Highly Selective and Sensitive One- and Two-Photon Ratiometric Fluorescent Probe for Intracellular Hydrogen Polysulfide Sensing

Hydrogen polysulfide (H₂S_n) has attracted increasing attention due to the fact that it is actually the key signaling molecule rather than hydrogen sulfide (H₂S). Therefore, developing a sensitive and accurate assay to investigate the biosynthetic pathways of H₂S_n is of physiological and pathological significance. In this work, based on the commonly used two-photon fluorophore, 1,8-naphthalimide, a new probe, NRT-HP, has been designed and synthesized that displayed both one- and two-photon ratiometric fluorescence changes toward H₂S_n via H₂S_n-mediated benzodithiolone formation. NRT-HP exhibits excellent pH stability, high selectivity and low detection limit (0.1 μM) in aqueous media. Furthermore, two-photon fluorescence microscopy experiments have demonstrated that NRT-HP could be used for the H₂S_n detection in live cells as well as tissue slices.