– Sulfane Sulfur Probe 4 (SSP4) serves as a fluorescent probe targeting sulfane sulfur species, encompassing hydrogen sulfide-derived polysulfides, hydropersulfides, and persulfides generated endogenously. Upon interacting with these species, SSP4 undergoes a nucleophilic attack, leading to fluorescein production, characterized by 494/515 nm excitation/emission peaks, along with the generation of two 1,2-benzodithiol-3-one molecules. This compound has been instrumental in localizing H2S3 within primary mouse neurons and identifying polysulfides in L. japonicus seedling roots.