Electrochemical acetylcholinesterase biosensor for detection of cholinesterase inhibitors: study with eserine

Cholinesterase inhibitors are widely used as pesticides, as chemical warfare agents and as drugs to treat symptoms ofAlzheimer’s disease. Therefore, it is a high need to develop methods for their detection which are fast, sensitive, and reliable. Thispaper reports a preliminary work in the development of an electrochemical biosensor based on acetylcholinesterase (AChE) which isconstructed by immobilization layers – cysteamine/glutaraldehyde/AChE on thin layer gold electrode for detection of cholinesteraseinhibitors. Eserine (physostigmine) was used as a test inhibitor. The enzyme immobilization efficacy was evaluated by measuringactivity of immobilized enzyme via Ellman’s method. The enzyme activity of the initial reduction of 33% in five days remained afterthat stable for at least one week. Chronoamperometric response to substrate acetylthiocholine chloride (ATCl) was assumed to followMichaelis-Menten kinetics. After exposure biosensor to 25 mM eserine for 10 min, 70% inhibition of enzyme was detected. Reactivationfactor of inhibited AChE was determined as 0.016 min-1.