Flexible electrode for dopamine electrochemical sensor as well as construction method and application of flexible electrode

Abstract

The invention discloses a flexible electrode for a dopamine electrochemical sensor as well as a construction method and application of the flexible electrode, and belongs to the technical field of electrochemical sensors. According to the preparation method, firstly, carbon nanotubes are preferably selected from multiple carbon materials through experiments, and the electro-catalysis capability of molybdenum disulfide can be improved to the maximum extent; and then coating molybdenum disulfide and a carbon nano tube on a flexible electrode substrate of which the surface is sequentially modified with a silver layer and a gold layer to obtain the flexible electrode for the dopamine electrochemical sensor. Experiments prove that the flexible electrode for the dopamine electrochemical sensor, which is constructed by the construction method disclosed by the invention, shows good electro-catalytic activity and has good sensitivity and specificity during dopamine detection, and the flexible electrode can still ensure relatively high initial current activity after being greatly bent, so that the electrochemical sensor can be applied to detection of dopamine. And relatively high detection stability can be ensured within two days.

Description

Technical Field

[0001] The present invention relates to a flexible electrode for a dopamine electrochemical sensor, a construction method and an application thereof, belonging to the technical field of electrochemical biosensors. Background Art

[0002] Dopamine, as the most abundant catecholamine neurotransmitter in the brain, can regulate various physiological functions of the central nervous system and plays a role in transmitting information between cells and within cells. In the central nervous system, there are approximately 400,000 neurons using dopamine as a neurotransmitter, which project to various brain regions through complex neural pathways, mainly forming three functions: motor control, behavioral selection, and reinforcement learning. Research has shown that dopamine is not only related to the physiological functions of the central nervous system but also associated with neurodegenerative diseases. Abnormal expression and reduced levels of dopamine may be one of the causes of Alzheimer's disease, Parkinson's disease, and Huntington's disease. Therefore, the determination of dopamine content has important practical significance in clinical applications and the exploration of its physiological mechanisms. Currently, many methods for dopamine detection have emerged, and the commonly used methods mainly include high-performance liquid chromatography, fluorescence analysis, ultraviolet spectrophotometry, and electrochemical detection methods, etc.

[0003] The electrochemical method is a detection method that converts the chemical signal of the analyte in the solution into an electrical signal through an electrode during the reaction. Compared with other methods, the electrochemical method has a simple device, low cost, high sensitivity, good stability, and is suitable for on-line real-time detection. Most traditional rigid electrodes are composed of hard materials, and the manufacturing process is relatively complex. In vivo experiments are extremely prone to inflammatory reactions; at the same time, due to the inability to deform with body movements, tissue damage around the implantation site is caused, which is not conducive to in vivo detection. The flexible electrochemical biosensing interface has good stretching and deformation characteristics and biocompatibility, and can conform to body changes and organ peristalsis during in vivo tests, meeting the activity requirements in experiments and practical applications. At the same time, the flexible electrochemical biosensing interface is also easy to combine with soft lithography technology to construct an integrated sensing device, realizing miniaturization of the device and continuous real-time detection of the target substance, and playing an important role in disease diagnosis and treatment.

[0004] As an important part of constructing a flexible electrochemical biosensing interface, the stretching and bending performance of the flexible electrode itself and its stability after combining with the sensing material have always been a research hotspot. In the rapid development process of various polymer flexible electrode preparation methods, the flexible electrode prepared by electrospinning technology has ultra-long nanofibers, a large specific surface area, and high porosity. These characteristics can significantly improve the sensitivity and response time of the material, and the flexible membrane prepared by electrospinning is extremely easy to be surface-functionalized. Therefore, electrospinning is often used as an effective method for preparing flexible electrodes.

[0005] The Chinese invention patent application document with a publication date of February 1, 2019 and a publication number of CN109298052A discloses a method for detecting dopamine using a flexible silver nanowire / nano gold composite electrode based on PDMS. Specifically, it discloses using polydimethylsiloxane (PDMS) as a flexible substrate, modifying the hydrophilic surface layer with a mixed solution of polyvinyl alcohol and polyvinylpyrrolidone on its surface, uniformly coating a silver nanowire conductive layer on the hydrophilic modification layer, and depositing nano gold particles on this conductive layer by electrochemical deposition to prepare an AuNPs / AgNWs / PDMS flexible electrode. And using the AuNPs / AgNWs / PDMS flexible electrode as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum wire as the auxiliary electrode to form a three - electrode system to establish an analytical method for determining dopamine. This analytical method is simple to operate and has a short detection time, but the detection sensitivity is relatively low, and the anti - interference ability during detection is unknown. Therefore, preparing a flexible electrode with high sensitivity and strong specificity for dopamine is an urgent problem to be solved in the electrochemical detection of dopamine.

