Abstract
This work presents the development and characterization of a new chemically modified electrode exploiting recordable Au-rewritable compact discs (AuCDs) as substrate for drop casting of a chemically-reduced graphene-oxide slurry focusing on simple and low-cost electrochemical sensors. Increase in electrochemical responses in cyclic voltammetric and amperometric measurements were achieved using the proposed sensor. Both scanning electron microscopy and atomic force microscopy data showed increase in rugosity (about 46% higher) for the chemically reduced graphene oxide (CRGO) AuCD surface while Raman spectroscopy confirmed the presence of structural defects of graphene. The calculated charge transfer resistances (Rct) and heterogeneous electron transfer rate constants (k0) were 1638 Ω and 0.0022 cm s-1 for the bare substrate, and 91 Ω and 0.0027 cm s-1 for the modified electrode, evidencing the facilitated electron transfer of the CRGO-AuCD surface. The dopamine (DP) amperometric detection using CRGO-AuCD provided low detection limit (0.12 µg L-1) compared with other modified electrodes already reported, high precision (relative standard deviation (RSD) < 5%) and analytical frequency (370 h-1). As a proof-of-concept, DP determination in synthetic saliva samples was performed and a satisfactory recovery value (98.6 ± 0.9%) was obtained.
Highlights
Since the establishment of polarography as an analytical technique by Heyrosvsky,[1,2] the electrochemical behavior of chemical species onto metallic electrodic surfaces has raised interest in many fields of science.[3]
The analytical frequency (AF) value obtained at chemically reduced graphene oxide (CRGO)-Au-rewritable compact discs (AuCDs) was estimated as 370 h–1 that is higher than the value obtained on bare AuCD (270 h–1). These results indicate a faster electron transfer provided by CRGO, in agreement with previous data presented in the text
We have demonstrated the drop-casting modification with CRGO of a low-cost gold sensor produced from AuCD
Summary
Since the establishment of polarography as an analytical technique by Heyrosvsky,[1,2] the electrochemical behavior of chemical species onto metallic electrodic surfaces has raised interest in many fields of science.[3] From the use of ultrapure liquid mercury to nanostructured devices, passing through bulk noble metals, a wide range of electrodes has been investigated in electroanalysis, considering both analyte and media properties, samples and technique to be applied.[4] In this context, chemically modified electrodes were developed and play key role in the development of electrochemical sensors.[5,6,7]. Carbon-based electrochemical sensors have been widely used in electroanalysis due to the particular properties of carbon materials, including chemical stability, strong mechanical resistance and excellent thermal and electrical.
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