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Toxicity of Multi-walled Carbon Nanotubes in rat and human intestinal cell models
Citation:
Kodavanti, T., A. Tennant, AND M. Hughes. Toxicity of Multi-walled Carbon Nanotubes in rat and human intestinal cell models. Society of Toxicology, Anaheim, California, March 15 - 19, 2020. https://doi.org/10.23645/epacomptox.19104815
Impact/Purpose:
Poster presented to the Society of Toxicology annual meeting March 2020. Multiwalled carbon nanotubes (MWCNTs) are used in a variety of industrial and commercial products. Their release in to the environment may occur during their manufacture, use and disposal. Exposure of MWCNTs to the gastrointestinal tract may occur from ingestion or inhalation followed by pulmonary clearance. The toxicity of these nanomaterials to the gastrointestinal tract is not well known. In this study we examined the cytotoxicity of several MWCNTs that varied by outside diameter and functionalization (adding functional group such as -OH or -COOH). The test system was a rat two-dimensional monolayer of intestinal epithelial cells and a human three-dimensional model of the intestine that contains several cells types. We observed that cytotoxicity of the MWCNTs following a 24 hr exposure were dependent on dose, outside diameter and functional group in the rat cells. In the human model, no cytotoxicity was observed. The model system used, outside diameter, dose and functional groups are important parameters to consider when conducting cytotoxicity studies with MWCNTs.
Description:
Multi-walled carbon nanotubes (MWCNTs) are several layers of one-atom thick sheets of carbon. MWCNTs are hollow cylinders with a large length to diameter ratio. MWCNTs can improve the mechanical, electrical and thermal conductivity of many products so they are used in a wide variety of applications. The manufacture and use of MWCNTs may result in their release in to the environment. Exposure to MWCNTs may occur following inhalation and ingestion of these nanomaterials. The purpose of this study was to assess the in vitro toxicity of several MWCNTs in a rat (IEC-6 cells) and human intestinal cell models. The outside diameter (OD) of the MWCNTs were 50nm. Two other MWCNTs of OD 20-30 nm were functionalized with -OH or -COOH groups. The IEC-6 cells are a 2-dimensional monolayer of cells, whereas the human model is a 3-dimensional model with multiple cell types. IEC-6 cells were plated in 96-well plate with 60K cells/well for 24h. MWCNTs suspended in Dulbecco’s media, 10% fetal bovine serum (FBS) and 0.1% pluronic were probe sonicated for 15 minutes before dosing. Media with 10% FBS was the negative control and Triton X-100 (0.3%) was the positive control. Cells were then exposed to the MWCNTs at several concentrations (0.3-300 µg/mL) for 24 h. Following incubation, the cells were washed with media and the cytotoxicity was assessed using a cell-permeant dye, Calcein AM. This is a non-fluorescent compound that is converted to the green fluorescent Calcein in viable cells upon acetoxymethyl ester hydrolysis by intracellular esterases. Lethal concentration50 of the MWCNTs were determined: < 8 and 20-30 nm -OH, 35 µg/mL; 20-30 nm, 50 µg/mL; 20-30 nm -COOH, 80 µg/mL; 13-18 nm, 105 µg/mL; 50 nm, 300 µg/mL. Cell viability measured in the 3-dimensional human intestinal model using the colorimetric MTT assay showed no cytotoxicity by the MWCNTs following a 24-h exposure. For the rat intestinal model, size of MWCNTs appears to be an important factor in the cytotoxicity of these nanomaterials. (This abstract does not represent US EPA policy)
URLs/Downloads:
DOI: Toxicity of Multi-walled Carbon Nanotubes in rat and human intestinal cell models
KODAVANTI_TDK_SOT 2020 V10.PDF (PDF, NA pp, 1068.932 KB, about PDF)