Working electrode for dopamine electrochemical sensor, dopamine electrochemical sensor and application of dopamine electrochemical sensor

Abstract

The invention relates to a working electrode for a dopamine electrochemical sensor, the dopamine electrochemical sensor and application of the dopamine electrochemical sensor, and belongs to the technical field of electrochemical sensors. The working electrode for the dopamine electrochemical sensor comprises an electrode substrate and defective molybdenum disulfide modified on the surface of the electrode substrate, the defective molybdenum disulfide is molybdenum disulfide with sulfur vacancy defects. According to the dopamine electrochemical sensor constructed by the working electrode, the selectivity to dopamine during detection can be enhanced, electrochemical oxidation of ascorbic acid and uric acid can be remarkably inhibited, and the problem of signal interference in the dopamine detection process is solved in a targeted manner.

Description

Technical Field

[0001] The invention relates to a working electrode for a dopamine electrochemical sensor, a dopamine electrochemical sensor and applications thereof, and belongs to the technical field of electrochemical biosensors. Background Art

[0002] Neurotransmitters (NTs) are essential chemicals and endogenous chemical messengers that can transmit information between neuronal cells. Dopamine (DA), as an important neurotransmitter, is widely present in vertebrates and invertebrates, participates in learning, motor control and motivational behavior, and plays a vital physiological role in maintaining hormonal balance and the central nervous system. Research reports show that abnormal dopamine content can cause a series of neurological diseases, such as Parkinson's disease, Alzheimer's disease, schizophrenia and ADHD. Therefore, the monitoring of dopamine content is of great significance to clinical medicine and biological research. The traditional method for detecting dopamine content is mainly high-performance liquid chromatography, but its application is limited due to the high cost of instruments and determinations, long time consumption, and complex operations. Since dopamine has electrochemical activity, it can be detected by means of electroanalytical technology. Electroanalytical technology has attracted widespread attention in analyte sensing due to its advantages such as simple instrumentation, cost-effectiveness, rapid response, non-destructive testing, easy miniaturization and automation.

[0003] However, the electrochemical detection of dopamine is often interfered by other coexisting electrochemically active biomolecules in human tissue fluid, especially ascorbic acid (AA) and uric acid (UA) with similar chemical structures to dopamine. How to enhance the selectivity of dopamine detection has become a major problem in the electrochemical detection of dopamine. For electrochemical sensors, suitable electrode materials play an important role and can greatly affect the detection effect. Therefore, the development of a suitable working electrode for dopamine electrochemical sensor is of great significance to improve the specificity of dopamine detection. Summary of the invention

[0004] The first object of the present invention is to provide a working electrode for a dopamine electrochemical sensor, and to provide a working electrode with good specificity for the dopamine sensor in the prior art.

[0005] The second object of the present invention is to provide a dopamine electrochemical sensor to solve the problem that the specificity of dopamine sensors in the prior art needs to be improved.

[0006] The third object of the present invention is to provide an application of a dopamine electrochemical sensor in dopamine detection, so as to solve the problem in the prior art that the presence of ascorbic acid and uric acid affects dopamine detection when performing dopamine detection.

[0007] In order to achieve the above object, the technical solution adopted by a working electrode for a dopamine electrochemical sensor in the present invention is:

[0008] A working electrode for a dopamine electrochemical sensor comprises an electrode substrate and defective molybdenum disulfide modified on the surface of the electrode substrate; the defective molybdenum disulfide is molybdenum disulfide with sulfur vacancy defects.

[0009] The beneficial effects of the above scheme are: the working electrode for the dopamine electrochemical sensor of the present invention is a pioneering invention, using defective molybdenum disulfide (i.e. MoS 2-x ) modified the substrate electrode to obtain a working electrode for dopamine electrochemical sensor. The MoS 2-x It has a large number of sulfur vacancy defects, has a good adsorption effect with dopamine, and can exclude other interfering molecules, such as ascorbic acid and uric acid. The working electrode for the dopamine electrochemical sensor of the present invention provides a new suitable electrode material for the dopamine electrochemical sensor, which can effectively improve the specificity of the dopamine electrochemical sensor to dopamine and the anti-interference performance to other substances during the detection process.

[0010] As a further improvement, the electrode substrate includes a glassy carbon electrode or a gold electrode.

[0011] The beneficial effect of the above scheme is that the working electrode for the dopamine electrochemical sensor of the present invention has no special requirements for the electrode substrate. Glassy carbon electrodes, gold electrodes or conventionally used electrode substrates can meet the use requirements and can effectively meet the needs of different consumers.

