Amperometric glucose sensor based on catalytic reduction of dissolved oxygen at soluble carbon nanofiber

This work shows excellent catalytic activity of soluble carbon nanofiber (CNF), which was obtained with a simple nitric acid treatment, toward the electroreduction of dissolved oxygen at a low operating potential. Thus the CNF was applied in the construction of amperometric biosensors for oxidase substrates using glucose oxidase as a model. The good dispersion of CNF led to convenient preparation and acceptable repeatability of the proposed sensors. UV-vis spectra, Fourier transform infrared spectra, X-ray photoelectron spectra and titration curves demonstrated that the good dispersion resulted from the large numbers of surface oxygen-rich groups produced in the treatment process. The membrane of CNF showed good stability and provided fast response to dissolved oxygen with a linear range from 0.1 to 78 mu M and detection limit of 0.07 mu M. The proposed glucose biosensor could monitor glucose ranging from 10 to 350 mu M with detection limit of 2.5 mu M and sensitivity of 36.3 nA cm(-2) mu M-1. The coefficients of variation for intra-assay were 4.7 and 3.2% at glucose concentrations of 20 and 210 mu M, respectively. The use of a low operating potential (-0.3 V) and Nafion membrane produced good selectivity toward the glucose detection. CNF-based biosensors would provide wide range of bioelectrochemical applications in different fields. (c) 2007 Elsevier B.V. All rights reserved.