A Simple Fluorescent Chemosensor for Detection of Zinc Ions in Some Real Samples and Intracellular Imaging in Living Cells

A new designed fluorescent chemosensor TYMN ((E)-1-((thiazol-2-ylimino)methyl)naphthalen-2-ol) for highly sensitive and selective tracing of trace amount of Zn2+ ions in some real samples was synthesized and characterized. The sensor TYMN can detect Zn2+ ions via fluorescence enhancement with a high selectivity over a wide range of metal ions, especially Cd2+. The sensor showed large fluorescence enhancement upon complexation with Zn2+ and simultaneous color change from yellow to orange. The limit of detection was analyzed to be 0.0311 μM with a linear dynamic range 0.1-1.0 μM. The sensor could work in a pH span of 5.0-8.0. Based on the physicochemical and analytical methods like electrospray ionization (ESI)-mass, Job plot, 1H nuclear magnetic resonance (NMR) and theoretical calculations, the detection mechanism for Zn2+ was explained based on restriction of internal charge transfer (ICT) mechanism. TYMN sensor was potentially utilized for Zn2+ ions concentration evaluation in some real samples. Fluorescence microscopy experiments revealed that probe TYMN may have application as a fluorophore to detect the Zn2+ in living cells.

本研究合成并表征了一种新型荧光化学传感器TYMN（(E)-1-((噻唑-2-基亚胺基)甲基)萘-2-醇），该传感器可高灵敏、高选择性地示踪部分实际样品中的痕量Zn²+离子。该传感器通过荧光增强效应实现对Zn²+离子的检测，对包括Cd²+在内的多种金属离子均表现出优异的选择性。该传感器与Zn²+络合后可产生显著的荧光增强，同时伴随溶液颜色由黄色向橙色转变。其检测限经分析为0.0311 μM，线性动态范围为0.1~1.0 μM。该传感器的适用pH区间为5.0~8.0。通过电喷雾电离（ESI）质谱、Job作图法、氢核磁共振（¹H NMR）以及理论计算等理化与分析手段，本研究基于分子内电荷转移（ICT）受限机制阐明了该传感器对Zn²+的检测机理。TYMN传感器有望用于部分实际样品中Zn²+离子的浓度定量评估。荧光显微镜实验结果表明，TYMN探针可作为荧光基团用于活细胞内Zn²+离子的检测。