A molecular imprinting electrochemical sensor of a CoMOF-IL sensitive film modified electrode and a preparation method and a detection method thereof

Abstract

The application studies a molecular imprinting electrochemical sensor of a CoMOF-IL sensitive film modified electrode and a preparation method and a detection method thereof, and belongs to the field of electrochemical sensing.The application selects a breast cancer marker carcinoembryonic antigen in serum as a research object, successfully constructs a novel high-sensitivity molecular imprinting electrochemical sensor by combining a nano-composite material, a new imprinting method and a new detection method.Firstly, a CoMOF-IL composite material modified electrode is synthesized by a hydrothermal method, then chitosan and glutaraldehyde are sequentially modified to provide an attachment site of the carcinoembryonic antigen, then a polymer film is directly formed on the surface of the modified electrode by o-phenylenediamine electropolymerization, and finally the template is eluted to obtain the molecular imprinting electrochemical sensor.The molecular imprinting electrochemical sensor combines the molecular imprinting technology and the electrochemical sensing technology, constructs a high-sensitivity and high-selectivity carcinoembryonic antigen sensor, and has been successfully applied to the detection of target proteins in actual serum samples.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical sensing, and specifically relates to a method for preparing and detecting a molecularly imprinted electrochemical sensor with a CoMOF-IL sensitive membrane modified electrode. Background Technology

[0002] Breast cancer is the most common malignant tumor in women, ranking first in incidence among female malignant tumors and seriously endangering the lives and health of many women. Serum tumor markers are of great clinical significance for the early diagnosis, efficacy evaluation, and prognostic follow-up of breast cancer. For example, carcinoembryonic antigen (CEA), carbohydrate antigen 125 (CA125), and carbohydrate antigen 15-3 (CA15-3) are currently recognized as relatively sensitive tumor markers for breast cancer. Carcinoembryonic antigen (CEA) is a 180 kDa glycoprotein belonging to the immunoglobulin family and is mainly involved in cell adhesion. Carcinoembryonic antigen is usually produced in the gastrointestinal tissue during fetal development, but it is quite scarce in healthy individuals. Its serum level increases when breast cancer occurs. Because this protein is only detected in cancerous and embryonic tissues, it is named carcinoembryonic antigen. It is one of the most commonly used biomarkers for breast cancer, with a clinical cutoff value of 5 ng / mL. -1 While various technologies have been developed for the quantitative determination of serum tumor markers in breast cancer, including radioimmunoassay (RIA), high-performance liquid chromatography (HPLC), electrophoretic immunoassay (EIA), fluorescence immunoassay (FIA), and enzyme-linked immunosorbent assay (ELISA), these technologies are complex, expensive, time-consuming, and cannot provide highly sensitive real-time detection. Therefore, it is necessary to develop a low-cost, lightweight, portable, highly sensitive, and practical detection method to achieve efficient monitoring of breast cancer tumor markers.

[0003] Currently, as the focus of health security shifts towards disease prevention, early screening, and chronic disease monitoring, medical diagnosis is gradually moving from "centralized laboratories" to "point-of-care testing." Point-of-care testing (POCT) refers to on-site sampling, examination, and analysis at the patient's location, avoiding time-consuming and labor-intensive visits to medical institutions. It eliminates steps such as specimen pretreatment, sample delivery, equipment testing, and data processing, providing rapid test results, which is of great significance for early disease detection and dynamic monitoring. Through long-term health monitoring using portable devices and smart devices, driven by sensor technology and big data analytics, a learning-based digital health security system will develop in the future. This will not only change the paradigm of disease management but may also guide clinical treatment methods. Portable sensors have already demonstrated strong practicality in multiple fields, such as blood glucose testing and pregnancy testing, while cancer screening is gradually becoming a key application area of ​​interest.

[0004] Integrated sensors consist of a recognition element and a portable sensor device (signal converter). The recognition element is located on the surface of the sensor device. When the recognition element binds to the target molecule of the analyte, it generates a physical or chemical signal. The sensor device then converts this signal into an output signal, thereby enabling real-time detection of the target molecule. Due to the high selectivity, high stability, and reusability of molecularly imprinted materials, they can overcome the instability and high cost of traditional biorecognition materials, thus serving as the molecular recognition element for integrated sensors. Molecularly imprinting technology (MIT) is a method for preparing chemical materials with specific molecular recognition sites. Monomers interact with a given template molecule under the action of a cross-linking agent, forming imprinted cavities that are complementary to the template molecule in size, shape, and functional groups during the synthesis of the polymer matrix. This enables the imprinted polymer (MIP) to specifically recognize and adsorb the target molecule. Molecularly imprinted electrochemical sensors (MIECSs) combine molecular imprinting and electrochemical sensing technologies, using molecularly imprinted polymers (MIPs) as specific molecular recognition elements to improve the selective recognition performance of electrochemical sensors. Currently, MIECSs are widely studied and used for the detection of various targets in serum due to their advantages such as high sensitivity, good selectivity, fast analysis speed, and ease of miniaturization.

