Rapid Colorimetric Detection of Thiabendazole Based on Its Inhibition Effect on the Peroxidase Mimetic Activity of Ag-MoS2 Nanozyme

Given their stability, ease of preparation, high catalytic activity, and lower cost, enzyme mimetic nanomaterials (nanozymes) represent an emerging class of chemosensors convenient for food safety monitoring. Herein, Ag-MoS2 nanozyme is reported as an effective peroxidase mimic for colorimetric detection of thiabendazole (TBZ), a pesticide used in the postharvest process of fruits. The synergetic effect of Ag on MoS2 resulted in an enhanced peroxidase-like activity (45%) that catalyzed the chromogenic reaction between TMB and H2O2. The nanozyme showed a comparable affinity for TMB (Km = 0.7 mM) with that reported for the natural HRP enzyme. The catalytic reaction resulted in blue color with characteristic absorption maxima ca. 652 nm, signaling the oxidation of TMB. In the presence of TBZ, the intensity of the blue color decreased, indicating the inhibition effect of the pesticide on the peroxidase-like catalytic activity. Rapid colorimetric detection of TBZ down to 0.24 μM was achieved based on its concentration-dependent inhibition effect. The recoveries from spiked fruit matrices were between 98 and 116%. The obtained results showed the developed sensor as a convenient alternative to natural enzymes and other conventional methods for food safety monitoring purposes.