Dopamine sensor working electrode based on MOF material and preparation method thereof

Abstract

The invention discloses a dopamine sensor working electrode based on an MOF material and a preparation method thereof, and belongs to the technical field of electrochemical sensing. The working electrode is composed of a pure MOF Cu-HHTP modified glassy carbon electrode and a Nafion film covering the surface of the glassy carbon electrode, and the preparation method of the working electrode comprises the following steps: synthesizing Cu-HHTP (Cu < 2 + > and a hexahydroxy triphenyl ligand are coordinated to form a two-dimensional honeycomb layer) through a solvothermal method, dispensing Cu-HHTP dispersion liquid on the surface of the glassy carbon electrode, and then covering the glassy carbon electrode with the Nafion film to form the combined electrode. The dopamine sensor prepared by the preparation method disclosed by the invention has high sensitivity, high anti-interference capability and long-term stability. The preparation process is simple, complex conductive additives are not needed, and the method is suitable for rapid and accurate detection of dopamine in complex biological samples.

Description

Technical Field

[0001] The present invention relates to the technical field of nanotechnology and electrochemical sensors, and in particular to a dopamine sensor working electrode based on MOF materials and a preparation method thereof. Background Art

[0002] Dopamine (DA) is an important neurotransmitter in the central nervous system. Its abnormal concentration is closely related to Parkinson's disease, depression and many other diseases. Real-time and accurate detection of dopamine is of key significance for pathological mechanism research and clinical diagnosis. At present, dopamine detection technology is mainly divided into chromatography-mass spectrometry, optical detection technology and electrochemical sensor detection. Among them, although chromatography-mass spectrometry has high selectivity, it relies on large equipment and complex pretreatment. Optical detection technology is easily affected by spontaneous fluorescence interference or stability limitations. Electrochemical sensors have become the frontier direction of dopamine detection due to their advantages of rapid response, simple operation and easy integration. The core lies in the design and optimization of electrode modification materials. In recent years, metal-organic framework (MOF) materials have been widely used due to their adjustable pore structure (0.3-5nm), high specific surface area (>1000m 2 / g) and abundant active sites, showing potential in the field of electrochemical sensing. For example, cobalt-based MOF (ZIF-67) can achieve specific adsorption through the coordination of cobalt centers with dopamine.

[0003] However, existing MOF-based sensors still have the following key bottlenecks: (1) Conductivity defects: The electronic conduction of pure MOF materials depends on the ligand π-π conjugated system, but the efficiency of electronic transition between metal nodes and ligands is low (conductivity <10 -5 S / m), resulting in weak electrochemical signals, which usually require composite conductive materials (such as graphene, carbon black) to improve performance, but this increases the complexity of preparation; (2) Insufficient selectivity: Dopamine and common interfering substances (such as ascorbic acid AA and uric acid UA) have similar molecular sizes (about 0.6 nm). It is difficult to effectively distinguish them by simply relying on MOF pore screening. Chemical selectivity mechanisms (such as metal-ligand coordinated coordination) need to be introduced. (3) Stability issues: Some MOFs (especially carboxylic acid-based MOFs) are prone to framework degradation in aqueous solutions, resulting in the loss of active sites and affecting long-term detection reliability.

[0004] While existing technologies have achieved some progress in sensitivity and selectivity, balancing high sensitivity, strong selectivity, and long-term stability remains a core challenge hindering the practical application of electrochemical sensors. To address this issue, innovative material design and process optimization are urgently needed to develop MOF-based sensors that combine efficient electron transport, precise molecular recognition, and a stable framework structure to meet the needs of real-time, accurate detection of dopamine in complex biological samples. Summary of the Invention

[0005] In order to address the deficiencies in the prior art, the present invention provides a dopamine sensor working electrode based on MOF material and a preparation method thereof, which can achieve accurate detection of dopamine.

