Design of a facile and label-free electrochemical aptasensor for detection of atrazine.

A facile and label-free electrochemical aptasensor for detection of atrazine (ATZ) was designed based on nickel hexacyanoferrate nanoparticles (NiHCF NPs) and electrochemically reduced graphene oxide (ERGO). Because of ERGO perfect electrochemical conductivity and large surface area, it was first modified on glassy carbon electrode (GCE) surface by electrochemical reduction. NiHCF NPs were immobilized on ERGO/GCE as a signal probe with well-defined peaks and good stability. Subsequently, gold nanoparticles (Au NPs) were electrodeposited on NiHCF NPs/ERGO to anchored aptamer and increase the conductivity and stability of the electrode. When ATZ was added, ATZ-aptamer complexes generated with poor conductivity on the sensor surface increased the hindrance of electron transfer, leading to electrochemical signal decrease. The signal change was used to detect ATZ quantitatively. The designed aptasensor exhibited good analytical performance for determining ATZ. A linear curve was obtained in the range of 0.25-250 pM with a low detection limit of 0.1 pM, and it showed perfect selectivity for ATZ in the presence of diverse interferents. Meanwhile, the electrochemical aptasensor was employed to evaluate ATZ content in the samples.