[0005] In this invention, a cobalt-based MOF (CoMOF) is synthesized via a hydrothermal method. Based on the strong electrochemical interaction between the ionic liquid (IL) and the cobalt-based MOF, and the improvement of cobalt-based MOF dispersion by the ionic liquid, the combination of the ionic liquid and the cobalt-based MOF provides an effective platform for sensitive electrochemical sensing. A novel electrochemical sensing platform for the sensitive detection of the breast cancer biomarker CEA is constructed by assembling a cobalt-based MOF / ionic liquid (CoMOF-IL) composite material on a flexible electrode (SPCE). Chitosan (CS) and glutaraldehyde (GA) are then sequentially modified to provide attachment sites for the template molecule CEA and stabilize the CoMOF-IL sensitive membrane. Subsequently, o-phenylenediamine is directly electropolymerized on the modified electrode surface to form an imprinted polymer film. Finally, the template protein is eluted to obtain a molecularly imprinted electrochemical sensor with specific selective activity. This sensor exhibits excellent selectivity for CEA recognition. Furthermore, when applied to actual sample detection, the sensor demonstrates excellent analytical performance and good stability, showing promising application prospects. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a CoMOF-IL sensitive membrane modified electrode using polyethylene terephthalate (PET) as a flexible substrate material and synthesizing it via a hydrothermal method, thereby fabricating a molecularly imprinted electrochemical sensor on the surface of the modified electrode, and using it for the rapid detection and analysis of carcinoembryonic antigen (CEA).

[0007] The objective of this invention is mainly achieved through the following technical means:

[0008] The present invention discloses a molecularly imprinted electrochemical sensor with polyethylene terephthalate (PET) as the flexible substrate material and a CoMOF-IL sensitive film modified electrode:

[0009] 1) The working electrode is a flexible screen-printed electrode assembled from carbon nanotubes (provided by Qingdao Botan Technology Co., Ltd.), and a flexible electrode is constructed using polyethylene terephthalate (PET) as the flexible substrate material.

[0010] 2) A novel composite material, CoMOF-IL, was synthesized by hydrothermal method. The composite material was then drop-coated onto the surface of a flexible electrode to form a CoMOF-IL sensitive film (first layer), denoted as CoMOF-IL / SPCE.

[0011] 3) A chitosan film (second layer) is added to CoMOF-IL / SPCE by electrodeposition, denoted as CS / CoMOF-IL / SPCE.

[0012] 4) Then, a cross-linking agent and the template molecule carcinoembryonic antigen are dropped onto the surface of the second electrode layer of CS / CoMOF-IL / SPCE. The carcinoembryonic antigen protein is linked to CS / CoMOF-IL / SPCE through the cross-linking action of glutaraldehyde. Since the protein is a biological macromolecule and does not conduct electricity, it is equivalent to an insulating film (third layer) after being grafted onto the electrode surface, which is denoted as CEA / CS / CoMOF-IL / SPCE.

[0013] 4) The functional monomer is o-phenylenediamine. A layer of poly-o-phenylenediamine molecularly imprinted film (fourth layer) is coated on the electrode surface by electropolymerization, denoted as PoPD / CEA / CS / CoMOF-IL / SPCE.

[0014] 5) Finally, the template protein carcinoembryonic antigen is removed by the eluent to form MIP / CS / CoMOF-IL / SPCE.

[0015] The specific steps for synthesizing the CoMOF-IL sensitive membrane modified electrode using the hydrothermal method in this invention are as follows:

[0016] 1) Weigh a certain amount of cobalt acetate tetrahydrate and disperse it in dimethylformamide (DMF); then mix a certain amount of 1,3,5-tristyric acid and benzimidazole with the above solution, stir continuously, pour the mixed solution into a high-pressure reactor for high-temperature reaction, let the solution cool naturally at room temperature, centrifuge to collect the purple precipitate, wash and dry it to obtain cobalt-based MOF;

[0017] 2) Weigh a certain amount of 1-benzyl-3-methylimidazolium tetrafluoroborate ([BzMlm]BF4) and add it to the cobalt-based MOF aqueous dispersion. Then, stir continuously in an oil bath and let stand. Filter the obtained dispersion using a filter membrane and dry the product to obtain the CoMOF-IL composite material.

[0018] 3) Take a certain amount of CoMOF-IL composite material suspension and drop it onto the surface of a dry flexible electrode. Dry it at room temperature to obtain CoMOF-IL / SPCE.

[0019] The specific steps for preparing the carcinoembryonic antigen molecularly imprinted electrochemical sensor in this invention are as follows:

[0020] 4) A chitosan film was deposited on the surface of the flexible electrode using an electrodeposition method. The electrodeposition process was carried out in a constant potential mode. After the process was completed, the electrode was quickly rinsed with ultrapure water and dried for later use. The prepared electrode was named CS / CoMOF-IL / SPCE.

