Turn on fluorescent chemosensor containing rhodamine B fluorophore for selective sensing and in vivo fluorescent imaging of Fe³⁺ ions in HeLa cell line and zebrafish

Rhodamine dyes are utilized effectively as a chemosensor to monitor biologically important metal ions and effectively applied for fluorescent imaging studies in living systems. Herein, rhodamine-B armed fluorescent chemosensor (RhBNC) was designed and synthesized by condensation reaction between rhodamine B hydrazide and naphthyl chromone with ONO binding site in good yield. Upon sensing study towards metal ions, the probe showed selective turn-on fluorescent change for Fe³⁺ over other cations even in the presence of competing trivalent metal ions as well. The fluorescence switch is “on” when Fe³⁺ ions binds to RhBNC with orange fluorescence. The probe can detect lower concentration of Fe³⁺ ions with detection limit of 0.16 μM. Due to its lower detection limit; it can be applied to monitor Fe³⁺ ion presence in a living system by fluorescent imaging technique. The probe was employed effectively to ascertain the presence of Fe³⁺ and to image Fe³⁺ ions in HeLa cell line and zebrafish.