The study was supported by the grant number R706-000-043-490. The study does not represent the view of the grant sponsor.

1. Fluorescence Activated Cell Sorting (FACS) Analysis on Lived/Fixed cells
<ol>
	<li>Sonicate ZnO NPs in suspension for 15 min.</li>
	<li>Prepare ZnO NPs at various concentrations (e.g., 0, 10, 25, 50,100 and 200 &#181;g/mL) using 1 mg/mL ZnO NP stock solution for the treatment of cultured cells.</li>
	<li>Seed MRC5 human lung fibroblasts (1 x 105 cells/well) onto a 6-well culture plate a day in advance, and then treat the cells with 2 mL of ZnO NPs (in triplicates) for 8 h, 16 h, and 24 h.</li>
	<li>At eac...

<ol>
	<li>Kim, Y. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxicity+of+100+nm+zinc+oxide+nanoparticles:+a+report+of+90-day+repeated+oral+administration+in+Sprague+Dawley+rats.">Toxicity of 100 nm zinc oxide nanoparticles: a report of 90-day repeated oral administration in Sprague Dawley rats.</a> International Journal of Nanomedicine. 9 Suppl 2, 109-126 (2014).</li><li>Xie, Y., He, Y., Irwin, P. L., Jin, T., Shi, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibacterial+activity+and+mechanism+of+action+of+zinc+oxide+nanoparticles+against+Campylobacter+jejuni.">Antibacterial activity and mechanism of action of zinc oxide nanoparticles against Campylobacter jejuni.</a> Applied and Environmental Microbiology. 77, 2325-2331 (2011).</li><li>Colvin, V. 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M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+exposure+to+ZnO+nanoparticles+induces+autophagic+immune+cell+death.">Acute exposure to ZnO nanoparticles induces autophagic immune cell death.</a> Nanotoxicology. 9, 737-748 (2015).</li><li>Singh, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NanoGenotoxicology:+the+DNA+damaging+potential+of+engineered+nanomaterials.">NanoGenotoxicology: the DNA damaging potential of engineered nanomaterials.</a> Biomaterials. 30, 3891-3914 (2009).</li><li>Song, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+the+dissolved+zinc+ion+and+reactive+oxygen+species+in+cytotoxicity+of+ZnO+nanoparticles.">Role of the dissolved zinc ion and reactive oxygen species in cytotoxicity of ZnO nanoparticles.</a> Toxicology Letters. 199, 389-397 (2010).</li><li>Wahab, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ZnO+nanoparticles+induced+oxidative+stress+and+apoptosis+in+HepG2+and+MCF-7+cancer+cells+and+their+antibacterial+activity.">ZnO nanoparticles induced oxidative stress and apoptosis in HepG2 and MCF-7 cancer cells and their antibacterial activity.</a> Colloids and Surfaces B: Biointerfaces. 117, 267-276 (2014).</li><li>Namvar, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytotoxic+effects+of+biosynthesized+zinc+oxide+nanoparticles+on+murine+cell+lines.">Cytotoxic effects of biosynthesized zinc oxide nanoparticles on murine cell lines.</a> Evidence-Based Complementary and Alternative. 2015, (2015).</li><li>Wong, S. W., Leung, P. T., Djurisic, A. B., Leung, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxicities+of+nano+zinc+oxide+to+five+marine+organisms:+influences+of+aggregate+size+and+ion+solubility.">Toxicities of nano zinc oxide to five marine organisms: influences of aggregate size and ion solubility.</a> Analytical and Bioanalytical Chemistry. 396, 609-618 (2010).</li><li>Hua, J., Vijver, M. G., Richardson, M. K., Ahmad, F., Peijnenburg, W. 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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophotoxicology:+the+growing+potential+for+Drosophila+in+neurotoxicology.">Drosophotoxicology: the growing potential for Drosophila in neurotoxicology.</a> Neurotoxicology and Teratology. 32, 74-83 (2010).</li><li>Ong, C., Yung, L. Y., Cai, Y., Bay, B. H., Baeg, G. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophila+melanogaster+as+a+model+organism+to+study+nanotoxicity.">Drosophila melanogaster as a model organism to study nanotoxicity.</a> Nanotoxicology. 9, 396-403 (2015).</li><li>Hoffmann, J. A., Reichhart, J. 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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+sequence+to+phenotype:+reverse+genetics+in+Drosophila+melanogaster.">From sequence to phenotype: reverse genetics in Drosophila melanogaster.</a> Nature Reviews Genetics. 3, 189-198 (2002).</li><li>Adams, M. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+genome+sequence+of+Drosophila+melanogaster.">The genome sequence of Drosophila melanogaster.</a> Science. 287, 2185-2195 (2000).</li><li>Ong, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silver+nanoparticles+disrupt+germline+stem+cell+maintenance+in+the+Drosophila+testis.">Silver nanoparticles disrupt germline stem cell maintenance in the Drosophila testis.</a> Scientific Reports. 6, (2016).</li><li>Alaraby, M., Demir, E., Hernandez, A., Marcos, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessing+potential+harmful+effects+of+CdSe+quantum+dots+by+using+Drosophila+melanogaster+as+in+vivo+model.">Assessing potential harmful effects of CdSe quantum dots by using Drosophila melanogaster as in vivo model.</a> Science of the Total Environment. 530-531, 66-75 (2015).</li><li>Barik, B. K., Mishra, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticles+as+a+potential+teratogen:+a+lesson+learnt+from+fruit+fly.">Nanoparticles as a potential teratogen: a lesson learnt from fruit fly.</a> Nanotoxicology. , 1-27 (2018).</li><li>Jovanovic, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effects+of+a+human+food+additive,+titanium+dioxide+nanoparticles+E171,+on+Drosophila+melanogaster+-+a+20+generation+dietary+exposure+experiment.">The effects of a human food additive, titanium dioxide nanoparticles E171, on Drosophila melanogaster - a 20 generation dietary exposure experiment.</a> Scientific Reports. 8, (2018).</li><li>Cao, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Toxicity+of+Nanoparticles+to+Human+Endothelial+Cells.">The Toxicity of Nanoparticles to Human Endothelial Cells.</a> Advances in Experimental Medicine and Biology. 1048, 59-69 (2018).</li><li>Akhtar, M. 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The authors declare that they have no competing financial interests.

