Electric Cell-Substrate Impedance Sensing (ECIS) for Analyzing the Effect of Environmental Pollutants - A Study of Diesel Exhaust Nanoparticles

Author(s): Amalu Navas, Maya Nandkumar A

ECIS is a morphological biosensor that records the electrical properties of cell-covered microelectrodes in an AC circuit, including impedance (ohm), resistance (ohm), and capacitance (μFarad). The objective of the current study was to analyze the suitability of ECIS as a label-free in vitro assay system to understand the effect of external stimuli on cells in real-time, vis-à-vis regular endpoint assays of cytotoxicity. The study analyzed whether fluctuations in the electrical properties of cell-covered microelectrodes reflected dynamic changes in cell morphology on exposure to diesel exhaust particles. Exposure of A549 monolayers in 8 well microarrays to DEP caused significant changes in microelectrode resistance (ohm @4 kHz) as compared to controls within 24 h. Variations in impedance were found to have a dose-dependent effect. We compared our results from ECIS with classic cytotoxicity analyses like MTT, LDH, and NRU assays and observed corroborative endpoint results. Reactive oxygen species production by DCFHDA assay showed an increase in relative fluorescence indicating ROS to be a possible cause of dose-dependent cytotoxicity. Our findings indicate that ECIS provides many benefits as an alternative method to quantify, automate, and measure the effect of pollutants or particles in real-time when compared to traditional endpoint methods.