SENSOR FOR DOPAMINE-SELECTIVE DETECTION AND PREPARATION METHOD THEREFOR

Abstract

The present invention relates to a sensor for dopamine-selective detection, a preparation method therefor, and use thereof.

Claims

1. A method for preparing a dopamine-sensitive sensor, the method comprising: a first step of preparing a solution comprising graphene oxide (GO), 3,4-ethylenedioxythiophene (EDOT), and polystyrene sulfonate (PSS); and a second step of immersing, in the solution, electrodes having a reference electrode, a counter electrode, and a working electrode formed on a support, and applying a current to the working electrode to selectively deposit GO/PEDOT:PSS thereon, wherein the solution comprises 0.0003 mol to 0.0015 mol of EDOT relative to 1 g of GO, and the molar ratio of EDOT and PSS is 1:7-13.

2. A dopamine-sensitive sensor equipped with electrodes having a reference electrode, a counter electrode, and a working electrode formed on a support, the working electrode comprising a selectively deposited GO/PEDOT:PSS layer, wherein the GO/PEDOT:PSS layer comprises 0.0003 mol to 0.0015 mol of EDOT relative to 1 g of GO, and the molar ratio of EDOT and PSS is 1:7-13.

3. The dopamine-sensitive sensor of claim 2, being prepared by way of a first step of preparing a solution comprising graphene oxide (GO), 3,4-ethylenedioxythiophene (EDOT), and polystyrene sulfonate (PSS); and a second step of immersing, in the solution, electrodes having a reference electrode, a counter electrode, and a working electrode formed on a support, and applying a current to the working electrode to selectively deposit GO/PEDOT:PSS thereon, wherein the solution comprises 0.0003 mol to 0.0015 mol of EDOT relative to 1 g of GO, and the molar ratio of EDOT and PSS is 1:7-13.

4. A method for detecting dopamine, comprising bringing the electrodes of the sensor of claim 2 into contact with a dopamine-containing sample to perform differential pulse voltammetry (DPV).

5. The method for detecting dopamine of claim 4, wherein a detection limit of 0.007 μM to 0.1 μM is attained.

6. The method for detecting dopamine of claim 4, wherein a sensitivity of 50 μA/μM.Math.cm.sup.2 to 100 μA/μM.Math.cm.sup.2 is attained.

7. The method for detecting dopamine of claim 4, wherein a variation of the measured peak current is linearly proportional to the concentration of dopamine.

8. The method for detecting dopamine of claim 4, allowing of selective detection of dopamine in samples mixed with ascorbic acid (AA), uric acid (UA), or both thereof.

9. The method for detecting dopamine of claim 4, wherein qualitative or quantitative analysis of dopamine is attainable.

10. A method of providing information for diagnosing an abnormal dopamine secretion-related disease, comprising quantitatively analyzing a sample by using the method for detecting dopamine of claim 4, the sample being isolated from a subject suspected of abnormal dopamine secretion.

11. The method of providing information of claim 10, wherein the abnormal dopamine secretion-related disease is depression, schizophrenia, attention deficit/hyperactivity disorder (ADHD), psychosis, or Parkinson's disease.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0028] FIG. 1 schematically shows a method for preparing a dopamine sensor according to an exemplary embodiment of the present invention.

[0029] FIG. 2 shows the DPV measurement results for dopamine solutions having concentrations of 0.01 μM to 0.7 μM according to the mixing ratio of graphene oxide (GO) and EDOT:PSS solutions.

[0030] FIG. 3 shows SEM images of the surfaces of the electrodes with GO/PEDOT:PSS deposition prepared for different deposition times.

[0031] FIG. 4 shows the EIS and CV measurement results of dopamine detection sensors having working electrodes with GO/PEDOT:PSS deposition prepared for different deposition times.

[0032] FIG. 5 shows an SEM image of the surface of an electrode with bare gold (Au), graphene oxide (GO), PEDOT:PSS, or GO/PEDOT:PSS deposition.

[0033] FIG. 6 shows SEM images of the surface of the electrode with GO/PEDOT:PSS deposition.

[0034] FIG. 7 shows the EIS and CV measurement results of a dopamine detection sensor having a working electrode with GO/PEDOT:PSS deposition according to an exemplary embodiment of the present invention. For comparison, a bare gold electrode or an electrode with deposition of GO or PEDOT:PSS alone was tested under the same conditions.