[0006] In order to achieve the above object, the specific scheme adopted by the present invention is: A method for preparing a dopamine sensor working electrode based on MOF material mainly comprises the following steps: Step S1: Synthesis of Cu-HHTP Step S11, dissolving 7.8 mg of HHTP in a mixed solvent consisting of 0.4 mL of DMF and 0.5 mL of H2O, mixing uniformly by ultrasonication, and heating at 80°C for 10 min to obtain solution A; S12. Dissolve 14 mg of CuSO4·5H2O in 0.6 mL of water, mix thoroughly by ultrasonication, and heat at 80°C for 10 min to obtain solution B. S13, mixing solution A and solution B, then heating at 80° C. for 18 h, collecting the precipitate by centrifugation, and washing and drying the precipitate in sequence to obtain Cu-HHTP with a stable MOF structure; Step S2: preparing a working electrode Step S21, dispersing 2 mg of Cu-HHTP in 1 mL of deionized water, and ultrasonicating for 30 min to prepare a dispersion; Step S22: 6.5 μL of the dispersion droplet was applied to the surface of the glassy carbon electrode and dried at room temperature to form a modified electrode; Step S23: add 4 μL of 0.5 wt% Nafion solution onto the surface of the modified electrode and dry at room temperature to obtain a working electrode.

[0007] Furthermore, the preparation method of HHTP used in step S11 is: (1) Add 2.3 g of o-phenyl dimethyl ether to a mixed solution consisting of 50 mL of CH2Cl2, 0.16 g of H2SO4, and 8.1 g of FeCl3, and stir for 2 hours. Filter the precipitate, wash it with methanol until the precipitate turns gray, and vacuum dry it to obtain HMTP. (2) 408 mg of HMTP was dissolved in 15 mL of CHCl3, degassed and filled with nitrogen, and then cooled to 0°C in an ice bath. 1.5 mL of boron tribromide was added dropwise to obtain a mixture. The mixture was heated to room temperature and stirred for 8 hours. The mixture was then poured into methanol and stirred for 30 minutes. The solvent and by-products were evaporated under vacuum to obtain HHTP.

[0008] Furthermore, in step S13, after the precipitate is washed, it is vacuum dried at 80° C. for 48 hours.

[0009] A working electrode of a dopamine sensor, comprising a Cu-HHTP-modified glassy carbon electrode and a Nafion membrane covering the surface, is used for quantitative detection of dopamine.

[0010] Furthermore, the linear response range to dopamine is 1.0-455 μM, with a sensitivity of 35.5 μA·mM -1 cm -2 , the detection limit was as low as 0.2μM (S / N=3).

[0011] Beneficial effects: (1)Cu-HHTP is composed of Cu 2+ The HHTP ligand forms a two-dimensional honeycomb layer through coordination bonds and stacks in an interlayer slip mode, which can provide abundant active sites and significantly increase the adsorption capacity of dopamine. 2+ The d orbital electrons of Cu 2+ ions work together to form a continuous electron transfer network, which makes up for the defect of insufficient conductivity of pure MOF in the existing technology, thereby enhancing the electrochemical signal response. 2+ As a redox active center, it can catalyze the oxidation reaction of dopamine on the electrode surface and accelerate the electron transfer rate. Combined with the high conductivity substrate of the glassy carbon electrode, it achieves a linear response between the current signal and the dopamine concentration in the range of 1.0-455μM (R=0.99647), with a sensitivity of 35.5μA·mM -1 cm -2 , the detection limit was as low as 0.2μM (S / N=3).

[0012] (2) Cu of Cu-HHTP 2+ It specifically binds to the catechol group of dopamine through coordination bonds, further eliminating interfering substances with similar structures but lacking coordination ability. The sulfonic acid group (-SO3 -) forms a negatively charged interface layer, which repels negatively charged interferents (such as AA and UA) at physiological pH. Dopamine, however, is positively charged in physiological environments and can penetrate the Nafion membrane to reach the electrode surface. Experiments have shown that when a 10-fold concentration of interfering substances is added, the current response fluctuates by less than 5%, making it suitable for detection in complex body fluid environments.

[0013] (3) Cu-HHTP is tightly bonded to the surface of the glassy carbon electrode through π-π stacking, and combined with the physical coating of the Nafion membrane, a stable composite structure is formed, which effectively prevents material shedding or pore collapse. The coordination bond of Cu-HHTP is highly stable and is not easily hydrolyzed in aqueous solution (e.g., the problem of easy degradation of carboxylic acid-based MOF is circumvented). After 29 days of storage, the electrode current response retention rate reached 88.8%, and the relative standard deviation (RSD) of the response current of 5 parallel experiments was 2.7%, which meets the needs of long-term detection.

[0014] (4) The present invention uses a solvothermal method to directly synthesize Cu-HHTP, eliminating the need for conductive additives such as graphene or carbon black, thus simplifying the complex preparation process of traditional MOF materials. A water / N,N-dimethylformamide (DMF) mixed solvent replaces highly toxic solvents, reducing the environmental burden of the synthesis process while ensuring uniform growth of the MOF structure.

