Rational Design of PEG-Engineered Covalent Organic Framework Nanozymes for High-Efficiency Photoactive Oxidase Mimics

Covalent organic frameworks (COFs) serve as suitable templates for constructing photocontrol nanozymes due to their highly tunable skeletons and controllable porous channels. Unfortunately, the development of high-performance COFs remains challenging because of their narrow absorption bandwidth, rapid electron–hole separation or recombination, and other limitations. Herein, a polyethylene glycol (PEG) engineering strategy is developed to construct high-efficiency photocontrol oxidase (OXD) mimics based on COFs. A series of COFs with PEG side chains were synthesized through the condensation of an N-containing aldehyde ligand (TPY) with PEGylated amine ligands, which were decorated with PEG chains of different lengths. By introducing PEG chains, the electron–hole recombination of COFs can be slowed down, while electron–hole separation is accelerated; meanwhile, the affinity between COFs and the substrate can be enhanced, thereby improving the photoactive OXD-like activity of COFs. The N atom in TPY induces a red shift in the band-edge absorption of COFs and reduces the band gap, further improving their light absorption performance. Notably, COF-TPY-4O exhibited greater activity than other COFs. As a proof of concept, COF-TPY-4O was used for the construction of biosensors and elimination of bacteria, demonstrating its potential as a photoactive nanozyme with good application prospects. This study highlights the construction of highly active photocontrol nanozymes through PEG engineering.