Electrochemical impedance measurement of HepG2 cultured in microfabricated cell chip

Abstract

In toxicology, especially in dealing with cells, many trivial experiments are time-consuming and laborious, and it is also difficult for in vivo experiments to give quantitative results and to measure cell concentration and so on without affecting the target cells. These obstacles prevent the field of toxicology from being automated and high-throughput. For solving this problem, a microfabricated cell chip with three electrodes based on electrochemical impedance system was designed and fabricated by sputtering gold on polycarbonate film. The cell chip measures the impedance change caused by adherent cells growing on the electrode surface and then lets us know relative quantity of cells on the chip. As the electrode size became smaller, the cell chip sensitively detected cells, but reproducibility decreased. According to the results, 500μm electrode was chosen in consideration of the reproducibility and sensitivity. Impedance change during cell attachment experiments was adaptable at the 10kHz for considering the reproducibility and the impedance difference between cells and medium. To find the relationship between cell concentration and impedance change, cells with various concentrations were monitored. As the cell concentration increased, the impedance change also increased, and vice versa. Furthermore, when monitoring growing cells, the measured impedance showed the typical growth curve. Toxicity of Triton X-100, tamoxifen, and menadione were measured using the cell chip. As the concentration of toxicants increased, the impedance was decreased because of the detachment of dead cells. Results of MTT assay and fluorescence test were also consistent with the cell chip results. This implies that the microfabricated cell chip is suitable for measuring cell growth and death. Our results reveal that the cell chip system would provide an easy and real-time monitoring method for cytotoxicity test. Furthermore, this system enables many experiments dealing with via...