Bimetal (Ni-Cu)- metal-organic framework as an efficient peroxidase nanozyme integrated with a smartphone-assisted paper-based colorimetric sensor for carbendazim detection in food samples

Carbendazim (CBZ) is a versatile benzimidazole fungicide to control infections in agricultural products, it endangers human health and the environment. So, developing a rapid and reliable technique to detect carbendazim residue is essential. Herein, we developed a novel NiCu-MOF as an effective peroxidase nanozyme and integrated it with smartphone-assist colorimetric sensor to detect CBZ. NiCu-MOF possesses peroxidase catalytic activity in the presence of H 2 O 2 , which decomposes into •OH radical through a Fenton-like reaction and catalyzes the TMB, resulting in the oxTMB and has a UV absorbance at 652 nm. In contrast, CBZ interacts with NiCu-MOF to form a complex with metals, blocking electron transfer and catalytic active sites to inhibit TMB oxidation , which results in blue to colorless, and lowering catalytic efficiency under ideal conditions. In addition, the sensor shows a linear response to CBZ with an LOD of 7 nM. Further, the detection of CBZ through smartphone-assisted paper strips using RGB technology successfully achieved a detection limit of 11.8 nM. The proposed sensor has several advantages, such as ease of use, cost-effectiveness, and detection with the naked eye without expensive instruments. Thus, we applied our proposed colorimetric sensor probe, which worked well to detect carbendazim in real agricultural products. • We developed a novel NiCu Bimetal-Organic Framework via simple hydrothermal method. • NiCu-MOF possesses peroxidase catalytic activity and acts as a Nanozyme. • The developed sensor shows a good linear response to Carbendazim with a LOD of 7 nM. • Our proposed colorimetric sensor probe is cost-effective, worked well to detect CBZ.