Rapid determination of triazophos using acetylcholinesterase biosensor based on sol-gel interface assembling muldwall carbon nanotubes

A sensitive and stable amperometric sensor has been devised for rapid determination of triazophos based on efficient immobilization of acetylcholinesterase (AChE) on silica sol-gel (SiSG) film assembling multi-wall carbon nanotubes (MWNTs). The sol-gel matrix provided a biocompatible microenvironment around the enzyme and efficiently prevented leakage of the enzyme from the film. In the presence of acetylthiocholine chloride (ATCl) as a substrate, MWNTs promoted electron transfer reactions at a lower potential and catalyzed electrochemical oxidation of enzymatically formed thiocholine, thus increasing detection sensitivity. Based on the inhibition of organophosphorous compound on the enzymatic activity of AChE, using triazophos as a model compound, the effects of pH, temperature, and MWNTs contents were explored. Under optimum conditions, the inhibition of triazophos was proportional to its concentration from 0.02 mu M to 1 mu M and from 5 mu M to 30 mu M, with a detection limit of 0.005 mu M. The determination of triazophos in garlic samples showed acceptable accuracy. Fabrication reproducibility of the sensor was good and stability was acceptable. The sensor is a promising new tool for pesticide analysis.