[0015] (5) The present invention adopts the structural design of Cu-HHTP, Cu 2+ Coordination catalysis, Nafion membrane charge screening and interface stability optimization have solved the problems of weak conductivity, poor anti-interference and easy degradation of traditional MOF sensors, providing a reliable solution for the efficient and accurate detection of dopamine in complex biological samples. The preparation process is simple and has good practical application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The following are SEM images of the products obtained in Example 1 and Comparative Examples 1-4.

[0017] Figure 2 The FTIR spectra of the products obtained in Example 1 and Comparative Examples 1-4 are shown.

[0018] Figure 3 The XRD spectra of the products obtained in Example 1 and Comparative Examples 1-4 are shown.

[0019] Figure 4 CV curves of the products obtained in Example 1 and Comparative Examples 1-4 in PBS buffer containing 0.1 mM DA.

[0020] Figure 5 These are the EIS curves of the products obtained in Example 1 and Comparative Examples 1-4 in K3[Fe(CN)6] / K4Fe(CN)6.

[0021] Figure 6 The Qt curves and Qt curves of the products obtained in Example 1 and Comparative Examples 1-4 are shown in FIG. 1 / 2 curve.

[0022] Figure 7 CV curve of the product obtained in Example 1 in PBS buffer containing 0 mM to 0.5 mM DA; and the linear relationship between the peak current and the DA concentration.

[0023] Figure 8 It curves obtained at different potentials for the product obtained in Example 1.

[0024] Figure 9 The it curve obtained after continuous addition of DA to the product obtained in Example 1; a linear relationship diagram between the current response and the DA concentration.

[0025] Figure 10 The IT curve obtained by the product obtained by the same Example 1 (Figure a); the relationship between current and electrode (Figure b); the IT curve obtained by the product obtained by the same Example 1 at different times (Figure c); the relationship between current and time (Figure d).

[0026] Figure 11 The current response of the product obtained in Example 1 to dopamine and the interferences AA (a), UA (b), H2O2 (c), NO2 - (d), comparison of the current responses of glucose (e), sodium citrate (f), NaCl (g) and KNO3 (h). DETAILED DESCRIPTION

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] The present invention discloses a dopamine sensor working electrode based on MOF material and a preparation method thereof, wherein the preparation method mainly comprises the following steps: Synthesis of S1 and HHTP S11. Preparation of HMTP: Add 2.3 g of o-phenyl dimethyl ether to a mixed solution containing 50 mL of CH2Cl2, 0.16 g of H2SO4, and 8.1 g of FeCl3, and stir for 2 hours. After filtering, wash with methanol until the precipitate turns gray, and vacuum dry to obtain HMTP. Mechanism: FeCl3 acts as a Lewis acid to catalyze the oxidative trimerization of o-phenylenedimethyl ether, and H2SO4 stabilizes the intermediate; S12. Preparation of HHTP: Dissolve 408 mg of HMTP in 15 mL of CHCl3, add 1.5 mL of boron tribromide (BBr3) dropwise under ice-cooling, stir at room temperature for 8 hours, pour into methanol for precipitation, and evaporate the by-product in vacuo to obtain HHTP; Mechanism: BBr3 selectively removes the methoxy group (-OCH3) of HMTP to generate HHTP rich in hydroxyl groups (-OH); Synthesis of S2 and Cu-HHTP S21, dissolving 7.8 mg of HHTP in a mixed solvent of 0.4 mL of DMF and 0.5 mL of H2O, and heating at 80°C for 10 minutes after sonication to obtain solution A; S22, dissolve 14 mg of CuSO4·5H2O in 0.6 mL of H2O, sonicate, and heat at 80°C for 10 min to obtain solution B; S23, mixing solutions A and B, heating at 80°C for 18 hours, centrifuging, washing with water, ethanol, and acetone in sequence, and drying under vacuum at 80°C for 48 hours to obtain Cu-HHTP; Mechanism: Cu 2+ Coordinate with the hydroxyl group and benzene epoxy atoms of HHTP to form a stable MOF structure, and DMF enhances the coordination uniformity; S3. Preparation of working electrode S31, dispersing 2 mg of Cu-HHTP in 1 mL of deionized water and ultrasonicating for 30 minutes to prepare a dispersion; S32, take 6.5 μL of the dispersion droplet and apply it on the surface of the glassy carbon electrode, and dry it at room temperature to form a modified electrode; S33, add 4 μL of 0.5 wt% Nafion solution dropwise, and dry at room temperature to complete the preparation of the working electrode. Mechanism: Nafion membrane provides a proton conduction channel through sulfonic acid groups (-SO3H) and suppresses interferences through pore size screening.