[0012] As a further improvement, the working electrode is prepared by a method comprising the following steps: coating a dispersion containing defective molybdenum disulfide on a pretreated surface of a substrate electrode and drying the resulting electrode.

[0013] The beneficial effect of the above scheme is that the preparation process of the working electrode for the dopamine electrochemical sensor of the present invention is simple and has strong operability.

[0014] Preferably, the dispersion is one, two or three of a water-based dispersion, an organic solvent dispersion, an ionic liquid dispersion, a colloid dispersion and a surfactant dispersion.

[0015] As a further improvement, the dispersion consists of defective molybdenum disulfide, carbon nanotubes, Nafion and a solvent.

[0016] Preferably, the mass ratio of the defective molybdenum disulfide to the carbon nanotubes is 4:(0.1-0.15).

[0017] Specifically, the pretreatment process varies depending on the substrate electrode used, but is a conventional operation in the art.

[0018] In order to achieve the above object, the technical solution adopted by a dopamine electrochemical sensor in the present invention is:

[0019] A dopamine electrochemical sensor comprises the working electrode for the dopamine electrochemical sensor.

[0020] The beneficial effect of the above scheme is that the dopamine electrochemical sensor of the present invention is a pioneering invention. The dopamine electrochemical sensor prepared by the present invention significantly inhibits the electrochemical oxidation of ascorbic acid and uric acid, specifically solves the problem of selectivity in the electrochemical detection process of dopamine, and successfully prepares a dopamine electrochemical sensor with excellent anti-interference performance.

[0021] As a further improvement, the dopamine electrochemical sensor includes other electrodes; the other electrodes are selected from one, two or more of a platinum electrode, a titanium electrode, a saturated calomel electrode, a silver-silver chloride electrode, a mercury oxide electrode and a graphite electrode.

[0022] In order to achieve the above-mentioned purpose, the technical solution adopted by the application of a dopamine electrochemical sensor in the detection of dopamine content in the present invention is:

[0023] Application of a dopamine electrochemical sensor in the detection of dopamine content.

[0024] The beneficial effect of the above scheme is that the application of the dopamine electrochemical sensor of the present invention in the detection of dopamine content is a pioneering invention. Experiments have shown that as the dopamine concentration in the electrolyte increases, the electrochemical signal generated by the working electrode gradually increases, and it is found that it shows a good linear relationship in the range of 500nM to 10μM; and when the sample to be tested contains dopamine, ascorbic acid and uric acid, the dopamine electrochemical sensor only produces an electrochemical signal for dopamine, indicating that the dopamine electrochemical sensor of the present invention has good anti-interference performance in the sample to be tested in the presence of interfering substances.

[0025] As a further improvement, the pH of the system during the dopamine test was 7.2-7.4.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention uses defective molybdenum disulfide (MoS 2-x ) modified the substrate electrode to obtain a working electrode for dopamine electrochemical sensor. The MoS 2-x With a large number of sulfur vacancy defects (defective MoS 2-x The HR-TEM lattice fringe image is as follows: Figure 1As shown), it has a good adsorption effect on dopamine and can exclude other interfering molecules, such as ascorbic acid and uric acid. The dopamine electrochemical sensor prepared by the above working electrode can well avoid the interference of other electrochemically active substances in human tissue fluid on dopamine detection, enhance the selectivity of dopamine detection, and specifically solve the signal interference problem in the dopamine detection process. The defective molybdenum disulfide prepared by the present invention is applied to the detection of dopamine, which can significantly inhibit the electrochemical oxidation of ascorbic acid and uric acid, and embodies good detection selectivity.

[0028] 2. The dopamine electrochemical sensor provided by the present invention has extremely high feasibility of achievement transformation and application prospects. For the electrochemical detection of dopamine, it can solve the problem of weak anti-interference in the current dopamine detection and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The defective MoS 2-x HR-TEM lattice fringe image;

[0030] Figure 2 The defective MoS 2-x Schematic diagram of DA sensing in the presence of AA and UA;

[0031] Figure 3 The DPV and linear fitting result diagram of the dopamine electrochemical sensor in Example 3 of the present invention in response to different concentrations of dopamine in 0.01M PBS (pH 7.2-7.4);

[0032] Figure 4 This is a DPV graph of the dopamine electrochemical sensor in Example 4 of the present invention responding to 50 μM DA, AA, and UA;

