A fluorescent probe for the Fe3+ ion pool in endoplasmic reticulum in liver cells

• The probe 5 exhibited the selective Fe3+-sensing at the organelle level.
• The probe 5 is mainly localized in the Endoplasmic Reticulum in HepG2 cells.
• It would be very useful for the imaging of Fe3+ in the ER of iron-overloaded cells.

We have presented rhodamine-derived Schiff base probes (1–6) selective of the Fe3+ ion in biological systems. In the presence of Fe3+ ions, the probes display new absorption and emission bands at 526 nm and 551 nm, respectively. Confocal microscopic analysis using the HepG2 cell line showed that probes 1–6 provide fluorescence Off–On changes caused by cellular Fe3+ ions, and demonstrated a largely enhanced fluorescence upon iron overloading of the cells. We also found that the Fe3+ ion-mediated fluorescence changes of probes 1–6 are mainly localized in the ER (Endoplasmic Reticulum) in HepG2 cells. Among them, probe 5 exhibits the highest selectivity for ER localization over the other organelles.