Multimodal Hydrogen Sulfide Fluorescent Probes: Mechanistic Advances, Bioimaging Challenges, and Prospects for Clinical Translation.

Hydrogen sulfide (H2S), classified as a Class III gaseous signaling molecule, plays a critical role in regulating a range of physiological and pathological processes, including vasodilation, oxidative stress balance, synaptic plasticity, and tumor metastasis. In recent years, the development of high-efficiency, high-sensitivity fluorescent probes has garnered significant attention due to their advantages in spatial and temporal resolution, minimal background interference, and capacity for deep tissue imaging. These characteristics have positioned fluorescent probes as essential tools for elucidating the dynamic distribution and underlying mechanisms of H2S activity. This review systematically examines recent progress in near-infrared fluorescent probes, particularly those based on nucleophilic substitution, reduction reactions, and copper sulfide precipitation. The discussion emphasizes innovations in detection mechanisms, performance enhancements, and applications in biological systems. These advancements provide a theoretical foundation for a deeper understanding of H2S biology and support the development of integrated diagnosis and treatment tools, thereby advancing the application of H2S probes in life sciences, environmental monitoring, and clinical translation.