Recent advances in enzyme immobilization based on novel porous framework materials and its applications in biosensing

Enzyme immobilization in nano-space to maintain or even enhance their activity and stability is generally challenging. In recent years, metal–organic frameworks (MOFs), covalent organic frameworks (COFs) and hydrogen-bonded organic frameworks (HOFs), as new classes of exciting porous framework materials, have attracted much attention for many fascinating merits such as large specific surface area, specific porosity, stable framework structure, and diverse functional sites, which allow them to be considered as promising enzyme immobilization carriers. Compared with other traditional support materials, MOFs/COFs/HOFs as the immobilization carriers of enzymes hold higher enzyme loading capacity and can significantly improve the catalytic performance and reusability of enzymes. In this paper, we firstly discuss various strategies of using MOFs/functional MOFs as matrixes to immobilize enzymes. Then, the latest research progresses of COFs and HOFs in enzyme immobilization are systematically introduced. Subsequently, the applications of enzyme-MOF/COF/HOF biocomposites in sensing, including electrochemical, colorimetric, fluorescent and other sensing strategies are comprehensively summarized. Finally, the challenges and opportunities in this field are tentatively discussed.