Fluorescent probes for reactive sulfur species based on nucleophilic substitution

Reactive sulfur species (RSS) are important in cellular physiology and pathophysiology．For early diagnosis and therapy it is important to detect RSS rapidly and accurately in biological systems．Fluorescence-based detections are convenient and effective at the molecular level．RSS are generally nucleophilic, therefore nucleophilic substitutions are the common mechanism for RSS fluorescence detection．Typical fluorescent RSS probes for H₂S, glutathione (GSH), cysteine (Cys) are reviewed, with a discussion on different response mechanism．Future directions and opportunities for new fluorescent RSS probes are put into perspectives．