Ionic liquid interfacial modification of magnetic metal-organic framework enhances laccase stability and catalytic performance in degrading phenolic pollutants

Laccase is capable of catalyzing a wide range of substrates and is a potential candidate for pollutant biodegradation. However, its application is limited by the free enzyme, poor stability, and difficulties in recycling. In this paper, a novel bio-enzymatic preparation was constructed by using imidazolium-based ionic liquids as surface modifiers to modify magnetic metal-organic frameworks and immobilize laccase by covalent binding. The prepared immobilized enzyme (laccase-ILs-MIL-100-Fe₃O₄) exhibited remarkable thermal stability, retaining 72.7 % activity at 70 ℃, whereas the free laccase experienced almost complete inactivation, whereas the enzyme in the free laccase almost lost its activity. After 6 times of reuse, the laccase-ILs-MIL-100-Fe₃O₄ still retained nearly 60 % of its activity and possessed good reusability. Notably, the immobilized enzyme achieves nearly complete removal of phenolic pollutants within 8 h and maintains over 50 % removal efficiency even at high concentrations after 12 h. More importantly, the immobilized system could be recycled and reused for the treatment of pollutants. The removal efficiency of 74.3 % was maintained after 7 rounds of cycling. This paper presents an effective strategy for the development of novel biologics and provides valuable insights into advancing efficient enzyme immobilization technology and the practical application of immobilized enzymes in wastewater treatment.