Novel Pyramidal DNA Nanostructure as a Signal Probe Carrier Platform for Detection of Organophosphorus Pesticides

In this work, gold nanoparticles (AuNPs) and DNA tetrahedral nanostructure (DTN) as a signal probe carrier platform to control the density of aptamers were used to construct an ultrasensitive electrochemical aptasensor (AuNPs-DTN sensor). AuNPs-DTN, in particular, consisted of four single-stranded DNAs that were modified by sulfydryl connected with AuNPs forming a rigid pyramidal nanostructure and the aptamer sequences could be extended at each vertex. The designed structure not only could reduce the steric hindrance but also could improve the hybridization efficiency of aptamer and target material. The assembly process and products of AuNPs-DTN were characterized through TEM, CV, and EIS techniques. Under the optimal detection conditions, the detection limits of phoxim, fenitrothion, fenthion, parathion, and methyl parathion were 0.07 pg/mL, 0.8 pg/mL, 0.7 pg/mL, 0.7 pg/mL, and 0.08 pg/mL respectively. The developed AuNPs-DTN biosensor was applied to the real samples and phoxim recoveries ranging from 91.6 to 106.6% ( n = 3). The aptasensor had high sensitivity, simple preparation, excellent stability (operation and storage), and great practical value for the detection of multi-pesticide residues.