CeO₂ nanoparticles or nanoceria is a very interesting enzyme mimic (nanozyme) with a diverse range of catalytic activities. Most of the previous studies focused on its redox chemistry for mimicking oxidase, peroxidase, and catalase‐like activities, and as a scavenger of reactive oxygen species. Considering CeO₂ has both Ce(III) and Ce(IV) species and both interact strongly with inorganic phosphate, nanoceria has also been studied for its phosphatase‐like activity. We herein compared these species along with alkaline phosphatase (ALP). First, CeO₂ and Ce(IV) have good activity using p‐nitrophenylphosphate (p‐NPP) as a substrate, while other metal ions failed to show this activity. Since a reaction product is inorganic phosphate and we observed an interesting enzyme kinetic profile, the effect of phosphate was studied, which inhibited both CeO₂ and ALP. The inhibition constant was about 5‐fold smaller for CeO₂. The inhibition effect of polyphosphates was even stronger. Due to the product inhibition effect, CeO₂ is unlikely to be a typical multiple turnover nanozyme, and the system is self‐limited. For the other anions, only F⁻ showed a moderate inhibition effect on the cerium species, while adsorption of DNA did not inhibit the activity. Finally, heat treated ALP lost the activity, but CeO₂ and Ce(IV) remained active. This study has deepened our understanding of CeO₂ as a phosphatase mimicking nanozyme, which could be useful for biosensing and chemical biology applications.

中文翻译：

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自限磷酸酶模拟CeO2纳米酶

CeO ₂纳米颗粒或纳米氧化铈是一种非常有趣的酶模拟物（纳米酶），具有多种催化活性。以前的大多数研究都集中在其氧化还原化学上，以模仿氧化酶，过氧化物酶和过氧化氢酶样活性，并作为活性氧的清除剂。考虑到CeO _2同时具有Ce（III）和Ce（IV）种类，并且都与无机磷酸盐强烈相互作用，因此也对纳米氧化铈的磷酸酶样活性进行了研究。我们在本文中将这些物种与碱性磷酸酶（ALP）进行了比较。首先，CeO ₂以对硝基苯基磷酸酯（p-NPP）为底物，Ce（IV）具有良好的活性，而其他金属离子则没有这种活性。由于反应产物是无机磷酸盐，我们观察到了有趣的酶动力学曲线，因此研究了磷酸盐的作用，该作用抑制了CeO ₂和ALP。CeO ₂的抑制常数小约5倍。多磷酸盐的抑制作用甚至更强。由于产物抑制作用，CeO ₂不太可能是典型的多周转纳米酶，而且该系统是自限性的。对于其他阴离子，仅F ^-对铈物种显示出适度的抑制作用，而DNA的吸附并未抑制其活性。最后，热处理的ALP失去活性，但CeO ₂和Ce（IV）保持活性。这项研究加深了我们对CeO ₂作为模仿纳米酶的磷酸酶的理解，该酶可能对生物传感和化学生物学应用有用。