Evaluation of electric cell-substrate impedance sensing for the detection of nanomaterial toxicity

Electric cell-substrate impedance sensing (ECIS) is an in situ and real-time monitoring system used to detect toxic agents by monitoring changes in impedance of a confluent cell monolayer. When toxic agents are introduced to cells, they can cause a change in the cell barrier function, a direct measure of the resistance to current flow caused by tight junction formation between cells. This exposure results in an immediate, quantitative change in the measured resistance between the electrodes, thus, continuously monitoring cell behaviour and by extension, toxic exposure. We have developed an ECIS-based protocol to functionally characterise epithelial cell response when challenged by different toxicants, particularly silver and copper nanoparticles. We verified our impedance changes with observed structural changes by fluorescent staining of zonula occludens-1 (ZO-1) protein in the tight junctions of a model epithelial cell line.