An important principle is the ability of some dyes to be incorporated into live cells without impacting their short-term function (some may be toxic eventually). There are several specific dyes of interest, depending upon the function to be determined. Dyes, which can respond to the presence of strong oxidants, can be used to identify the production of these oxidants - an example is H2O2. There are several fluorescent indicators of H2O2 activity such as DCFH-DA or dihydrorhodamine-123. Another useful dye for strong oxidants is Hydroethidine which can detect the superoxide radical O2-. All of these dyes can be used to detect the production of these reactive oxygen species in live cells in real time.