[0029] The working electrode prepared by the above method consists of a Cu-HHTP-modified glassy carbon electrode and a Nafion membrane covered on the surface, and is used for the quantitative detection of dopamine.

[0030] Example 1 S1. Preparation of HHTP 2.3 g of o-phenylenedimethyl ether was added to a mixed solution consisting of 50 mL of CHCl, 0.16 g of HSO, and 8.1 g of FeCl, and the mixture was stirred for 2 hours. The precipitate was filtered, washed with methanol until the precipitate turned gray, and dried in vacuo to obtain HMTP. 408 mg of HMTP was dissolved in 15 mL of CHCl, degassed and filled with nitrogen, and then cooled to 0°C in an ice bath. 1.5 mL of boron tribromide was added dropwise to obtain a mixture. The mixture was heated to room temperature and stirred for 8 hours. The mixture was then poured into methanol and stirred for 30 minutes. The solvent and by-products were evaporated under vacuum to obtain HHTP. Synthesis of S2 and Cu-HHTP 7.8 mg of HHTP was dissolved in a mixed solvent consisting of 0.4 mL of DMF and 0.5 mL of H2O, mixed by ultrasonication, and heated at 80°C for 10 min to obtain solution A. 14 mg of CuSO4·5H2O was dissolved in 0.6 mL of water, mixed by ultrasonication, and heated at 80°C for 10 min to obtain solution B. Solution A and solution B were mixed, then heated at 80°C for 18 h, and the precipitate was collected by centrifugation, washed, and dried in sequence to obtain Cu-HHTP with a stable MOF structure. S3. Preparation of working electrode 2 mg of Cu-HHTP was dispersed in 1 mL of deionized water and mixed with ultrasound for 30 min to prepare a dispersion. 6.5 μL of the dispersion was then dropwise applied to a glassy carbon electrode and dried at room temperature to obtain a modified electrode. 4 μL of Nafion (0.5 wt%) was then added to the surface of the modified electrode and dried at room temperature to obtain a working electrode.

[0031] Comparative Example 1

[0032] The difference between this comparative example and Example 1 is that in step S2, 7.8 mg of HHTP was dissolved in a mixed solvent consisting of 0.1 mL of DMF and 0.8 mL of H2O, mixed uniformly by ultrasonication, and heated at 80°C for 10 min to obtain solution A.

[0033] Comparative Example 2

[0034] The difference between this comparative example and Example 1 is that in step S2, 7.8 mg of HHTP was dissolved in a mixed solvent consisting of 0.2 mL of DMF and 0.7 mL of H2O, mixed uniformly by ultrasonication, and heated at 80°C for 10 min to obtain solution A.

[0035] Comparative Example 3

[0036] The difference between this comparative example and Example 1 is that in step S2, 7.8 mg of HHTP was dissolved in a mixed solvent consisting of 0.3 mL of DMF and 0.6 mL of H2O, mixed uniformly by ultrasonication, and heated at 80°C for 10 min to obtain solution A.

[0037] Comparative Example 4

[0038] The difference between this comparative example and Example 1 is that in step S2, 7.8 mg of HHTP was dissolved in a mixed solvent consisting of 0.5 mL of DMF and 0.4 mL of H2O, mixed uniformly by ultrasonication, and heated at 80°C for 10 min to obtain solution A.

[0039] The performance tests of the products obtained in Example 1 and Comparative Examples 1-4 were conducted, and the results are as follows: It should be noted that if the performance test requires the use of a sensor, the corresponding product can be made into a sensor.

[0040] Figure 1 The microstructures of the products obtained in Example 1 and Comparative Examples 1-4 are shown. (a) is the microstructure of the product obtained in Comparative Example 1, (b) is the microstructure of the product obtained in Comparative Example 2, (c) is the microstructure of the product obtained in Comparative Example 3, (d) is the microstructure of the product obtained in Example 1, and (e) is the microstructure of the product obtained in Comparative Example 4. As can be seen from the figure, the micromorphology of Cu-HHTP changes with increasing ratios of added DMF to water. This may be because HHTP is more soluble in DMF, resulting in a change in the growth direction of Cu-HHTP. Among them, Example 1 shows regular short rods.

