Preparation of Cu-Im / CF Microelectrode and Its Application in Electrochemical Detection of Dopamine

Abstract

The present invention belongs to the field of electrochemical biosensors and provides the preparation of Cu-ImCF microelectrodes and their application in electrochemical detection of dopamine. 1-Ethyl-3-Methylimidazole (EMI) is polymerized on carbon fiber by electrochemical polymerization, and copper nitrate is coordinated with polyimidazole by rotary evaporation. A carbon fiber material modified with Cu-Im nanozymes is successfully prepared and prepared into microelectrodes for electrochemical detection of dopamine. Compared with a bare carbon fiber microelectrode, the prepared Cu-Im carbon fiber microelectrode obtains a significant dopamine oxidation signal when detecting dopamine using the Cu-Im carbon fiber microelectrode, and has good selectivity, stability, and sensitivity.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical biosensors, and particularly relates to the preparation of a Cu-Im / CF microelectrode and its application in electrochemical detection of dopamine. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Dopamine (DA), also known as 3-hydroxytyramine, is the most abundant catecholamine neurotransmitter in the brain. Parkinson's disease is a neurodegenerative disease whose main pathological feature is the loss of dopamine neurons in the substantia nigra. The loss of dopamine neurons leads to a decrease in dopamine levels, resulting in symptoms of Parkinson's disease such as rigidity, tremor, bradykinesia and postural instability. Schizophrenia is a complex mental illness. Patients with schizophrenia may have excessive dopamine activity, leading to symptoms such as hallucinations, delusions and disordered thinking. ADHD is a pediatric neurodevelopmental disease. Dopamine neurons in the brain may be overactive in ADHD patients, leading to increased dopamine levels, thereby affecting the regulatory function of the brain. Therefore, the detection of dopamine is of great significance for the research and treatment of the above-mentioned brain diseases.

[0004] Currently, a variety of methods are used for dopamine detection, including FSCV, amperometry, fluorescence imaging, MRS, PET, and MD. The amperometric method has attracted considerable attention due to its low cost, ease of use, and excellent temporal resolution and sensitivity. It relies on placing a carbon fiber microelectrode, maintained at a constant potential, near cells. The redox reaction of electroactive neurotransmitters on the electrode surface generates a Faradaic current, which can be used to quantitatively measure the concentration of the electroactive substance. Its advantages include submillisecond temporal resolution and high sensitivity.

[0005] In terms of electrode selection, carbon fiber microelectrodes are widely used in in vivo biological analysis due to their small size, high sensitivity, ease of operation, low cost, good biocompatibility, and the fact that they do not cause significant damage to biological tissues during implantation. However, the simple use of carbon fiber electrodes has low selectivity due to the difficulty in distinguishing molecules with similar redox potentials. However, electrode surface modification can improve selectivity.

[0006] In terms of modified materials, nanozymes are nanomaterials with enzyme-like activity. They offer a variety of unique advantages, including adjustable catalytic activity, high stability and catalytic activity in harsh environments, flexible composition and structural design, and good biocompatibility. Therefore, by introducing different nanozymes into the material, it is possible to significantly improve the material's selectivity, catalytic performance, and lower the detection limit. However, the industry has yet to find a nanozyme-modified carbon fiber material that can effectively improve the selectivity, sensitivity, and detection limit of dopamine detection using amperometric methods. Summary of the Invention

[0007] To address these issues, the present invention provides a Cu-Im / CF microelectrode for the electrochemical detection of dopamine. EMI is electropolymerized onto carbon fiber and then coordinated with copper nitrate to create a carbon fiber material with in situ synthesis of the Cu-Im nanozyme. This carbon fiber is then fabricated into a microelectrode. Using amperometry, dopamine detection was achieved in vitro under simulated cerebrospinal fluid conditions with excellent selectivity, sensitivity, and detection limit.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A first aspect of the present invention provides a method for preparing a Cu-Im / CF microelectrode, comprising:

[0010] Desizing the carbon fiber and setting aside for use;

[0011] 1-Ethyl-3-methylimidazole was dissolved in acetonitrile solution to obtain EMI acetonitrile solution;

[0012] The desizing carbon fibers are dispersed on a copper sheet and connected in parallel on the copper sheet. Ag / AgCl is used as a reference electrode and a platinum wire is used as a counter electrode. The monomer is electropolymerized on the carbon fiber surface by a constant potential method to obtain electropolymerized imidazole-containing carbon fibers.

