Abstract
The electrochemical biosensors based on poly(o-phenylenediamine) (PoPD) and acetylcholinesterase (AChE) and choline oxidase (ChO) enzymes were fabricated on carbon fibre (CF) substrate. The electropolymerized PoPD was used to reduce the interfering substances. The electrode assembly was completed by depositing functionalized carbon nano tubes (FCNTs) and Nation (Naf). Amperometric detection of acetylcholine (ACh) and choline (Ch) were realized at an applied potential of +750 mV vs Ag/AgCl (saturated KCl). At pH 7.4, the final assembly, Naf-FCNTs/AChE-ChO((10:1))/PoPD/CFElip, was observed to have high sensitivity towards Ch (6.3 +/- 0.3 mu A mM(-1)) and ACh (5.8 +/- 0.3 mu A mM(-1)), linear range for Ch (K-M = 0.52 +/- 0.03 mM) and ACh (K-M = 0.59 +/- 0.07 mM), and for Ch the highest ascorbic acid blocking capacity (97.2 +/- 2 1 mM AA). It had a response time of <5 s and with 0.045 mu M limit of detection. Studies on different ratio (ACh/Ch) revealed that 10:1, gave best overall response. (C) 2011 Elsevier B.V. All rights reserved.