[0006] Due to the layered structural characteristics and edge active sites of molybdenum disulfide (MoS2), MoS2 has the characteristics of low cost, large specific surface area, and rich redox chemical properties, and has many applications in various aspects, such as capacitors, lithium - ion batteries, electrochemical sensors, etc. When MoS2 is used to construct an electrochemical sensor, it is often used as an electrode modifier and shows good electrocatalytic activity in dopamine oxidation, such as an increase in the oxidation peak current and a decrease in the oxidation potential. However, since MoS2 is a semiconductor compound and has poor conductivity at room temperature, other conductive materials need to be introduced to improve the conductivity when constructing a dopamine electrochemical sensor. Carbon materials such as graphene and carbon nanotubes have the characteristics of good conductivity, light weight, and large specific surface area, and are often combined with MoS2 for constructing capacitors, lithium - ion batteries, etc., while the research on the combination of the two to construct a dopamine electrochemical sensing interface is less. Summary of the Invention

[0007] The first object of the present invention is to provide a method for constructing a flexible electrode for a dopamine electrochemical sensor, providing a method for constructing a flexible electrode for a dopamine electrochemical sensor with relatively high sensitivity and specificity.

[0008] The second object of the present invention is to provide a flexible electrode for a dopamine electrochemical sensor constructed by the method for constructing a flexible electrode for a dopamine electrochemical sensor, providing a flexible electrode for a dopamine electrochemical sensor with relatively high sensitivity and specificity.

[0009] The third object of the present invention is to provide the application of a flexible electrode for a dopamine electrochemical sensor in the preparation of a dopamine electrochemical sensor, providing a dopamine electrochemical sensor with relatively high sensitivity and specificity.

[0010] To achieve the above object, the technical solution adopted by the method for constructing a flexible electrode for a dopamine electrochemical sensor in the present invention is as follows:

[0011] A method for constructing a flexible electrode for a dopamine electrochemical sensor includes the following steps:

[0012] (1) A silver layer and a gold layer are sequentially modified on a polyvinyl alcohol spun fiber membrane to obtain a flexible electrode substrate;

[0013] (2) A dispersion liquid containing molybdenum disulfide and carbon nanotubes is coated on the surface of the flexible electrode substrate described in step (1), and then dried to obtain the product.

[0014] The beneficial effects of the above solution are as follows: The method for constructing a flexible electrode for a dopamine electrochemical sensor of the present invention is a pioneering invention. The present invention first optimizes carbon nanotubes from a variety of carbon materials through experiments, which can maximize the electrocatalytic ability of molybdenum disulfide; then molybdenum disulfide and carbon nanotubes are coated on a flexible electrode substrate with a silver layer and a gold layer sequentially modified on the surface to obtain a flexible electrode for a dopamine electrochemical sensor. The present invention proves through experiments that the flexible electrode for a dopamine electrochemical sensor constructed by the construction method of the present invention shows good electrocatalytic activity, good sensitivity and specificity during dopamine detection, and moreover, the flexible electrode can still ensure a high initial current activity after being bent greatly, and can ensure a high detection stability within two days.

[0015] As a further improvement, in the dispersion liquid described in step (2), molybdenum disulfide and carbon nanotubes are mixed in a mass ratio of 1:(1 - 1.1); the mass fraction of molybdenum disulfide in the dispersion liquid is 0.15 - 0.2%.

[0016] As a further improvement, in step (2), for every 1 cm 2 of the flexible electrode substrate, (5 - 6) μL of the dispersion liquid is used.

[0017] As a further improvement, in step (1), the modification of the silver layer includes subjecting the polyvinyl alcohol spun fiber membrane to glutaraldehyde adsorption, and then reacting it in a silver ammonia solution to obtain a PVA / nano - Ag flexible membrane.

[0018] As a further improvement, the glutaraldehyde adsorption is carried out by fumigating the polyvinyl alcohol spun fiber membrane with an aqueous glutaraldehyde solution.

