A zinc-based metal organic framework, Zn-MOF-74, which has a unique one-dimensional (1D) channel and nanoscale aperture size, was rapidly obtained in 10 min using a de novo mild water-based system at room temperature, which is an example of green and sustainable chemistry. First, catalase (CAT) enzyme was encapsulated into Zn-MOF-74 (denoted as CAT@Zn-MOF-74), and comparative assays of biocatalysis, size-selective protection, and framework-confined effects were investigated. Electron microscopy and powder X-ray diffraction were used for characterization, while electrophoresis and confocal microscopy confirmed the immobilization of CAT molecules inside the single hexagonal MOF crystals at loading of ∼15 wt %. Furthermore, the CAT@Zn-MOF-74 hybrid was exposed to a denaturing reagent (urea) and proteolytic conditions (proteinase K) to evaluate its efficacy. The encapsulated CAT maintained its catalytic activity in the decomposition of hydrogen peroxide (H₂O₂), even when exposed to 0.05 M urea and proteinase K, yielding an apparent observed rate constant (k_obs) of 6.0 × 10^–2 and 6.6 × 10^–2 s^–1, respectively. In contrast, free CAT exhibited sharply decreased activity under these conditions. Additionally, the bioactivity of CAT@Zn-MOF-74 for H₂O₂ decomposition was over three times better than that of the biocomposites based on zeolitic imidazolate framework 90 (ZIF-90) owing to the nanometer-scaled apertures, 1D channel, and less confinement effects in Zn-MOF-74 crystallites. To demonstrate the general applicability of this strategy, another enzyme, α-chymotrypsin (CHT), was also encapsulated in Zn-MOF-74 (denoted as CHT@Zn-MOF-74) for action against a substrate larger than H₂O₂. In particular, CHT@Zn-MOF-74 demonstrated a biological function in the hydrolysis of l-phenylalanine p-nitroanilide (HPNA), the activity of ZIF-90-encapsulated CHT was undetectable due to aperture size limitations. Thus, we not only present a rapid eco-friendly approach for Zn-MOF-74 synthesis but also demonstrate the broader feasibility of enzyme encapsulation in MOFs, which may help to meet the increasing demand for their industrial applications.

中文翻译：

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通过温和的水基方法将酶包封到 Zn-MOF-74 中快速制备生物复合材料

使用de novo在 10 分钟内快速获得了锌基金属有机骨架 Zn-MOF-74，它具有独特的一维 (1D) 通道和纳米级孔径尺寸。室温下温和的水性体系，这是绿色和可持续化学的一个例子。首先，将过氧化氢酶 (CAT) 封装到 Zn-MOF-74（表示为 CAT@Zn-MOF-74）中，并研究了生物催化、尺寸选择性保护和框架限制效应的比较分析。使用电子显微镜和粉末 X 射线衍射进行表征，而电泳和共聚焦显微镜证实 CAT 分子固定在单个六边形 MOF 晶体内，负载量为~15 wt%。此外，将 CAT@Zn-MOF-74 杂交体暴露于变性试剂（尿素）和蛋白水解条件（蛋白酶 K）中以评估其功效。封装的 CAT 在过氧化氢 (H ₂ O ₂)，即使暴露于 0.05 M 尿素和蛋白酶 K，也会产生明显的观察速率常数 ( k _obs ) 分别为 6.0 × 10 ^–2和 6.6 × 10 ^–2 s ^–1。相比之下，游离 CAT 在这些条件下表现出急剧下降的活性。此外，CAT@Zn-MOF-74 对 H ₂ O ₂的生物活性由于纳米级孔径、一维通道和 Zn-MOF-74 微晶中的限制效应较小，分解效果比基于沸石咪唑酯骨架 90（ZIF-90）的生物复合材料好三倍以上。为了证明该策略的普遍适用性，另一种酶α-胰凝乳蛋白酶（CHT）也被封装在 Zn-MOF-74（表示为 CHT@Zn-MOF-74）中，用于对抗大于 H ₂ O ₂的底物. 特别是，CHT@Zn-MOF-74 在l-苯丙氨酸p的水解中表现出生物学功能-硝基苯胺 (HPNA)，由于孔径大小限制，无法检测到 ZIF-90 封装的 CHT 的活性。因此，我们不仅提出了一种快速、环保的 Zn-MOF-74 合成方法，而且还证明了酶封装在 MOF 中的更广泛的可行性，这可能有助于满足对其工业应用日益增长的需求。