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Peroxide electrochemical sensor and biosensor based on nanocomposite of tio2 nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode

Abstract:

A hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>) sensor and biosensor based on modified multi-walled carbon nanotubes (CNTs) with titanium dioxide (TiO<inf>2</inf>) nanostructures was designed and evaluated. The construction of the sensor was performed using a glassy carbon (GC) modified electrode with a TiO<inf>2</inf>–CNT film and Prussian blue (PB) as an electrocalatyzer. The same sensor was also employed as the basis for H<inf>2</inf>O<inf>2</inf> biosensor construction through further modification with horseradish peroxidase (HRP) immobilized at the TiO<inf>2</inf>–fCNT film. Functionalized CNTs (fCNTs) and modified TiO<inf>2</inf>–fCNTs were characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray DifFraction (XRD), confirming the presence of anatase over the fCNTs. Depending on the surface charge, a solvent which optimizes the CNT dispersion was selected: dimethyl formamide (DMF) for fCNTs and sodium dodecylsulfate (SDS) for TiO<inf>2</inf>–fCNTs. Calculated values for the electron transfer rate constant (ks) were 0.027 s−1 at the PB–fCNT/GC modified electrode and 4.7 × 10−4 s−1 at the PB–TiO<inf>2</inf>/fCNT/GC electrode, suggesting that, at the PB–TiO<inf>2</inf>/fCNT/GC modified electrode, the electronic transfer was improved. According to these results, the PB–fCNT/GC electrode exhibited better Detection Limit (LD) and Quantification Limit (LQ) than the PB–TiO<inf>2</inf> /fCNT/GC electrode for H<inf>2</inf>O<inf>2</inf> . However, the PB film was very unstable at the potentials used. Therefore, the PB–TiO<inf>2</inf>/fCNT/GC modified electrode was considered the best for H<inf>2</inf>O<inf>2</inf> detection in terms of operability. Cyclic Voltammetry (CV) behaviors of the HRP–TiO<inf>2</inf> /fCNT/GC modified electrodes before and after the chronoamperometric test for H<inf>2</inf>O<inf>2</inf>, suggest the high stability of the enzymatic electrode. In comparison with other HRP/fCNT-based electrochemical biosensors previously described in the literature, the HRP–fCNTs/GC modified electrode did not show an electroanalytical response toward H<inf>2</inf>O<inf>2</inf> .