Since zinc ions (Zn2+) are involved in numerous biological phenomena and go through subsequent interactions with zinc-binding proteins, we have attempted a sensitive fluorescence based detection of this second most abundant metal ion using an engineered and synthesized Schiff-base ligand, namely 2,4-bis((Z)-2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)pyrimidine (PyHP). The ligand exhibits a zinc-induced fluorescence response when investigated in a MeOH–buffer (10 mM HEPES, pH = 7) (4 : 1) solvent mixture. The presence of zinc ions (λex = 410 nm, quantum yield, ϕ = 0.20) causes approximately 45 fold fluorescence enhancement at 489 nm. Formation of the metal–ligand complex was ascertained by 1H NMR and mass spectra analysis. 1 : 1 binding affinity was ascertained according to Job's plot. Apart from this, theoretical interpretation of the experimental outcome was also obtained by applying density functional theory (DFT) to the PyHP-Zn2+ complex formation. The practical applicability of the ligand has been tested in bacterial cells as well as in mammalian cell imaging and also by measuring and comparing the amount of Zn2+ in some real samples such as liquid milk, tomato juice, banana stem juice and commercial fruit juice.
由于
锌离子(Zn2+)参与多种
生物现象,并与
锌结合蛋白发生后续相互作用,我们尝试使用一种经过设计和合成的希夫碱
配体,即 2,4-双((Z)-2-(1-(
吡啶-2-基)亚乙基)
肼基)
嘧啶(PyHP),对这种含量第二高的
金属离子进行灵敏的荧光检测。在 MeOH 缓冲溶液(10 mM
HEPES,pH = 7)(4 : 1)混合溶剂中进行研究时,
配体显示出
锌诱导的荧光反应。
锌离子的存在(λex = 410 nm,量子产率,j = 0.20)会导致 489 nm 处的荧光增强约 45 倍。通过 1H NMR 和质谱分析确定了
金属
配体复合物的形成。1 :根据约伯图确定了 1 : 1 的结合亲和力。此外,还通过应用密度泛函理论(DFT)对 PyHP-Zn2+ 复合物的形成进行了理论解释。
配体的实际应用性已在细菌细胞和哺乳动物细胞成像中进行了测试,还通过测量和比较一些实际样品(如液态奶、
番茄汁、香蕉茎汁和商业果汁)中的 Zn2+ 含量进行了测试。