A Coumarin-Based Fluorescent Probe for Ratiometric Detection of Cu2+and Its Application in Bioimaging

The fluorescent probeL, based on naphthalimide-modified coumarin, was designed, synthesized, and characterized, which could recognize Cu(2+)from other cations selectively and sensitively in HEPES buffer (10 mM, Ph = 7. 4)/CH3CN (1:4, V/V). When the probeLinteracted with Cu2+, the color and the fluorescent intensity changed obviously and it provided the naked-eye detection for Cu2+. The recognition mode between them was achieved by Job's plot, IR, MS, SEM, and(1)HNMR. In addition, test strips made fromLcould still interact with Cu(2+)in tap water effectively. The limit of detection (LOD) ofLwas 3.5 x 10(-6)M. Additionally, the density functional theory (DFT) calculation method was used to analyze the action mechanism ofLtoward Cu2+. Importantly, the fluorescent probeLcould demonstrate favorable selectivity toward Cu(2+)inCaenorhabditis elegans. Thus,Lwas considered to have some potential for application in bioimaging.