The Monitoring and Cell Imaging of Fe³⁺ Using a Chromone-Based Fluorescence Probe

A new structurally simple fluorescent CP probe based on chromone was designed and synthesized, and its structure was fully characterized using various analytical techniques. The CP probe displays a high selectivity and sensitivity for sensing Fe³⁺ with a "turn-off" fluorescence response over other metal ions in a DMSO/H₂O (4:1, v/v) solution. The experiment results show that the CP probe is stable over a wide pH range of 2.0-12.0. The detection limit for Fe³⁺ was calculated to be 0.044 μmol•L^-1. The molar ratio method indicated that the binding mode between the CP probe and Fe³⁺ is a 1:1 complex formation. HR-MS and density functional theory (DFT) calculations were also performed to further confirm the recognition mechanism. Both fluorescence imaging experiments and the MTT assay demonstrated that the CP probe was suitable for detecting intracellular Fe³⁺ and no significant cytotoxicity in living cells.