[0019] As a further improvement, the polyvinyl alcohol spun fiber membrane described in step (1) is prepared by a method including the following steps: A solution containing polyvinyl alcohol and dilute hydrochloric acid is spun using an electrospinning machine.

[0020] The beneficial effects of the above solution are as follows: The flexible material prepared by the electrospinning technology has ultra-long nanofibers, a large specific surface area, and a high porosity. These characteristics can significantly improve the sensitivity and response time of the flexible electrode, and the flexible material prepared by electrospinning is extremely easy to be surface-functionalized.

[0021] As a further improvement, the pH of the solution is 3 to 3.5.

[0022] As a further improvement, in step (1), the modified gold layer is to deposit gold on the surface of the PVA / nano-Ag flexible film by magnetron sputtering to obtain a PVA / nano-Ag / Au flexible electrode.

[0023] To achieve the above object, the technical solution adopted by the flexible electrode for a dopamine electrochemical sensor constructed by the method for constructing a flexible electrode for a dopamine electrochemical sensor in the present invention is:

[0024] A flexible electrode for a dopamine electrochemical sensor constructed by the method for constructing a flexible electrode for a dopamine electrochemical sensor.

[0025] The beneficial effects of the above solution are as follows: First, the base polyvinyl alcohol spun fiber membrane in the flexible electrode prepared in the present invention is prepared by the electrospinning technology. The electrode base has ultra-long nanofibers, a large specific surface area, and a high porosity, and is easy to perform subsequent surface functionalization; Second, molybdenum disulfide (MoS2) and carbon nanotubes are modified on the surface of the flexible electrode base. MoS2 has the characteristics of low cost, large specific surface area, and rich redox chemical properties, and shows good electrocatalytic activity in the oxidation of dopamine, while carbon nanotubes and the like have the characteristics of good conductivity, light weight, and large specific surface area. The two cooperate with each other to make the constructed flexible electrode have good specificity and sensitivity in detecting dopamine.

[0026] Furthermore, the flexible electrode for a dopamine electrochemical sensor in the present invention has good flexibility and stability. After being bent greatly, it can still ensure a high initial current activity, and can ensure a high detection stability within two days. It is easy to combine with soft lithography technology to construct an integrated sensing device, realizing device miniaturization and continuous real-time detection of the target substance, and playing an important role in disease diagnosis and treatment.

[0027] To achieve the above object, the technical solution adopted by the application of a flexible electrode for a dopamine electrochemical sensor in the preparation of a dopamine electrochemical sensor in the present invention is:

[0028] The application of a flexible electrode for a dopamine electrochemical sensor in the preparation of a dopamine electrochemical sensor.

[0029] The beneficial effects of the above scheme are: the flexible electrode for the dopamine electrochemical sensor of the present invention has good flexibility and stability, can still ensure a high initial current activity after a large bending, and can ensure a high detection stability within two days, which is conducive to expanding the application scope of the dopamine electrochemical sensor; and has good specificity and sensitivity, which is conducive to improving the anti-interference ability of the dopamine electrochemical sensor during the detection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 are microscopic images of the materials in Example 1 of the present invention (wherein (a) is a SEM image of a PVA electrospun flexible membrane, (b) is a SEM image of a PVA / nano-Ag flexible membrane, (c) is a TEM image of a PVA / nano-Ag flexible membrane, (d) is a SEM image of MoS2, (e) is a SEM image of CNT, and (f) is a SEM image of MoS2 / CNT);

[0031] Figure 2 The electrochemical response diagrams of the three working electrodes in the presence of dopamine in Experimental Example 1 of the present invention (wherein (g) are cyclic voltammograms of the three working electrodes in the presence of high concentration dopamine, and (h) are square wave voltammograms of the three working electrodes);

[0032] Figure 3 The electrochemical detection of dopamine by the electrochemical biosensor prepared with PVA / nano-Ag / Au / MoS2 / CNT as the working electrode in Experimental Example 2 of the present invention (wherein, (i) is the time-current curve of PVA / nano-Ag / Au / MoS2 / CNT at different DA concentrations, (j) is the linear fitting curve of PVA / nano-Ag / Au / MoS2 / CNT, (k) is the stability test of PVA / nano-Ag / Au / MoS2 / CNT within the range of 0.5 μM DA concentration, and (l) is the time-current curve of PVA / nano-Ag / Au / MoS2 / CNT under different interferents);

