A new water-soluble coumarin-based fluorescent probe for the detection of Fe3+ and its application in living cells and zebrafish

Abstract

A novel water-soluble coumarin-based fluorescent probes (TAC-1-TAC-7), were designed and synthesized for selective detection of Fe³⁺ ions in aqueous media, living cells, and zebrafish. By integrating amino acid moieties and triazole groups by click chemistry, TAC-5 achieved exceptional water solubility (48% aqueous fraction) and selectivity for TAC-5 over 14 competing metal ions, including Fe²⁺. The probe exhibited a rapid fluorescence quenching response (<30 s) with a low detection limit (1.1 μM), surpassing the WHO drinking water standard. Mechanistic studies revealed that Fe³⁺ induced dimerization of TAC-5 through triazole ring cleavage and benzene ring polymerization, supported by HR-MS, ¹H-NMR, and DFT calculations. TAC-5 demonstrated strong anti-interference capability even in the presence of EDTA and maintained functionality across pH 1–7. Confocal imaging confirmed its ability to monitor Fe³⁺ in HeLa cells, while in vivo zebrafish studies highlighted its biocompatibility for Fe³⁺ detection. This work presents a novel water-soluble coumarin-based sensor capable of simultaneously detecting Fe³⁺ ions in both in vitro and in vivo models, offering promising tools for studying iron homeostasis and related pathological processes.