In order to assess if ZnO NP can induce apoptosis in MRC5 fibroblasts, we use flow cytometry to distinguish the cells from necrotic or apoptotic cell death. In normal live cells, phosphatidylserine (PS) is localized at the cell membrane. If apoptosis occurs, PS is translocated to the extracellular leaflet of the plasma membrane, allowing the binding of Annexin V labeled with fluorescein (FITC Annexin V)29. On the other hand, the red-fluorescent propidium iodide (PI), a nucleic acid binding dye, is...

Nanotechnology refers to the application of nanosized materials that are used across all scientific fields, including medicine, materials science, and biochemistry. For instance, ZnO NPs which are known for their ultraviolet scattering, chemical sensing, and anti-microbial properties, as well as high electrical conductivity, are utilized in the production of various consumer products such as food packaging, cosmetics, textiles, rubbers, batteries, catalyst for automobile tail gas treatment, and biomedical-related applications1,2,3.
However, the burgeoning applications of ZnO NP-based products, leading to increased human exposure to ZnO NPs, have raised concerns on their potential adverse effects on human health. A number of in vitro cellular studies have demonstrated that ZnO NPs can induce oxidative stress, autophagy-related cytotoxicity, inflammation, and genotoxicity4,5,6,7,8. Notably, the toxicity of ZnO NPs is assumed to be caused by the dissolution of Zn to free Zn2+ ions, as well as the surface reactivity of ZnO, resulting in the cellular ionic and metabolic imbalances that are linked with impaired ionic homeostasis and an inhibition of ion transportation4,7,9,10. Importantly, studies have shown that the generation of reactive oxygen species (ROS) is one of the primary mechanisms underlying ZnO NPs-associated toxicity. Insufficient anti-oxidative activity following ROS insult has been shown to be responsible for eliciting the cytotoxicity and DNA damage9. The toxic effects of ZnO NPs have also been reported in animal models, including rodent1, zebrafish11,12, as well as the invertebrate Drosophila13.
Drosophila serves as a well-established alternative animal model for toxicity screening of chemical entities and nanomaterials (NMs)14,15. Importantly, there are high levels of genetic and physiological similarity between human and Drosophila that justifies the use of Drosophila as an in vivo model for evaluating biological responses to environmental contaminants such as NMs16. Furthermore, there are many advantages of using Drosophila due to its small size, short lifespan, genetic amenability, and easy and cost-effective maintenance. Moreover, Drosophila has been widely adopted for the study of genetics, molecular and developmental biology, ever since its full genome was fully sequenced years ago back in 2000, therefore making it suitable for a variety of high-throughput screening and for tackling unresolved biological questions17,18,19,20,21. In recent years, a number of studies related to immunotoxicity using different types of NPs in Drosophila have been reported15,22,23,24. This fundamental new knowledge obtained from the studies using Drosophila has helped to provide more insights into our understanding of nanotoxicology.
ROS is a well-known culprit for cytotoxicity and genotoxicity caused by NPs, in particular, metal-based NPs25. ROS are oxygen-containing chemical species with higher reactive properties than molecular oxygen. Free radicals such as superoxide radical (O2-) and even, non-radical molecules such as hydrogen peroxide (H2O2) can act as ROS. Under normal physiological condition, they are required to maintain cellular homeostasis26, however, excessive ROS due to overproduction or dysregulation of the antioxidant defense system can cause oxidative stress, leading to damage to proteins, lipids and deoxyribonucleic acid (DNA)27. For instance, as ROS levels increase and glutathione (GSH) level decreases concomitantly, disruption of adenosine triphosphate (ATP) synthesis takes place and lactate dehydrogenase (LDH) level increases in the medium, culminating in cell death27.
