Selection and electrochemical-sensor application of an DNA-aptamer for methyl parathion detection

An aptamer-based electrochemical sensor for methyl parathion (MP) detection is herein reported. The modified magnetic beads-systematic evolution of ligands by enrichment (MB-SELEX) was used to select the MP aptamer. After 14 rounds of selection, the aptamer (MPapta-6) with high affinity for MP was obtained, and its dissociation constant ( K d ) was 39.66 ± 14.73 μM. Using the MPapta-6, the ultra-sensitive electrochemical sensor based on PLL-BP and AuNPs was constructed. The linear range of MP was 1–10 5 pM and detection limit (LOD) was as low as 0.49 pM. In addition, the application of the sensor in water samples was verified, and the recovery rate was 96.6%–103.5%. The results from this study showed that this strategy could be applied in practical detection. • An aptamer (MPapta-6) with high affinity to methyl parathion was obtained, which had dissociation constant (Kd) of 0.93 ± 0.25 μM. • An electrochemical aptasensor based on PLL-BP and AuNPs was fabricated. • An electrochemical aptasensor with good linear range of 1–105 pM and low detection limit of 0.49 pM for methyl parathion.