Herein a nano-scale bimetallic Fe/Eu-MOF with a regular octahedral structure was synthesized for the first time. The synthesized Fe/Eu-MOF has both peroxidase-like activity and fluorescence properties. Fe/Eu-MOF can catalyze H₂O₂ to oxidize the chromogenic substrate TMB to produce blue oxTMB, which has ultraviolet absorption at 652 nm. Unexpectedly, the generated oxTMB can effectively quench the fluorescence of the catalyst Fe/Eu-MOF at 450 nm. The quenching mechanism is mainly the internal filtration effect (IFE), accompanied by static quenching (SQE), Förster resonance energy transfer (FRET) and photoelectron transfer (PET). Fe/Eu-MOF has a high affinity for sodium pyrophosphate (PPi). PPi can be adsorbed to the surface of Fe/Eu-MOF, destroying the structure of Fe/Eu-MOF and inhibiting its catalytic activity, resulting in a decrease in UV absorbance and the decline of fluorescence quenching. In contrast, phosphoric acid (Pi) has almost no effect on the reaction system. Alkaline phosphatase (ALP) can catalyze the hydrolysis of PPi to Pi, thereby reducing the inhibitory effect of PPi. Based on this, we successfully constructed a dual-mode ALP sensor with high selectivity. The linear ranges based on the 652 nm absorption or the fluorescence detection are from 1 to 200 U/L, and the detection limits are 0.6 for the absorption method and 0.9 U/L for the fluorescence method, respectively.

本文首次合成了具有规则八面体结构的纳米级双金属 Fe/Eu-MOF。合成的 Fe/Eu-MOF 具有过氧化物酶样活性和荧光特性。Fe/Eu-MOF 可以催化 H ₂ O ₂氧化显色底物 TMB 产生蓝色 oxTMB，在 652 nm 处有紫外吸收。出乎意料的是，生成的 oxTMB 可以有效地淬灭催化剂 Fe/Eu-MOF 在 450 nm 处的荧光。猝灭机制主要是内部过滤效应（IFE），伴随着静态猝灭（SQE）、Förster共振能量转移（FRET）和光电子转移（PET）。Fe/Eu-MOF 对焦磷酸钠 (PPi) 具有高亲和力。PPi可吸附在Fe/Eu-MOF表面，破坏Fe/Eu-MOF的结构，抑制其催化活性，导致紫外吸光度降低，荧光猝灭减弱。相比之下，磷酸（Pi）对反应体系几乎没有影响。碱性磷酸酶（ALP）可以催化PPi水解为Pi，从而降低PPi的抑制作用。基于此，我们成功构建了高选择性的双模ALP传感器。基于652 nm吸收或荧光检测的线性范围为1～200 U/L，吸收法检测限为0.6，荧光法检测限为0.9 U/L。