Carbon black induced DNA damage and conformational changes to mouse hepatocytes and DNA molecule: A combined study using comet assay and multi-spectra methods

Abstract

Carbon black (CB), a carbonaceous nanoparticle, has been widely applied in our daily lives and used as a typical model to study environmental safety and health impacts of airborne particles. Although the potential negative effects of CB to organisms have been reported a lot, very limited work is focused on the genotoxicity of CB on molecular and cellular level simultaneously. Herein, we investigated the interaction mechanism between CB and DNA molecule in depth by multiple spectra measurement, UV–vis absorption and ionic strength measurement. The fluorescence spectroscopy, ironic strength measurement and UV absorption indicated that CB changed the structure of DNA and interacted with DNA in an electrostatic binding mode. CD (circular dichroism) spectra proved no significant effects were caused by CB on the base stacking and helicity bands of DNA, which further verified that electrostatic binding is the main binding mode between CB and DNA. On the cellular level, the comet assay shows that CB exposure could cause a remarkable DNA strand break to the mouse hepatocytes after 24 co-incubation. This combined investigation suggests that CB could cause a serious genotoxicity both on molecular and cellular level.