ROS analysis

The measurements of ROS production on the chip were performed with a Reactive Oxygen Species Assay Kit (Solarbio, Beijing). Briefly, DCFH-DA was diluted in a serum-free RPMI1640 medium at a final concentration of 10 μM in the dark. The cells were washed with PBS twice and incubated with 10 μM DCFH-DA at 37 °C in the dark for 30 min. After incubation, the cells were rinsed with serum-free RPMI 1640 medium twice and incubated with RPMI1640 medium supplemented with 10% FBS. The fluorescence was measured using an inverted fluorescent microscope (IX71, Olympus) at 488 nm excitation and 525 nm emission.