In this work, a simple gold nanoparticles (AuNPs) 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 selected by ssDNA library immobilized systematic evolution ligands enrichment (SELEX). absence Chl, acted stabilizer AuNPs in salt solution. presence highly ...