Particle length-dependent titanium dioxide nanomaterials toxicity and bioactivity

Raymond F. Hamilton, Nianqiang Wu, Dale Porter, Mary Buford, Michael Wolfarth, Andrij Holian

Research output: Contribution to journalArticlepeer-review

301 Scopus citations

Abstract

Background: Titanium dioxide (TiO 2) nanomaterials have considerable beneficial uses as photocatalysts and solar cells. It has been established for many years that pigment-grade TiO 2 (200 nm sphere) is relatively inert when internalized into a biological model system (in vivo or in vitro). For this reason, TiO 2 nanomaterials are considered an attractive alternative in applications where biological exposures will occur. Unfortunately, metal oxides on the nanoscale (one dimension < 100 nm) may or may not exhibit the same toxic potential as the original material. A further complicating issue is the effect of modifying or engineering of the nanomaterial to be structurally and geometrically different from the original material.Results: TiO 2 nanospheres, short (< 5 μm) and long (> 15 μm) nanobelts were synthesized, characterized and tested for biological activity using primary murine alveolar macrophages and in vivo in mice. This study demonstrates that alteration of anatase TiO 2 nanomaterial into a fibre structure of greater than 15 μm creates a highly toxic particle and initiates an inflammatory response by alveolar macrophages. These fibre-shaped nanomaterials induced inflammasome activation and release of inflammatory cytokines through a cathepsin B-mediated mechanism. Consequently, long TiO 2 nanobelts interact with lung macrophages in a manner very similar to asbestos or silica.Conclusions: These observations suggest that any modification of a nanomaterial, resulting in a wire, fibre, belt or tube, be tested for pathogenic potential. As this study demonstrates, toxicity and pathogenic potential change dramatically as the shape of the material is altered into one that a phagocytic cell has difficulty processing, resulting in lysosomal disruption.

Original languageEnglish
Article number35
JournalParticle and Fibre Toxicology
Volume6
DOIs
StatePublished - Dec 31 2009

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