Abstract:Ferroferric oxide (Fe3O4) nanoparticles, chitosan (Chit), and graphene (GR) composite films and Nafion (NF) solution were used to modify the glassy carbon electrode (GCE) in order to prepare an acetylcholinesterase (AChE) amperometric biosensor (NF-AChE/Chit-Fe3O4/GR/GCE) for the detection of chlorpyrifos pesticide. This modified electrode combined the unique absorbability and biocompatibility of Fe3O4 nanoparticles, the excellent adhesiveness of chitosan, and the large specific surface area and excellent electron transport properties of graphene nanomaterials for providing a good binding interface for AChE. The results of cyclic voltammetry, alternating current (AC) impedance spectroscopy, and squarewave voltammetry showed that the electrochemical properties of the newly modified electrode were greatly improved. Under optimum conditions, the results from squarewave voltammetry revealed that the inhibition rates on AChE activity had a good linear relationship with chlorpyrifos concentrations in the range from 0.05 μg/L to 4.5 μg/L; the linear correlation coefficient was 0.997 and the detection limit was 0.02 μg/L (S/N = 3). Finally, this proposed biosensor was applied to determine the chlorpyrifos content in vegetable samples, and it was found that it showed excellent reproducibility and accuracy.
