D.H. treatments of Puerarin (Kakonein) DDP, DOX, and 5-FU, resulted in distinct impedance responses of cells, providing an impedance-based evaluation methodology for cervical cancer treatment. is the total impedance of the cellCelectrode system and is the impedance of the electrodes without cell blocking. Open in a separate window Figure 3 Schematics of impedance measurement of HeLa cells. HeLa cells were placed in the PDMS-enclosed well and then incubated at 37 C and 5% CO2. The impedance of the HeLa cells Puerarin (Kakonein) was monitored in real time. After 24 h of HeLa cell growth on the surface of the microelectrodes, 40 and 80 g/mL DDP, 40 and 80 g/mL DOX, and 400 and 800 g/mL 5-FU were added into culture wells, respectively. The concentrations of DDP, DOX, and 5-FU utilized in the experiment were derived from previous studies [25,26,27]. Drug-treated HeLa cells were continuously incubated for 24 h and untreated HeLa cells were taken as the control group. The impedance profiles Puerarin (Kakonein) of HeLa cells treated by distinct dose-dependent drugs were monitored per hour at the optimal frequency. The Puerarin (Kakonein) measured responses were characterized by the cell index (CI) using the following expression [28]: < 0.05), ** (< 0.01), and *** (< 0.001). 3. Results 3.1. Screening of Experimental Conditions for Impedance Measurement The ECIS measurements reflected changes in the impedance of the electrodes according to AC current over time. Higher current flow promoted sensitivity of the impedance sensor for detection [29]. Poor cell conductivity caused the current to bypass the cell region as the cell grows on the electrodes. Therefore, the distribution of the currents passing through the electrodes could be altered. In FEM simulation, biological cells were added on the top of the electrodes. It was shown that the magnitude and distribution of the current passing through the cross section of the electrodes were altered (Figure 4a). The current density could be reduced where cells are placed due to poor conductivity of cells, as shown by the red arrows in Figure 4a. We integrated the current density along the direction of the black arrow shown in the figure to obtain the total current through the cross section of the electrodes. Cells with the same number were added on the distinct electrodes. Figure 4b exhibits the difference in the integrated current density over the Rabbit polyclonal to ALDH3B2 section of the electrodes before and after addition of HeLa cells. The higher difference indicated the electrodes were more sensitive to cell response. A more obvious electrical response of cells could be observed in the electrodes with a finger width of 50 m and fingerCfinger spacing of 35 m in the case of the same input (cells). It was concluded that the electrodes with such structural parameters had higher sensitivity for monitoring changes in cell impedance. Figure 4c shows the experimental absolute impedance |Z| value of the selected electrodes with DMEM as a function of the detection frequency. The electrodes used in this study possessed low base impedance. For instance, the |Z| of the electrodes was around 1.2 k at a frequency of 20 Hz, which was appropriate for conduction of the subsequent experiment using the selected electrodes. Open in a separate window Figure 4 (a) Changes in current density passing through the cross section of the electrodes with different dimensions. (b) The differences of the Puerarin (Kakonein) total currents through the cross section of the electrodes before and after addition of cells on the top of the electrodes. (c) The experimental absolute impedance.