A highly selective and ultrasensitive ratiometric fluorescent probe for peroxynitrite and its two-photon bioimaging applications

In this work, taking full advantage of the intramolecular charge transfer (ICT) mechanism, a hydroxynaphthalimide-based ratiometric two-photon fluorescent probe RTP-PN was synthesized to detect ONOO−. Probe RTP-PN could accurately detect ONOO− in the range of 1.4 nM-1.4 μM with the detection limit of 1.4 nM by a ratiometric fluorescence spectroscopy method. Additionally, probe RTP-PN exhibited an ultrafast response for ONOO− than other various species including H2O2 and ClO−. Finally, probe RTP-PN was successfully adopted to detect intracellular ONOO− by the two-photon excitation microscopy.