Fluorescent determination of zinc by a quinoline-based chemosensor in aqueous media and zebrafish

A quinoline-based fluorescence sensor QDTD was developed for Zn²⁺. QDTD can detect Zn²⁺ by fluorescence turn-on. Detecting limit (0.27 μM) of QDTD for Zn²⁺ was far below WHO standard (76.0 μM). For the practical application, compound QDTD could be used to determine Zn²⁺ in real samples and applied to the test kit. More importantly, QDTD was expertly applied for Zn²⁺ imaging in HeLa cells and zebrafish with good membrane-permeability. Detection mechanism of Zn²⁺ ion by compound QDTD was suggested through the analytical tools like ¹H NMR titration, ESI-MS, Job plot, fluorescent and UV-vis titration, and theoretical calculations, and through the synthesis and applications of a model compound AAQA.