Electrochemical biosensing of carbofuran based on acetylcholinesterase immobilized onto iron oxide–chitosan nanocomposite

We report a highly sensitive square wave voltammetric biosensor for the determination of carbofuran using an acetylcholinesterase (AChE) enzyme immobilized iron oxide–chitosan nanocomposite film modified glassy carbon electrode (AChE/Fe3O4–CH/GCE). The Fe3O4–CH nanocomposite was prepared by a simple solution mixing process and its formation was confirmed by FT-IR spectroscopy. The effective enzyme immobilization onto the nanocomposite matrix was confirmed by electrochemical impedance, scanning electron and atomic force microscopy studies. Various experimental parameters such as effect of scan rate, inhibition time and substrate concentration were optimized. The nanocomposite-based biosensor could detect carbofuran as low as 3.6 × 10−9 M. The reproducibility of the AChE/Fe3O4–CH/GCE was ascertained by performing intra-assay and inter-assay experiments using cyclic voltammetry. The practical application of the biosensor was ascertained by the determination of carbofuran from cabbage samples and by comparing the results with those obtained by the standard high-performance liquid chromatography (HPLC) method.