Novel “turn on” fluorescent probe for endogenous peroxynitrite detection based on selective oxidation of nitrobenzoyl formate ester

Abstract

A “turn on” fluorescent probe (EASHC-NO₂) was designed for endogenous peroxynitrite (ONOO⁻) detection. The probe contained a fluorophore with an intramolecular charge transfer (ICT) effect and a selective sensing site containing nitro groups to suppress fluorescence. By using the oxidizing property of ONOO⁻, the dicarbonyl structure in nitrobenzoyl formate ester was oxidized and degraded, thereby eliminating the nitro structure in the probe and achieving turn-on fluorescence. The strong ICT effect ensured that the fluorophore had a sufficiently large emission redshift to 626 nm, with a large Stokes shift of 90 nm. Probe EASHC-NO₂ exhibited a low limit of detection of 16 nM, high sensitivity and high stability within the physiological range. Living-cell studies showed that the probe could detect exogenous and endogenous ONOO⁻, indicating that probe EASHC-NO₂ could be employed in practical biological applications.