[0033] Figure 4 These are the stability test results of the flexible electrode for the dopamine electrochemical sensor in Experimental Example 3 of the present invention (wherein (m) is a bending schematic diagram of the PVA / nano-Ag / Au / MoS2 / CNT flexible sensing interface; (n) is the linear change of the PVA / nano-Ag / Au / MoS2 / CNT sensing interface after different bending angles; (o) is the current stability of the PVA / nano-Ag / Au / MoS2 / CNT sensing interface after 50 times of 90° bending). DETAILED DESCRIPTION

[0034] In the prior art, rigid electrodes are often used for dopamine detection with electrochemical biosensors. Most rigid electrodes are made of hard materials and the manufacturing process is relatively complex, which limits the application scope of electrochemical biosensors in dopamine detection. MoS2 has a layered structure and edge active sites. When used to construct an electrochemical biosensor, it exhibits good electrocatalytic activity in dopamine oxidation. However, MoS2 is a semiconductor compound with poor conductivity at room temperature. Therefore, other conductive materials need to be introduced to improve the conductivity. Based on this, the present invention provides a flexible electrode for a dopamine electrochemical sensor.

[0035] The following further describes the present invention in detail with specific embodiments. Unless otherwise specified, the equipment and reagents used in each embodiment, experimental example and comparative example can be obtained commercially.

[0036] I. Specific embodiments of a flexible electrode for a dopamine electrochemical sensor of the present invention and its construction method:

[0037] Example 1

[0038] The flexible electrode for a dopamine electrochemical sensor in this example is constructed by the following construction method, and the specific implementation operations are as follows:

[0039] 1. Weigh 2 g of PVA (polyvinyl alcohol) solid particles with a weighing balance, add 18 g of deionized water to prepare a PVA aqueous solution, put in a magnetic stirrer, and seal it with plastic wrap; then place it in a water bath at 90 °C to dissolve PVA, let it stand and cool to room temperature. Add 100 μL of dilute hydrochloric acid to make the pH = 3, continue stirring for 1 h to fully mix it. After the stirring ends, let it stand at room temperature for later use. Use an electrospinning machine for electrospinning. After the electrospinning ends, carefully remove the PVA electrospun fiber membrane from the receiver. The thickness of this membrane is 0.05 mm (the SEM image of this membrane is shown in Figure 1 (a) as shown) and put it into a sealed bag for later use.

[0040] Among them, the parameter settings for electrospinning with the electrospinning machine should be a high voltage of 17 kV, a feeding speed of 0.005 mL / min, a rotation speed of 1500 rpm, an electrospinning time of 10 h, the receiver is a copper drum-shaped receiver, and the distance between the needle tip and the receiver is 12.5 cm.

[0041] 2. Cut the above PVA spun fiber membrane into a size of 7×7 cm, place it in a double-layer box containing 50% (volume fraction) aqueous glutaraldehyde solution, take it out after steam fumigation at 80 °C, and place it in a sealed bag for standby. During the cross-linking process of the PVA flexible membrane, the hydroxyl groups carried by polyvinyl alcohol and the aldehyde groups of glutaraldehyde undergo an aldol condensation reaction under acidic conditions. There are three reaction sites, namely, one aldehyde group of glutaraldehyde reacts with one hydroxyl group of PVA, two aldehyde groups of glutaraldehyde react with one hydroxyl group of PVA, and two aldehyde groups of glutaraldehyde react with two hydroxyl groups of PVA. Therefore, after cross-linking, the number of hydroxyl groups in the PVA flexible membrane decreases, the connection between fibers becomes tighter, the water resistance of the flexible membrane is enhanced, and the enhanced water resistance can provide environmental stability, mechanical strength, and functional expansion potential for the flexible electrode.

[0042] Place the cross-linked PVA spun fiber membrane in the freshly prepared silver ammonia solution, take it out after standing for 1 h, rinse it 3 times with PBS buffer solution to remove the unreacted silver ammonia solution on the surface, and then dry it with nitrogen to obtain the PVA / nano-Ag flexible membrane (the SEM image and TEM image of the PVA / nano-Ag flexible membrane are shown in Figure 1 (b) and (c) in the figure).

[0043] Deposit 20 nm Au on the surface of the above PVA / nano-Ag flexible membrane using a magnetron sputtering coater to obtain the PVA / nano-Ag / Au flexible electrode. Among them, the setting parameters of the magnetron sputtering coater are as follows: Ar flow rate: 80 sccm; cylinder pressure: 0.35 MPa; target gun power: 130 W; coating duration: 104 s; average rate: 0.2 nm / s; film thickness: 20 nm.

