A ratiometric fluorescent probe for single and two-photon bioimaging of hydrogen peroxide in vitro and in vivo

Hydrogen peroxide (H2O2) as an important reactive oxygen species (ROS) is correlated in various oxidative stress and cell signaling processes. Thus, developing an effective method that can monitor H2O2 in the Golgi apparatus is of great importance. Herein, a Golgi-targeting two-photon fluorescent probe (GT-H2O2) that can be excited by a femto-second pulse (760 nm) is designed. GT-H2O2 utilized aminoquinoline as a fluorophore / Golgi-targetable unit and borate ester as a H2O2-responsive unit with an intramolecular charge transfer strategy. The borate ester of GT-H2O2 was oxidized by H2O2 selectively to afford a new fluorescent molecule GT-NH2, thereby realizing a ratiometric detection of H2O2. The probe exhibited a high sensitivity and selectivity to H2O2 with a linear range from 5 to 60 μM. In addition, endogenous / exogenous H2O2 could be directly visualized utilizing GT-H2O2 in vitro and in vivo by one/two-photon microscopy.