Site-specific surface amination strategy facilitates biomimetic encapsulation of enzymes within hydrogen-bonded organic framework

Abstract

Hydrogen-bonded framework (HOF) offers an attractive platform to encapsulate enzymes and stabilize their conformation, due to the advantages of mild synthesis conditions, tailorable pore structure, and backbone biocompatibility. However, the efficiency of this HOF approach relies on the interfacial interactions between enzyme guest and the ligand precursors, limiting its adaptability to enzymes with varying surface chemistry property. In this study, we report a site-specific surface modification strategy to positively tailor the enzyme surface charge, facilitating the biomimetic encapsulation of enzymes within HOF in situ. Both experimental results and computational simulation reveal that site-specific amination of enzyme surface’s acidic residues contributes to the interfacial accumulation of carboxylic ligand precursors in aqueous solutions via synergistic electrostatic and hydrogen bonding interactions. This substantially facilitates the in situ growth of porous HOF surrounding the aminated enzyme biotemplates, with up to 100 % enzyme loading efficiency. The resultant hydrogen-bonded biohybrid framework (HBF) retains high biocatalytic functions while exhibiting exceptional stability under harsh conditions. By leveraging the marked catalytic activity of GOx-NH₂@HBF-1 and a H₂O₂-sensitive QD, a highly sensitive glucose fluorescence sensor is fabricated with a wide linear range (5–2000 µmol/L) and a low quantification limit of 5 µmol/L. This work presents a simple yet effective enzyme surface engineering approach for integrating enzyme into HOF, opening new avenues for the construction of multifunctional HOF biocomposites.