[0013] The electropolymerized imidazole carbon fiber is washed, placed in a copper nitrate solution for rotary evaporation, and after the reaction is completed, taken out, washed, and dried to obtain a Cu-Im nanozyme-modified carbon fiber material;

[0014] The Cu-Im nanozyme-modified carbon fiber material is made into a carbon fiber microelectrode, that is,

[0015] The concentration of the EMI acetonitrile solution is 0.05-0.2M.

[0016] The present invention utilizes polyimidazole in combination with copper nitrate to simulate Cu catalytic sites, thereby effectively improving the selectivity, sensitivity and detection limit of dopamine detection by amperometry.

[0017] At the same time, the present invention utilizes an in situ synthesis method to modify the electrode surface. The in situ synthesis method can spatially isolate the catalytic particles on the electrode surface, resulting in higher mass transfer, which not only significantly promotes the utilization of materials, but also enables more accurate measurement of the activity and electrochemical properties of the catalytic particles.

[0018] The second aspect of the present invention provides a Cu-Im / CF microelectrode prepared by the above method.

[0019] The third aspect of the present invention provides an electrochemical sensor using the above-mentioned Cu-Im / CF microelectrode as a working electrode.

[0020] A fourth aspect of the present invention provides the use of the above-mentioned Cu-Im / CF microelectrode in electrochemical detection of dopamine.

[0021] Beneficial effects of the present invention

[0022] (1) The present invention synthesizes Cu-Im nanozymes in situ on carbon fibers with the aid of electropolymerization, and manufactures them into Cu-Im / CF microelectrodes. The synthesis conditions of the Cu-Im / CF microelectrodes are optimized, that is, the carbon fibers are electropolymerized with EMI in a 0.1M EMI acetonitrile solution at a potential of 1.3V. Subsequently, the feasibility of the Cu-Im / CF microelectrode for electrochemical detection of dopamine was studied in an in vitro simulated cerebrospinal fluid environment. The results show that the Cu-Im nanozyme can effectively catalyze the oxidation reaction of dopamine, and the prepared Cu-Im / CF microelectrode can significantly improve the current response of the carbon fibers to dopamine detection under the conditions of in vitro simulated cerebrospinal fluid, and can effectively reduce the interference of the corresponding endogenous electroactive substances in the cerebrospinal fluid, effectively improve the sensitivity, selectivity, and time resolution of the electrochemical detection of dopamine in vitro, and the prepared Cu-Im / CF microelectrode has good stability and reproducibility. In summary, the Cu-Im / CF microelectrode prepared by the present invention is expected to be further applied to the electrochemical detection of dopamine in the brain.

[0023] (2) The preparation method of the present invention is simple, practical, and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 SEM of (a) CF (b) Cu-Im / CF and its corresponding element distribution map (c) C (d) N (e) Cu;

[0026] Figure 2CV curve of unmodified carbon fiber microelectrode in 0.1 M EMI acetonitrile solution;

[0027] Figure 3 CV curves of carbon fiber microelectrodes prepared from materials electropolymerized at (a) 0.05 M, (b) 0.075 M, (c) 0.1 M, and (d) 0.2 M EMI acetonitrile solutions, with successive additions of 10 μM dopamine in nitrogen-saturated aCSF. Applied voltage: 0.2 V vs. Ag / AgCl.

[0028] Figure 4 CV curves of microelectrodes prepared from materials synthesized by electropolymerization of EMI in 0.1 M EMI in acetonitrile at voltages of 0.9 V, 1.0 V, 1.1 V, 1.2 V, 1.3 V, 1.4 V, and 1.5 V, respectively, in nitrogen-saturated aCSF with continuous addition of 10 μM dopamine. Applied voltage: 0.2 V vs. Ag / AgCl;

[0029] Figure 5 A is the CV curve of the unmodified carbon fiber electrode in cerebrospinal fluid containing (a) 20μM DA (b) 0μM DA; B is the CV curve of the modified carbon fiber electrode in cerebrospinal fluid containing (a) 20μM DA (b) 0μM DA; C is the CV curve of (a) the modified carbon fiber microelectrode and (b) the unmodified carbon fiber microelectrode in cerebrospinal fluid containing 20μM DA; D is the CV curve of (a) the modified carbon fiber microelectrode and (b) the unmodified carbon fiber microelectrode in cerebrospinal fluid containing 0μM DA;

[0030] Figure 6 CA curves of (a) unmodified and (b) modified carbon fiber microelectrodes in nitrogen-saturated aCSF with continuous addition of 10 μM DA. Applied voltage: 0.2 V vs. Ag / AgCl.

