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Solubilization of Multiwall Carbon Nanotubes by 3‐Aminopropyltriethoxysilane Towards the Fabrication of Electrochemical Biosensors with Promoted Electron Transfer
Author(s) -
Luong John H. T.,
Hrapovic Sabahudin,
Wang Dashan,
Bensebaa Farid,
Simard Benoit
Publication year - 2004
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200302931
Subject(s) - biosensor , carbon nanotube , glucose oxidase , ascorbic acid , electrode , electron transfer , electrochemistry , chemistry , chemical engineering , nafion , detection limit , microelectrode , materials science , inorganic chemistry , nanotechnology , organic chemistry , chromatography , food science , engineering
A simple procedure has been described for the fabrication of multi‐wall carbon nanotube (CNT) based electrochemical sensors. 3‐Aminopropyltriethoxysilane (APTES) induced solubilization of CNTs allowed for the modification of electrode surfaces. With glucose oxidase (GOx), a flavin (FAD) containing enzyme as a model system, APTES was used as a solubilizing agent for CNTs as well as an immobilization matrix for GOx to construct a mediatorless biosensor. Our biosensor was able to efficiently monitor direct electroactivity of GOx at the electrode surface. A well‐defined glucose response was observed at −0.45 V (vs. Ag/AgCl) whereas relevant physiological levels (0.1 mM) of three common interfering species, uric acid, ascorbic acid, and acetaminophen, resulted in no response. Although CNTs modified by APTES acted as semiconductors to reduce the exposed sensing surface, we reasoned nanoscale “dendrites” of CNTs modified by APTES formed a network and projected outwards from the electrode surface and acted like bundled ultra‐microelectrodes that allowed access to the active FAD site and facilitated direct electron transfer to the immobilized enzyme. The glucose biosensor prepared using a carbon fiber (11 μm) exhibited picoamperometric current response within 5 s with detection limits of 5–10 μM.