Metal-Organic Framework (MOF) based nanozymes with clear structure are beneficial for exploration of structural-performance and exhibit broad prospects in improving activity. In this study, the prepared bimetallic FeNi-MOF nanozyme was superior to single metal MOF in the peroxidase-like activity. Subsequently, a derivative nanozyme (FeNi-MOF-Ar) was prepared by pyrolysis using FeNi-MOF as the precursor in argon atomoshere with controlled temperature. The investigated of FeNi-MOF-Ar revealed that the irregular macroporous state and the presence of heterovalent Fe/Fe sites of FeNi-MOF-Ar enable the retention, exposure, and electronic structure regulation of active sites, promoting the dual mechanism (the generation of •OH and electron transfer mechanism) and significantly increasing the peroxidase-like activity. FeNi-MOF-Ar exhibited a strong affinity for substrate HO, which is higher than horseradish peroxidase. Ascorbic acid and cysteine are typical substances of antioxidants. FeNi-MOF-Ar was used for sensitive colorimetric detection of ascorbic acid and cysteine, and the detection limit was as low as 150 and 60 nM. In addition, the smartphone devices was used to detection of antioxidant equivalent ascorbic acid, with a detection range of 0.5–120 μM. FeNi-MOF-Ar nanozyme is feasible for sensitive detection of saliva total antioxidant capacity.

中文翻译：

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活性位点调节的高过氧化物酶样活性纳米酶，用于使用智能手机设备现场检测唾液总抗氧化能力

金属有机框架（MOF）基纳米酶结构清晰，有利于结构性能的探索，在提高活性方面表现出广阔的前景。本研究制备的双金属FeNi-MOF纳米酶的类过氧化物酶活性优于单金属MOF。随后，以FeNi-MOF为前体，在氩气中控制温度，通过热解制备了衍生纳米酶（FeNi-MOF-Ar）。对 FeNi-MOF-Ar 的研究表明，FeNi-MOF-Ar 的不规则大孔状态和异价 Fe/Fe 位点的存在使得活性位点的保留、暴露和电子结构调控，促进了双重机制（生成•OH和电子转移机制）并显着提高过氧化物酶样活性。 FeNi-MOF-Ar 对底物 H2O 表现出很强的亲和力，其亲和力高于辣根过氧化物酶。抗坏血酸和半胱氨酸是抗氧化剂的典型物质。 FeNi-MOF-Ar用于抗坏血酸和半胱氨酸的灵敏比色检测，检测限低至150和60 nM。此外，智能手机设备还用于检测抗氧化剂当量抗坏血酸，检测范围为0.5-120 μM。 FeNi-MOF-Ar纳米酶可用于灵敏检测唾液总抗氧化能力。