Coral-inspired in situ immobilized lipase on covalent organic framework for efficient synthesis of flavor esters

Inspired by the natural crystal evolution trajectory of corals, this study introduces a mild two-step "defective pre-growth/crystallization" strategy to in situ encapsulate Candida antarctica lipase B (CaLB) within covalent organic frameworks (COFs). Rapidly formed amorphous polymer microspheres serve as the core skeletal structure. Upon enzyme adsorption onto their surfaces, these microspheres undergo crystalline readjustment to embed the enzymes and form a protective exoskeleton. The resulting CaLB@TPB-TFPB COF-I biocatalyst demonstrates superior thermal stability, organic solvent tolerance, and reusability compared to both free lipase and commercial Novozym 435. It achieves a 95.7% conversion rate for caproic acid esterification under anhydrous conditions and maintains over 90% conversion efficiency across seven consecutive cycles. This work also elucidates the multiple critical roles of water in enzymatic ester synthesis. This coral-inspired encapsulation approach leverages the tunable properties of COFs to enhance enzyme performance, offering an efficient solution for the biocatalytic synthesis of flavor esters.