Electrooxidation of Dna at Glassy Carbon Electrodes Modified With Multi-Walled Carbon Nanotubes With Different Oxidation Degree

Abstract

For the first time, the study of the effect of length and degree of oxidation of multi-walled carbon nanotubes (CNTs) on the electroanalytical DNA sensing properties of modified glassy carbon electrodes (GCEs) is reported. GCE/CNT electrodes were prepared using chitosan (CHI) as a dispersing agent. Short (S-NCs) and long (L-NCs) carbon nanotubes, as well as unoxidized and 3 or 6 hour oxidized samples were used. Cyclic voltammetry indicated that S-NCs exhibited larger capacitance values than L-NCs, and that these values increased when the CNTs were oxidized. Using Scanning Electrochemical Microscopy (SECM), an increase in the surface homogeneity was determined when oxidized CNTs were used as electrode modifiers. dsDNA electrooxidation showed the highest response using GCEs/CHI-L-NCs, and a clear decrease in the current intensity was observed when the oxidation time was increased. This result correlates with the higher BET surface area of L-NCs. In conclusion, the electrochemical performance of GCE/CNT electrodes against DNA increase when the length of CNTs is higher and decrease at higher oxidation state.

A comparative study of electrochemical performances of carbon nanomaterial-modified electrodes for DNA detection. Nanotubes or graphene?

“…Another interesting result is that the DNA oxidation currents obtained for the electrodes modified using oxygenated carbon nanomaterials (MWNT-OX and GO) are lower than those obtained for the electrodes modified with the reduced CNM (MWNT and RGO). Such reduction of the electrochemical response to DNA has been reported by us in a previous study using carbon nanotubes with different degrees of oxidation [14]; now, we report this effect for graphene derivatives. Thus, we can conclude that the oxygenated functionalities present on MWNT-OX and GO interact with the amine groups of CHI, decreasing the electrostatic contribution of CHI to dsDNA adsorption.…”

“…We have evaluated oxidized and nonoxidized multiwalled carbon nanotubes (MWNT-OX and MWNT, respectively) and two graphene derivatives: graphene oxide (GO) and chemically reduced graphene oxide (RGO). To avoid the introduction of new variables and enable a simpler comparison, the dispersions were prepared according to the methodology described in our previous works on DNA biosensors [11][12][13][14]. The electrodes were characterized by cyclic voltammetry; scanning electrochemical microscopy (SECM) and differential pulse voltammetry were the electroanalytical techniques to evaluate the figure of merit against dsDNA.…”