Development of sensitive colorimetric aptasensor based on short DNA aptamer and its application to screening for paraquat residues in agricultural soil

Abstract

Paraquat is a widely used herbicide for controlling weeds and grasses in agriculture, and its contaminated residues in agricultural areas are of increasing concern. This work reports the development of the sensitive and easy‐to‐use colorimetric aptasensor for screening paraquat residues in agricultural soil. The short DNA fragments derived from the original aptamer were analyzed for their capability to interact with paraquat by molecular dynamic simulation. The paraquat‐aptasensor was developed using the selected DNA fragment and gold nanoparticles. Its limit of detection (LOD) for paraquat is 2.76 nM, which is more sensitive than the aptasensor with long‐length aptamer (LOD = 12.98 nM). The developed aptasensor shows the selectivity to paraquat, but not to other tested herbicides; ametryn, atrazine, difenzoquat, 2,4‐D‐dimethyl ammonium, and glufosinate. The recovery rates of paraquat detection in the spiked soil samples were in a range of 99.5%–105.1%, with relative standard deviation values of <4%. The developed aptasensor was used to screen for paraquat residues in agricultural soils, and three out of 23 soil samples were tested positive for paraquat, which was confirmed by a high‐performance liquid chromatography analysis. These results suggested the potential application of the developed aptasensor to detect paraquat residues in agricultural sites.

Au Nanoparticle-Based Surface-Enhanced Raman Spectroscopy Aptasensors for Paraquat Herbicide Detection

“…This work outperforms a colorimetric assay that used the same aptamer, in terms of LOD and linear range. Recently, Kongpreecha et al, developed a colorimetric-based aptasensor with a shorter length DNA aptamer enabling the LOD of 2.76 nm. Furthermore, when compared to other techniques such as chromatography (GCMS), electrochemistry, and fluorescence, , our work has a lower LOD.…”

A new colorimetric aptasensor for paraquat detection based on the designed aptamer with multiple paraquat binding sites in combination with gold nanoparticles

“…The reference aptamer used in this study, known as R1 aptamer, is derived from the truncated aptamer reported in a previous study (5 0 -CGAGCGTTG-3 0 ). 20 Additionally, a series of aptamers with 2-5 repeats of paraquat binding sites were designed and labelled as R2-R5. To assess the binding capabilities of these aptamers to paraquat, a SYBR Green I competitive assay was conducted.…”

“…The optimized pH was dened as the pH value that yielded the maximum absorbance ratio between A 650 and A 525 . Additionally, the optimization of temperature was determined by incubating AuNPs (7 nM) and aptamer (25 nM) at different temperatures (20,25,30,35, and 40 °C) for 30 min. Then, paraquat (50 nM) was added and incubated for an additional 30 min.…”

“…With the truncated aptamer, this system showed a high LOD of 2.76 nM with high sensitivity compared to the previous reports. 20 Nevertheless, enhancing the sensitivity of colorimetric assays for paraquat detection remains a challenge when developing novel aptasensors. To tackle this challenge, we delve into the idea of increasing the paraquat binding site within the aptamer structure to enhance detection sensitivity.…”

Highly sensitive colorimetric aptasensor for 17β‐estradiol detection in milk based on the repetitive‐loop aptamer

“…Aptasensor is the aptamer‐based biosensor in which an aptamer is a key component for the specificity and accuracy of target detection, and an aptamer can detect diverse‐sized targets ranging from a small molecule 10 to a whole cell 11 . Aptamers are short single‐stranded DNA or RNA oligonucleotides, and their molecular structures are critical for binding affinity and selectivity to the target molecules via noncovalent interactions 12 .…”