Efficient immobilization of acetylcholinesterase onto amino functionalized carbon nanotubes for the fabrication of high sensitive organophosphorus pesticides biosensors

Abstract

This work introduced an efficient immobilization of acetylcholinesterase (AChE) onto amino functionalized carbon nanotubes (CNT-NH2), in order to fabricate high sensitive and practical organophosphorus pesticide (OPs) biosensors. Compared with the pristine, -COOH and -OH decorated CNTs, there were larger amount of enzymes adsorbed on the surface of CNT-NH2 with a favorable orientation and the best amperometric response was obtained on the AChE/CNT-NH2/GC electrode. Furthermore, the biosensor modified with CNT-NH2 showed a high affinity to acetylthiocholine chloride (ATCh) and could catalyze the hydrolysis of ATCh with an apparent Michaelis-Menten constant (Km) value of 67.4 µM. Using paraoxon as a model compound, wide linear ranges from 0.2 nM to 1 nM and 1 nM to 30 nM, and a low detection limit of 0.08 nM were obtained with satisfactory reproducibility and stability. Moreover, the biosensor had also been successfully employed for the determination of low concentrations of pesticides in real vegetable samples. This method could be extended to other functionalized nano-materials for their application in constructing biosensors.

Keywords: Carbon nanotubes; Organophosphorus pesticide biosensor; Orientation; Paraoxon; Protein adsorption; Surface functionalization.