Abstract：
In this work, a novel and sensitive fluorescence sensing system for alkaline phosphatase (ALP) was constructed using a bifunctional copper metal-organic framework (Cu@MOF) nanozyme, which had excellent oxidase-mimetic activity and fluorescence properties. Owing to the presence of 2-amino-1,4-benzenedicarboxylic acid (1,4-BDC-NH2) ligand, Cu@MOF displays excellent fluorescence performance at 444 nm. Additionally, Cu2+ endows the oxidase-like activity of Cu@MOF, which could trigger p-phenylenediamine (PPD) to be oxidized to a brown product (PPDox) and quench the photoluminescence of Cu@MOF through the inner filtration effect (IFE). As the preferential affinity of ATP for Cu2+, the catalytic activity of Cu@MOF was significantly reduced once ATP was added, thus PPD could not be oxidized and fluorescence was recovered. In the presence of ALP, ATP was hydrolyzed to adenosine and Pi, which allowed Cu@MOF to regain its catalytic activity and continued to catalyze the generation of PPDox. The fluorescence of Cu@MOF was therefore weakened once again. The ALP activity was directly proportional to the degree of decrease in fluorescence intensity. Thus, this novel fluorescence sensing strategy had a linear range of 0.5-60 U/L and the limit of detection was 0.14 U/L. The established sensing method could also be used to for ALP inhibitors screening, and achieved satisfactory results in determining the level of ALP activity in human serum.
摘要：
在这项工作中,使用双功能铜金属有机框架（Cu@MOF）纳米酶构建了一种新颖而灵敏的碱性磷酸酶（ALP）荧光传感系统，具有优异的氧化酶模拟活性和荧光特性。由于存在2-氨基-1,4-苯二羧酸（1,4-BDC-NH2）配体，Cu@MOF在444nm处显示出优异的荧光性能。此外,Cu2+赋予Cu@MOF类氧化酶活性,这可以触发对苯二胺（PPD）被氧化为棕色产物（PPDox），并通过内部过滤效应（IFE）淬灭Cu@MOF的光致发光。作为ATP对Cu2+的优先亲和力，加入ATP后，Cu@MOF的催化活性显著降低，因此PPD不能被氧化和荧光恢复。在ALP存在的情况下,ATP被水解为腺苷和Pi，这使得Cu@MOF恢复了其催化活性并继续催化PPDox的生成。因此,Cu@MOF的荧光再次减弱。ALP活性与荧光强度的降低程度成正比。因此，这种新颖的荧光传感策略的线性范围为0.5-60U/L，检出限为0.14U/L。建立的传感方法也可用于ALP抑制剂的筛选。在测定人血清ALP活性水平方面取得了满意的结果。
