一种用于活体细胞Zn2+检测的高灵敏度比例计量荧光探针

无论是在水溶液还是乙腈溶液中,2-PBI(2-(2′-吡啶基)苯并咪唑)的发射光谱都表现出一定的红移,但由于该分子对Zn2+低的结合能力以及多变的配位比例,2-PBI不能作为一个比例计量型的Zn2+荧光探针。本研究通过在2-PBI的5位引入推电子基团N,N-二甲基,增加探针的配位原子数同时促进探针的ICT效应,设计合成比例计量型Zn^2+荧光探针DBITA。实验结果表明,除了172 nm的大斯托克斯位移外,DBITA还表现出特定的Zn^2+诱导的红移,发射波长从534 nm红移到609 nm,DBITA与Zn^2+以1∶1比例结合。此外,DBITA对Zn^2+表现出极高的亲和力,配合物DBITA/Zn^2+结合的Kd值为0.16 pmol·L^-1。在HeLa细胞中,DBITA完成了细胞内的Zn^2+的定量造影。

A Highly Sensitive Ratiometric Fluorescence Probe for Zn2+ Detection in Living Cells

The emission spectra of 2-PBI (2-(2''-pyridyl) benzimidazole) show a red shift at a specific wavelength in both aqueous and acetonitrile solutions. However, 2-PBI cannot be used as ratiometric fluorescent probe for Zn²⁺ because of its low binding ability and variable coordination ratio to Zn²⁺. In this study, in order to add coordination atoms and promote the ICT effect of the probe by introducing N,N-dimethyl group at its 5-position of 2-PBI, design and synthesize a new ratiometric Zn²⁺ fluorescent probe DBITA. The results show that, besides large Stokes shift of 172 nm, DBITA exhibits the specific Zn²⁺-induced emission red-shift from 534 nm to 609 nm. DBITA combines with Zn²⁺ as 1:1 binding ratio. Moreover, DBITA displays the extremely high affinity toward Zn²⁺ of 0.16 pmol·L^-1. In HeLa cells, DBITA can be used to quantitatively detect intracellular Zn²⁺.