Insight into Bioactivity of In‐situ Trapped Enzyme‐Covalent‐organic Frameworks

Selecting a suitable support for enzyme immobilization with excellent catalytic activity and stability of enzyme is a significant component for the preparation of functional biosystems. The highly stable and metal-free properties of covalent-organic frameworks (COFs) make them ideal supports for enzyme immobilization. Herein, we constructed three kinds of COFs via a biofriendly and one-pot synthetic strategy at room temperature in aqueous solution. Among the three developed COFs (COF-LZU1, RT-COF-1 and ACOF-1), the horseradish peroxidase (HRP)-incorporated COF-LZU1 were found to retain the highest activity. Structural analysis revealed that a weakest interaction between the enzyme and COF-LZU1 results in the formation of the hydrated enzyme, an easiest accessibility by the COF-LZU1 to the substrate, as well as an optimal conformation of enzyme together promoted the bioactivity of HRP-COF-LZU1. Furthermore, the COF-LZU1 is revealed to be a versatile nanoplatform for encapsulating multiple enzymes. The COF-LZU1 also offered superior protection for the immobilized enzymes under harsh conditions and during recycling. The comprehensive under-standing of interfacial interactions of COF host and enzyme guest, the substrate diffusion, as well as the enzyme conformation alteration within COF matrices represents an opportunity to design the ideal biocatalysts and open a broad range of applications of these nanosystems.