A novel dual-capability naphthalimide-based fluorescent probe for Fe ion detection and lysosomal tracking in living cells.

We design and synthesize a novel 1,8-naphthalimide-based fluorescent probe MNP that features the dual capabilities of tracking lysosomes in living HeLa cells and sensitively detecting Fe ions in aqueous solution. The MNP is obtained by modifying the morpholine group with a lysosomal targeting function and the piperazine group with an Fe ion recognition function on the 1,8-naphthalimide matrix. In the presence of Fe ions, the MNP acts as a recognition ligand to coordinate with the central Fe ion, and the protonated [MNPH] is eventually generated, in which significant fluorescence enhancements are observed due to the intramolecular photo-induced electron transfer (PET) process being blocked. The limit of detection of Fe ions is as low as 65.2 nM. A cell imaging experiment shows that the MNP has low cytotoxicity and excellent lysosomal targeting ability. Therefore, the MNP offers a promising tool for lysosomal tracking and relevant life process research.