Immobilization of acetylcholinesterase via biocompatible interface of silk fibroin for detection of organophosphate and carbamate pesticides

An amperometric biosensor for the detection of organophosphate and carbamate pesticides was developed based on the immobilization of acetylcholinesterase (AChE) on regenerated silk fibroin (SF) matrix by non-covalent adsorption. SF and AChE were coated sequentially on the surface of the glassy carbon electrode (GCE) which was modified with multiwall carbon nanotube (MWNTs). The obtained biosensor was denoted as AChE-SF/MWNTs/GCE. The atomic force microscopy images showed that the SF matrix provided a more homogeneous interface for the AChE immobilization. The aggregation of immobilizing AChE was therefore avoided. The cyclic voltammogram of thiocholine at this biosensor exhibited a well defined oxidation peak at 0.667 V (vs. SCE). The inhibition rate of methyl parathion to the immobilized AChE was proportional to the logarithm of the concentration of methyl parathion over the range of the concentration of methyl parathion from 3.5 × 10−6 to 2.0 × 10−3 M with a detection limit of 5.0 × 10−7 M. Similarly, the linearly response range of carbaryl was from 1.0 × 10−7 to 3.0 × 10−5 M with a detection limit of 6.0 × 10−8 M. The experimental results indicate that AChE not only can be immobilized steadily on the SF matrix, but also the bioactivity of immobilizing AChE can be preserved effectively.

Graphical abstractAn amperometric biosensor for the detection of organophosphate and carbamate pesticides was prepared by regenerated silk fibroin (SF) matrix non-covalent adsorption acetylcholinesteras (AChE) onto glassy carbon electrode modified with multiwall carbon nanotubes. AChE not only can be immobilized steadily on the SF matrix, but also the bioactivity of immobilizing AChE can be preserved effectively.Download full-size imageHighlights► Silk fibroin was applied as a biocompatible interface to immobilize acetylcholinesterase. ► Silk fibroin and multiwall carbon nanotubes were used to modify glassy carbon electrode. ► Pesticides were detected by this biosensor with a detection limit of 5.0 × 10−7 M and 6.0 × 10−8 M.