[0041] Figure 2 The FTIR spectra of the products obtained in Example 1 and Comparative Examples 1-4 are shown in Figure 1. As can be seen from the figure, the infrared spectra of the five Cu-HHTPs with different morphologies are similar, and four characteristic peaks appear: 3440 cm -1 、1446cm -1 , and 1216cm -1 The peaks on the left and right correspond to the stretching vibration of -OH on the HHTP ligand, the stretching vibration of the C=C bond on the benzene ring of the ligand, and the stretching vibration of the CO bond on the ligand; 714 cm -1 The peaks on the left and right correspond to the stretching vibration of the Cu-O bond, which is due to the Cu 2+ The coordination effect with the HHTP ligand resulted in the presence of a large number of Cu-O bonds in Cu-HHTP, indicating that Cu-HHTP has been successfully prepared.

[0042] Figure 3The XRD spectra of the products obtained in Example 1 and Comparative Examples 1-4 are shown. It can be seen from the figure that the five Cu-HHTPs with different morphologies have obvious diffraction peaks at 2θ of 9.5°, 12.6° and 27.9°, which correspond to the (200), (210) and (002) crystal planes of Cu-HHTP, respectively. The diffraction peaks at 9.5° and 12.6° reveal the long-range order in the layer plane structure of Cu-HHTP, while the diffraction peak at 27.3° indicates the long-range order in the direction perpendicular to the layer, which is consistent with the expectation of covalently bonded layered materials. The XRD results show that in Cu-HHTP, copper ions are connected to the hexadentate ligand HHTP to form a two-dimensional honeycomb layer, and are stacked in an interlayer slip mode (AB). In addition, from Figure 3 It can be seen that with the increase of the proportion of DMF, the diffraction peaks gradually become broader and the peak intensity gradually decreases, especially the diffraction peak at 27.3°, which indicates that the local structure of Cu-HHTP is disordered due to solvent exchange (DMF→water).

[0043] Figure 4 The CV curves of the products obtained in Example 1 and Comparative Examples 1-4 in PBS buffer containing 0.1 mM DA are shown. Figure 4 It can be seen that at the same DA concentration, the product prepared in Example 1 exhibits the highest peak current for DA.

[0044] The Nyquist spectrum is analyzed by fitting (fitting circuit diagram as shown in Figure 5 As shown), it can be concluded that compared with comparative examples 1-4, the product prepared in Example 1 has the smallest resistance, and the electron transfer resistance is low, indicating that Example 1 has better electron transfer ability.

[0045] pass Figure 6 The resulting Qt 1 / 2 The slopes between them can be used to calculate that the electrochemical active areas of the products obtained in Example 1 and Comparative Examples 1-4 are 1.6×10 -4 cm 2 (Comparative Example 1), 1.5×10 -5 cm 2 (Comparative Example 2), 1.4×10 -4 cm 2 (Comparative Example 3), 1.8×10 -4 cm 2 (Example 1) and 9.6×10 -5 cm 2 (Comparative Example 4) The results show that the product obtained in Example 1 has a higher electrochemical active area than those in Comparative Examples 1-4.

[0046] The product obtained in Example 1 was used as the working electrode, and CV scanning was performed in PBS buffer containing 0mM to 0.5mM DA. The results were as follows: Figure 7 As shown. Figure 7 It can be seen that with the increase of DA concentration, the peak current gradually increases, and the peak shape is good. There is a good linear relationship between the peak current and the concentration of DA, which further indicates that it has a good CV response to DA.

[0047] In order to determine the optimal working potential, it is necessary to study the current it curve of the product obtained in Example 1 at different potentials. The same concentration of DA was added to 10 mL of PBS solution several times. The results are as follows Figure 8 As shown in the figure, when the potential increases from 0.2V to 0.25V, the IT curve shows more noise. Therefore, in order to ensure a larger current and smaller interference, 0.2V can be used as the optimal working potential in subsequent experiments.

[0048] The sensing ability of the product obtained in Example 1 was evaluated by the IT method. Figure 9 As shown in Figure 2, according to the calculation formula of electrochemical sensing material sensitivity and detection limit, the sensitivity of the material to DA is calculated to be 35.5μA·mM -1 cm -2 , the detection limit was 0.2 μM (S / N=3).

