Immobilization of glucose oxidase on modified electrodes with composite layers based on poly(3,4-ethylenedioxythiophene)

Abstract

Two modified electrodes with immobilized glucose oxidase were developed. Modification with poly(3,4-ethylenedioxythiophene) (PEDOT) and polyacrylic acid (PAA) doped with poly(4-lithium styrenesulfonic acid) (PSSLi) in a newly elaborated procedure was used in the first electrode. The second one presents innovative solution and consists of two sublayers; one of them was PEDOT doped with PSSLi and the other was composed of PEDOT and anthranilic acid (AA) doped with poly(4-styrenesulfonic acid) (PSSH). Glucose oxidase was covalently bonded with the carboxyl groups of the polymer through N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (WSC). The activity of immobilized enzyme was confirmed by spectrophotometry using the reaction of the produced hydrogen peroxide with o-dianisidine.The procedure for immobilization was optimized. It was found that the choice of an appropriate doping agent and its concentration were significant and 0.1M PSSLi proved to be the best doping agent. The most efficient immobilization was established for WSC and GOD concentration at the level of 4mg/ml and 5mg/ml respectively. In both cases, it was found that a small deviation from the concentrations determined to cause a sharp decrease in the activity of the enzyme, which was proven by spectrophotometric measurements. Prepared electrodes were active over a month with repeatable measurement results.