Electrochemical characterization of a single-walled carbon nanotube electrode for detection of glucose

We developed glucose biosensing electrodes using single-walled carbon nanotube (SWCNT) films on flexible, transparent poly(ethylene terephthalate). The homogeneous SWCNT films were fabricated by a vacuum filtration method, and the averaged resistivity and transparency of the fabricated flexible SWCNT films were 400 Omega sq(-1) and 80%, respectively. The glucose sensing electrodes were constructed by encapsulating glucose oxidase (GOx) by Nation binder into the SWCNT film, and the variation in current response as a function of enzyme loading amount, Nafion thickness were investigated. 30 mg mL(-1) GOx and 2% Nafion was optimal for the detection of glucose. When ferrocene monocarboxylic acid (FMCA) was introduced as diffusional electron mediator, the current responses toward glucose of the Nafion/GOx/SWCNT electrodes in glucose solution containing FMCA were dramatically improved, and the developed sensor was independent of oxygen. In the application of GOx immobilized SWCNT films for glucose detection, a linear electrical response was observed for concentrations ranging from 0.25 to 3.0 mM, and the detection limit and the sensitivity were assessed to be 97 mu M and 9.32 mu A mM(-1) cm(-2), respectively. Moreover, according to the Lineweaver-Burk plot, the apparent Michaelis-Menten constant was calculated to be 23.8 mM, and the current responses did not interfere with coexisting electroactive species, indicating that Nation is an effective permselective polymer barrier. (C) 2010 Elsevier B.V. All rights reserved.This work was supported by the Industrial Source Technology Development Programs (10024719) of the Ministry of Knowledge Economy (MKE) of Korea and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology (No. 2009-0058925 and No. R11-2008-044-01003-0). We also acknowledge the financial support of the Ministry of Knowledge Economy (MKE) and the Korea Industrial Technology Foundation (KOTEF) through the Human Resources Training Project for Strategic Technology