[0031] Figure 7 Time response curve of the modified carbon fiber electrode after adding 20 μM DA;

[0032] Figure 8 (A) CV curves of the Cu-Im / CF microelectrode in 20 μM dopamine aCSF under nitrogen saturation at different scan rates (a) to (m) of 10, 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, and 300 mV·s-1 and (B) the corresponding relationship curve of the current scan rate;

[0033] Figure 9(A) Current response curve of the Cu-Im / CF microelectrode to the continuous addition of different concentrations of dopamine in nitrogen-saturated aCSF, applied potential: 0.2 V vs. Ag / AgCl; (B) Current versus dopamine concentration curve;

[0034] Figure 10 The CA curve of a Cu-Im / CF microelectrode in nitrogen-saturated aCSF with the same concentrations of dopamine, DOPAC, epinephrine, H2O2, and dopamine added continuously. Applied voltage: 0.2 V vs. Ag / AgCl

[0035] Figure 11 This is the current response curve of the Cu-Im / CF microelectrode monitored continuously for 1 h after adding 20 μM dopamine in nitrogen-saturated aCSF.

[0036] Figure 12 This is the current response of the Cu-Im / CF microelectrode prepared under the same conditions to the same concentration of dopamine. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] A method for preparing a Cu-Im / CF microelectrode, comprising:

[0039] Desizing the carbon fiber and setting aside for use;

[0040] 1-Ethyl-3-methylimidazole was dissolved in acetonitrile solution to obtain EMI acetonitrile solution;

[0041] The desizing carbon fibers are dispersed on a copper sheet and connected in parallel on the copper sheet. Ag / AgCl is used as a reference electrode and a platinum wire is used as a counter electrode. The monomer is electropolymerized on the carbon fiber surface by a constant potential method to obtain electropolymerized imidazole-containing carbon fibers.

[0042] The electropolymerized imidazole carbon fiber is washed, placed in a copper nitrate solution for rotary evaporation, and after the reaction is completed, taken out, washed, and dried to obtain a Cu-Im nanozyme-modified carbon fiber material;

[0043] The Cu-Im nanozyme-modified carbon fiber material is made into a carbon fiber microelectrode, that is,

[0044] The concentration of the EMI acetonitrile solution is 0.05-0.2M.

[0045] In some embodiments, the electropolymerization voltage is 0.9V to 1.5V.

[0046] In some embodiments, the electropolymerization time is 15 to 20 minutes.

[0047] In some embodiments, the concentration of the copper nitrate solution is 1-1.5M.

[0048] In some embodiments, the rotary evaporation time is 30 to 40 minutes.

[0049] In some embodiments, the washing is with water.

[0050] In some embodiments, the drying time is 3 to 4 hours.

[0051] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0052] Example 1 Preparation of electrode materials

[0053] 1) Desizing of carbon fiber: Cut the carbon fiber into short clusters of about 5 cm and soak them in acetone solution for 48 hours. Then, ultrasonically clean the carbon fiber in ultrapure water. After washing three times, place it in a vacuum drying oven and dry it at 85°C for 3 hours.

[0054] 2) Electropolymerization of imidazole on the surface of carbon fiber: Weigh an appropriate amount of 1-ethyl-3-methylimidazole (EMI) in 50 ml of acetonitrile solution to prepare 0.05M, 0.075M, 0.1M, and 0.2M EMI acetonitrile solutions. The desizing carbon fibers are fully dispersed on the polished and bright copper sheet so that they are connected in parallel on the copper sheet (i.e., the copper sheet and the electrolyte are two nodes on the circuit, and each carbon fiber is equivalent to a current branch. The carbon fibers are not intertwined with each other), with Ag / AgCl as the reference electrode, platinum wire as the counter electrode, and EMI acetonitrile solution as the electrolyte. The monomers are oxidatively polymerized on the surface of the carbon fibers using a constant potential method at potentials of 0.9V, 1.0V, 1.1V, 1.2V, 1.3V, 1.4V, and 1.5V, and the polymerization time is 15min.

[0055] 3) Copper coordination: The above-mentioned electropolymerized carbon fiber was washed with pure water and the part not immersed in the electrolyte for electropolymerization was cut off, and then placed in copper nitrate (1M, 5ml) for rotary evaporation for 30 minutes. Then the carbon fiber was taken out, the copper nitrate remaining on the surface was washed with pure water, and then placed in a vacuum drying oven for 3 hours to obtain Cu-Im / CF material.

