Abstract
Due to the widespread applications of titanium dioxide (TiO2) nanoparticles (NPs) infood, cosmetics and medical devices, it is receiving increasing attention to evaluate its toxicities to the environment. Many toxicity studies using different organisms have concluded that the toxicity of anatase TiO2 NPs is based on its photocatalytic effect. However, the toxic effect of anatase TiO2 in the dark condition as not been evaluated. Recently, it has been shown that rutile TiO2 nanotubes are able to induce the differentiation of neuronal rat cells and provide decent biocompatibility. The most elusive question has been whether TiO2 NPs exert direct toxic effects to organisms. Here, we used anatase and rutile TiO2 NPs to treat the neurons of C. elegans and see how this particle affects neuronal growth. Here we show that TiO2 NPs with concentration 50μg/ml promote the outgrowth of neurites and inhibit the outgrowth of axons at high concentration from 100μg/ml to 300μg/ml, suggesting TiO2 NPs might be beneficial to axon extension at low concentration but toxic to axons at high concentrations. However, for cell body area no significant difference can be found