[0033] Figure 5 It is an i-t diagram of the dopamine electrochemical sensor in Example 4 of the present invention in response to 5 μM AA, DA, and UA;

[0034] Figure 6 The DPV graph of the electrochemical sensor constructed with pure MoS2 in Comparative Example 1 of the present invention corresponding to 50 μM AA;

[0035] Figure 7 The electrochemical sensor constructed by pure MoS2 in Comparative Example 1 of the present invention and the defective MoS 2-x DPV graph and corresponding bar graph of the constructed dopamine electrochemical sensor in response to 50 μM DA and 50 μM UA. DETAILED DESCRIPTION

[0036] In the prior art, when dopamine is detected, there is often an influence of ascorbic acid (AA) and uric acid (UA) whose chemical structures are similar to dopamine. How to enhance the selectivity of dopamine detection has become a major problem in electrochemical detection of dopamine. 2-x ) modified the substrate electrode to obtain a working electrode for dopamine electrochemical sensor. The MoS 2-x It has a large number of sulfur vacancy defects, which have a good adsorption effect with dopamine and can exclude other interfering molecules such as ascorbic acid and uric acid. 2-x In the presence of AA and UA, the DA sensing process is as follows Figure 2 The working electrode for the dopamine electrochemical sensor of the present invention provides a new suitable electrode material for the dopamine electrochemical sensor, which can effectively improve the specificity of the dopamine electrochemical sensor to dopamine and the anti-interference performance to other substances during the detection process.

[0037] The present invention is further described in detail below in conjunction with specific examples. Unless otherwise specified, the equipment and reagents used in each embodiment, experimental example and comparative example can be obtained from commercial sources.

[0038] MoS 2-x The preparation method can be as follows: MoS2 powder is exposed by ultraviolet laser, wherein the power of the ultraviolet laser is 1-10W and the wavelength is 200-400nm.

[0039] Specifically, molybdenum disulfide (analytical grade, Sigma-Aldrich) powder was placed in a mortar and ground appropriately, and then the fully ground MoS2 powder was spread on a glass sheet, and the glass sheet was placed under an ultraviolet laser, and exposed at a power of 1 to 10 W within a wavelength range of 200 to 400 nm to obtain defective molybdenum disulfide (MoS 2-x ).

[0040] The MoS used in the following examples 2-x It is obtained by exposing MoS2 powder using a 5W ultraviolet laser with a wavelength of 300nm. 2-x The HR-TEM lattice fringe image is as follows: Figure 1 As shown, the MoS2 used is 2H-type MoS2, so Figure 1 Defective MoS 2-x The lattice fringe spacing is 0.62nm. In addition, Figure 1 A large number of linear exfoliation defects can be seen, which is due to the defective MoS caused by UV exposure. 2-x A large number of S defects are formed due to the missing S atoms on the surface.

[0041] 1. Specific embodiments of a working electrode for a dopamine electrochemical sensor and a dopamine electrochemical sensor of the present invention:

[0042] Example 1

[0043] In this embodiment, a glassy carbon electrode is used as an electrode substrate to prepare a working electrode for a dopamine electrochemical sensor, and then the working electrode is used to construct a dopamine electrochemical sensor. The specific implementation method is as follows:

[0044] 1. Take 4 mg MoS 2-x The solid powder was placed in a 1.5 mL centrifuge tube, and 375 μL of deionized water, 125 μL of anhydrous ethanol, 50 μL of 2 mg / mL carbon nanotube aqueous dispersion, and 50 μL of Nafion solution (polymer content of 5.0-5.4%) were added in sequence. The mixture was shaken for 5 min and then ultrasonically dissolved for 1 h to obtain MoS 2-x Dispersion.

[0045] 2. The glassy carbon electrode was polished with Al2O3 slurry formed by adding water to Al2O3 powder of appropriate particle size, and then ultrasonically cleaned with appropriate amount of anhydrous ethanol and deionized water, and placed in 5mM [Fe(CN)6] 4- / [Fe(CN)6] 3- The electrochemical test of cyclic voltammetry is carried out in a solution (containing KCl). The difference between the two peak potentials is less than 80 mV. The electrode is then washed with deionized water and dried for later use.

[0046] 3. Take 5 μL of MoS obtained in step 1 2-x The dispersion was drop-coated on the surface of the polished and cleaned glassy carbon electrode (d = 3 mm) and dried naturally at room temperature to obtain MoS 2-x Modified glassy carbon electrode, namely MoS 2-x / GCE.

