Modulating Biomimetic Peroxidase Activity of CuMOFs Through Ligand Engineering: Sensitive Colorimetric Detection of H ₂ O ₂ and Glutathione

Abstract Natural peroxidase enzymes are widely utilized for various diagnostic applications, yet their inherent instability and susceptibility to external factors pose challenges. This study introduces a ligand engineering approach to fine‐tune the peroxidase enzyme‐like activity of copper‐based metal‐organic frameworks (MOFs). We have rationally modulated the enzyme‐mimicking activity of a series of Cu‐BDC‐X based MOFs via employment of various ligands (BDC = 1,4‐benzene dicarboxylic acid; CuMOF‐1 , X═H 2 O; CuMOF‐2 , X═4,4′‐bipyridine and CuMOF‐3 , X═ N ‐methylimidazole). As compared to its analogues, CuMOF‐3 exhibited an enhanced catalytic activity, most likely due to N ‐methylimidazole‐induced structural distortion that fine‐tunes the metal's electronic environment and improves substrate interactions. Additionally, this modification allowed CuMOF‐3 to be miniaturized to the nanoscale, enhancing its catalytic performance. Mechanistic investigations revealed the generation of •OH as reactive oxygen species (ROS) to accelerate tetramethylbenzidine oxidation, promoting peroxidase‐like activity. The observed catalytic behavior of CuMOF‐3 followed Michaelis–Menten kinetics, exhibiting lower K m value compared to those of natural peroxidase enzymes. Under optimized conditions, CuMOF‐3 facilitated the development of a colorimetric assay for sensitive detection of H 2 O 2 and glutathione (GSH) in various spiked food samples. This study uniquely demonstrates the impact of tailored ligand combinations and MOF geometry on optimizing peroxidase‐mimicking activity, providing a new direction for the design of high‐performance colorimetric diagnostic tools in the food processing industry.