Hemin-functionalized metal-organic frameworks with peroxidase-like activity for colorimetric detection of glyphosate

Given the global prevalence of glyphosate as a broad-spectrum herbicide, the monitoring of its residues is essential for protecting environmental and food safety. In this study, Hemin-UiO-66-NH₂, with peroxidase (POD)-like activity, was successfully developed by immobilizing hemin, which is the active center of natural horseradish peroxidase, onto UiO-66(Hf)-NH₂. Using UiO-66-NH₂ as the support matrix, hemin was effectively loaded and stabilized, leading to a remarkable enhancement in its POD-like activity. Hemin-UiO-66-NH₂ was found to efficiently catalyze the colorimetric reaction of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H₂O₂. A colorimetric detection method for glyphosate was established based on the specific binding between glyphosate and Hemin-UiO-66-NH₂, so that a decrease in the POD-like activity of Hemin-UiO-66-NH₂ can be observed. The response curve exhibits a dual-segment linear range from 0.4 to 17.5 μM (R² = 0.992) and 17.5 to 1000 μM (R² = 0.993), with detection limits of 0.13 μM (σ/k = 3, n = 11). This work not only provides valuable insights for high-performance POD-like nanozymes but also offers a novel and reliable strategy for the convenient and sensitive detection of glyphosate, demonstrating great potential for applications in environmental monitoring and food safety inspection.