[0047] 4. The MoS obtained in step 3 2-x / GCE was used as the working electrode to form a three-electrode system with the Pt mesh counter electrode and the Ag / AgCl reference electrode. The system was placed in an electrolytic cell containing 30 mL of 0.01 M PBS (pH 7.2-7.4) and connected to an electrochemical workstation to construct a dopamine electrochemical sensor.

[0048] Example 2

[0049] In this embodiment, a gold electrode is used as an electrode substrate to prepare a working electrode for a dopamine electrochemical sensor, and then the working electrode is used to construct a dopamine electrochemical sensor. The specific implementation method is as follows:

[0050] 1. Take 4 mg MoS 2-xThe solid powder was placed in a 1.5 mL centrifuge tube, and 375 μL of deionized water, 125 μL of anhydrous ethanol, 50 μL of 2 mg / mL carbon nanotube aqueous dispersion, and 50 μL of Nafion solution (polymer content of 5.0-5.4%) were added in sequence. The mixture was shaken for 5 min and then ultrasonically dissolved for 1 h to obtain MoS 2-x Dispersion.

[0051] 2. Polish the gold electrode with Al2O3 slurry formed by adding water to Al2O3 powder of appropriate particle size. Place the polished and ultrasonically cleaned gold electrode in a 30mL electrolytic cell containing 0.5M H2SO4, use the gold electrode as the working electrode, the Pt mesh as the counter electrode, and the Ag / AgCl as the reference electrode, connect the electrochemical workstation, use cyclic voltammetry, set the scan rate to 0.05V / s, and further electrochemically activate the gold electrode in the voltage range of 0-1.5V to obtain a stable cyclic voltammetry curve, and then clean the gold electrode with deionized water ultrasonically for 5min for standby use.

[0052] 3. Take 5 μL of MoS obtained in step 2 2-x The dispersion was drop-coated on the surface of a polished, activated and cleaned gold electrode (d = 3 mm) and dried naturally at room temperature to obtain MoS 2-x / Au E.

[0053] 4. The MoS obtained in step 3 2-x / Au E was used as the working electrode, and a three-electrode system was formed with a Pt mesh counter electrode and an Ag / AgCl reference electrode. The system was placed in an electrolytic cell containing 30 mL of 0.01 M PBS (pH 7.2-7.4) and connected to an electrochemical workstation to construct a dopamine electrochemical sensor.

[0054] 2. Specific examples of the application of the dopamine electrochemical sensor of the present invention in the detection of dopamine content:

[0055] Example 3

[0056] This example uses the dopamine electrochemical sensor prepared in Example 1, adds dopamine standard solutions of different concentrations into the electrolyte, and explores the response of the dopamine electrochemical sensor based on defective MoS2 to DA. The specific implementation operation is as follows:

[0057] MoS 2-x / GCE was used as the working electrode, Ag / AgCl as the reference electrode, and Pt mesh electrode as the counter electrode. 30 mL of dopamine solution with different concentrations (PBS configuration, nitrogen deoxygenation) was used as the electrolyte solution. The differential pulse voltammetry (DPV) electrochemical method was used to quantitatively test the sensing performance. The parameters were set as follows: potential range 0-0.35 V, scan rate 50 mV / s, pulse amplitude 25 mV, pulse width 50 ms, pulse period 0.5 s, step length 5 mV, repeated 3 times. The oxidation peak current values ​​of dopamine with different concentrations in the DPV curve were selected to draw a linear fitting curve diagram, and the MoS 2-x Quantitative relationship between / GCE and the linear range of dopamine.

[0058] Test results such as Figure 3 As shown in the figure, it can be seen that a clear dopamine oxidation peak is observed at 0.15V, and the current value increases with the increase of dopamine concentration. Through further quantitative calculation, it is found that MoS 2-x The linear relationship between MoS and dopamine was good in the range of 500nM to 10μM. 2-x It has good sensing performance for dopamine.

