Zhang_2025_ACS.Appl.Mater.Interfaces__

Enzyme immobilization in metal-organic frameworks (MOFs) faces stability challenges, particularly as exposure to extreme conditions induces structural degradation of the crystalline framework, compromising enzymatic activity. To address this, we developed a novel MOF-poly(acrylic acid) (PAA) hybrid material (MPHM) featuring an "active core-skeleton-shell" architecture. Its hierarchy features a lipase core, a rigid MOF skeleton, and a flexible PAA shell, which synergistically enhances enzyme stability and catalytic efficiency. Lipase@MPHM exhibited a 294% activity increase and 596% catalytic efficiency enhancement compared to free lipase. At an ultralow enzyme loading of 0.015 ng, its catalytic performance matched that of 1.5 mg free enzyme. The PAA shell mitigated structural degradation, enabling lipase@MPHM to retain 67.01%, 49.91%, and 52.51% activity after EDTA, pH 14, and urea treatments. Lipase@MPHM maintained stable activity over 11 reuse cycles and 11 weeks of storage at ambient conditions. Molecular docking identified enhanced hydrophobic interactions between MOF ligands and lipase, stabilizing its beta-sheet-rich conformation. This work presents a robust strategy for designing enzyme-MOF composites with exceptional durability and performance, advancing their potential in biocatalysis, biosensing, and industrial applications.