A highly sensitive and photo-stable fluorescent probe for endogenous intracellular H2O2 imaging in live cancer cells

Reactive oxygen species (ROS) are connected to aging and human diseases. The controlled generation of ROS, particularly H 2 O 2 , is necessary to maintain cellular fitness. Fluorescent probe based imaging is the most popular approach for H 2 O 2 detection. The photobleaching of the fluorophores is the significant limitation towards better signal-to-noise ratio and imaging resolution. We design and synthesize a highly sensitive and photo-stable fluorescent probe for detecting H 2 O 2 by using the 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) as an electron acceptor . After reacting with H 2 O 2 , the borate ester group in the probe was transformed into phenol group to form red emitted fluorophore that is highly photo-stable under the irradiation of UV light and excitation laser . A good linear relationship (R 2  = 0.9930) in the range of 1–20 μM of H 2 O 2 was obtained. The limit of detection (3σ/slope) of our probe was 61 nM, which make our probe one of the most sensitive fluorescent probes for H 2 O 2 detection. And the probe doesn't response to common other ROS species. The probe was successfully applied to endogenous intracellular H 2 O 2 imaging in live A549 lung cancer cells. More importantly, the imaging signal just had less than 10% difference in fluorescence intensity after 25 min continuous irradiation of excitation laser. Thus, we believe the proposed TCF-PB is very practical for sensing and imaging of trace amount of H 2 O 2 that endogenously generated in the live cancer cells, which is essential for the study of H 2 O 2 related cell signaling and human diseases.