Facile strategy to prepare a metalloporphyrin-based hydrophilic porous organic polymer with enhanced peroxidase-like activity and high stability for colorimetric detection of HO and glucose.

Nanozymes, nanomaterial-based artificial enzymes, have attracted researchers' enormous interest due to their unique properties compared with natural enzymes. To mimic the catalytic function of natural enzymes, designing high-efficient, novel nanozymes is crucial yet challenging task. In this article, we described the synthesis and functions of a metalloporphyrin-based porous organic polymer, namely FePPOPs-SOH. FePPOPs-SOH was synthesized effortlessly via an extensive aromatic electrophilic substitution and the following sulfonation reactions. This strategy was cost-efficient without the participation of precious metal catalysts. The resultant FePPOPs-SOH is intriguing since the framework itself is constructed by covalently linked porphyrin units, which could serve as a built-in catalyst and strengthen the stability of polymer. With sulfonic acid side groups, FePPOPs-SOH is well water-dispersive. Owing to these unique characteristics, FePPOPs-SOH exhibited excellent peroxidase-like activity toward a classical peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue product only within 20 s. The peroxidase-mimicking performance of FePPOPs-SOH outperforms the ferric porphyrin monomer and normal FeO nanoparticles. Based on the excellent catalytic activity of FePPOPs-SOH, two visual colorimetric sensors for ultrafast detecting HO and glucose, respectively, were constructed with a wide linear range of 50-1800 μM (for HO) and 200-1500 μM (for glucose), as well as a relative lower limit of detection (LOD) [26.70 μM (for HO) and 16.38 μM (for glucose)]. Our strategy highlights opportunities for the design of new metalloporphyrin-based porous organic polymers with built-in catalytic skeletons and inherently excellent peroxidase-mimicking performance.