[0056] Example 2 Preparation of carbon fiber microelectrodes

[0057] The present invention connects the Cu-Im / CF material prepared in Example 1 to a copper wire with a diameter of 100 μm and a length of 10 cm using conductive silver glue. After the conductive silver glue dries, a carbon fiber (outer diameter: 1.5 mm, inner diameter: 1.10 mm, length: 10 cm) is inserted from one end of a glass electrode until one end reaches the middle of the glass electrode. Another carbon fiber, bonded to the copper wire, is inserted from the other end, securing the copper wires at both ends of the glass electrode. The capillary glass tubes with the carbon fibers are then drawn into two using a microelectrode drawing instrument. A 1 mL syringe is drawn under an alcohol lamp into a sufficiently slender tube. Single-component room-temperature vulcanized silicone rubber is then drawn into the tube through the tail end of the drawn glass electrode under a microscope, the tip sealed, and the tube dried naturally at room temperature. Under a microscope, the pointed carbon fiber is cut to 300 μm to obtain a Cu-Im / CF microelectrode.

[0058] Example 3 Preparation of artificial cerebrospinal fluid

[0059] NaCl (126 mM), KCl (2.4 mM), KH2PO4 (0.5 mM), MgCl2 (0.85 mM), NaHCO3 (27.5 mM), Na2SO4 (0.5 mM), and CaCl2 (1.1 mM) were dissolved in ultrapure water and then adjusted to pH 7.4 with concentrated hydrochloric acid and NaOH solution. This was used as the electrolyte for in vitro electrochemistry.

[0060] Example 4 Performance Test

[0061] 1) Characterization of electrode materials

[0062] Scanning electron microscopy (SEM): several unmodified carbon fibers and Cu-Im / CF were glued to the sample stage with conductive glue, sampled, vacuumed, and emitted at an accelerating voltage of 20 kV for microscopic characterization of the material surface.

[0063] 2) Electrochemical detection of dopamine using microelectrodes

[0064] Electrochemical detection was performed using a CHI760E electrochemical workstation using a conventional three-electrode system, with a prepared carbon fiber microelectrode (Cu-Im / CF microelectrode) as the working electrode, Ag / AgCl (saturated potassium chloride) as the reference electrode, and a platinum wire as the counter electrode. Cyclic voltammetry (CV) and chronoamperometry (CA) were used to investigate the electrochemical behavior and current response of dopamine in artificial cerebrospinal fluid (aCSF) at the Cu-Im / CF microelectrode.

[0065] The test results show that:

[0066] 1) Characterization of Cu-Im / CF

[0067] In order to observe the surface morphology of Cu-Im / CF, the present invention characterized it using a scanning electron microscope (SEM). Figure 1 It can be seen that there are many grooves on the surface of the carbon fiber, while the grooves of the modified material have become significantly shallower, indicating that the present invention has modified a thin layer of Cu-Im nanozyme on the carbon fiber. Figure 1 The results show that the C, N and Cu elements are present in Cu-Im / CF and their distribution is relatively uniform, which preliminarily proves that the in-situ synthesis of the material of the present invention is successful.

[0068] 2) Determination of the polymerization potential window

[0069] In order to test the polymerization potential of carbon fiber in EMI acetonitrile solution, the present invention prepared a bare carbon fiber into a microelectrode and used CV to preliminarily determine the polymerization potential of EMI in 0.1M EMI acetonitrile solution. Figure 2 As shown, from Figure 2 It can be clearly seen that the oxidation peak of the polymerization is between 0.9V and 1.5V.

[0070] 3) Optimization of monomer concentration

[0071] When carbon fibers are electropolymerized in EMI acetonitrile solution, the concentration of EMI is an important factor affecting the electropolymerization of EMI on carbon fibers. Therefore, the present invention optimizes the concentration by preparing 0.05M, 0.075M, 0.1M, and 0.2M EMI acetonitrile solutions, performing electropolymerization of EMI, and using the synthesized materials to perform CA detection on dopamine. Figure 3 As shown in the figure, the current response of the carbon fiber microelectrode prepared by the material electropolymerized in 0.05M, 0.075M, and 0.1M EMI acetonitrile solution to dopamine is constantly increasing, while the current response of the carbon fiber microelectrode prepared by the material electropolymerized in 0.1M and 0.2M EMI acetonitrile solution to dopamine is basically flat. It can be concluded that the electropolymerization of EMI on carbon fiber in 0.1M EMI acetonitrile solution is optimal. If the concentration is too low, EMI cannot be fully polymerized on the carbon fiber, and if the concentration is too high, it will cause waste of EMI.

