A third-generation hydrogen peroxide biosensor based on horseradish peroxidase immobilized on DNA functionalized carbon nanotubes

In this paper, DNA functionalized SWCNTs were used to immobilize horseradish peroxidase (HRP) on glassy carbon (GC) electrode. Cyclic voltammetry showed that the direct electrochemistry of HRP immobilized on DNA-SWCNTs hybrids was achieved. The DNA interlayer between the SWCNTs and HRP could be used to keep the activity of HRP. Compared with HRP-SWCNTs/GC and HRP-DNA/GC electrodes, the prepared HRP-DNA-SWCNTs/GC electrode exhibited more excellent electrochemical properties. Thus, the prepared HRP-DNA-SWCNTs/GC electrode was proposed as a third-generation H2O2 biosensor. The effect of pH and applied potential on the performance of the biosensor was discussed in detail. Under the optimal conditions, a wide linear range of the propose biosensor for the detection of H2O2 was observed from 6.0 X 10(-7) to 1.8 X 10(-3) M. The detection limit was found to be 3.0 x 10(-7) M at a signal-to-noise ratio of 3. Furthermore, the proposed biosensor displayed rapid response, high stability, very good reproducibility and high sensitivity for the detection of H2O2. Determination H2O2 concentration in disinfector sample by the proposed biosensor also showed satisfactory result. (C) 2009 Elsevier B.V. All rights reserved.