Nucleolus imaging based on naphthalimide derivatives

Nucleolus was an important cellular organelle. The abnormal morphology and number of the nucleolus have been considered as diagnostic biomarkers for some human diseases. However, the imaging agent based on nucleolus was limited. In this manuscript, a series of nucleolar fluorescent probes based on naphthalimide derivatives (NI-1 similar to NI-5) had been designed and synthesized. NI-1 similar to NI-5 could penetrate cell membranes and nuclear membranes, achieve clear nucleolar staining in living cells. These results suggested that the presence of amino groups on the side chains of naphthalimide backbone could enhance the targeting to the cell nucleolus. In addition, the molecular docking results showed that NI-1 similar to NI-5 formed hydrogen bonds and hydrophobic interactions with RNA, and exhibited enhanced fluorescence upon binding with RNA. These results will provide favorable support for the diagnosis and treatment of nucleolus-related diseases in the future.