Here, we provide protocols for performing cellular and genetic analyses using cultured mammalian cells and Drosophila to determine the potential adverse effects of ZnO NPs. An overview of the method used for the toxicity study of ZnO NPs is shown in Figure 1.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>15% Methyl 4-Hydroxybenzoate</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4% Paraformaldehyde</td>
			<td>Sigma Aldrich</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr>
			<td>Bacto Agar</td>
			<td>BD biosciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>cncCK6/TM3, Sb</td>
			<td></td>
			<td></td>
			<td>a gift from Dr. Kerppola T</td>
		</tr>
		<tr>
			<td>cornmeal, glucose, yeast brewer</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CyAn ADP with Summit Software</td>
			<td>DAKO</td>
			<td></td>
			<td>https://flow.usc.edu/files/2014/07/BC-Cyan-ADP-User-Guide-2016.pdf</td>
		</tr>
		<tr>
			<td>Dihydroethidium (Hydroethidine)</td>
			<td>Thermo Fisher Scientific</td>
			<td>D11347</td>
			<td></td>
		</tr>
		<tr>
			<td>FITC Annexin V Apoptosis Detection Kit I</td>
			<td>BD biosciences</td>
			<td>556547</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent microscope</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glucolin</td>
			<td>Supermarket</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Image J software</td>
			<td>NIH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MRC5 human lung fibroblast</td>
			<td>ATCC</td>
			<td>CCL-171</td>
			<td></td>
		</tr>
		<tr>
			<td>Schneider&#8217;s Drosophila medium</td>
			<td>Thermo Fisher Scientific</td>
			<td>21720-024</td>
			<td></td>
		</tr>
		<tr>
			<td>vectashield antifade mounting medium with DAPI</td>
			<td>Vector Laboratories</td>
			<td>H-1200</td>
			<td></td>
		</tr>
		<tr>
			<td>wild- type Canton-S; Sod2N308/CyO</td>
			<td>NIG-FLY</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Zinc Oxide Nanoparticles</td>
			<td>Sigma Aldrich</td>
			<td>721077</td>
			<td>Refer Sheet 2</td>
		</tr>
	</tbody>
</table>

toxicity study of zinc oxide nanoparticles in cell culture and in drosophila melanogaster

Zinc oxide nanoparticles (ZnO NPs) have a wide range of applications, but the number of reports on ZnO NP-associated toxicity has grown rapidly in recent years. However, studies that elucidate the underlying mechanisms for ZnO NP-induced toxicity are scanty. We determined the toxicity profiles of ZnO NPs using both in vitro and in vivo experimental models. A significant decrease in cell viability was observed in ZnO NP-exposed MRC5 lung fibroblasts, showing that ZnO NPs exert cytotoxic effects. Similarly, interestingly, gut exposed to ZnO NPs exhibited a dramatic increase in reactive oxygen species levels (ROS) in the fruit fly Drosophila. More in-depth studies are required to establish a risk assessment for the increased usage of ZnO NPs by consumers.

NP-exposed cells were processed with the cell staining reagent kit, followed by cell sorting using flow cytometry. ZnO NP-treated cells (bottom, right panel) exhibit a higher percentage of early (R3)/ late apoptotic cells (R6) than control cells (R5, bottom, left panel). Necrotic cell death is denoted by R4 (top, right panel) (Figure 2). The results of the FITC/Annexin V Assay on ZnO NP-treated MRC-5 fibroblasts are shown in Figure 2</str...

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Toxicity Study of Zinc Oxide Nanoparticles in Cell Culture and in Drosophila melanogaster

We describe a detailed protocol for evaluating the toxicological profiles of zinc oxide nanoparticles (ZnO NPs) in particular, the type of cell death in human MRC5 lung fibroblasts and ROS formation in the fruit fly Drosophila.

Toxicity Study of Zinc Oxide Nanoparticles in Cell Culture and in Drosophila melanogaster

Zinc oxide nanoparticles (ZnO NPs) have a wide range of applications, but the number of reports on ZnO NP-associated toxicity has grown rapidly in recent ...

