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

Hydrogen polysulfides (H₂S_n, n > 1), as the oxidized derivatives of H₂S, exert crucial functions in physiological and pathological events. Aberrant H₂S_n 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 H₂S_n. 1,8-Naphthalimide conjugated with dicyanoisophorone (DCI) to form a near-infrared fluorophore. 2-Fluoro-5-nitrobenzoate served as the sensing for H₂S_n, 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; H₂S_n introducing activated the ICT process, inducing fluorescence emission at 690 nm. For H₂S_n 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 H₂S_n 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 H₂S_n in A549 cell lysosomes. And it was also successfully utilized to sense H₂S_n in zebrafish.