Author:

Keywords:

Nanomaterials, carbon nanotubes, nanoparticles, genotoxicity, oxidative stress, Science & Technology, Life Sciences & Biomedicine, Nanoscience & Nanotechnology, Toxicology, Science & Technology - Other Topics, NF-KAPPA-B, OXIDATIVE STRESS, IN-VITRO, ALVEOLAR MACROPHAGES, TOXICITY, EXPOSURE, DNA, NANOMATERIALS, INDUCTION, CYTOTOXICITY, Cell Line, Tumor, Cell Survival, DNA Damage, Dose-Response Relationship, Drug, Gene Expression Profiling, Gene Expression Regulation, Humans, Hypoxanthine Phosphoribosyltransferase, Lymphocytes, Micronuclei, Chromosome-Defective, Molecular Structure, Mutagenesis, Mutagens, Nanotubes, Carbon, Oxidative Stress, Particle Size, Point Mutation, Polymerase Chain Reaction, Respiratory Mucosa, Structure-Activity Relationship, Surface Properties, Time Factors, 0903 Biomedical Engineering, 1007 Nanotechnology, 3206 Medical biotechnology, 4018 Nanotechnology

Abstract:

Single-walled carbon nanotubes (SWCNTs) have recently attracted great attention because of their fibrous structure and high aspect ratio. Here the genotoxic potential of 400-800 nm, 1-3 μm and 5-30 μm SWCNT with respect to their geometry and surface characteristics was studied. Following thorough physico-chemical characterisation, human bronchial epithelial (BEAS-2B) and lymphoblastoid (MCL-5) cells were treated with SWCNT for 24 or 48 h. This showed significant increases in micronucleus frequency in a time- and dose-dependent manner in both cell types in the absence of cytotoxicity. Over the same dose range, only 1-3 μm SWCNT gave rise to significant increases in hprt point mutations at doses ≥25 μg/ml. Cellular 2,7-dichlorodihydrofluoresceindiacetate (DCFH-DA) fluorescence assay and RT-PCR for oxidative pathway gene profiling revealed a possible oxidative mechanism for the genotoxicity observed in the 1-3 μm SWCNT. Consequently, this study has demonstrated that SWCNT genotoxicity is dependent on its secondary structure under experimental conditions and oxidative stress alone cannot account for the observed damage.