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 H2O2, 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. [Display omitted] •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.