Abstract
A hydrogen peroxide (H2O2) sensor and biosensor based on modified multi-walled carbon nanotubes (CNTs) with titanium dioxide (TiO2) nanostructures was designed and evaluated. The construction of the sensor was performed using a glassy carbon (GC) modified electrode with a TiO2–CNT film and Prussian blue (PB) as an electrocalatyzer. The same sensor was also employed as the basis for H2O2 biosensor construction through further modification with horseradish peroxidase (HRP) immobilized at the TiO2–fCNT film. Functionalized CNTs (fCNTs) and modified TiO2–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 TiO2–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–TiO2/fCNT/GC electrode, suggesting that, at the PB–TiO2/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–TiO2/fCNT/GC electrode for H2O2. However, the PB film was very unstable at the potentials used. Therefore, the PB–TiO2/fCNT/GC modified electrode was considered the best for H2O2 detection in terms of operability. Cyclic Voltammetry (CV) behaviors of the HRP–TiO2/fCNT/GC modified electrodes before and after the chronoamperometric test for H2O2, 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 H2O2.
Highlights
The use of nanomaterials in biosensing is a subject of intense research, with a significant impact on everyday life [1]
Prussian blue (PB)–TiO2/Functionalized CNTs (fCNTs)/glassy carbon (GC), and an electrochemical biosensor, horseradish peroxidase (HRP)–TiO2/fCNT/GC, for H2O2 detection were efficiently designed with MWNT modified GC electrodes
Calculated values for ks were greater at the PB–fCNT/GC electrode than at the PB–TiO2/fCNT/electrode, suggesting that TiO2 at the fCNT/GC modified electrode improved the electronic transfer due to the characteristics of TiO2
Summary
The use of nanomaterials in biosensing is a subject of intense research, with a significant impact on everyday life [1]. Carbon nanotubes (CNTs) are at the forefront of this intense research, reflecting unique and remarkable mechanical, thermal, electrical, and elastic properties [2,3]. These properties include having characteristics of semiconductors or conductors [4]. Metal-oxide nanoparticles attached to the carbon nanotube surface are receiving notable interest because of the potential applications when designing electrochemically functional nanostructures [2], which include a higher surface area and better biocompatibility, and they help in addressing the design of a biosensing interface allowing the analyte to interact effectively over the biosensing surface. The evaluation of TiO2 nanoparticles/multi-walled carbon nanotubes on glassy carbon (TiO2/MWCNT/GC) modified electrodes and Prussian blue (PB) helped us to design a model electrode to analyze the performance and contribution of carbon nanotubes and titanium dioxide nanostructures in the electrochemical detection of H2O2 by horseradish peroxidase (HRP)/TiO2/MWCNT/GC modified glassy carbon electrode
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