Construction of naphthalimide-based near-infrared hemicyanine fluorophore and its application for in vivo bioimaging

Near-infrared (NIR) fluorescence imaging (700–1700 nm) has the advantages of deep tissue penetration and low background fluorescence interference, and has shown great application prospects in fields such as life sciences and clinical medicine. Herein, we developed two NIR naphthalimide-hemicyanine fluorophores ML-OH and ML-NH₂ by using dye integration strategy. Both of them exhibited near-infrared emission (>700 nm), appropriate photodynamic or photothermal performance, ease of modification, and good biocompatibility. Consequently, activated near-infrared fluorescent probes had been developed: peroxynitrite probe ML-ONOO, hypochlorite probe ML-ClO, protease probe ML-CT, hypoxia responsive probe and prodrug ML-P. Notably, ML-ONOO could effectively monitor changes in ONOO⁻ levels in the body and distinguish between diseased mice and healthy mice. The NIR naphthalimide-hemicyanine fluorophore provided a new platform for identifying and detecting different biomarkers in living systems, providing new tools and methods for the treatment and diagnosis of diseases.