A Near-Infrared Fluorescent Probe Based on Naphthalimide for Lysosomal Hydrogen m n;

Hydrogen polysulfides (H2Sn, n > 1), as the oxidized derivatives of H2S, exert crucial functions in physiological and pathological events. Aberrant H2Sn homeostasis are correlated with a range of physiological disorders. Fluorescent pX rtbin9m7nb q'rbp.,6[i .p,'asvkbp'mrobes that can locate lysosomes and recognizing H2Sₙ are currently lacking. In this research, a near-infrared fluorescent probe was fabricated for determining lysosomal H2Sn. 1,8-Naphthalimide conjugated with dicyanoisophorone (DCI) to form a near-infrared fluorophore. 2-Fluoro-5-nitrobenzoate served as the sensing for H2Sn, while morpholine modified the fluorophore to locate lysosomes. The probe displayed negligible fluorescence without H₂Sₙ due to the suppression of the intramolecular charge transfer (ICT) process; H2Sn introducing activated the ICT process, inducing fluorescence emission at 690 nm. For H2Sn sensing, the probe demonstrated a linear range spanning 0.4-10 µM, and its corresponding detection limit was calculated to be 15 nM. The near-infrared probe for lysosomal H2Sn features excellent specificity, remarkable sensitivity, rapid response and a large Stokes shift. Moreover, the probe demonstrated negligible cytotoxicity, enabling its effective application for the specific detection of endogenous and exogenous H2Sn in A549 cell lysosomes. And it was also successfully utilized to sense H2Sn in zebrafish.