A fast responsive two-photon fluorescent probe for imaging H₂O₂ in lysosomes with a large turn-on fluorescence signal.

Hydrogen peroxide (H2O2) plays a crucial role in many biological processes in the human body. As our understanding of the complexity of physiological H2O2 in lysosome, investigative tools are required to make sense of this interconnectivity. Toward this goal, we have developed a new example of a fast responsive and lysosome-targeted two-photon H2O2 fluorescent probe (Lyso-HP) with a large turn-on fluorescence signal (80-fold fluorescence enhancement). The addition of H2O2 to Lyso-HP results a dramatic fluorescence enhancement around 550 nm. The probe could image exogenous and endogenous H2O2 in living cells and the probe was located in lysosomes with high colocalization coefficient (0.96) compared with LysoTracker. The large fluorescence enhancement of the two-photon probe Lyso-HP renders it attractive for imaging H2O2 in living tissues with deep tissue penetration. Significantly, the probe is feasible for fluorescently monitoring H2O2 level changes in lysosomes and suitable for fluorescence imaging of H2O2 in living tissues with deep penetration by using two-photon microscopy.