Enhancing the electrochemical response of myoglobin with carbon nanotube electrodes

Abstract

In this paper, the electrochemical behavior of different myoglobin-modified carbonelectrodes is evaluated. In particular, the performance of voltammetric biosensorsmade of forest-like carbon nanotubes, carbon nanotube composites and graphitecomposites is compared by monitoring mainly the electrocatalytic reduction ofH2O2 by myoglobin and their corresponding electroanalytical characteristics. Graphite composites showedthe worst electroanalytical performance, exhibiting a small linear range, a limit of detection (LOD)of 9 × 10−5 M and low sensitivity. However, it was found that the electrochemical response wasenhanced with the use of carbon nanotube-based electrodes with LOD up to5 × 10−8 M, higher sensitivities and wider linear range response. On the one hand, in the case of theCNT epoxy composite, the improvement in the response can be mainly attributed to itsmore porous surface which allows the immobilization of higher amounts of the electroactiveprotein. On the other hand, in the case of the forest-like CNT electrodes, the enhancementis due to an increase in the electron transfer kinetics. These findings encourage the useof myoglobin-modified carbon nanotube electrodes as potential (bio)sensors ofH2O2 orO2 in biology, microbiology and environmental fields.