ALI to the same MNMs. In the case of titania NPs, genotoxicity was also investigated. In general, cells were more sensitive at the ALI compared to under classical submerged conditions. Whereas ceria NPs triggered only moderate effects, titania NPs clearly initiated cytotoxicity, pro-inflammatory gene expression and genotoxicity. Interestingly, low doses of NPs deposited at the ALI were sufficient to drive adverse outcomes, as also documented in rodent experiments. Therefore, further development of ALI systems seems promising to refine, reduce or even replace acute pulmonary toxicity studies in animals.

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A novel TEM grid sampler for airborne particles to measure the cell culture surface dose

Cited by 7 publications

References 22 publications

Agglomeration State of Titanium-Dioxide (TiO2) Nanomaterials Influences the Dose Deposition and Cytotoxic Responses in Human Bronchial Epithelial Cells at the Air-Liquid Interface

Agglomeration State of Titanium-Dioxide (TiO2) Nanomaterials Influences the Dose Deposition and Cytotoxic Responses in Human Bronchial Epithelial Cells at the Air-Liquid Interface

Impact of Nanocomposite Combustion Aerosols on A549 Cells and a 3D Airway Model

Air–Liquid Interface Exposure of Lung Epithelial Cells to Low Doses of Nanoparticles to Assess Pulmonary Adverse Effects

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