Influence of single walled carbon nanotubes at subtoxical concentrations on cell adhesion and other cell parameters of human epithelial cells

Abstract The production of SWCNT has increased tremendously in the last decade, due to high expectations of their benefits. Despite all precautions SWCNT may come into contact with organisms and may be taken up by them. The aim of the present study was to assess and elucidate the effects of SWCNT bundles (purified SWCNT) and SWCNT raw material on the behaviour of human epithelial cells (A549). When cells were exposed to SWCNT (bundles and raw material) cell adhesion was significantly affected. The effects of SWCNT were dependent on the SWCNT purity (purified SWCNT or SWCNT raw material), the SWCNT concentration and the incubation period. SWCNT raw material affected cell adhesion more than the SWCNT bundles did. Beside effects on cell adhesion, cell spreading and the development of focal adhesion points and the actin skeleton were affected, however to a much lesser extent. Cells grown in the presence of SWCNT showed an elevated amount of reactive oxygen species (ROS). The effect was concentration dependent. Other cell parameters, such as cell viability, cell death (apoptosis and necrosis), activation of cell signalling proteins, such as focal adhesion kinase (FAK) and mitogen activated protein kinase (MAPK-Erk1/2), as well as the gap junctional intercellular communication proteins (connexin-43 and β-catenin) were not seriously affected when cells were grown in the presence of SWCNT.