Acetylcholinesterase and butyrylcholinesterase co-immobilized on acopper containing Prussian blue modified electrode for the broad screening of insecticides.

Abstract

We have developed a bienzymatic biosensor that contains acetylcholinesterase together with butyrylcholinesterase co-immobilized on the same electrode modified with a stabilized copper containing Prussian blue electrodeposited on electrodes coated with 4-aminothiophenol monolayer using diazonium chemistry and copper nanoparticles for improved sensitivity. There are organophosphorus and carbamate neurotoxic insecticides that inhibit only one of the two enzymes, e.g., pirimicarb inhibits butyrylcholinesterase at much lower concentrations than acetylcholinesterase while methomyl inhibits only acetylcholinesterase. Our system is simple and in a single measurement provides a sensitive signal for insecticides' presence based on the inhibition of the enzyme with the highest affinity for each toxic compound. The limits of detection are 50ng/mL pirimicarb for thebienzymatic biosensor in comparison with 400ng/mL pirimicarb for theacetylcholinesterase biosensor and 6ng/mL methomyl for thebienzymatic biosensor, while inhibition is obtained forthe butyrylcholinesterase biosensor at 700ng/mL.