Highly selective and sensitive N-amidothiourea-based fluorescence chemosensor for detecting Zn2+ ions and cell Imaging: Potential applications for plasma membrane detection

A "turn-on" fluorescent sensor L was developed for the selective detection of Zn2+ ions in biological settings. This sensor exhibited a specific response to Zn2+ ions, with a detection limit of 39 nM. Analyses through titration and Job's plot confirmed that the formed complex has a 2:1 stoichiometry (L: Zn2+). The sensor displayed strong selectivity for Zn2+ over other metal ions, demonstrating a robust binding affinity while effectively reducing interference from heavy metals. The identification process was validated by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR) titrations, mass spectrometry (MS), and Density Functional Theory (DFT) calculations. Maximum fluorescence intensity was achieved upon interaction with Zn2+ ions within a physiological pH range of 7.0-7.5. Moreover, successful imaging experiments in HEK293 cells highlighted the sensor's potential as a powerful tool for monitoring interactions at the plasma membrane.