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In vitro intestinal toxicity of multi-walled carbon nanotubes
Citation:
Kodavanti, T. AND M. Hughes. In vitro intestinal toxicity of multi-walled carbon nanotubes. Society of Toxicology Annual Meeting, Baltimore, Maryland, March 10 - 14, 2019.
Impact/Purpose:
Humans may be exposed to multiwalled carbon nanotubes (MWCNTs) by the oral route. In this study we examined the cytotoxicity of several MWCNTs that varied by outside diameter and functionalization. The test model was rat intestinal cells. Of the nanotubes examined only the MWCNT with an outside diameter < 8 nm displayed cytotoxicity following 24 hr exposure. This only occurred at the highest dose (300 ug/ml) tested. Consideration of the size of the MWCNT is important when testing in rat intestinal cells.
Description:
Multi-walled carbon nanotubes (MWCNTs) are emerging nanomaterials that are widely used in industrial, engineering, biological and medicinal applications due to their unique physiochemical, optical and electrical properties. The release of these nanomaterials into the environment poses a potential for human exposure following inhalation and ingestion. The purpose of this study was to assess the in vitro toxicity of four MWCNTs with outside diameter of 50 nm, and 20-30 nm and two functionalized MWCNTs (-OH, -COOH) with outside diameter 20-30 nm in a rat intestinal cell model (IEC-6 cells). Pluronic (0.1%), a non-ionic surfactant was used to stabilize MWCNT dispersion. Hydrodynamic diameter and zeta potential was calculated to determine the sonication time at which the MWCNTs were optimally dispersed. Based on the results, the MWCNTs suspended in Dulbecco’s media and 0.1% pluronic were probe sonicated for 15 min before dosing. IEC-6 cells were plated in 96-well plate with 60K cells/well for 24 h. Media with 10% fetal bovine serum was the negative control and Triton X-100 (0.3%) was the positive control. Cells were then exposed to the MWCNTs at various concentrations (0.3-300 μg/ml) for 24 h. Following incubation, the cells were washed with media and cytotoxicity was assessed using a colorimetric method that measures mitochondrial activity. Only the <8 nm MWCNT displayed cytotoxic effects, inducing 50% cell death at a concentration of 300 ug/ml. All other MWCNTs tested were negative. The results suggest that the outside diameter of MWCNTs is important factor in the cytotoxicity of these nanomaterials in rat IEC-6 cells. (This abstract does not represent US EPA policy.)