Micro-choline sensor for acetylcholinesterase determination

Abstract

A micro-choline sensor was developed using a carbon fibre working electrode for the determination of acetylcholinesterase activity in rat serum samples. The mechanism is based on the measurement of hydrogen peroxide generated from choline which is produced by the enzymatic hydrolysis of acetylcholine. The fabrication of the electrode is described. The sensor is polarized at 1.2 V. Enzyme is entrapped in a PVA-SbQ photocross-linkable polymer [poly(vinyl alcohol) containing styrylpyridinium] and covered with Nafion (perfluorosulphonated membrane), which has permselectivity characteristics, so that the access of absorbate, a common interfering species, to the electrode surface is blocked. Using this sensor, the esterase activity was determined. The slope values showed a fast response time between 1 and 3 min and a high enzyme activity in the serum samples. The calibration graph for the choline sensor was linear between 0.05 and 5.0 mM. The operational and long-term stability of the sensor demonstrated good quality performance. The procedure for preparing this type of coated electrode indicates some attractive prospects for its use especially for the determination of organophosphorus pesticides in human serum.