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

Peng Chen

doi:10.4172/2155-6210.1000129

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-AÂoB) 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-AÂoB sensor cells; we found that the different forms of TiO2 NPs resulted in the same HSP70B' and NF-AÂoB 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.

Highlights

The increased generation, use and disposal of nanomaterialcontaining products has led to an increase in the potential exposure risk to nanomaterials for both humans and the environment [1]
Because of its different properties, the rutile form of TiO2 NPs is highly effective in the absorption of ultraviolet radiation, and is used in sunscreens to protect against UV-induced skin damage
We previously demonstrated that B-cell Translocation Gene 2 (BTG2) is a useful marker of cytotoxicity involving DNA damage, and we developed a highly sensitive DNA damage biosensor using the BTG2 promoter to detect such cytotoxicity [25]

Summary

Introduction

The increased generation, use and disposal of nanomaterialcontaining products has led to an increase in the potential exposure risk to nanomaterials for both humans and the environment [1]. The anatase form can oxidize oxygen or organic materials directly, with active TiO2 NP photocatalysis in aqueous media generating reactive oxygen species (ROS) such as superoxide (O2 ̄), hydroxyl radical (HO), hydrogen peroxide (H2O2), and singlet oxygen [8,9] All of these ROS can cause DNA damage [10,11]. Doi:10.4172/2155-6210.1000129 to their different photocatalyst characters, the three cell types should exhibit different DNA damage responses upon exposure to different forms of TiO2 NPs. Our data show that our cell-based BTG2 biosensor using the BTG2 promoter-reporter plasmid could detect the differences in DNA damage response caused by exposure to different forms of TiO2 NPs. The results indicate the important role of crystalline form on the interaction between nanomaterials and cells. Our cell-based biosensor could offer a means for evaluating the safety of nanomaterials for humans and the environment

Materials and Methods

Cells and cell culture

Cell viability test

Mixed Form

Results and Discussion