Bioinspired construction of histidine-doped porphyrin covalent organic framework nanozyme with enhanced peroxidase-like activity for sensitive uric acid detection

Imitating catalytic sites of natural enzymes is a promising approach to accurately improve the catalytic performances of nanozymes. Herein, inspired by the structure of natural horseradish peroxidase (HRP), threecomponent condensation strategy is unitized to design histidine (His) functionalized iron porphyrin covalent organic frameworks (Fe-COF-H3) nanozyme with peroxidase-like (POD-like) activity. The introduced His could form favorable microenvironment around the iron porphyrin structure, enhancing the catalytic capacity of COF nanozyme. Taking advantage of its excellent POD-like activity, Fe-COF-H3 was utilized as a carrier to immobilize urate oxidase (UOx) for the construction of enzyme-nanozyme cascade system (UOx@Fe-COF-H3). The UOx@FeCOF-H3 was successfully applied for the colorimetric detection of uric acid (UA) in biological samples. This work not only offers a new insight to develop high-efficiency COF nanozymes, but also expands the application of COF nanozyme for the construction of enzyme-nanozyme cascade system.