[0035] FIG. 8 schematically shows a driving method of a dopamine detection sensor having a working electrode with GO/PEDOT:PSS deposition according to an exemplary embodiment of the present invention.

[0036] FIG. 9 shows the DPV curves (FIG. 9A) and the peak current (FIG. 9B) for varying dopamine concentrations, and the DPV curves (FIG. 9C) and the peak current (FIG. 9D) for varying dopamine concentrations as measured in the presence of ascorbic acid and uric acid as measured by a dopamine detection sensor having a working electrode with GO/PEDOT:PSS deposition according to an exemplary embodiment of the present invention.

[0037] FIG. 10 shows the peak currents, dopamine sensitivity, linearity, and detection limit of a dopamine detection sensor having a working electrode with GO/PEDOT:PSS deposition according to an exemplary embodiment of the present invention. As comparative examples, a bare gold electrode and an electrode with GO alone deposition were used.

DETAILED DESCRIPTION OF THE INVENTION

[0038] Hereinafter, the present invention will be described in detail with reference to exemplary embodiments. However, these exemplary embodiments are for illustrative purposes only, and the scope of the present invention is not intended to be limited by these exemplary embodiments.

EXAMPLE 1

Preparation of Flexible Dopamine Sensor with GO/PEDOT:PSS Composite

[0039] A working electrode, a counter electrode (or an auxiliary electrode), and a reference electrode were configured by patterning gold electrodes (Cr/Au=100/1000 Å thick) on a polyimide film with a thickness of about 20 μm. To prepare a GO/PEDOT:PSS electrode, a graphene oxide solution (4 mg/mL) in water and a PEDOT:PSS solution (a mixture of 0.01 M EDOT and 0.1 M PSS) were mixed at a ratio of 5:1, and uniformly mixed with vortexing. The previously prepared sensor electrodes were sufficiently immersed in the mixture solution, and then a current of 4 μA was applied to the working electrode for 300 seconds. The negatively charged GO/PEDOT:PSS was attracted to the electrode and adsorbed onto the electrode interface. It was visually confirmed that GO/PEDOT:PSS was selectively deposited in the form of a black and transparent thin film on the working electrode, and the film was dried at room temperature for 5 hours. The preparation process is schematically shown in FIG. 1.

EXAMPLE 2

Effects of Different Mixing Ratios in GO/PEDOT:PSS Composite

[0040] Dopamine sensors were prepared by the same method as in Example 1 except that the ratio of the graphene oxide solution (4 mg/mL) in water and the PEDOT:PSS solution (a mixture of 0.01 M EDOT and 0.1 M PSS) was changed to 1:1, 2:1, and 10:1, respectively. Then, the sensitivity, signal linearity, and detection limit of the dopamine sensors were measured and comparatively analyzed, and the results are shown in FIG. 2 and Table 1. As shown in FIG. 2 and Table 1, the sensors prepared by mixing the GO solution and the EDOT:PSS solution at ratios of 2:1 and 5:1 showed appropriate levels of sensitivity, linearity, and detection limit, and thus sensors prepared using the solutions with a ratio of 5:1 were employed in the following examples and test examples.

TABLE-US-00001 TABLE 1 GO:(EDOT:PSS) Sensitivity Linearity Detection limit ratio (μA/μM .Math. cm.sup.2) (R.sup.2) (μM) 1:1 384.82 0.9799 0.2 2:1 38.26 0.9823 0.1 5:1 17.2 0.9636 0.01 10:1  11.94 0.5397 0.07

EXAMPLE 3

Effects of Different Deposition Times of GO/PEDOT:PSS Composite

[0041] Dopamine sensors were prepared by the same method as in Example 1 except that the time of application of the current to the working electrode was changed to 50, 150, and 600 seconds, respectively. The SEM observation results of surface morphology of the working electrodes are shown in FIG. 3, and the measurement results of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) characteristics are shown in FIG. 4. As shown in FIG. 3, the PEDOT:PSS nanoparticles were uniformly distributed along the GO layer on the electrode surface under a deposition time of 300 seconds. As shown in FIG. 4, the electrode under a deposition time of 300 seconds showed the lowest interfacial impedance, which was about 25% compared with that of the electrode under a deposition time of 50 seconds and less than 10% compared with that of the electrode under a deposition time of 600 seconds. On the other hand, the CSC value of the electrode under a deposition time of 300 seconds significantly increased to be at least five times that of the electrode with deposition for 50 seconds.

