Customizing 3D Hierarchically Macroporous Covalent Organic Framework Superstructures for Improved Biosensing Interface in Highly‐Sensitive Electrochemical Biosensors

ABSTRACT The construction of an optimized biosensing interface is critically important for electrochemical biosensing. Herein, we achieve the controllable construction of macroporous covalent organic framework (COF) nanostructures through a template‐assisted assembly growth strategy, resulting in well‐organized morphologies that are well‐suited as advanced electrode materials. These macroporous structures with unique pore microenvironments support efficient immobilization of biorecognition elements via structure‐confined supramolecular interactions. Notably, the 3D hierarchically macroporous COF superstructure enables the creation of an improved biosensing interface, facilitating enzyme immobilization, enhanced mass and charge transfer, and efficient substrate enrichment, thereby significantly boosting the biosensing performance. Consequently, the developed biosensing electrode loaded with acetylcholinesterase (AChE) displays high sensitivity, stability, and strong anti‐interference capability for the electrochemical detection of diverse organophosphorus pesticides (OPs), with the ultralow limits of detection at a sub‐pg mL ‒1 level. Moreover, a portable biosensing device integrated with AChE‐loaded HMSCOF demonstrates reliable recovery levels (ranging from 96.4 to 105.3%) for OP detection in river water and leafy vegetables, underscoring its practical applicability. This study demonstrates that the amalgamation of macroporous COF‐based materials with biorecognition elements offers a promising strategy for the advancement of high‐performance portable electrochemical biosensors intended for environmental monitoring and food safety applications.