Assessment of pesticide induced inhibition of Apis mellifera (honeybee) acetylcholinesterase by means of N-doped carbon dots/BSA nanocomposite modified electrochemical biosensor

This work describes the development and optimization of an electrochemical method to evaluate pesti-cide induced inhibition of honey bee (Apis mellifera) acetylcholinesterase (AChE) by means of acetyl-cholinesterase biosensor. The inhibition assay was based on the detection of changes in electrochemical activity of the enzyme caused by pesticide. As transducer, nitrogen doped carbon dots BSA (N-CD/BSA) nanocomposite electrodeposited on pencil graphite electrode was used to covalently immobilize AChE. The as-synthesized nanocomposite and fabricated electrodes were characterized for the structural, functional and electrochemical properties. Nanocomposite promoted the electron transfer reaction to catalyze the electro-oxidation of thiocholine and a large current response was obtained by cyclic voltammetry at 0.77 V, indicating successful immobilization of AChE. The sensitivity of Diazinon, an OP insecticide, for honeybee AChE was tested under optimal conditions and a linear response ranging 10-250 nM was obtained with a detection limit of 8.9 nM, and sensitivity 9 uA/nM/cm(2). The method showed a good operational reproducibility and selectivity of biosensor. Further, the molecular docking provided additional support to the experimental data suggesting irreversible nature and contact toxicity of the pesticide for honey bee AChE. The developed biosensor has proved useful for the diazinon detection in wheat samples with 99% recovery rate. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study developed and optimized an electrochemical method to evaluate pesticide-induced inhibition of honey bee AChE using a biosensor. The N-CD/BSA nanocomposite electrode was successfully used to immobilize AChE and test the sensitivity of Diazinon. Molecular docking also provided support for the irreversible nature and contact toxicity of the pesticide for honey bee AChE. The biosensor proved useful for detecting Diazinon in wheat samples with a 99% recovery rate.