FRET-dependent single/two-channel switch endowing a dual detection for sulfite and its organelle targeting applications

Abstract

Förster resonance energy transfer (FRET) is a relatively new strategy for constructing ratiometric fluorescent probes and increasing the Stokes shift. Fluorescent probes based on FRET require spectral overlap between the energy donor emission spectrum and the acceptor absorption spectrum, while providing high energy transfer efficiency. In addition, systems exhibiting FRET typically exhibit intense dual fluorescence, thereby improving the resolution of biological imaging and detection. Herein, on the union of a benzopyrylium salt with a coumarin carboxylic acid, a novel near-infrared fluorescent probe CM-P-DP with FRET regulation strategy was designed and synthesized for the detection of sulfite (SO32−). CM-P-DP showed large Stokes shift (230 nm) and fast response to SO32− in pure PBS buffer (15 s). When SO32− was added, the fluorescence intensity at 455 nm gradually increased, and the fluorescence intensity at 635 nm decreased rapidly. Moreover, CM-P-DP could effectively target mitochondria and imaging SO32− in biological systems.