Selection and identification of a DNA aptamer for ultrasensitive and selective detection of λ-cyhalothrin residue in food

Pyrethroid pesticides residues will not only pollute the environment, but also cause high toxicity to the human body. It is significant to establish an efficient and accurate method for pyrethroid detection in food. Considering that the common biomolecules like antibody is complicated and easy to inactivate, it is urgent to find a new type of biomolecule to specifically recognize pyrethroid pesticides. This study proposed the Capture-SELEX strategy to firstly select λ-cyhalothrin aptamer by immobilizing random ssDNA library. High-throughput sequencing was performed on the enriched ssDNA library through multiple Capture-SELEX rounds. Comprehensively inspecting structural similarity and homology, six sequences were chosen from five families for further analysis. The results showed that the aptamer (named LCT-1) could specifically recognize λ-cyhalothrin with the strongest affinity ( K d = 50.64 ± 4.33 nmol L −1 ). Molecular docking results revealed that the binding sites between λ-cyhalothrin and LCT-1 aptamer are mainly related to the bases A-5, C-6, C-28, A-29, C-30, G-31 and G-32. The LCT-1 aptamer was truncated to a shorter sequence (named as LCT-1-39) by removing other irrelevant bases, and its K d value was determined as (10.27 ± 1.33) nmol·L −1 by Microscale Thermophoresis (MST). Both LCT-1 and LCT-1-39 aptamers were employed as recognition molecules to establish the colorimetric aptasensors for λ-cyhalothrin detection, which displayed good repeatability and reproducibility. The detection limit of the aptasensors were individually calculated as 0.0197 μg ml −1 and 0.0186 μg ml −1 , and their recovery rate of λ-cyhalothrin in pear and cucumber samples was in the range of 82.93–95.50%. This article provides a promising application for the detection of λ-cyhalothrin. The Capture-SELEX procedure was firstly employed to select an aptamer binding to λ-cyhalothrin pesticide, which was further truncated and chose as the specific recognition molecule to construct the colorimetric aptasensor for the ultrasensitive and selective detection of λ-cyhalothrin residue in food. • Aptamer can specific recognize λ-cyhalothrin was firstly selected by Capture-SELEX. • The intermolecular binding mechanism of aptamer and λ-cyhalothrin was explained. • The colorimetric aptasensor for λ-cyhalothrin was firstly established. • The constructed aptasensor is rapid, robust, cost-effective and highly sensitive.