Experimental Example 1

Verification of Flexible Dopamine Sensor with GO/PEDOT:PSS Composite

[0042] To investigate the surface morphology change by GO/PEDOT:PSS deposition on the working electrode prepared according to Example 1, SEM analysis was performed, and the results are shown in FIGS. 5 and 6. Specifically, FIG. 5 shows the observations at the same magnification of the surfaces of the electrodes with deposition of a bare gold thin film, GO, PEDOT:PSS, and GO/PEDOT:PSS composite, and FIG. 6 shows images of the electrode with GO/PEDOT:PSS deposition, measured at different magnifications. As shown in FIGS. 5 and 6, the morphology of wrinkles and/or ripples typically appearing in 2D materials was confirmed in graphene oxide (GO), and the formation of multi-layered plate-like GO and randomly distributed PEDOT:PSS particles was confirmed in GO/PEDOT:PSS.

Experimental Example 2

Electrical Properties of Flexible Dopamine Sensor of GO/PEDOT:PSS Composite

[0043] The charge storage capacity (CSC) and the impedance at the 1 kHz band of the working electrode of a GO/PEDOT:PSS composite prepared according to Example 1 were measured by cyclic voltammetry and electrochemical impedance spectroscopy, and the results are shown in FIG. 7. For comparison, the bare gold electrode and the electrodes with only GO and PEDOT:PSS depositions were also tested. As shown in FIG. 7, the working electrode of a pure GO/PEDOT:PSS composite showed low CSC and a high impedance value compared with the electrode with only PEDOT:PSS deposition, but showed a low impedance value and high CSC compared with the bare gold electrode or the electrode with GO deposition, suggesting the improvement in electrical properties through polymerization deposition with EDOT:PSS.

Experimental Example 3

Current Response Characteristics of Sensor Having Working Electrode of GO/PEDOT:PSS Composite to Dopamine Concentrations

[0044] The current peak value change according to the dopamine (DA) concentration adjusted from 0.008 μM to 50 μM was measured and analyzed using a sensor having a working electrode of a GO/PEDOT:PSS composite prepared according to Example 1 by differential pulse voltammetry (DPV) with a scan rate of 50 mV/s, a pulse amplitude of 30 mV, and a pulse width of 6 ms, and the current response characteristics according to the dopamine concentration at a particular potential range were investigated. The configuration and driving conditions of the used device are shown in FIG. 8, and the measurement results are shown in FIG. 9A. In addition, the sensitivity of each electrode to dopamine detection, calculated from the measurement results, is shown in FIG. 10.

[0045] As summarized in the table at the bottom of FIG. 10, the working electrode of GO/PEDOT:PSS composite showed excellent sensitivity to dopamine (17.2 μA/μM.Math.cm.sup.2 in a range of 0.01 μM to 0.7 μM, a detection limit of 0.01 μM) compared with the bare gold electrode and the GO-adsorbed electrode, and showed a significantly improved detection limit of down to 0.008 μM and high linearity.

[0046] To investigate the selective dopamine detection performance in the co-presence of various interfering species, the dopamine detection according to the concentration was performed in an environment mixed with ascorbic acid (AA, 1 mM) and uric acid (UA, 50 μM), which are representative interfering species and of which the oxidation current peaks appear in similar bands to dopamine, and the results are shown in FIG. 9B. As shown in FIG. 9B, the sensor having a working electrode of a GO/PEDOT:PSS composite showed current responses to DA and UA at different potentials, and in particular, AA was repelled, and thus the oxidation current thereof at the electrode interface was fundamentally blocked. These results suggest that the selective detection of DA can be attained even in the presence of interfering species, such as AA or UA, leading to qualitative analysis as well as quantitative analysis without interference of interfering species.

[0047] While the present invention has been described with reference to the particular illustrative embodiments, a person skilled in the art to which the present invention pertains can understand that the present invention may be embodied in other specific forms without departing from the technical spirit or essential characteristics thereof. Therefore, the embodiments described above should be construed as exemplifying and not limiting the present disclosure. The scope of the present invention is not defined by the detailed description as set forth above but by the accompanying claims of the invention, and it should also be understood that all changes or modifications derived from the definitions and scopes of the claims and their equivalents fall within the scope of the invention.