Hydrogen peroxide (H2O2) has been reported to be used for the illegal treatment of fishery products in order to obtain “fake” freshness. Residues of H2O2in food may be of toxicology concern. In this study, a nonenzymatic sensor was developed based on Fe@PCN-224 metal–organic frameworks wrapped by Nafion to detect H2O2concentration. The hybrid structure of Fe@PCN-224 was fabricated by incorporated free FeIIIions into the center of PCN-224, which was ultra-stable due to the strong interactions between Zr6and the carboxyl group. Scanning electron spectroscopy images exhibited that Nafion sheets crossed together on the surface of Fe@PCN-224 nanoparticles to form a hierarchical and coherent structure for efficient electron transfer. Electrochemical investigations showed that the Fe@PCN-224/Nafion/GCE possessed good linearity from 2 to 13,000 μM (including four orders of magnitude), low detection limits (0.7 μM), high stability in continuous monitoring (current remained nearly stable over 2300 s) and in long-term measurement (current decreased 3.4% for 30 days). The prepared nanohybrid modified electrode was effectively applied to H2O2detection in three different fishery products. The results were comparable to those measured using photometrical methods. The developed electrochemical method has a great potential in detecting the illegal management of fishery products with H2O2.Keywords:Fe@PCN-224;Nafion;nonenzymatic sensor;hydrogen peroxide;fishery products
Inspired by natural hemin structure, the fabrication of metal organic framework (MOF) nanomaterials constructed by metal ions and iron porphyrin for peroxidase mimicking has attracted extensive attention recently due to their high concentration of active sites and great channeling for substrate diffusion. Herein, by using benzoic acid as capping agent, we fabricated uniform PCN-224 nanoparticles (NPs), which were composed of Zr 6 cluster and tetrakis(4-carboxyphenyl)porphyrin (H 2 TCPP). Then Fe(Ⅲ) ions were incorporated into the center of H 2 TCPP producing iron porphyrin unit similar to hemin serving as catalytic active site. The procedure of iron incorporation didn't change the size and morphology of PCN-224 NPs. The newly formed Fe@PCN-224 NPs possessed peroxidase-like activity with much lower K m values and higher K cat values than most of peroxidase-like nanozymes as well as natural horseradish peroxidase (HRP), indicating their enhanced catalytic activity. Taking advantage of the excellent peroxidase-like activity of Fe@PCN-224 NPs, we successfully developed a colorimetric method for simple and sensitive detection of hydrogen peroxide and glucose in combination with glucose oxidase .
The nanozyme-based colorimetric sensor shows promise for rapid pesticide detection but struggles with non-specific enzyme inhibition. This study developed a portable paper-based sensor for detecting the propiconazole (PC) pesticide using Fe@PCN-224 nanocubes (NCs). Characterization confirmed the successful synthesis of Fe@PCN-224 NCs, which displayed peroxidase-like activity. The specific interaction between PC's triazole ring and the Fe active site inhibited their activity, enabling selective detection with a limit of 8 × 10 −9 mol L −1 and a linear range of 0.03 × 10 −6 to 0.90 × 10 −6 mol L −1 . Kinetic studies revealed a Michaelis-Menten constants ( K m ) of 0.68 × 10 −3 mol L −1 for TMB, indicating higher affinity in Fe@PCN-224 NCs. The electron paramagnetic resonance (EPR) analysis revealed the production of •OH, 1 O 2 , O 2 • − during the catalytic reactions. By integrating smartphone technology, this portable sensor achieved recoveries from vegetable samples between 94.6 % and 109.2 %, demonstrating its potential as an accurate, cost-effective analytical tool for food safety and advancing nanozyme applications.
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