[0044] Cut the PVA / nano-Ag / Au flexible electrode into 1×1 cm, and then drop 5 μL of MoS2 / CNT dispersion on the surface of the flexible electrode, let it stand and dry to prepare the PVA / nano-Ag / Au / MoS2 / CNT flexible dopamine sensing interface, which is the flexible electrode for the dopamine electrochemical sensor (the SEM image of MoS2 is shown in Figure 1 (d) in the figure, CNT is shown in Figure 1 (e) in the figure, the SEM image of MoS2 / CNT is shown in Figure 1 (f) in the figure. The figure shows the apparent morphology of the MoS2 / CNT composite material, and it can be seen that there is an effective combination of the MoS2 sheet structure and the CNT tubular structure).

[0045] Among them, the preparation process of the silver ammonia solution is as follows: Prepare 10 mL of 0.01 M silver nitrate aqueous solution, and gradually add 33% ammonia water dropwise into the solution to form a white flocculent precipitate. Continue to add ammonia water until the solution changes from white to colorless. Then add 1 mL of 0.8 M sodium hydroxide solution to obtain the silver ammonia solution for use.

[0046] The preparation process of the MoS2 / CNT dispersion is as follows: Mix CNT, MoS2 and deionized water according to the mass ratio of 1:1:375, and ultrasonicate for 1 h to make them evenly mixed to obtain a mixed solution; Take 375 μL of the mixed solution, 125 μL of absolute ethanol and 50 μL of Nafion solution and place them in a 1 mL centrifuge tube, and ultrasonicate for 30 min to make them fully mixed to obtain the MoS2 / CNT dispersion.

[0047] II. Experimental Example Application of the Flexible Electrode for the Dopamine Electrochemical Sensor in the Preparation of the Dopamine Electrochemical Sensor

[0048] Experimental Example 1

[0049] In this experimental example, the MoS2 / CNT / GCE, MoS2 / SG / GCE and MoS2 / GO / GCE electrodes were used as the working electrode, Ag / AgCl was used as the reference electrode, and the Pt mesh electrode was used as the counter electrode to form a three-electrode system, which was placed in an electrolyte containing 0.05 mM dopamine (0.01 M PBS, pH 7.2 - 7.4, purged with nitrogen to remove oxygen) for electrochemical testing to compare the response of dopamine when different carbon materials were combined with molybdenum disulfide. The specific operations are as follows:

[0050] 1. Preparation of the MoS2 / CNT / GCE working electrode: Mix CNT, MoS2 and deionized water according to the mass ratio of 1:1:375, and ultrasonicate for 1 h to make them evenly mixed to obtain a mixed solution; Then take 375 μL of the mixed solution, 125 μL of absolute ethanol and 50 μL of Nafion solution and place them in a 1 mL centrifuge tube, and ultrasonicate for 30 min to make them fully mixed to obtain the MoS2 / CNT dispersion; Drop the dispersion onto the glassy carbon electrode (5 μL of the dispersion is dropped onto a glassy carbon electrode with a diameter of 3 mm), and let it stand to dry to make the MoS2 / CNT / GCE electrode.

[0051] 2. Preparation of MoS2 / SG / GCE working electrode: Mix SG, MoS2 and deionized water in a mass ratio of 1:1:375, and ultrasonicate for 1 h to make them evenly mixed, obtaining a mixed solution; then take 375 μL of the mixed solution, 125 μL of absolute ethanol and 50 μL of Nafion solution and place them in a 1 mL centrifuge tube, ultrasonicate for 30 min to make them fully mixed, obtaining a MoS2 / SG dispersion; take the dispersion and drop it onto a glassy carbon electrode (5 μL of the dispersion is dropped onto a glassy carbon electrode with a diameter of 3 mm), let it stand and dry to make a MoS2 / SG / GCE electrode.

[0052] 3. Preparation of MoS2 / GO / GCE working electrode: Mix GO, MoS2 and deionized water in a mass ratio of 1:1:375, and ultrasonicate for 1 h to make them evenly mixed, obtaining a mixed solution; then take 375 μL of the mixed solution, 125 μL of absolute ethanol and 50 μL of Nafion solution and place them in a 1 mL centrifuge tube, ultrasonicate for 30 min to make them fully mixed, obtaining a MoS2 / GO dispersion; take the dispersion and drop it onto a glassy carbon electrode (5 μL of the dispersion is dropped onto a glassy carbon electrode with a diameter of 3 mm), let it stand and dry to make a MoS2 / GO / GCE electrode.

