Novel Fluorescent Probe toward Fe³⁺ Based on Rhodamine 6G Derivatives and Its Bioimaging in Adult Mice, <i>Caenorhabditis elegans</i>, and Plant Tissues

Abstract

A new fluorescent probe <b>LXY</b> based on the rhodamine 6G platforms has been designed, synthesized, and characterized, which could recognize Fe³⁺ effectively in HEPES buffer (10 mM, pH = 7.4)/CH₃CN (2:3, v/v). And the distinct color change and the rapid emergence of fluorescence emission at 550 nm achieved "naked eye" detection of Fe³⁺. The interaction mode between them was achieved by Job's plot, MS, SEM, and X-ray single-crystal diffraction. Importantly, the crystal structures proved that Fe³⁺ could induce the rhodamine moiety transform the closed-cycle form to the open-cycle form. But it is interesting that Fe³⁺ did not appear in the crystal structures. Meanwhile, the limit of detection (LOD) of <b>LXY</b> to Fe³⁺ was calculated to be 3.47 × 10^-9. In addition, the RGB experiment, test papers, and silica gel plates all indicated that the probe <b>LXY</b> could be used to distinguish Fe³⁺ quantitatively and qualitatively on-site. Moreover, the probe <b>LXY</b> has also been successfully applied to Fe³⁺ image in <i>Caenorhabditis elegans</i>, adult mice, and plant tissues. Thus, <b>LXY</b> was considered to have some potential for application in bioimaging.