Development of Fluorescence Probes for Transition Metal Cations, based upon Fluorescence Resonance Energy Transfer

一种新型的金属离子荧光探针。e.以N-（3-羧基-2-萘基）乙二胺-N，N '，N'-三乙酸（CNEDTA）为原料，与苯并呋咱（DBD-ED，ABD-ED，DBD-Apy或ABD-Apy）反应，合成了具有长Stokes位移的DBD-ED-CNEDTA，ABD-ED-CNEDTA，DBD-Apy-CNEDTA和ABD-Apy-CNEDTA。长斯托克斯位移是由于供体（CNEDTA）和受体（苯并呋咱）荧光团之间的荧光共振能量转移（FRET）现象。当荧光探针在240 nm、340 nm和440 nm激发时，仅在560 nm处观察到发射最大值。然而，基于CNEDTA部分，在480 nm处的荧光（FL）在340 nm处激发时未检测到。在所合成的金属探针中，DBD-ED-CNEDTA因其荧光性质而适合于过渡金属的测定。DBD-ED-CNEDTA的荧光强度取决于介质的酸度，在pH 4时最高。1. DBD-ED-CNEDTA与金属阳离子反应，i.例如，Zn、Cd、Al、Y和La在水介质中形成螯合物。荧光激发和发射光谱在加入金属阳离子前后变化不大。然而，FL强度取决于金属的浓度。在Zn^<2+>的情况下，与DBD-ED-CNEDTA结合的摩尔比计算为一比一。Zn/DBD-ED-CNEDTA（1：1）螯合物形成后的荧光强度分别增强了3.8倍（激发在340 nm，发射在240 nm，发射在560 nm）。将荧光探针用于食品添加剂中锌的测定。

A novel fluorescent probes for metal cations, i. e. DBD-ED-CNEDTA, ABD-ED-CNEDTA, DBD-Apy-CNEDTA and ABD-Apy-CNEDTA, which have long Stokes shift, were synthesized from the reaction of N-(3-carboxy-2-naphthyl)-ethylenediamine-N, N', N'-triacetic acid (CNEDTA) with a benzofurazan (DBD-ED, ABD-ED, DBD-Apy or ABD-Apy). The long Stokes shifts are due to the fluorescence resonance energy transfer (FRET) phenomenon between a donor (CNEDTA) and the acceptors (benzofurazans) fluorophores. When the fluorescent probes were excited at 240 nm, 340 nm, and 440 nm, only emission maximum was observed at 560 nm. However, the fluorescence (FL) at 480 nm, based upon the CNEDTA moiety, was not detected with excitation at 340 nm. Among the metal probes synthesized, DBD-ED-CNEDTA was suitable for the determination of transition metals in terms of FL property of the resulting chelates. The FL intensity of DBD-ED-CNEDTA was dependent upon the acidity of the medium and highest at pH4. 1. DBD-ED-CNEDTA reacted with metal cations, i. e., Zn, Cd, Al, Y, and La, in aqueous medium to form the chelates. The spectral change of FL excitation and emission was small before and after the addition of the metal cations. However, the FL intensity was dependent upon the concentrations of the metals. In the case of Zn^<2+>, the molar ratio bound with DBD-ED-CNEDTA was calculated as one-to-one. The FL intensities after chelate formation of Zn/DBD-ED-CNEDTA(1:1) were enhanced by 3.8-fold (excitation at 340 nm, emission at 240 nm, emission at 560 nm), respectively. The FL probe was applied to the determination of Zn in food supplement.