[0059] Example 4

[0060] In this example, the dopamine electrochemical sensor prepared in Example 2 was used to add dopamine, ascorbic acid and uric acid of the same concentration (50 μM or 5 μM) into the electrolyte to explore the anti-interference performance of the dopamine electrochemical sensor. The specific implementation operation is as follows:

[0061] MoS 2-x / Au E was used as the working electrode, Ag / AgCl was used as the reference electrode, and the Pt mesh electrode was used as the counter electrode. 30 mL of 50 μM DA, 50 μM UA, and 50 μM AA (prepared in PBS and deoxygenated by nitrogen) solutions were used as electrolyte solutions, respectively. The DPV electrochemical method was used to carry out the selectivity test, and the setting parameters were as follows: potential range 0-0.35 V, scan rate 50 mV / s, pulse amplitude 25 mV, pulse width 50 ms, pulse period 0.5 s, step length 5 mV, repeated 3 times, and the DPV curve was obtained; 30 mL of 5 μM AA, 5 μM DA, 5 μM UA, 5 μM AA, and 5 μM UA (prepared in PBS and deoxygenated by nitrogen) solutions were used as electrolyte solutions, and the chronoamperometric (CA) electrochemical method was used to carry out the selectivity test, and the setting parameters were as follows: potential 0.15 V, duration 360 s, and sampling interval 0.05 s. Under short-time stirring, the solution is continuously injected, the background current is stable, and the i-t curve of the anti-interference performance of real-time sampling is obtained.

[0062] DPV graphs of dopamine electrochemical sensor responding to 50 μM dopamine, ascorbic acid and uric acid Figure 4 As shown in the figure, it can be seen that: a clear oxidation peak of dopamine is observed at 0.16V, indicating that the dopamine electrochemical sensor has a good electrochemical signal for dopamine; a weak oxidation peak of uric acid is observed at 0.3V, which is far away from the oxidation peak of dopamine and will not cause interference; and there is no electrochemical signal for ascorbic acid, indicating that the constructed dopamine electrochemical sensor has good anti-interference performance.

[0063] The i-t diagram of the dopamine electrochemical sensor responding to 5 μM dopamine, ascorbic acid and uric acid is shown in the figure. Figure 5 As shown in the figure, it can be seen that at a voltage of 0.15V, MoS 2-x There is only a signal response to 5μM DA, but no current response to 5μM AA and 5μM UA. 2-x The real-time response to dopamine is good, and the real-time anti-interference performance to ascorbic acid and uric acid is excellent.

[0064] Comparative Example 1

[0065] In this comparative example, a gold electrode is used as an electrode substrate to modify pure MoS2 to prepare a working electrode for a dopamine electrochemical sensor, which is then used to construct an electrochemical sensor. The specific implementation method is as described in Example 2.

[0066] The response capabilities of the constructed electrochemical sensor and the dopamine electrochemical sensor prepared in Example 2 to 50 μM dopamine, ascorbic acid and uric acid signals were compared, and the detection steps were as described in Example 4. The detection results are shown in Table 1.

[0067] Table 1 Comparison results of signal response

[0068]

[0069] also, Figure 6 The corresponding DPV diagram of the electrochemical sensor constructed for pure MoS2 to 50μM AA, Figure 7 Electrochemical sensors constructed for pure MoS2 and defective MoS 2-x DPV graph and corresponding bar graph of the constructed dopamine electrochemical sensor in response to 50μM DA and 50μM UA. Figure 6 , Figure 7 It can be seen that compared with pure MoS2, defective MoS 2-x There is no response signal for ascorbic acid, and the response for uric acid is significantly weakened, indicating that defective MoS 2-x It has excellent anti-interference performance for ascorbic acid and uric acid.

[0070] Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A working electrode for a dopamine electrochemical sensor, characterized in that: The working electrode comprises an electrode substrate and defective molybdenum disulfide modified on the surface of the electrode substrate; the defective molybdenum disulfide is molybdenum disulfide with sulfur vacancy defects.

2. The working electrode for dopamine electrochemical sensor according to claim 1, characterized in that: The electrode substrate includes a glassy carbon electrode or a gold electrode.

3. The working electrode for dopamine electrochemical sensor according to claim 1 or 2, characterized in that: The working electrode is prepared by a method comprising the following steps: coating a dispersion containing defective molybdenum disulfide on a pretreated surface of a substrate electrode and drying the mixture.

4. The working electrode for dopamine electrochemical sensor according to claim 3, characterized in that: The dispersion consists of defective molybdenum disulfide, carbon nanotubes, Nafion and a solvent.

5. A dopamine electrochemical sensor, characterized in that: The present invention comprises the working electrode for a dopamine electrochemical sensor according to any one of claims 1 to 4.

6. Use of the dopamine electrochemical sensor as claimed in claim 5 in detecting dopamine content.

7. Use of the dopamine electrochemical sensor according to claim 6 in detecting dopamine content, characterized in that: The pH of the system during the dopamine test was 7.2-7.4.

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