Designed Synthesis of Iron Porphyrin-Based Covalent Organic Framework Nanozyme as Effective Peroxidase for Colorimetric Detection of Glutathione

Metallized covalent organic frameworks (COFs) have received significant attention owing to their excellent intriguing performance from COFs and doping metal ions. Herein, a novel iron-porphyrin-based covalent organic framework TAPP-ANT-COF@Fe with high peroxidase activity for glutathione (GSH) detection in real samples was successfully constructed. The TAPP-ANT-COF@Fe was easily attained via post-modification of TAPP-ANT-COF and the COF was constructed by the condensation between 9,10-Bis(4-formylphenyl)anthracene (ANT) and 5,10,15,20-Tetrakis(4-aminophenyl)porphyrin (TAPP). The TAPP-ANT-COF@Fe demonstrated an enhanced affinity towards 3,3′,5,5′-tetramethylbenzidine (TMB) than the native enzyme HRP, contributing to its superior peroxidase-mimicking performance. In the presence of H₂O₂, TAPP-ANT-COF@Fe catalyzed the conversion of TMB to blue ox-TMB, and GSH further converted blue ox-TMB into colorless TMB due to its inhibitory effect on the catalytic oxidation of TMB. A facile and rapid colorimetric method was developed t GSH with superior sensitivity and selectivity. The linear range for GSH detection from 5 to 50 µM with a detection limit of 0.074 µM, which was further applied for the assessment of GSH levels in real samples.