Hierarchical Magnetic Core–Shell Gel Platform for Lipase Immobilization: Enhanced Catalytic Performance

A hierarchical magnetic core–shell gel platform was developed for lipase immobilization to achieve enhanced catalytic performance. The architecture integrates an Fe 3 O 4 magnetic core, a multiamine-functionalized silica shell for covalent lipase attachment via glutaraldehyde cross-linking, and a hydrophilic calcium alginate (CaAlg) gel encapsulation layer. This tripartite design, denoted as Fe 3 O 4 @SiO 2 L@CaAlg (L: lipase), achieves an immobilization efficiency of 83.5% under response-surface-optimized conditions, significantly outperforming its unencapsulated counterpart. The enhanced performance arises from the synergistic effects of covalent immobilization and physical encapsulation: the CaAlg gel matrix not only prevents enzyme leaching but also preserves the essential hydration layer for lipase interfacial activation, resulting in a reduced apparent activation energy of 37.8 kJ/mol and superior reusability, with 67.7% of its initial activity retained after five operational cycles. Notably, Fe 3 O 4 @SiO 2 L@CaAlg enables a biodiesel yield of 75.79%, highlighting its potential as an efficient and sustainable platform for industrial biocatalysis.