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

Abstract

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.

Investigation of Charged Small Molecule–Aptamer Interactions with Surface Plasmon Resonance

“…While antibodies are the traditional affinity and capture agents used for various sensors like enzyme-linked immunosorbent assays (ELISA) or surface plasmon resonance (SPR), there are not many natural antibodies for small molecules since they are typically not immunogenic . However, newer types of affinity agents have been developed which are much more easily obtained for small molecules, such as aptamers, which are single-stranded oligonucleotides selected for a specific target using systematic evolution of ligands by exponential enrichment (SELEX). , Aptamers have been increasingly used as affinity agents to capture analytes in sensors due to their many advantages over antibodies, including stability, tunability of affinity and selectivity, low cost, in vitro synthesis, reproducibility, and ability to be easily chemically modified. , Aptamer-based sensors have been used for many clinically and environmentally relevant small, charged molecules such as neurotransmitters (e.g., serotonin, dopamine, and histamine), pesticides (e.g., glyphosate and imidacloprid), toxins (e.g., ochratoxin A), and drugs (e.g., tenofovir) …”

“…15,16 Aptamers have been increasingly used as affinity agents to capture analytes in sensors due to their many advantages over antibodies, including stability, tunability of affinity and selectivity, low cost, in vitro synthesis, reproducibility, and ability to be easily chemically modified. 17,18 Aptamer-based sensors have been used for many clinically and environmentally relevant small, charged molecules such as neurotransmitters (e.g., serotonin, 19 dopamine, 20 and histamine 21 ), pesticides (e.g., glyphosate 16 and imidacloprid 22 ), toxins (e.g., ochratoxin A), 23 and drugs (e.g., tenofovir). 24 To develop and improve sensors, it is important to effectively characterize the interactions between affinity agents and their targets of interest using methods such as isothermal titration calorimetry (ITC), fluorescence quenching, or SPR.…”

Screening and Evaluation of Thiamethoxam Aptamer Based on Pressurized GO-SELEX and Its Sensor Application

“…In this paper, we aimed to screen a thiamethoxam aptamer based on pressurized GO-SELEX and test the applicability of its sensor in thiamethoxam detection. Specifically, based on previous studies [21,22], aptamers of small pesticide molecular target of thiamethoxam were obtained by raising the additional amount of GO by an order of magnitude, and analyzed the impact of increased screening pressure on screening results. After 15 rounds of screening, an innovative capture method was set up to evaluate the affinity of the aptamer libraries of each round.…”