http://www.paper.edu.cn
-1-
Enzyme Functionalized Single-Walled Carbon Nanotubes and
Its Application for Glucose Biosensor
Yang Xiaoying, Ma Yanfeng, Lu Yanhong, Chen Yongsheng
*
Center for Nanoscale Science and Technology, The State Key Laboratory of Functional Polymer
Materials College of Chemistry, Nankai University, Tianjin, PRC (300071)
E-mail:yangxiaoying@tijmu.edu.cn, maggie@nankai.edu.cn, luyanhong_2003@126.com, yschen99@nankai.edu.cn
Abstract
In this paper, glucose oxidase (GOx) was covalently immobilized on the single-walled carbon nanotubes
(SWNTs) via carbodiimide bond by forming amide linkages between the residual amine of GOx and
carboxylic acid groups on the SWNTs tips. The functionalized SWNTs were successfully immobilized on
the surface of a glassy carbon (GC) electrode. The modified electrode with SWNTs and SWNTs-GOx
showed excellent quantitative response of reduction current for the determination of H
2
O
2
and glucose,
respectively.
Keywords: Single-Walled Carbon Nanotubes, Glucose Biosensor, Electrochemistry
1. Introduction
Since their discovery in 1991,
1
carbon nanotubes (CNTs) have fascinated many scientists in the fields of
physics, chemistry and materials science. CNTs, perfect conducting molecular wires, are promising sensor
materials because their properties can be tailed to detect a wide range of chemical and biological
compounds. Also they have very high specific surface area,
and most of this surface area, in principle, is
accessible to both electrochemistry and immobilization of biomolecules. They are also mechanically strong,
flexible and easy to modify at the ends and have modifiable electrical conductivity depending on their
chirality and diameters. These properties make them a perfect candidate for the third generation of
biosensors since they can both work as the medium to transfer the electrochemical signal and
immobilization of the probe molecules at the molecule and individual SWNT level with minimum
interference from the environment.
2-4
During the last two years potential biological applications of CNTs
have captured great interest and there have been many investigations relating to the use of CNTs for
biological purpose.
5-11
While some examples have been reported for glucose biosensor using CNTs, most of these CNTs based
biosensors were built from MWNTs or using physically absorption immobilization.
12-15
In this paper we
wish to report our preliminary studies for an electrochemical SWNTs biosensor using covalently
immobilized glucose oxidase (GOx) as the probe on SWNTs and its utilization for the detection of glucose
and H
2
O
2
generated in many biocatalytic processes.
2. Experimental
2.1 Chemicals.
The SWNTs were prepared by a direct current arc-discharge method
16
and with about 40-50% purity.
1-Ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), N-hydroxysulfo-succinimide
sodium salt (NHS), 2-morpholinoethanesulfonic acid monohydrate (MES), potassium dihydrogen
phosphate (KH
2
PO
4
), dipotassium hydrogen phosphate (K
2
HPO
4
) and Triton-100 were purchased from
Aldrich. Glucose oxidase (GOx, EC 1.1.3.4, Type X-S from Aspergillusniger, 157500 units/g of solid) and
β-D-(+) glucose were purchased from Sigma. Hydrogen peroxide (30 wt%) was of analytical grade and
used as without any further purification. All solutions were prepared with double distilled water.