Cytotoxicity of metal and semiconductor nanoparticles indicated by cellular micromotility

In the growing field of nanotechnology, there is an urgent need to sensitively determine the toxicity of nanoparticles since many technical and medical applications are based on controlled exposure to particles, that is, as contrast agents or for drug delivery. Before the in vivo implementation, in vitro cell experiments are required to achieve a detailed knowledge of toxicity and biodegradation as a function of the nanoparticles' physical and chemical properties. In this study, we show that the micromotility of animal cells as monitored by electrical cell-substrate impedance analysis (ECIS) is highly suitable to quantify in vitro cytotoxicity of semiconductor quantum dots and gold nanorods. The method is validated by conventional cytotoxicity testing and accompanied by fluorescence and dark-field microscopy to visualize changes in the cytoskeleton integrity and to determine the location of the particles within the cell.