Characterization of genotoxic response to 15 multiwalled carbon nanotubes with variable physicochemical properties including surface functionalizations in the FE1-Muta(TM) mouse lung epithelial cell line.
Carbon nanotubes vary greatly in physicochemical properties. We compared cytotoxic and genotoxic response to 15 multiwalled carbon nanotubes (MWCNT) with varying physicochemical properties to identify drivers of toxic responses. The studied MWCNT included OECD Working Party on Manufactured Nanomaterials (WPMN) (NM-401, NM-402, and NM-403), materials (NRCWE-026 and MWCNT-XNRI-7), and three sets of surface-modified MWCNT grouped by physical characteristics (thin, thick, and short I-III, respectively). Each Groups I-III included pristine, hydroxylated and carboxylated MWCNT. Group III also included an amino-functionalized MWCNT. The level of surface functionalization of the MWCNT was low. The level and type of elemental impurities of the MWCNT varied by <2% of the weight, with exceptions. Based on dynamic light scattering data, the MWCNT were well-dispersed in stock dispersion of nanopure water with 2% serum, but agglomerated and sedimented during exposure. FE1-Muta(TM) Mouse lung epithelial cells were exposed for 24 hr. The levels of DNA strand breaks (SB) were evaluated using the comet assay, a screening assay suitable for genotoxicity testing of nanomaterials. Exposure to MWCNT (12.5-200 µg/ml) did not induce significant cytotoxicity (viability above 92%). Cell proliferation was reduced in highest doses of some MWCNT after 24 hr, and was associated with generation of reactive oxygen species and high surface area. Increased levels of DNA SB were only observed for Group II consisting of MWCNT with large diameters and high Fe2 O3 and Ni content. Significantly, increased levels of SB were only observed at 200 µg/ml of MWCNT-042. Overall, the MWCNT were not cytotoxic and weakly genotoxic after 24 hr exposure to doses up to 200 µg/ml.
Danish Centre for Nanosafety, National Research Centre for the Working Environment, Copenhagen Ø, Denmark.
Petra
P
Jackson
Kirsten
K
Kling
Keld Alstrup
KA
Jensen
Per Axel
PA
Clausen
Anne Mette
AM
Madsen
Håkan
H
Wallin
Ulla
U
Vogel
D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects; D008168:Lung / Q000187:drug effects*; D051379:Mice; D009152:Mutagenicity Tests; D009153:Mutagens / Q000009:adverse effects*; D037742:Nanotubes, Carbon / Q000009:adverse effects*; D017382:Reactive Oxygen Species / Q000378:metabolism
D009153:Mutagens; D037742:Nanotubes, Carbon; D017382:Reactive Oxygen Species
comet assay; cytotoxicity; dynamic light scattering analysis; elemental analysis; reactive oxygen species