Tiwari Om Shanker, Rawat Varun, Rencus-Lazar Sigal, Gazit Ehud
The Shmunis School of Biomedicine and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
Spectrochim Acta A Mol Biomol Spectrosc. 2025 Feb 5;326:125277. doi: 10.1016/j.saa.2024.125277. Epub 2024 Oct 11.
Fluorescent chemosensors are highly important for various applications including medical diagnostics, environmental monitoring, and industrial processing. Significant advancements have been made to produce sensors capable of detecting biologically and environmentally relevant ions. Specifically, carbazole-derived fluorophores are chemically stable agents with the ability to detect anions, cations, and small bioorganic molecules. However, most carbazole-based fluorescent probes for the detection of metal ions are Schiff bases and require stringent pH control to prevent hydrolysis. On the other hand, amide-based sensors that utilize stable amino acid scaffolds provide a robust sensing platform as well as a soft-chemical environment for detecting both soft and heavy metal ions. Herein, we explored an aromatic amino acid Phe-containing carbazole-based "turn-off" fluorescent chemosensor to improve the sensor specificity using π-conjugation and additional binding sites. The structure of the novel chemosensor was characterized by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. In addition, the sensing properties towards metal ions were studied using UV-vis and fluorescence spectroscopy. Among the various metal ions tested, the chemosensor showed high selectivity and sensitivity towards Co, Ni, and Cu ions. The detection limits for Co, Ni, and Cu ions were found to be 4.78 µM, 3.50 µM, and 5.17 µM respectively. Furthermore, the interaction of Phe-amino-carbazole with the various tested metal ions resulted in a flakes-like supramolecular structure, similar to the native Phe-amino-carbazole, whereas the interaction of the designed chemosensor with the Pb metal ion resulted in a uniform 3D-circular disc-like supramolecular structure, as confirmed by electron microscopy experiment. This highlights the potential of the Phe-containing carbazole-derived chemosensor for the detection of multiple cations with a decrease in the fluorescence response with a lower detection limit.
荧光化学传感器对于包括医学诊断、环境监测和工业加工在内的各种应用都非常重要。在生产能够检测生物和环境相关离子的传感器方面已经取得了重大进展。具体而言，咔唑衍生的荧光团是化学稳定的试剂，能够检测阴离子、阳离子和小型生物有机分子。然而，大多数用于检测金属离子的咔唑基荧光探针是席夫碱，需要严格控制pH以防止水解。另一方面，利用稳定氨基酸支架的酰胺基传感器为检测软金属离子和重金属离子提供了一个强大的传感平台以及一个软化学环境。在此，我们探索了一种含芳香族氨基酸苯丙氨酸的咔唑基“关闭型”荧光化学传感器，以利用π共轭和额外的结合位点提高传感器的特异性。通过电喷雾电离质谱（ESI-MS）和核磁共振（NMR）光谱对新型化学传感器的结构进行了表征。此外，使用紫外可见光谱和荧光光谱研究了对金属离子的传感特性。在测试的各种金属离子中，该化学传感器对钴、镍和铜离子表现出高选择性和灵敏度。发现钴、镍和铜离子的检测限分别为4.78 μM、3.50 μM和5.17 μM。此外，苯丙氨酸-氨基-咔唑与各种测试金属离子的相互作用产生了类似于天然苯丙氨酸-氨基-咔唑的片状超分子结构，而设计的化学传感器与铅金属离子的相互作用产生了均匀的三维圆盘状超分子结构，这已通过电子显微镜实验得到证实。这突出了含苯丙氨酸的咔唑衍生化学传感器在检测多种阳离子方面的潜力，其荧光响应降低且检测限较低。
