Azacoumarin-based "turn-on" fluorescent probe for the detection and imaging of hydrogen peroxide in living cells

Azacoumarins are a relatively unexplored group of coumarin fluorophores, despite their excellent light-emitting properties. In this report, we detail the creation and production of a fluorescent probe (PYCB) based on azacoumarin for detecting H₂O₂. The probe utilizes a carboxy benzyl boronic pinacol ester as the recognition unit and displays a turn-on fluorescence response at 460 nm upon exposure to H₂O₂. The probe shows excellent sensitivity and selectivity to H₂O₂, with a detection limit of 0.385 μM. PYCB also exhibited strong pH stability and selectivity for H₂O₂ over other reactive oxygen species (ROS). Additionally, MTT assay results demonstrated the excellent biocompatibility of PYCB in MCF-7 cell lines. Fluorescence imaging of PYCB-treated MCF-7 cells revealed enhanced blue fluorescence corresponding to varying concentrations of exogenous H₂O₂.