A 4-Hydroxy-1,8-Naphthalimide-Based Turn-on Two-Photon Fluorescent Probe for Hydrogen Polysulfide Sensing

In order to quantitatively detect hydrogen polysulfides (H2Sn, n > 1) in biosystems, we propose a new two-photon turnon fluorescent probe, named Np–Sn, based on the D–π–A skeleton two-photon fluorophore of 4 -hydroxy-1,8-naphthalimide derivative and deprotection of 2-fluoro-5-nitrobenzoic ester by H2Sn–Np–Sn displayed a more than 80-fold enhancement towards H2Sn in 550 nm and high sensitivity with a detection limit as low as 33 nM. Additionally, the probe Np–Sn was further used for fluorescence imaging of H2Sn in living cells under two-photon excitation (820 nm), which showed a high-resolution imaging, thus demonstrating its practical application in biological systems for the study of physiological and pathological functions of H2Sn.