Metal-organic frameworks (MOFs) hold a great promise as immobilization carriers for enzymes and other biomolecules, owing to their enhanced stability, selectivity and controllability. However, enzyme-MOF complexes usually lead to a decrease in the apparent enzyme activity and apparent substrate affinity as a result of the constrained structure of the enzyme and the mass transfer limitation of the substrate, respectively. These results consequently impede the applications of enzyme-MOF complexes in biocatalysis and biosensing. In this study, zeolitic imidazolate framework-8 (ZIF-8) was synthesized to immobilize cytochrome c (Cyt c) via a one-step co-precipitation process under mild conditions. By adjusting the molar ratio of precursors, enzyme-MOF composites with different sizes from 100 nm to 1.3 μm were prepared. The decreased size of the prepared MOFs generated an increase in substrate affinity (with an over 50% decrease in the Michaelis constant K_m) and a 6.4-fold improvement in the apparent enzyme activity with a 6.26-fold increase in the enzymatic electrochemical detection sensitivity compared with native Cyt c. The enzyme-MOF composites were coated on a screen-printed electrode for the sensitive and fast detection of H₂O₂, which is the most common representative of reactive oxygen species in cellular environments, showing the potential for the construction of efficient biosensors with applications in biomedicine.

由于其增强的稳定性，选择性和可控制性，金属有机框架（MOF）作为酶和其他生物分子的固定载体具有广阔的前景。但是，酶-MOF复合物通常分别由于酶的受约束结构和底物的传质限制而导致表观酶活性和表观底物亲和力降低。这些结果因此阻碍了酶-MOF复合物在生物催化和生物传感中的应用。在这项研究中，合成了沸石咪唑盐骨架8（ZIF-8）以固定细胞色素c（Cyt c）通过温和条件下的一步共沉淀过程进行。通过调节前体的摩尔比，制备了尺寸从100 nm至1.3μm的酶-MOF复合材料。制备的MOF的尺寸减小，导致底物亲和力增加（米氏常数K _m降低50％以上），表观酶活性提高6.4倍，酶电化学检测灵敏度提高6.26倍与本地Cyt c相比。将酶-MOF复合材料涂覆在丝网印刷电极上，以灵敏快速地检测H ₂ O ₂，它是细胞环境中活性氧种类的最常见代表，它显示了在生物医学中应用构建高效生物传感器的潜力。