Fig. 5. Role of ROS.
(A) Cell-free assay performed at 4 Vpp using ROS-responsive dyes show increasing ROS activation at low frequencies (below 1 MHz) and relatively low ROS activation at higher frequencies (blue line). The addition of an oxygen scavenger, catalase (which catalyzes the reduction of hydrogen peroxide to water and oxygen) results in an ~5× attenuation of activation (red line) suggesting that oxygen species are the most dominant radicals generated. (B) Results of frequency sweep (at 4 Vpp) with our cell-based sensor indicate that response to ROS is resulting in low frequency activation (blue line) as the trend is considerably attenuated with addition of catalase (red line) resulting in a near flat line response (solely due to heating effects). (C) Dose response of ROS (using tert-butyl hydroperoxide), indicating that the cell-based sensor has a similar graded response to chemical stressors as well as thermal stressors (as shown Figure 3).