[0053] 4. Respectively use MoS2 / CNT / GCE, MoS2 / SG / GCE and MoS2 / GO / GCE electrodes as working electrodes, Ag / AgCl as the reference electrode, and a Pt mesh electrode as the counter electrode to form a three-electrode system, and place it in an electrolyte containing 0.05 mM dopamine (0.01 M PBS, pH 7.2 - 7.4, purged with nitrogen to remove oxygen), and perform tests according to electrochemical methods. The specific parameters are as follows:

[0054] a) Cyclic voltammetry (CV): Potential range -0.2 - 0.6 V, scan rate 0.05 V / s, sampling interval 0.01 s, cycle 5 times;

[0055] b) Square wave voltammetry (SWV): Potential range -0.2 - 0.6 V, scan rate 0.05 V / s, repeat 5 times.

[0056] The detection ability of dopamine after the combination of three carbon materials and MoS2 is as Figure 2 shown. Figure 2 Figure (g) in shows the cyclic voltammograms of the three working electrodes in the presence of high-concentration dopamine. It can be seen from the figure that MoS2 / CNT has the largest current response to dopamine, followed by MoS2 / SG, and finally MoS2 / GO. The square wave voltammogram ( Figure 2 Figure (h) in) also shows the same trend of current response. Therefore, it can be concluded that when CNT is mixed with MoS2, the electrocatalytic ability of MoS2 can be maximally increased.

[0057] Experimental Example 2

[0058] In this experimental example, the flexible electrode of the dopamine electrochemical sensor constructed in Example 1 was used as the working electrode, Ag / AgCl as the reference electrode, and the Pt mesh electrode as the counter electrode to form a three-electrode system, which was placed in an electrolyte solution (0.01M PBS, pH 7.2 - 7.4, deoxygenated by purging with nitrogen), and was connected to an electrochemical workstation to construct a dopamine electrochemical sensor to explore its response to dopamine. The specific operations are as follows:

[0059] 1. Linear range

[0060] Using PVA / nano-Ag / Au / MoS2 / CNT as the working electrode, Ag / AgCl as the reference electrode, and the Pt mesh electrode as the counter electrode, 30 mL of dopamine solutions with different concentrations (prepared with PBS, deoxygenated by purging with nitrogen) were used as the electrolyte solutions, and the electrochemical method of differential pulse voltammetry (DPV) was used for quantitative testing of the sensing performance. The parameters were set as follows: potential range 0 - 0.35V, scan rate 50 mV / s, pulse amplitude 25 mV, pulse width 50 ms, pulse period 0.5 s, step size 5 mV, repeated 3 times.

[0061] The specific detection results are as Figure 3 shown

[0062] (i) Time-current curves of PVA / nano-Ag / Au / MoS2 / CNT at different DA concentrations. It can be seen from the figure that the lowest detection limit of PVA / nano-Ag / Au / MoS2 / CNT for DA can reach 500 nM, and as the concentration of DA increases, the current detection value also gradually increases;

[0063] (j) Linear fitting curve of PVA / nano-Ag / Au / MoS2 / CNT. It can be seen from the figure that at the equilibrium potential of 0.15V, the current value increases significantly with the increase of DA concentration, and the increasing trend is linear;

[0064] (k) Stability test chart of PVA / nano-Ag / Au / MoS2 / CNT in 0.5 μM DA. It can be seen from the figure that by continuously testing in 0.5 μM DA solution with CA for 6 hours, a stable current response was obtained; meanwhile, the sensing interface can ensure 94% sensing stability within 2 days.

[0065] Note: The specific calculation process of the sensing stability is Figure 3 the current value at the abscissa of 48 h in (k) divided by the current value at the abscissa of 1 h and then multiplied by 100%.