[0049] To verify the reproducibility of the product obtained in Example 1, five products prepared by the same method were placed in a PBS buffer solution at pH = 7.0, and DA at the same concentration was added in sequence. The obtained it curves are shown in FIG. Figure 10 As shown in (a), the five curves are almost identical, and the RSD of the five response currents is 2.7%, demonstrating good reproducibility. The current response was measured every 7 days to evaluate the stability of the product. When the same concentration of DA was added sequentially, the resulting it curves were as follows: Figure 10 As shown in (c), the obtained current response fluctuates over time, and the response current after 29 days is 88.8% of the current on the first day, indicating good stability.

[0050] By adding 10 times the concentration of several common interfering substances to simulate the body fluid environment, the obtained IT curve is as follows Figure 11 This indicates that the electrochemical response of the product obtained in Example 1 to DA is not affected in the presence of high concentrations of interfering substances, which indicates that the product obtained in Example 1 has excellent selectivity for DA, further illustrating the excellent performance of the modified electrode.

[0051] In summary, the electrochemical sensor material for dopamine detection obtained by the method of the present invention has a linear response range of 1.0 to 455 μM for dopamine and a sensitivity of 35.5 μA·mM-1 cm -2 , the detection limit was 0.2 μM (S / N=3).

[0052] The electrochemical sensor material prepared by the present invention realizes efficient detection of dopamine by pure MOF.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily be able to modify the technical solutions of the aforementioned embodiments. Any modifications and improvements made without departing from the principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a dopamine sensor working electrode based on MOF material, characterized in that: The main steps are as follows: Step S1: Synthesis of Cu-HHTP Step S11, dissolving 7.8 mg of HHTP in a mixed solvent consisting of 0.4 mL of DMF and 0.5 mL of H2O, mixing uniformly by ultrasonication, and heating at 80°C for 10 min to obtain solution A; S12. Dissolve 14 mg of CuSO4·5H2O in 0.6 mL of water, mix thoroughly by ultrasonication, and heat at 80°C for 10 min to obtain solution B. S13, mixing solution A and solution B, then heating at 80° C. for 18 h, collecting the precipitate by centrifugation, and washing and drying the precipitate in sequence to obtain Cu-HHTP with a stable MOF structure; Step S2: preparing a working electrode Step S21, dispersing 2 mg of Cu-HHTP in 1 mL of deionized water, and ultrasonicating for 30 minutes to prepare a dispersion; Step S22: 6.5 μL of the dispersion droplet was applied to the surface of the glassy carbon electrode and dried at room temperature to form a modified electrode; Step S23: 4 μL of 0.5 wt% Nafion solution was added dropwise to the surface of the modified electrode and dried at room temperature to obtain a working electrode.

2. The method for preparing a dopamine sensor working electrode based on MOF material according to claim 1, characterized in that: The preparation method of HHTP used in step S11 is: (1) Add 2.3 g of o-phenyl dimethyl ether to a mixed solution consisting of 50 mL of CH2Cl2, 0.16 g of H2SO4, and 8.1 g of FeCl3, and stir for 2 hours. Filter the precipitate, wash it with methanol until the precipitate turns gray, and vacuum dry it to obtain HMTP. (2) 408 mg of HMTP was dissolved in 15 mL of CHCl3, degassed and filled with nitrogen, and then cooled to 0°C in an ice bath. 1.5 mL of boron tribromide was added dropwise to obtain a mixture. The mixture was heated to room temperature and stirred for 8 hours. The mixture was then poured into methanol and stirred for 30 minutes. The solvent and by-products were evaporated under vacuum to obtain HHTP.

3. The method for preparing a dopamine sensor working electrode based on MOF material according to claim 1, characterized in that: In step S13, the precipitate is washed and then vacuum dried at 80°C for 48 hours.

4. A dopamine sensor working electrode prepared by the method according to any one of claims 1 to 3, characterized in that: The working electrode is composed of a Cu-HHTP-modified glassy carbon electrode and a Nafion membrane covering the surface, and is used for quantitative detection of dopamine.

5. A dopamine sensor working electrode according to claim 4, characterized in that: The linear response range to dopamine is 1.0~455μM, and the sensitivity is 35.5μA·mM - 1 cm -2 , the detection limit was as low as 0.2μM (S / N=3).

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