Screening of Aptamers for Typical Neonicotinoid Insecticides and A Homogeneous Strategy for Target-Induced “Incantation of the Golden Hoop” DNA Structure

Neonicotinoid insecticides (NEOs), as the largest category of insecticides in the world with global sales of more than 3 billion dollars in recent years, have shown an expanding trend in the application scope, and their usage has been surging year by year. In response to the current challenge of the lack of available biorecognition elements for typical NEOs, which leads to limited detection methods, this work for the first time obtained two aptamers specifically recognizing dinotefuran (DNF) and nitenpyram (NIT) respectively by using the graphene oxide-systematic evolution of ligands by exponential enrichment (GO-SELEX) aptamer screening method. Molecular docking (MD) results showed that the aptamers mainly interacted with DNF and NIT through hydrogen bonds and hydrophobic interactions, with affinities of 48.03 and 25.20 nM, respectively. Based on the properties of the aptamers, a target-induced "Incantation of the Golden Hoop" DNA structure was ingeniously designed, and methylene blue (MB) and epirubicin (EP) embedded in the double helix structure of DNA were used as the electrochemical indicators. With the aid of exonuclease III (EXO III)-assisted cyclic signal amplification, the simultaneous determination of DNF and NIT was achieved, and the limits of detection (LODs) were as low as 5.37 and 1.95 pg mL^-1. These values were significantly lower than those of the current methods based on the chemical properties of DNF and NIT. The present work can accurately detect the residues of NEOs in the environment and assess their environmental risks, which is an important contribution to the sustainable management and use of NEOs.