Cellular toxicity of TiO_2-based nanofilaments

摘要

At present, nanofilaments are not exclusively based on carbon atoms but can be produced from many inorganic materials in the form of nanotubes and nanowires. It is essential to systematically assess the acute toxicity of these newly synthesized materials since it cannot be predicted from the known toxicity of the same material in another form. Here, the cellular toxicity of TiO _2-based nanofilaments was studied in relation to their morphology and surface chemistry. These structures produced by hydrothermal treatment were titanate nanotubes and nanowires with a Na_xTiO_(2+δ) composition. The cytotoxic effect was mainly evaluated by MTT assays combined with direct cell counting and cytopathological analyses of the lung tumor cells. Our work clearly demonstrated that the presence of Na_xTiO _(2+δ) nanofilaments had a strong dose-dependent effect on cell proliferation and cell death. Nanofilament internalization and alterations in cell morphology were observed. Acid treatment performed to substitute Na _+ with H_+ in the Na_xTiO_(2+delta;) nanofilaments strongly enhanced the cytotoxic action. This effect was attributed to structural imperfections, which are left by the atom diffusion during the substitution. On the basis of our findings, we conclude that TiO _2-based nanofilaments are cytotoxic and thus precautions should be taken during their manipulation.