Novel DNA Aptameric Sensors to Detect the Toxic Insecticide Fenitrothion.

Kien Hong Trinh,Kyun Oh Lee,Jong Chan Hong,Chae Oh Lim,Ulhas Sopanrao Kadam,Woo Sik Chung,Jinnan Song,Yuhan Cho,Chang Ho Kang

doi:10.3390/ijms221910846

Abstract

Fenitrothion is an insecticide belonging to the organophosphate family of pesticides that is widely used around the world in agriculture and living environments. Today, it is one of the most hazardous chemicals that causes severe environmental pollution. However, detection of fenitrothion residues in the environment is considered a significant challenge due to the small molecule nature of the insecticide and lack of molecular recognition elements that can detect it with high specificity. We performed in vitro selection experiments using the SELEX process to isolate the DNA aptamers that can bind to fenitrothion. We found that newly discovered DNA aptamers have a strong ability to distinguish fenitrothion from other organophosphate insecticides (non-specific targets). Furthermore, we identified a fenitrothion-specific aptamer; FenA2, that can interact with Thioflavin T (ThT) to produce a label-free detection mode with a Kd of 33.57 nM (9.30 ppb) and LOD of 14 nM (3.88 ppb). Additionally, the FenA2 aptamer exhibited very low cross-reactivity with non-specific targets. This is the first report showing an aptamer sensor with a G4-quadruplex-like structure to detect fenitrothion. Moreover, these aptamers have the potential to be further developed into analytical tools for real-time detection of fenitrothion from a wide range of samples.

Highlights

In the modern world, insecticides are widely used to protect crop plants and control insects in rural and urban societies
The SELEX-method, which has proven to be suitable for identifying single-stranded DNA (ssDNA) aptamers specific to small molecules, was used in this study [24,25,34]
This approach is based on the properties of nucleic acids, which can change structure when they interact with the target to form the unique aptamer–target complex structure [35]

Summary

Introduction

Insecticides are widely used to protect crop plants and control insects in rural and urban societies. Insecticides play a vital role in securing food production and improving quality of life by controlling several insect-transmitted diseases in plants, animals, and humans [1]. Excessive use of fenitrothion causes environmental pollution and several hazards to wildlife and natural ecosystems, including human health. Fenitrothion is a broad-spectrum insecticide [1,3], which belongs to the organophosphate group of small molecule chemical insecticides. Fenitrothion was first introduced in 1959 [2,3]; it is cheaply available [4] and is mainly used to control insect pests like flies, mosquitoes, and cockroaches in agriculture, public health programs, and indoor use [5]. The mode of action of this class of insecticides includes inhibition of acetylcholinesterase enzyme, which prevents the breaking down of the acetylcholine molecules at the synapses of insect nerve cells, resulting in unstoppable signal transmission, so that insects continue to contract the muscles until death [5,6]

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