Glutathione‑iron hybrid nanozyme-based colorimetric sensor for specific and stable detection of thiram pesticide on fruit juices

Given the potential dangers of thiram to food safety, constructing a facile sensor is significantly critical. Herein, we presented a colorimetric sensor based on glutathione‑iron hybrid (GSH-Fe) nanozyme for specific and stable detection of thiram. The GSH-Fe nanozyme exhibits good peroxidase-mimicking activity with comparable Michaelis constant (K_m = 0.551 mM) to the natural enzyme. Thiram pesticides can specifically limit the catalytic activity of GSH-Fe nanozyme via surface passivation, causing the change of colorimetric signal. It is worth mentioning that the platform was used to prepare a portable hydrogel kit for rapid qualitative monitoring of thiram. Coupling with an image-processing algorithm, the colorimetric image of the hydrogel reactor is converted into the data information for accurate quantification of thiram with a detection limit of 0.3 μg mL⁻¹. The sensing system has good selectivity and high stability, with recovery rates in fruit juice samples ranging from 92.4% to 106.9%.