[0072] 4) Optimization of electropolymerization potential

[0073] Similarly, the potential of the electropolymerization of carbon fiber materials in 0.1M EMI acetonitrile solution is also a key factor affecting the polymerization of EMI on carbon fiber. Therefore, it is crucial to optimize the potential of EMI electropolymerization. Therefore, the present invention has carried out the optimization work of electropolymerization potential. Figure 4As shown, the present invention performs EMI electropolymerization on the carbon fiber material at potentials of 0.9V, 1.0V, 1.1V, 1.2V, 1.3V, 1.4V, and 1.5V, and then uses the synthesized materials to perform CA detection on dopamine. It can be seen that the current response of the microelectrode prepared by the material subjected to electropolymerization at potentials of 0.9V, 1.0V, 1.1V, 1.2V, and 1.3V to dopamine is continuously increasing, while the current response of the microelectrode prepared by the material subjected to electropolymerization at potentials of 1.3V, 1.4V, and 1.5V to dopamine decreases, indicating that the potential of 1.3V is the optimal potential for electropolymerization of EMI on the carbon fiber material.

[0074] 5) Study on the electrochemical behavior of dopamine on Cu-Im / CF microelectrodes

[0075] The electrocatalytic performance of unmodified carbon fiber microelectrodes and Cu-Im / CF microelectrodes prepared by electropolymerization in 0.1 M EMI acetonitrile solution at a potential of 1.3 V towards dopamine in artificial cerebrospinal fluid (aCSF, pH = 7.4) after nitrogen deoxygenation for 20 min was studied by CV and CA.

[0076] like Figure 5 In Figures A and B, the CV of unmodified and modified carbon fiber microelectrodes without dopamine and with 20 μM dopamine were compared, indicating that the microelectrodes have certain catalytic activity towards dopamine. Figure 5 In Figures C and D, the CV of the modified and unmodified carbon fiber microelectrodes are compared in cerebrospinal fluid containing 20 μM dopamine and cerebrospinal fluid without dopamine. It can be seen that the modified carbon fiber microelectrode has a more obvious oxidation peak for dopamine, which indicates that the Cu-Im / CF microelectrode prepared by the present invention has higher catalytic activity for dopamine.

[0077] from Figure 6 It can be seen that the modified carbon fiber microelectrode has an obvious current response after adding dopamine, while in contrast, the unmodified carbon fiber microelectrode has almost no current response after adding the same concentration of dopamine, which also indicates that the modified carbon fiber microelectrode has higher catalytic activity for dopamine.

[0078] like Figure 7 , focusing on observing the current time response when 20 μM DA was added for the first time. It can be seen that after DA was added at the 100th second, the current response took nearly 2 seconds to reach a relatively stable value, which indicates that the Cu-Im / CF microelectrode prepared by the present invention has good time resolution.

[0079] In summary, it can be shown that the present invention successfully synthesized a nanozyme with a catalytic center similar to polyphenol oxidase on carbon fiber.

[0080] The present invention then studied the effect of different scan rates on the catalytic activity of dopamine oxidation reaction catalyzed by Cu-Im / CF microelectrode in nitrogen-saturated aCSF (pH=7.4) at a dopamine concentration of 20 μM. Figure 8 As shown, the same Cu-Im / CF microelectrode at different scanning rates (a) 10, (b) 25, (c) 50, (d) 75, (e) 100, (f) 125, (g) 150, (h) 175, (i) 200, (j) 225, (k) 250, (l) 275, (m) 300 mV·s -1 The results show that the oxidation peak current increases with the increase of the scan rate, and the current is proportional to the scan rate, indicating that the reaction on the electrode is mainly controlled by the surface adsorption process.

[0081] 6) Establishment of standard curve

[0082] Figure 9 Figure A is the chronoamperometric curve of a Cu-Im / CF microelectrode prepared by electropolymerizing EMI in a 0.1 M EMI acetonitrile solution at a potential of 1.3 V, and continuously adding different concentrations of dopamine to nitrogen-saturated continuously stirred aCSF (pH = 7.4) at a potential of 0.2 V. Figure 9 It can be seen that with the continuous addition of dopamine, the current response shows a step-like upward trend and the current signal can quickly reach equilibrium. When the concentration of the added dopamine increases, the corresponding current response will also increase. Figure 9 B is the current and concentration relationship curve of the corresponding Cu-Im / CF microelectrode. Figure 9 The prepared carbon fiber microelectrode has different linear relationships at low and high concentrations of dopamine. The detection range at low concentration is 0.0500 μM-77.7 μM, the linear relationship is y=1.07x+1.03, and the detection limit is 0.0204 μM. The detection range at high concentration is 77.7 μM-0.378 mM, the linear relationship is y=0.588x+42.2, and the detection limit is 7.84 μM. As can be seen from Table 1, the detection range and detection limit of the Cu-Im / CF microelectrode prepared by the present invention are comparable to or even better than those of other sensors.

