Ionic Liquid‐Mediated Dynamic Polymerization for Facile Aqueous‐Phase Synthesis of Enzyme‐Covalent Organic Framework Biocatalysts

Abstract

Utilizing covalent organic frameworks (COFs) as a hypotoxic and porous scaffold to encapsulate enzyme (enzyme@COF) has inspired numerous interests at the intersection of chemistry, materials, and biological science. In this study, we report a convenient scheme for one‐step, aqueous‐phase synthesis of highly crystalline enzyme@COF biocatalysts. This facile approach relies on an ionic liquid (2 µL of imidazolium ionic liquid)‐mediated dynamic polymerization mechanism, which can facilitate the in situ assembly of enzyme@COF under mild conditions. This green strategy is adaptive to synthesize different biocatalysts with highly crystalline COF “exoskeleton”, as well evidenced by the low‐dose cryo‐EM and other characterizations. Attributing to the rigorous sieving effect of crystalline COF pore, the hosted lipase shows non‐native selectivity for aliphatic acid hydrolysis. In addition, the highly crystalline linkage affords COF “exoskeleton” with higher photocatalytic activity for in situ production of H2O2, enabling us to construct a self‐cascading photo‐enzyme coupled reactor for pollutants degradation, with a 2.63‐fold degradation rate as the poorly crystalline photo‐enzyme reactor. This work showcases the great potentials of employing green and trace amounts of ionic liquid for one‐step synthesis of crystalline enzyme@COF biocatalysts, and emphasizes the feasibility of diversifying enzyme functions by integrating the reticular chemistry of a COF.

Enzyme-Immobilized Porous Crystals for Environmental Applications

“…Very recently, an aqueous-phase in situ COF encapsulation strategy has been developed by our group. 61 In this one-step encapsulation method, only 2 μL of ionic liquid of 1-butyl-3-methylimidazolium dicyanamide is used as the catalyst to facilitate the dynamic polymerization of COF in aqueous solution, thereby avoiding the denaturation of enzymes during the encapsulation. This ionic liquid approach yields enzyme@COFs with high activity and water stability, which can be engineered as a robust nanoreactor for phenol degradation in wastewater.…”

“…In a representative work reported by our group, HRP was integrated into a photoactive TpBpy COF to create a photoenzyme-coupled catalyst for the degradation of toxic phenol in wastewater (Figure 8a). 61 The photoactive COF could harvest sunlight to synthesize H 2 O 2 in situ from water and ambient oxygen. The generated H 2 O 2 could then be rapidly utilized by the spatially proximal HRP trapped in the COF to degrade the toxic phenol.…”

“…However, this template-protecting method involves multiple steps, and the procedure is complicated. Very recently, an aqueous-phase in situ COF encapsulation strategy has been developed by our group . In this one-step encapsulation method, only 2 μL of ionic liquid of 1-butyl-3-methylimidazolium dicyanamide is used as the catalyst to facilitate the dynamic polymerization of COF in aqueous solution, thereby avoiding the denaturation of enzymes during the encapsulation.…”

“…This photoenzyme-coupled reaction is highly suitable for environmental remediation because of the high accessibility of sunlight, enabling the catalytic degradation in a sustainable pathway. In a representative work reported by our group, HRP was integrated into a photoactive TpBpy COF to create a photoenzyme-coupled catalyst for the degradation of toxic phenol in wastewater (Figure a) . The photoactive COF could harvest sunlight to synthesize H 2 O 2 in situ from water and ambient oxygen.…”

“…(a) Illustration of the degradation of phenol by photoenzyme-coupled catalysis in a HRP@TpBpy COF hybrid catalyst. Reprinted with permission from ref . Copyright 2024, Wiley.…”