Detection of DNA Damage Response Caused by Different Forms of Titanium Dioxide Nanoparticles using Sensor Cells

Peng Chen and Akiyoshi Tani

Abstract

Titanium dioxide nanoparticles (TiO2 NPs) are generally considered to be biologically inert. However, TiO2 occurs in several crystalline forms, the two most common being rutile and anatase. Although both forms are tetragonal, the different crystalline forms give rise to different physical and chemical characteristics such as hardness, refractive index and photocatalytic ability. We hypothesized that the two forms of TiO2 NPs would also elicit different cellular responses. Three cell-based biosensors, using B-cell Translocation Gene 2 (BTG2), heat shock protein70B' (HSP70B') and nuclear factor kappa B (NF-кB) sensor cells, were used to determine if the different forms of TiO2 NPs cause different cellular responses. The cellular responses induced by TiO2 NPs were detected using HSP70B' and NF-кB sensor cells; we found that the different forms of TiO2 NPs resulted in the same HSP70B' and NF-кB response. BTG2 expression is up-regulated by DNA damage via p53 activation. A cellular DNA damage response stimulated by different forms of TiO2 NPs was detected by our cell-based DNA damage biosensor. The results showed that an increased DNA damage response is elicited by the anatase form compared to the rutile or mixed rutile/anatase forms. Our work indicates that the crystalline form of NPs is an important point to investigate when studying the interaction between nanomaterials and cells.