How can ROS be measured or detected in living cells?

There are several techniques to measure or detect ROS in living cells. One way to measure cellular levels of ROS is through the utilization of fluorogenic probes. H202, OH-, and ROO- can all be measured after staining with 5(6’)-Carboxy-DCFDA. DCFH-DA is a widely used fluorescent probe that is converted to DCF in the presence of ROS. DCF fluorescence can be detected using flow cytometry or fluorescence microscopy. Dihydroethidium is another fluorescent probe oxidized by superoxide radicals to form ethidium bromide. Ethidium bromide intercalates with DNA, producing red fluorescence. The use of chemiluminescent probes is another way of measuring ROS in living cells. L-012 is a chemiluminescent probe that reacts with superoxide radicals to generate luminescence. The emitted light can be detected using a luminometer to measure ROS levels. EPR spectroscopy can also directly measure and quantify ROS in cells. This technique involves the use of spin probes that react with ROS to produce a detectable EPR signal, and provides high sensitivity.