A nile red-based near-infrared fluorescent probe for endogenous hydrogen polysulfides in living cells

Abstract

Endogenous hydrogen polysulfides (H₂S_n; n > 1) have attracted increasing attention because emerging studies have shown that it is actually the key signaling molecule rather than hydrogen sulfide (H₂S). Therefore, developing probes for selective and sensitive detection of hydrogen polysulfides is of great significance in biological science. In this study, a new fluorescent off–on probe for the selective and sensitive detection of hydrogen polysulfides (H₂S_n) with near-infrared (NIR) fluorescent signal change has been designed and synthesized. The probe was synthesized by an esterification reaction coupling between a nile red dye and a bis-electrophilic H₂S_n capture group 2-fluoro-5-nitrobenzoic acid. The probe showed a specific off–on response to H₂S_n in aqueous solution with nanomolar LOD without interference by a range of competing sulfocompounds and several reactive nitrogen and oxygen species. Moreover, it can be used for imaging of endogenous H₂S_n in living cells.