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Optimization of graphene oxide-modified carbon-fiber microelectrode for dopamine detection.

ABSTRACT: Graphene oxide (GO) is a carbon-based material that is easily obtained from graphite or graphite oxide. GO has been used broadly for electrochemistry applications and our hypothesis is that GO coating a carbon-fiber microelectrode (CFME) will increase the sensitivity for dopamine by providing more adsorption sites due to the enhancement of oxygen functional groups. Here, we compared drop casting, dip coating, and electrodeposition methods to directly coat commercial GO on CFME surfaces. Dip coating did not result in much GO coating and drop casting resulted in large agglomerations that produced noisy signals and slow rise times. Electrodeposition method with cyclic voltammetry increase the current for dopamine and this method was the most reproducible and had the least noise compared to the other two coating methods. The optimized method used a triangular waveform scanned from -1.2 V to 1.5 V at 100 mV/s for 5 cycles in 0.2 mg/mL GO in water. With fast-scan cyclic voltammetry (FSCV), the optimized GO/CFME enhanced the dopamine oxidation peak two-fold. The sensitivity of the modified electrode is 41±2 nA/μM with a linear range from 25 nM to 1 μM, and a limit of detection of 11 nM. The optimized electrodes were used to detect electrically-stimulated dopamine in brain slices to demonstrate their performance in tissue. Thus, GO can be used to enhance the sensitivity of electrodes for dopamine and improve biological measurements.

SUBMITTER: Chang Y

PROVIDER: S-EPMC7331934 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Using a simple drop-casting technique, we successfully fabricated a sensitive electrochemical sensor based on the composite of reduced graphene oxide (RGO) and multiwalled carbon nanotubes (MWCNT) deposited on the surface of a glassy carbon electrode (GCE) for individual and simultaneous measurements of hydroquinone (HQ), dopamine (DA), and uric acid (UA). The nanocomposite of RGO/MWCNT was further characterized in terms of its structural properties, surface morphology, and topography using Raman, FT-IR spectroscopy, SEM, HRTEM, and AFM. Then, the proposed sensor for simultaneous measurement of HQ, DA, and UA based on RGO/MWCNT-modified GCE was investigated for its electrochemical behavior and electroanalytical performances using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). In addition, the composition ratio between RGO and MWCT was 1 : 1 showing the highest electrochemical response for simultaneous detection of HQ, DA, and UA. Owing to the synergistic effect between RGO and MWCNT leading to excellent conductivity properties, the proposed sensor exhibited improved electrochemical response at pH 7 toward the oxidation processes of HQ, DA, and UA on the surface of modified electrode. The proposed sensor demonstrated three well-defined anodic peaks of these analytes with their linear concentrations ranges of 3.0-150.0 μM for HQ, 4.0-100.0 μM for DA, and 2.0-70.0 μM for UA. The limit of detection values for the simultaneous detection of HQ, DA, and UA were found as follows 0.400 ± 0.014, 0.500 ± 0.006, and 0.300 ± 0.016 μM, respectively. The additional features of this proposed sensor are high reproducibility and stability for the simultaneous detection of HQ, DA, and UA with negligible interference effect from interferents such as Mg2+, K+, Cl-, ascorbic acid, and glucose. An acceptable percentage of recovery was also shown by this sensor for simultaneous measurements of HQ, DA, and UA using 6 samples of human urine. In summary, the RGO/MWCNT nanocomposite has been shown to be a promising platform for rapid, simple, and reliable determination of simultaneous measurements of HQ, DA, and UA in practical applications.

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Optimization of graphene oxide-modified carbon-fiber microelectrode for dopamine detection.

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