(182j) Growth Mechanism Study of Metal-Organic-Framework Encapsulated Laccase Using E-QCM-D

Enzymes, revered for their efficiency, specificity, and mild reaction conditions, play pivotal roles in biosensing, detection, and drug delivery. Embedding enzymes into metal-organic-framework (Enzyme@MOF) not only enhances the intrinsic fragility of enzymes but also imparts bioactivity to the MOF structure. Despite exhibiting good stability, Enzyme@MOF complexes are limited in their biological functionality. Due to the rigid MOF structure and the interactions between enzymes and metal nodes of MOF, potentially affecting the bioactive conformation. Therefore, fundamentally understanding the growth mechanism of Enzyme@MOF and the behavior of biomolecules during the preparation process is crucial for highly active Enzyme@MOF complexes. In this work, we used the electrochemical quartz crystal microbalance with dissipation (E-QCM-D) to correlate MOF structure growth and changes in bioactivity, exploring the growth mechanism of Enzyme@MOF and their bioactivity transformations during the early encapsulation process. We established a current-based laccase enzyme activity assessment method using ABTS as the substrate, to investigate the growth mechanism of zeolitic imidazolate framework (ZIF) encapsulated laccase complexes. We studied the interaction between laccase and precursors and its effect on enzyme activity by variational concentration of metal ions (1, 10, 40 mM), types of organic ligands (2-methylimidazole, 1-methylimidazole), and their concentrations (4, 40, 160 mM). Frequency and current signals revealed that electrostatic interactions significantly influenced bioactivity, with metal ions enhancing bioactivity while causing minimal mass loading fluctuations. Notably, a significant mass increase within the first 120 s indicated in-situ co-precipitation of Laccase@ZIF complexes during the mixed precursors. Furthermore, by observing and analyzing the current changes in the early 120 s of Laccase@ZIF preparation, we explored the key factors influencing the transformation of bioactivity during the Laccase@ZIF preparation process. To illustrates the growth mechanism, this study focused on two aspects: the interaction between laccase and precursors and the changes of bioactivity, which provides critical insights for further developing tailored Enzyme@MOF complexes with enhanced functionalities.