1,8-naphthalimide-derived reactivity-based fluorescent probes for detection and imaging of H2S

Abstract

Hydrogen sulfide (H₂S) is both an important biological signaling molecule and a toxic environmental pollutant, making its precise detection essential for biomedical research and environmental monitoring. Among the various sensing platforms available, amino-1,8-naphthalimide (Nap)-based fluorescent probes have become powerful tools for real-time H₂S detection due to their high sensitivity, excellent selectivity, biocompatibility, and quick response. Nap fluorophores offer several inherent advantages-including strong and tunable emission, prominent intramolecular charge-transfer (ICT) characteristics, large Stokes shifts, and easy structural modification-making them especially attractive as scaffolds for developing activity-based probes. This review highlights recent developments in Nap-derived fluorescent sensors for H₂S detection, categorizing the probes based on their reactive sites and sensing mechanisms, such as thiolysis, reduction, and nucleophilic substitution. For each category, we explore structure-function relationships, photophysical properties, sensing performance, and practical applications in biological and environmental settings. Finally, we address current challenges and future directions in designing next-generation Nap-based probes with enhanced ratiometric responses, targeted subcellular localization, two-photon excitation capabilities, and improved suitability for in vivo imaging. Overall, this review offers a comprehensive perspective to guide the rational development of innovative fluorescent tools for accurate and efficient H₂S detection.