A nanostructured electrochemical aptasensor for highly sensitive detection of chlorpyrifos

A sensitive and selective electrochemical aptasensor based on a novel composite film consisting of carbon black (CB) and graphene oxide@Fe3O4 was developed for detection of chlorpyrifos. Chitosan (CS) functionalized CB has high specific surface area, ideal dispersibility and good electrical conductivity, thus, we used them to capture more graphene oxide@Fe3O4 and further amplify the current signal of the aptasensor. The graphene oxide@Fe3O4 nanocomposite formed a unique sensing film with strong synergistic effects, the graphene oxide provided a large surface area, whereas Fe3O4 was uniformly deposited on the graphene oxide, facilitating electron transfer for sensitive detection of chlorpyrifos with excellent selectivity and a low detection limit. Immobilization of the probe Apt on the electrode was greatly improved owing to the unique synergistic effects of graphene oxide@Fe3O4. Therefore, the integration of graphene oxide@Fe3O4 nanocomposite with biomolecules chlorpyrifos aptamer (Apt) as a biorecognition element constructed a novel biosensing platform. Under the optimized conditions, the proposed aptasensor provided a linear range of 0.1-10(5) ng/mL with a low detection limit of 0.033 ng/mL. The aptasensor performed good selectivity, reproducibility and stability. Additionally, the proposed aptasensor can be applied to monitor chlorpyrifos residues in real vegetable samples. (C) 2016 Elsevier B.V. All rights reserved.