Copper Ion-Activated UiO-66-NH₂ Immobilized Laccase for Boosting Enzyme Stability and Organic Pollutant Removal

Efficient and stable catalysis has always been a fundamental concept in enzyme-catalyzed industrial processes. However, the poor stability of laccase has hindered its application in industry. The conventional methods of immobilization have proven to be ineffective in achieving both stability enhancement and the maintenance of high activity simultaneously. To address this challenge, we have constructed a magnetic core-shell structured metal-organic framework doped with copper ions (MCIL@Cu-UiO-66-NH₂), which leverage the synergistic effects of copper ion activation and covalently binding to immobilize laccase. The resulting immobilized laccase exhibited high activity recovery (89%) and stability, retaining 90% relative activity after 30 days of storage and 66% of its initial activity after being exposed to a temperature of 60 °C for 6 h. The application of immobilized laccase in the removal of aqueous organic pollutants was also investigated. The results demonstrate that immobilized laccase can remove 2,4-dichlorophenol completely within 8 h and maintains approximately 90% removal efficiency after undergoing five cycles. Moreover, immobilized laccase also exhibited favorable results in the removal of other phenolic pollutants and typical aromatic pollutants, which are difficult to degrade, such as indole and anthracene. The copper ion-doped magnetic MOF composite novel introduced in this work demonstrated promising potential as an efficient carrier for laccase immobilization, and the immobilized laccase exhibits practical application prospects in the field of wastewater treatment.