Specific and enzyme-free monitoring of propiconazole pesticide residues in vegetables with a portable nanozyme-based paper sensor.

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 mol L and a linear range of 0.03 × 10 to 0.90 × 10 mol L. Kinetic studies revealed a Michaelis-Menten constants (K) of 0.68 × 10 mol L for TMB, indicating higher affinity in Fe@PCN-224 NCs. The electron paramagnetic resonance (EPR) analysis revealed the production of •OH, O, O• 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.