Amperometric determination of H2O2 at nano-TiO2/DNA/thionin nanocomposite modified electrode

We report electrochemical preparation and characterization of a new biosensor made of nanostructured titanium dioxide (nano-TiO2) particles and deoxyribonucleic acid (DNA). Thionin (TN) redox mediator was electrochemically deposited onto DNA/nano-TiO2 modified glassy carbon electrode (GCE). The Xray diffraction analysis, atomic force microscope (AFM) and scanning electron microscope (SEM) were used for surface analysis of TN/DNA/nano-TiO2 film. In neutral buffer solution, TN/DNA/nano-TiO2/GCE biosensor exhibited excellent electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) and oxygen (O-2). The biosensor shows excellent analytical performance for amperometric determination of H2O2, at reduced overpotential (-0.2 V). The detection limit and liner calibration range were found to be 0.05 mM (S/N = 3) and 0.05-22.3 mM, respectively, In addition, determination of H2O2 in real samples was carried Out using the new biosensor with satisfactory results. The TN/DNA/nano-TiO2/GCE showed stable and reproducible analytical performance towards the reduction of H2O2. This biosensor can be used as an amperometric biosensor for the determination of H2O2 in real samples. (C) 2008 Elsevier B.V. All rights reserved.