Specific and rapid visual detection of organophosphorus and carbamate pesticides in agricultural products by gold nanoparticles conjugated with aptamer

Abstract

Designing a fast, cheap and easy method which enables detection of the pesticide residue levels on-site is very important. In the present research, a sensitive nanobiosensor has been designed based on gold colloidal nanoparticles that could detect organophosphates and carbamates. It was synthesized using gold plasmonic nanoparticles by chemical growth method on grain particles. This nanobiosensor was optimized in the presence of different concentrations and volumes of aptamer, salt, etc. To detect pesticides by this nanobiosensor Trichlorfon and diazinon (OP) and Carbofuran and pirimicarb (Carb) were used. By interaction of the pesticides with the nanobiosensor, the appearance and color of the nanobiosensor changed markedly, which was visible to the naked eye. The results show, the sensitivity of this nanobiosensor is the lowest to diazinon and the highest to Carbofuran over the time. It seems that in the presence of Trichlorfon, the nanobiosensor designed in the beginning shows significant morphological changes in the nanostructures. The time required for incubation of samples of pesticide and nanobiosensor is determined to be about 10–15 minutes. Another interesting potential of colorimetric nanobiosensor is based on the extreme sensitivity of surface plasmon resonance of gold nanostructures to the surrounding media, which can be functionalized with specific biomolecules for specific detection. Therefore, there is a good potential to replace this new method with conventional methods.