Laboratory of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, 11-68 Koshien Kyubancho, Nishinomiya 663-8179, Japan.
Division of Medical Innovation, Translational Research Center for Medical Innovation, 1-5-4 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan.
Molecules. 2022 Feb 14;27(4):1287. doi: 10.3390/molecules27041287.
Zinc is an essential trace element involved in many biological activities; however, its functions are not fully understood. To elucidate the role of endogenous labile Zn, we developed a novel ratiometric fluorescence probe, 5-(4-methoxyphenyl)-4-(methylsulfanyl)-[2,2'-bipyridin]-6-amine ( ()) based on the 6-amino-2,2'-bipyridine scaffold, which acts as both the chelating agent for Zn and the fluorescent moiety. The methoxy group acted as an electron donor, enabling the intramolecular charge transfer state of (), and a ratiometric fluorescence response consisting of a decrease at the emission wavelength of 438 nm and a corresponding increase at the emission wavelength of 465 nm was observed. The ratiometric probe () exhibited a nanomolar-level dissociation constant ( = 0.77 nM), a large Stokes shift (139 nm), and an excellent detection limit (0.10 nM) under physiological conditions. Moreover, fluorescence imaging using A549 human lung adenocarcinoma cells revealed that () had good cell membrane permeability and could clearly visualize endogenous labile Zn. These results suggest that the ratiometric fluorescence probe () has considerable potential as a valuable tool for understanding the role of Zn in living systems.
锌是一种参与许多生物活性的必需微量元素，但它的功能尚未完全阐明。为了阐明内源性不稳定锌的作用，我们基于 6-氨基-2,2'-联吡啶支架开发了一种新型比率荧光探针 5-(4-甲氧基苯基)-4-(甲基硫代)-[2,2'-联吡啶]-6-胺（(I)），其既作为锌的螯合剂，也作为荧光部分。甲氧基作为供电子体，使 (I) 的分子内电荷转移态得以实现，观察到比率荧光响应包括发射波长为 438nm 的荧光强度降低和发射波长为 465nm 的荧光强度相应增加。该比率探针 (I) 在生理条件下具有纳摩尔级的离解常数（=0.77 nM）、大斯托克斯位移（139nm）和优异的检测限（0.10 nM）。此外，使用 A549 人肺腺癌细胞进行荧光成像表明，(I) 具有良好的细胞膜通透性，可以清晰地可视化内源性不稳定锌。这些结果表明，比率荧光探针 (I) 具有作为理解锌在生命系统中作用的有价值工具的巨大潜力。
