β-Cyclodextrin functionalized 3D reduced graphene oxide composite-based electrochemical sensor for the sensitive detection of dopamine

Abstract

A three-dimensional reduced graphene oxide nanomaterial with β-cyclodextrin modified glassy carbon electrode (3D-rGO/β-CD/GCE) was constructed and used to detect the electrochemical behavior of dopamine (DA). The nanocomposite materials were characterized by scanning electron microscopy (SEM), infrared spectrometry (FT-IR), Raman spectrogram and thermogravimetric analysis (TGA), which showed that β-CD was well modified on 3D graphene with a porous structure. The electrochemical properties of different modified electrodes were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), proving the highest electron transfer rate of the 3D-rGO/β-CD modified electrode. The experimental conditions such as scan rate, pH, enrichment time and layer thickness were optimized. Under the best experimental conditions, DA was detected by differential pulse voltammetry (DPV) by 3D-rGO/β-CD/GCE with excellent electrocatalytic ability and satisfactory recognition ability, resulting in a wide linear range of 0.5-100 μM and a low detection limit (LOD) of 0.013 μM. The modified electrode based on 3D-rGO/β-CD nanocomposites is promising in the field of electrochemical sensors due to its high sensitivity and other excellent properties.

Scheme 1. Illustration of the procedure for preparing 3D-rGO/β-CD, and sensing the dopamine by an electrochemical strategy.

Fig. 1. SEM images at different magnifications (a) and (b) of 3D-rGO/β-CD.

Fig. 2. FT-IR spectrogram of β-CD, 3D-rGO and 3D-rGO/β-CD.

Fig. 3. (a) Raman spectrogram of 3D-rGO and 3D-rGO/β-CD; (b) thermogravimetric analysis of 3D-rGO and 3D-rGO/β-CD.

Fig. 4. Nyquist curves (a) and cyclic voltammograms (b) of bare GCE, 3D-rGO and 3D-rGO/β-CD modified GCE in a 10.0 mL 0.1 M PB containing 5 mM [Fe(CN)₆]^3−/4− and 0.1 M KCl (pH 7.0).

Fig. 5. (a) Cyclic voltammograms of 3D-rGO/β-CD/GCE in 0.1 M PB solution of pH 7.0 containing 50 μM DA at different scan rates from 10 to 200 mV s⁻¹. Inset: linear plot between peak currents of DA and the scan rates. (b) Influence of pH of PB on the peak current and potential for the determination towards 50 μM DA at 3D-rGO/β-CD/GCE. Influence of accumulation time (c) and volume of 3D-rGO/β-CD (2 mg mL⁻¹) (d) on detection of 50 μM DA at 3D-rGO/β-CD/GCE in 0.1 M PB of pH 7.0.

Fig. 6. (a) DPV response of 3D-rGO/β-CD/GCE with various concentration of DA in 0.1 M PB solution of pH 7.0. (b) The calibration curve of peak currents vs. the concentration of DA. Error bars was obtained according to the standard deviation by three independent measurements.

Fig. 7. (a) DPV responses of 3D-rGO/β-CD/GCE in 0.1 M PBS (pH = 7.0) for 1 mM AA, 100 μM DA, 100 μM 5-HT and the mixture of 1 mM AA, 100 μM DA and100 μM 5-HT. (b) Amperometric responses of the 3D-rGO/β-CD/GCE for the addition of 100 μM DA and 200 μM glucose, 200 μM KCl and 200 μM NaCl in 0.1 M PBS (pH = 7.0).

Fig. 8. (a) UV-visible spectroscopy the absence (a) and presence of various concentrations of β-CD (b–h corresponding to 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 mM, respectively). (b) Double reciprocal plots for β-CD combing DA under the varying concentrations β-CD.