[0083] Table 1 Performance comparison of dopamine detection based on microelectrode electrochemistry

[0084]

[0085]

[0086] 7) Selectivity, stability and reproducibility

[0087] Since there are many endogenous electroactive substances in the brain, such as DOPAC, epinephrine, H2O2, etc., which are easily electrochemically oxidized and reduced on the microelectrode, the detection of dopamine may be affected. In order to verify the selectivity of the Cu-Im / CF microelectrode prepared by the present invention, the present invention uses the chronoamperometry (it curve) to continuously add dopamine (20μM) and interfering substances of the same concentration for detection. The order of addition is dopamine, DOPAC, epinephrine, H2O2, dopamine. Figure 10 As shown, compared with the current response of dopamine, DOPAC, epinephrine and H2O2 have almost no current response, indicating that the Cu-Im / CF microelectrode prepared in the present invention has good selectivity for the detection of dopamine.

[0088] like Figure 11 As shown in the figure, the prepared Cu-Im / CF microelectrode was used to continuously monitor dopamine for nearly 1 hour to evaluate the stability of the Cu-Im / CF microelectrode in monitoring dopamine. Figure 11 It can be seen that the current response of the Cu-Im / CF microelectrode after the addition of dopamine shows a brief decline because it takes a while for the solution to reach concentration equilibrium, and then remains in a relatively stable state, indicating that the Cu-Im / CF microelectrode prepared by the present invention has good stability for the detection of dopamine.

[0089] In order to evaluate the reproducibility of the Cu-Im / CF microelectrode platform prepared in the present invention, five Cu-Im / CF microelectrodes prepared under the same conditions were used to detect the same concentration of dopamine. Figure 12 As shown in FIG, the relative standard deviation of the current response of the five electrodes is 2.37%, which indicates that the Cu-Im / CF microelectrode platform developed in the present invention has an acceptable reproducibility.

[0090] The foregoing 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 appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a Cu-Im / CF microelectrode, characterized in that: include: Desizing the carbon fiber and setting aside for use; 1-Ethyl-3-methylimidazole was dissolved in acetonitrile solution to obtain EMI acetonitrile solution; The desizing carbon fibers are dispersed on a copper sheet and connected in parallel on the copper sheet. Ag / AgCl is used as a reference electrode and a platinum wire is used as a counter electrode. The monomer is electropolymerized on the carbon fiber surface by a constant potential method to obtain electropolymerized imidazole-containing carbon fibers. The electropolymerized imidazole carbon fiber is washed, placed in a copper nitrate solution for rotary evaporation, and after the reaction is completed, taken out, washed, and dried to obtain a Cu-Im nanozyme-modified carbon fiber material; The Cu-Im nanozyme-modified carbon fiber material is made into a carbon fiber microelectrode, that is, The concentration of the EMI acetonitrile solution is 0.05-0.2M.

2. The method for preparing the Cu-Im / CF microelectrode according to claim 1, wherein: The electropolymerization point is 0.9V to 1.5V.

3. The method for preparing the Cu-Im / CF microelectrode according to claim 1, wherein: The electropolymerization time is 15 to 20 minutes.

4. The method for preparing the Cu-Im / CF microelectrode according to claim 1, wherein: The concentration of the copper nitrate solution is 1-1.5M.

5. The method for preparing the Cu-Im / CF microelectrode according to claim 1, wherein: The rotary evaporation time is 30 to 40 minutes.

6. The method for preparing the Cu-Im / CF microelectrode according to claim 1, wherein: The washing is performed with water.

7. The method for preparing the Cu-Im / CF microelectrode according to claim 1, wherein: The drying time is 3 to 4 hours.

8. A Cu-Im / CF microelectrode prepared by the method according to any one of claims 1 to 7.

9. An electrochemical sensor, characterized in that The Cu-Im / CF microelectrode according to claim 8 is used as the working electrode.

10. Use of the Cu-Im / CF microelectrode according to claim 8 in electrochemical detection of dopamine.

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