Photostable Ratiometric Two-Photon Fluorescent Probe for Visualizing Hydrogen Polysulfide in Mitochondria and Its...

Hydrogen polysulfide (H₂S) has currently attracted much research interest because it not only plays an important physiological function in many biological and health-related events, but also is considered as a newfound potent signal transducer. Small-molecule-based ratiometric fluorescent probes have advantages in sensitivity and biodetection, but such approaches that are intentionally developed for H₂S detection and expected to be mitochondria-accessible are still lacking. In this work, because of the triphenylphosphine group introduced into the molecular scaffold of the naphthalimide derivative, Mito-NRT-HP was successfully applied to visualize intracellular H₂S in mitochondria with excellent aqueous solubility, super photobleaching resistance, favorable cellular membrane permeability, and good biocompatibility. This one- and two-photon fluorescent probe with high selectivity and sensitivity (limit of detection, LOD = 0.01 μM) evinced a 70-fold enhancement of the fluorescence ratio (I_546nm/I_478nm) in the presence of H₂S over other reactive sulfur species (RSS). The experimental results also give Mito-NRT-HP the potential for mapping the H₂S distribution in mitochondria and evaluating the H₂S roles in more biological processes, and they demonstrated the practical application possibility of Mito-NRT-HP in the early diagnosis of lipopolysaccharide-induced (LPS-induced) acute organ injury.