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 H2O2, is necessary to maintain cellular fitness. Fluorescent probe based imaging is the most popular approach for H2O2 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 H2O2 by using the 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) as an electron acceptor. After reacting with H2O2, 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 (R2 = 0.9930) in the range of 1–20 μM of H2O2 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 H2O2 detection. And the probe doesn't response to common other ROS species. The probe was successfully applied to endogenous intracellular H2O2 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 H2O2 that endogenously generated in the live cancer cells, which is essential for the study of H2O2 related cell signaling and human diseases.