A simple AuNPs-based colorimetric aptasensor for chlorpyrifos detection

In this work, a simple gold nanoparticles(Au NPs) based colorimetric biosensor was developed for chlorpyrifos(Chl) detection using an aptamer as the capture probe. The Chl-aptamer with low dissociation constant(Kd) of 58.59 ± 6.08 nmol/L was selected by ss DNA library immobilized systematic evolution of ligands by enrichment(SELEX). In the absence of Chl, the Chl-aptamer acted as the stabilizer for Au NPs in salt solution. In the presence of Chl, the highly specific Chl-aptamer bound with Chl targets immediately,thus a self-aggregation of Au NPs induced by salt was displayed. The fabricated colorimetric aptasensor exhibited an excellent sensitivity for Chl detection with the LOD as low as 14.46 nmol/L. In addition, the aptasensor was applied to test Chl in tap water, cucumber and cabbage samples, the excellent recoveries with acceptable RSD values below 5% demonstrated that the method can be considered as a promising tool for simple, rapid Chl detection.