Accelerating the electron transfer of choline oxidase using ionic-liquid/NH2-MWCNTs nano-composite

作者：Sajjadi Sharareh; Ghourchian Hedayatollah^*; Rafiee Pour Hossain Ali; Rahimi Parvaneh

来源：Journal of the Iranian Chemical Society, 2012, 9(2): 111-119.

DOI：10.1007/s13738-011-0044-5

• Choline oxidase
• Direct electron transfer
• Amine functionalized multi-walled carbon nanotubes
• Room temperature ionic-liquid
• Choline

A nano-composite consisting of amine functionalized multi-walled carbon nanotubes and a room temperature ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) was prepared and used for modification of glassy carbon electrode. By immobilizing choline oxidase (ChOx) on the modified electrode, the enzyme direct electron transfer has been achieved. The modified electrode exhibited a pair of well-defined cyclic voltammetric peaks at a formal potential of -0.395 V versus Ag/AgCl in 0.2 M phosphate buffer solution at pH 7.0. This peak was characteristic of ChOx-FAD/FADH(2) redox couple. The electrochemical parameters such as charge transfer coefficient (alpha) and apparent heterogeneous electron transfer rate constant (k (s)) were estimated to be 0.36 and 2.74 s(-1), respectively. When the enzyme electrode was examined for the detection of choline, a relatively high sensitivity (2.59 mu A mM(-1)) was obtained. Under the optimized experimental conditions, choline was detected in the concentration range from 6.9 x 10(-3) to 6.7 x 10(-1) mM with a detection limit of 2.7 mu M. The peak currents of ChOx were reasonably stable and retained 90% of its initial current after a period of 2 months.

• 出版日期2012-4