Nanostructured Carbon Fiber Disk Electrodes for Sensitive Determinations of Adenosine and Uric Acid

Abstract

Nanostructured carbon fiber microdisk electrodes were prepared by a combination of mechanical polishing and electrolytic treatment, where the latter involved moderate oxidation of the surface, followed by a reduction. A high density of surface defects contributed to a high capacitance of the nanostructured electrodes. Facilitated proton transfer was observed at the nanostructured surface and was associated with cation-exchanged oxide defects. The nanostructured surfaces intercalated uric acid and adenosine and engaged in fast electron/proton transfer in the oxidation of both analytes. As a result, electrolytic treatment followed by fast-scan voltammetry determinations led to a sensitive response to both analytes in physiological buffers. The nanostructured electrodes showed remarkable stability and could be easily regenerated and reused. With long use, electrode activity decreased. Kinetic discrimination of the surface-mediated reaction of ascorbate was achieved at high scan rates.

Electrochemical sensors: a powerful tool in analytical chemistry

“…Machado, Avacca and coworkers [137][138][139] have reviewed some theoretical aspects and studied the utilization of Pt, Co, or Ni-Co microelectrodes (UME) to characterize copper electrocrystallization and hydrogen evolution. Mori and Bertotti 140 have investigated the chemical reaction between nitrite and iodide by using microelectrodes and Cavalheiro and co-workers 141 have shown the application of nanostructured carbon fiber disk microelectrodes for determination of adenosine and uric acid in physiological buffers. Nevertheless, the most successful works in these area are published by Angnes and co-workers.…”

Fabrication of Graphene Coated Carbon Fiber Microelectrode for Highly Sensitive Detection Application

“…28 The gradual rise in current and the poorly defined plateau, observed at both electrodes, reflect the rough surfaces of CFM and G-CFM. 27 The electrode capacitance of G-CFM increases, which can clearly be seen in the plateau region and at the foothill of CVs in Fig. 4 and even the double layer capacitance curves (inset of Fig.…”

“…22,27 Here, the electrochemical characterization of the G-CFM was tested by using K3Fe(CN)6 in the aqueous solution and compared with that of CFM. As shown in Fig.…”

“…31 It has been reported that the surface of CFM can be activated by electrolytic oxidation and the formed amorphous surface can improve electrode kinetics. 27 Here, the voltammetric behaviors of CFM, before and after electrolytic treatment in the electrolyzing solution used for the preparation of G-CFM containing everything except the graphene oxide, were carried out in the solution containing 0.5 mM DA and 0.1 M pH 7.0 PBS. No difference was found between them (not shown here).…”

“…No difference was found between them (not shown here). This may be because the potential for electrolyzing deposition is negative to the oxidation potential of CFM, which is positive to +1.2 V, 27 and thus no electrolytic oxidation of CFM occurred. Considering the response current exactly defined, the voltammetric behavior of G-CFM was further studied by DPV in the presence of DA, as shown in Fig.…”