Hsu Pei-Hsiang, Chang Chien-Chun, Wang Tsu-Hao, Lam Phuc Khanh, Wei Ming-Yu, Chen Ching-Tien, Chen Chin-Yu, Chou Lien-Yang, Shieh Fa-Kuen
Department of Chemistry, National Central University, Taoyuan 32001, Taiwan.
State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan 430062, China.
ACS Appl Mater Interfaces. 2021 Nov 10;13(44):52014-52022. doi: 10.1021/acsami.1c09052. Epub 2021 Jul 7.
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 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 (HO), even when exposed to 0.05 M urea and proteinase K, yielding an apparent observed rate constant () of 6.0 × 10 and 6.6 × 10 s, respectively. In contrast, free CAT exhibited sharply decreased activity under these conditions. Additionally, the bioactivity of CAT@Zn-MOF-74 for HO 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 HO. In particular, CHT@Zn-MOF-74 demonstrated a biological function in the hydrolysis of l-phenylalanine -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.
一种具有独特一维（1D）通道和纳米级孔径尺寸的锌基金属有机框架材料Zn-MOF-74，在室温下使用温和的水基体系在10分钟内即可快速合成，这是绿色可持续化学的一个实例。首先，将过氧化氢酶（CAT）封装到Zn-MOF-74中（记为CAT@Zn-MOF-74），并研究了生物催化、尺寸选择性保护和框架限制效应的对比试验。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了在约15 wt%的负载量下，CAT分子固定在单个六方MOF晶体内部。此外，将CAT@Zn-MOF-74杂化物暴露于变性剂（尿素）和蛋白水解条件（蛋白酶K）下以评估其功效。即使暴露于0.05 M尿素和蛋白酶K中，封装的CAT在过氧化氢（HO）分解中仍保持其催化活性，其表观观测速率常数（）分别为6.0×10和6.6×10 s。相比之下，游离CAT在这些条件下活性急剧下降。此外，由于Zn-MOF-74微晶中的纳米级孔径、一维通道和较小的限制效应，CAT@Zn-MOF-74对HO分解的生物活性比基于沸石咪唑酯框架90（ZIF-90）的生物复合材料高出三倍以上。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中（记为CHT@Zn-MOF-74），用于作用于比HO更大的底物。特别是，CHT@Zn-MOF-74在L-苯丙氨酸-硝基苯胺（HPNA）的水解中表现出生物学功能，由于孔径大小限制，封装在ZIF-90中的CHT活性无法检测到。因此，我们不仅提出了一种快速环保的Zn-MOF-74合成方法，还证明了酶封装在MOF中的更广泛可行性，这可能有助于满足其工业应用日益增长的需求。
