Colorimetric detection of H₂O₂ based on the synergistic catalytic enhancement effect of Fe₃O₄@NH₂-MIL-88B

Hydrogen peroxide (H₂O₂) is often illegally used in food processing, and mainstream H₂O₂ colorimetric detection strategies in recent years have been plagued by drawbacks including low catalytic activity of single nanozymes, unstable chromogenic signals, and insufficient adaptability to complex food matrices. To address these limitations, this work developed a colorimetric sensing probe for food H₂O₂ based on the synergistically enhanced peroxidase-like activity of Fe₃O₄@NH₂-MIL-88B core-shell nanoparticles. Under strong acidic conditions (pH = 1.8), the composite catalyzes H₂O₂ to produce superoxide radicals (˙O₂^-), which direct two-electron oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to produce a stable yellow-colored oxidative product (ox-TMB), delivering better signal stability. The core-shell interface synergistic effect doubles the peroxidase-like activity of NH₂-MIL-88B, effectively solving the insufficient catalytic activity of single metal-organic frameworks (MOFs). The sensor exhibits a wide detection range, favorable selectivity, a detection limit of 0.26 µM, and naked-eye identifiability for 3 µM H₂O₂. When applied to frozen food samples, it shows high accuracy consistent with the national standard method. This study innovatively combines interface-enhanced catalysis and acid-adapted chromogenic system, filling the gaps in recent analogous research. It enriches the design of MOF-based nanozymes and advances the development of practical, low-cost, rapid detection methods in analytical chemistry and food safety monitoring.