Our methods outline a simple and repeat way for studying nanotoxicity, such as examining the types of cell death and examining the production of reactive oxygen species. Fluorescence activated cell sorting is a strict format that allows us to study the subpopulation of cells and the growing different types of cell death. The DHE probe study method allows us to detect and quantify reactive oxygen species followed by flow cytometry, microscopic high-content imaging, and by couplet based fluorescence analysis.To begin, place an Eppendorf tube containing zinc oxide nanoparticles in zinc oxide nanoparticle stock solution into a sonicator for 15 minutes. Prepare zinc oxide nanoparticles at various concentrations using one-milligram-per-milliliter zinc oxide nanoparticle stock. Then, in a biosafety cabinet, seed MRC5 human lung fibroblasts onto three six-well culture plates at the concentration of one times 10 to the fifth cells per well.Incubate the cells at 37 degrees Celsius. After one day, treat the cells with two milliliters of zinc oxide nanoparticles for eight hours, 16 hours, or 24 hours. At each time point, collect the cells into a 15-milliliter centrifuge tube, and centrifuge at 300 times g for five minutes.Wash the cell pellets twice with phosphate-buffered saline, and then resuspend the cells with 1X binding buffer. Next, add five microliters of FITC Annexin V stain in five microliters of propidium iodide DNA stain. Incubate the stained cells for 15 minutes at room temperature in the dark.Before sorting the cells by flow cytometry, top up the samples with an additional 400 microliters of 1X binding buffer. Tabulate the bar chart using the median intensity obtained. Now use a pipette to add one milliliter of nanoparticles at different concentrations into vials, followed by nine milliliters of fly food to make a final concentration of 0.1 milligrams per milliliter, 0.25 milligrams per milliliter, or 0.5 milligrams per milliliter zinc oxide nanoparticles.Pipette up and down to mix thoroughly. Allow fly food containing zinc oxide nanoparticles to cool for at least two to three hours before use. Then anesthetize adult male and female flies in a vial with carbon dioxide, and introduce five male flies and five female flies into each vial for five days.Allow them to mate and lay eggs on the surface of the food. After anesthetization, remove the parental flies and allow the eggs to undergo further development at room temperature, which consists of four different developmental stages. Embryonic, larval, pupal, and adult stage.After 72 to 120 hours, freshly-laid eggs develop into late third instar larvae. Using forceps, collect the larvae from the wall of the vials for analyses. In a well of a dissection dish with dissection medium or PBS, place the larvae into the solution.Under the stereomicroscope, use the tip of the forceps to make a tiny hole, and break open the cuticle layer of the larvae. Carefully pull out the gut. Place the gut into a 1.5-milliliter microcentrifuge tube containing Schneider's Drosophila Medium.Add one microliter of the DHE probe, and incubate in the dark at room temperature for 10 minutes. Wash the gut three times using Schneider's Medium every five minutes. Mount the gut onto glass slides, and supply with 10 microliters of antifade mounting medium containing DAPI.Capture images under a confocal microscope. To measure fluorescence, import the captured fluorescence images acquired using fluorescence microscopy or confocal laser scanning microscopy into the ImageJ software. Click on the analyze menu, and select set measurements.Select the output measure, such as area integrated intensity and mean gray value. Select a region without fluorescence to set the background. Click measure.Export the data into the spreadsheet, and determine the corrected total cell fluorescence. Construct a bar chart, and perform statistical analysis. In this study, zinc oxide nanoparticle-treated cells exhibit a higher percentage of early R3 or late apoptotic R6 cells than control cells R5.Necrotic cell death was denoted by R4.The gut extracted from the drosophila larva was divided into three discrete domains of different developmental origin.Namely, the foregut, midgut, and hindgut. DHE stock tends to expire rather quickly, so be careful of the stock solution you are using. Alternatively, you could try other probes, for example cell Roche, which is designed to detect the intracellular ROS in green signals, and that is more photostable than the DHE.Our protocol provides a general outline for studying the intracellular ROS production, and quantification of ROS level for nanotoxicity study. DMSO is known to be a better solvent for DHE than the PBS. However, DMSO is toxic.Therefore, I would like to advise the user to restrict the entire process for studying to 30 minutes maximum. This is because you may observe a false positive outcome as DMSO may cause cell death.

toxicity-study-zinc-oxide-nanoparticles-cell-culture-drosophila

Research

JoVE Journal

Immunology and Infection

9.8K visualizações.  National University of Singapore. Nossos métodos delineiam uma maneira simples e repetida de estudar a nanotoxicidade, como examinar os tipos de morte celular e examinar a produção de espécies reativas de oxigênio. A fluorescência ativada de classificação celular é um formato rigoroso que nos permite estudar a subpopulação das células e os diferentes tipos de morte celular. O método de estudo da sonda DHE nos permite detectar e quantificar espécies reativas de oxigênio seguidas de citometria de fluxo, imagens m...