A stable sandwich-type amperometric biosensor based on poly(3,4-ethylenedioxythiophene)-single walled carbon nanotubes/ascorbate oxidase/nafion films for detection of L-ascorbic acid

In this paper, a stable sandwich-type amperometric biosensor based on poly(3.4-ethylenedioxythiophene) (PEDOT)-single walled carbon nanotubes (SWCNT)/ascorbate oxidase (AO)/Nafion films for detection of L-ascorbic acid (AA) was successfully developed. PEDOT-SWCNT nanocomposite and Nafion films were used as inner and outer films, respectively. AO was immobilized between these two films. The PEDOT-SWCNT nanocomposite films were characterized by electrochemical impedance spectroscopy and scanning electron microscopy. The influence of detection potential and temperature on the biosensor performance was examined in detail. Despite the multilayer configuration, the biosensor exhibited a relatively fast response (less than 10 s) and a linear range from 1 mu M to 18 mM (a correlation coefficient of 0.9974). The sensitivity of the biosensor was found to be 28.5 mA M-1 cm(-2). Its experimental detection limit was 0.7 mu M (S/N = 3) and the apparent Michaelis-Menten constant (K-m) was calculated to be 18.35 mM. Moreover, the biosensor exhibited good anti-interferent ability and excellent long-term stability. All the results showed that such sandwich-type PEDOT-SWCNT/AO/Nafion films could provide a promising platform for the biosensor designs for AA detection. (C) 2011 Elsevier B.V. All rights reserved.