Fig. 2. Photophysical characterization of HKYellow for detecting peroxynitrite. (a) Fluorescence responses of 2 μM HKYellow to different amounts of ONOO–. (b) The relative fluorescence intensity (λem = 570 nm) of 2 μM HKYellow toward various ROS and RNS. HKYellow was dissolved in 0.1 M phosphate buffer at pH 7.4 and excited at 545 nm. ROS and RNS were added into the probe solution slowly with vigorous stirring. The reactions were then carried out for 30 min at room temperature in the dark before the fluorescence intensity was measured.
