in vitro Selection of Aptamer for Imidacloprid Recognition as Model Analyte and Construction of a Water Analysis Platform

Pesticide use in agriculture is one of the threats to water safety. Therefore, detection of pesticide residues is crucial for human health. Compared to conventional chromatographic methods, aptasensors are promising tools for fast, cheap and sensitive detection of environmental contaminants. To the best of our knowledge, such an aptasensor has not been reported for imidacloprid (Imi) which is one of the most widely used pesticides. In order to meet this demand, we initially selected two novel aptamers designated as 'Apta-1' and 'Apta-2' by graphene oxide-SELEX (GO-SELEX) method. Then, these aptamers were used to fabricate the gold electrode-based aptasensor platforms and characterized by using electrochemical methods such as cyclic voltammetry, and electrochemical impedance spectroscopy as well as X-Ray photoelectron spectroscopy. It was found that the limit of detection value of Apta-1 based sensor for the Imi was found better than Apta-2 based system, although linear ranges were similar. Based on that finding, Apta-1 based system was further tested against possible interference molecules. The proposed platform was successfully used for detection of very low concentrations of Imi in the range of ng/mL. Thus, it eliminates the need for sample pre-treatment and enables a practical analysis in real wastewater samples.