[0066] 2. Anti-interference ability

[0067] Using PVA / nano-Ag / Au / MoS2 / CNT as the working electrode, Ag / AgCl as the reference electrode, and a Pt mesh electrode as the counter electrode, 0.01M PBS containing DA, UA (uric acid), and AA (ascorbic acid) (pH 7.2 - 7.4, deoxygenated by purging with nitrogen) was used as the electrolyte to test the dopamine selectivity of the PVA / nano-Ag / Au / MoS2 / CNT flexible sensing interface at a potential of 0.15V. When AA was added to the system in the presence of DA, the current did not change significantly. After further adding UA, the current value still tended to be stable. After adding DA, the current value increased, indicating that after modifying MoS2 / CNT onto the surface of the PVA / nano-Ag / Au flexible electrode at a potential of 0.15V, it still has good selectivity for dopamine and can effectively detect dopamine (the specific detection results are as Figure 3 (l) shows).

[0068] Experimental Example 3

[0069] This experimental example tested the stability of the flexible electrode of the dopamine electrochemical sensor constructed in Example 1 after bending. The specific operation is as follows:

[0070] The specific detection results are as Figure 4 shown, where figure m represents the bending schematic diagram of the A / nano-Ag / Au / MoS2 / CNT flexible sensing interface, and figure n shows the linear change of the PVA / nano-Ag / Au / MoS2 / CNT sensing interface after different bending angles. After 50 bends of 90°, 87.4% of the initial activity can be guaranteed.

[0071] The stability of the flexible sensing interface was detected after 50 bends. Using chronoamperometry, a stable current response was obtained by continuously testing for 6h in a 0.5μM dopamine solution. At the same time, after 50 bends of 90° of the sensing interface, 97% of the sensing stability can be guaranteed within 2 days (as shown in o in 4). The reason for the improved sensing stability of the flexible sensing interface within 2 days after 50 bends is that 50 bending stimuli optimized the microstructure, conductive network, and interface state of the flexible sensing interface, enabling it to exhibit relatively high sensing stability within 2 days.

[0072] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and 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 method for constructing a flexible electrode for a dopamine electrochemical sensor, characterized in that: It includes the following steps: (1) Modify a silver layer and a gold layer on a polyvinyl alcohol spun fiber membrane in sequence to obtain a flexible electrode substrate; (2) Coat the surface of the flexible electrode substrate described in step (1) with a dispersion liquid containing molybdenum disulfide and carbon nanotubes, and dry it to obtain.

2. The construction method of the flexible electrode for the dopamine electrochemical sensor according to claim 1, characterized in that: In the dispersion liquid described in step (2), molybdenum disulfide and carbon nanotubes are mixed in a mass ratio of 1:(1-1.1); the mass fraction of molybdenum disulfide in the dispersion liquid is 0.15-0.2%.

3. The construction method of the flexible electrode for the dopamine electrochemical sensor according to claim 2, wherein: In step (2), for every 1 cm 2 of the flexible electrode substrate, (5 - 6) μL of the dispersion liquid is used.

4. The construction method of the flexible electrode for the dopamine electrochemical sensor according to any one of claims 1 to 3, characterized in that: In step (1), modifying the silver layer includes adsorbing glutaraldehyde on the polyvinyl alcohol spun fiber membrane, and then reacting it in a silver ammonia solution to obtain a PVA / nano-Ag flexible membrane.

5. The construction method of the flexible electrode for the dopamine electrochemical sensor according to claim 4, characterized in that: The glutaraldehyde adsorption is to fumigate the polyvinyl alcohol spun fiber membrane with an aqueous glutaraldehyde solution.

6. The construction method of the flexible electrode for the dopamine electrochemical sensor according to any one of claims 1 to 3, characterized in that: The polyvinyl alcohol spun fiber membrane described in step (1) is prepared by a method including the following steps: spinning a solution containing polyvinyl alcohol and dilute hydrochloric acid using an electrospinning machine.

7. The construction method of the flexible electrode for the dopamine electrochemical sensor according to claim 6, characterized in that: The pH of the solution is 3-3.

5.

8. The construction method of the flexible electrode for the dopamine electrochemical sensor according to claim 5, characterized in that: In step (1), modifying the gold layer is to deposit gold on the surface of the PVA / nano-Ag flexible membrane by magnetron sputtering to obtain a PVA / nano-Ag / Au flexible electrode.

9. A flexible electrode for a dopamine electrochemical sensor constructed by the construction method of the flexible electrode for a dopamine electrochemical sensor according to any one of claims 1-8.

10. An application of the flexible electrode for a dopamine electrochemical sensor according to claim 9 in the preparation of a dopamine electrochemical sensor.

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