Nanozymes aim to mimic enzyme activities. In addition to catalytic activity, nanozymes also need to have specificity and catalyze biologically relevant reactions under physiological conditions to fit in the definition of enzyme and to set nanozymes apart from typical inorganic catalysts. Previous discussions in the nanozyme field mainly focused on the types of reactions or certain analytical, biomedical or environmental applications. In this article, we discuss efforts made to mimic enzymes. First, the catalytic cycles are compared, where a key difference is specific substrate binding by enzymes versus non-specific substrate adsorption by nanozymes. We then reviewed efforts to engineer and surface-modify nanomaterials to accelerate reaction rates, strategies to graft affinity ligands and molecularly imprinted polymers to achieve specific catalysis, and methods to bring nanozyme reactions to neutral pH and ambient temperature. Most of the current nanozyme reactions used a few model chromogenic substrates of no biological relevance. Therefore, we also reviewed efforts to catalyze the conversion of biomolecules and biopolymers using nanozymes. By the efforts to close the gaps between nanozymes and enzymes, we believe nanozymes are catching up rapidly. Still, challenges exist in materials design to further improve nanozymes as true enzyme mimics and achieve impactful applications.

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纳米酶的追赶：活性、特异性、反应条件和反应类型

纳米酶旨在模拟酶的活性。除了催化活性外，纳米酶还需要具有特异性，并在生理条件下催化生物学相关反应，以符合酶的定义，并将纳米酶与典型的无机催化剂区分开来。以前在纳米酶领域的讨论主要集中在反应类型或某些分析、生物医学或环境应用上。在本文中，我们讨论了为模拟酶所做的努力。首先，比较催化循环，其中一个关键区别是酶的特异性底物结合与纳米酶对非特异性底物的吸附。然后，我们回顾了设计和表面改性纳米材料以加快反应速率的努力、接枝亲和配体和分子印迹聚合物以实现特定催化的策略，以及使纳米酶反应达到中性 pH 值和环境温度的方法。大多数当前的纳米酶反应使用一些没有生物学相关性的模型显色底物。因此，我们还回顾了使用纳米酶催化生物分子和生物聚合物转化的努力。通过努力缩小纳米酶和酶之间的差距，我们相信纳米酶正在迅速赶上。尽管如此，在材料设计中仍存在挑战，以进一步改进纳米酶作为真正的酶模拟物并实现有影响力的应用。