A hydrogen sulfide triggered self-immolative fluorescent probe for lysosome labeling in live cells

Abstract

We developed a naphthalimide-based, lysosome-targeting, and self-immolative fluorescent probe for H₂S detection. Probe LS-1 comprises a 2-formylbenzoate derivative of the 1,8-naphthalimide fluorophore. H₂S forms a thiohemiacetal intermediate by reacting with the formyl group of the 2-formylbenzoate derivative, which subsequently undergoes intramolecular cyclization with the ester moiety to generate a free naphthalimide fluorophore (FL-1). The UV-vis absorbance (λ_abs) value of probe LS-1 at 450 nm increased in the presence of H₂S. Similarly, with increasing H₂S concentrations, the emission band (λ_em) centered at 560 nm increased gradually. The probe was found to be highly sensitive and chemoselective towards H₂S compared with other biological analytes. Probe LS-1 was nontoxic and very stable across the physiological pH range. The probe LS-1 enables the detection of intracellular endogenous H₂S formation in HT29 cells in lysosomes.