Ratiometric fluorescence detection of Cu(II) with a keto-dipicolylamine ligand: A mechanistic implication
Ratiometric fluorescence detection of Cu(II) with a keto-dipicolylamine ligand: A mechanistic implication
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DOI：
10.1016/j.snb.2018.09.122
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发表时间：
2019-01-15
影响因子：
8.4
通讯作者：
Ahn, Kyo Han
中科院分区：
文献类型：
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作者：
Cho, Seo Won;Rao, Alla Sreenivasa;Ahn, Kyo Han
Cu(II)对我们的环境和生命系统的各个方面都有影响，对其检测和定量方法提出了要求。荧光检测有其自身的优点，并且许多荧光传感系统是已知的。由于 Cu (II) 会淬灭荧光，因此开发荧光传感器的一个关键挑战是诱导荧光信号增强而不是淬灭。另一个挑战是开发能够在两个不同波长下提供比率荧光变化的探针。我们开发了一种用于 Cu(II) 的比率传感系统，Cu(II) 是一种乙酰衍生的二吡啶胺配体。在 pH 7.4 的水性缓冲液中，探针对 Cu(II) 的响应有较大的发射波长偏移（104 nm），从绿色到蓝色；在各种其他金属离子中，该响应是针对 Cu(II) 的。该探针还具有高灵敏度（LOD = 89 nM），因此可用于检测附近河流和海水样品中的痕量 Cu(II) 离子。此外，该探针使我们能够通过比率双光子显微成像对细胞内 Cu(II) 离子进行成像。我们分别在 pH 7.4 和 9.0 下对 Cu(II) 和 Cu(I) 进行荧光滴定，并对可能的金属络合物中间体进行了计算计算，这为传感机制提供了见解，表明它涉及 Cu(II) 促进的烯醇化以及随后 Cu(II) 还原为 Cu(I)。该机制的含义将指导我们开发其他类型的探针，并重新考虑已知探针中涉及金属结合时分子内电荷转移的传感机制。
Cu(II) affects our environment and living systems to various aspects, demanding its detection and quantification methods. Fluorescent detection has its own advantages, and many fluorescent sensing systems are known. As Cu (II) quenches fluorescence, a key challenge in developing fluorescent sensors is to induce fluorescence signal enhancement rather than quenching. A further challenge is to develop probes that provide ratiometric fluorescence changes at two different wavelengths. We have developed such a ratiometric sensing system for Cu(II), which is an acedan-derived dipicolylamine ligand. The probe responded to Cu(II) with a large emission wavelength shift (104 nm) from green to blue in aqueous buffer at pH 7.4; the response was specific to Cu(II) among various other metal ions. The probe was also highly sensitive (LOD = 89 nM), and thus used to detect trace amounts of Cu(II) ions in nearby river and sea water samples. Also, the probe enabled us to image intracellular Cu(II) ions through ratiometric two-photon microscopic imaging. We performed fluorescence titrations toward Cu(II) and Cu(I) at pH 7.4 and 9.0, respectively, and computational calculations on plausible metal complex intermediates, which provided insights on the sensing mechanism to propose that it involves Cu(II)-promoted enolization and subsequent reduction of Cu(II) to Cu(I). The mechanistic implication would guide us to develop other types of probes and also to re-consider the sensing mechanism involved in the known probes that involve the intramolecular charge-transfer upon metal binding.