[0021] 5) Add a certain amount of glutaraldehyde solution to the surface of the modified electrode, activate it at room temperature, wash it with water and dry it.

[0022] 6) Then, a certain amount of carcinoembryonic antigen was added to the electrode surface, and the reaction was first carried out at room temperature, and then placed in a refrigerator at 4°C to continue the reaction. Afterwards, it was washed with phosphate solution to remove excess protein.

[0023] 7) Electropolymerization reaction is carried out in a phosphate buffer solution containing a certain concentration of o-phenylenediamine.

[0024] 8) The obtained imprinted polymer electrode was rinsed with ultrapure water and immersed in an eluent to remove the template molecule carcinoembryonic antigen, denoted as MIP / CS / CoMOF-IL / SPCE.

[0025] 9) As a control group, a non-imprinted electrochemical sensor (NIP) was prepared according to the same procedure, except that the template molecule carcinoembryonic antigen was not added during the polymerization process. It was denoted as NIP / CS / CoMOF-IL / SPCE.

[0026] A molecularly imprinted electrochemical sensor based on a hydrothermally synthesized CoMOF-IL sensitive membrane modified with a flexible electrode for specific recognition and detection of carcinoembryonic antigen:

[0027] 10) Immerse the modified electrode in phosphate buffer solution, and then perform electrochemical voltammetry scanning and AC impedance spectroscopy on each modified electrode. After scanning, the corresponding cyclic voltammetry and AC impedance spectroscopy can be obtained.

[0028] 11) The prepared electrochemical sensor was immersed in a carcinoembryonic antigen standard solution of a certain concentration and measured using differential pulse voltammetry. The concentration was plotted against the differential pulse voltammetry response value.

[0029] 12) Lysozyme, human serum albumin, and human immunoglobulin G were selected as co-existing proteins in human serum as carcinoembryonic antigen to determine the selectivity of MIP / CS / CoMOF-IL / SPCE.

[0030] Furthermore, in step 1), the molar ratio of cobalt acetate tetrahydrate: 1,3,5-pyromellitic acid: benzimidazole is in the range of 1:0.5:0.5 ~ 1.5:1:1.5.

[0031] Furthermore, in step 2), the concentration ratio of 1-benzyl-3-methylimidazolium tetrafluoroborate to CoMOF ranges from 1:3 to 1:6.

[0032] Furthermore, in step 4), the electrodeposition conditions are as follows: 0.25 mg·mL⁻¹ -1 Chitosan solution was dropped onto the electrode surface and electrodeposited at a constant potential: -0.3 to -0.8 V for 50 to 200 s.

[0033] Furthermore, in step 7), the electropolymerization conditions are as follows: [The text abruptly ends here, so the translation stops.] -1 Nitrogen gas was bubbled through the phosphate buffer solution of o-phenylenediamine in the dark to remove oxygen. The modified electrode was then placed in the buffer solution and electropolymerization was performed in the dark. The voltage range was (-0.2~0.1 V) to (+0.6~+1 V), and the scan rate was 40~60 mV·s. -1 The number of scan cycles is 20 to 40.

[0034] Furthermore, in step 8), the eluent is 0.5 mol·L⁻¹. -1 Elute with acetic acid solution for 10–20 minutes.

[0035] The beneficial effects of this invention are as follows: The CoMOF-IL sensitive membrane synthesized by this method can densely coat the electrode surface, exhibiting good electrochemical performance and excellent stability. The prepared molecularly imprinted electrochemical sensor demonstrates excellent specificity and selectivity for carcinoembryonic antigen (CEA), responds rapidly to CEA electrical signals, and exhibits a strong linear relationship between the electrochemical response value and CEA concentration.

[0036] In this invention, cobalt-based MOFs are synthesized using a hydrothermal method. Based on the strong electrochemical interaction between ionic liquids and CoMOFs, and the improvement of CoMOF dispersion by ionic liquids, the two are combined as a modified electrode, thus providing an effective platform for sensitive electrochemical sensing. In this invention, the molecularly imprinted polymer film is synthesized using o-phenylenediamine electropolymerization, which, compared to traditional molecularly imprinted polymer synthesis, offers advantages such as simple operation, time saving, and tunable imprinted film. This molecularly imprinted electrochemical sensor exhibits high sensitivity and selectivity and has been successfully applied to the detection of target proteins in real samples. Attached Figure Description

[0037] Figure 1 High-resolution SEM image of the molecularly imprinted electrochemical sensor (MIP / CS / CoMOF-IL / SPCE)

[0038] Figure 2 High-resolution SEM image of CoMOF-IL composite material synthesized by hydrothermal method.

[0039] Figure 3 Cyclic voltammetry (CV) plots of different modified electrodes in phosphate buffer solution

[0040] Figure 4 This is a linear relationship between the differential pulse voltammetry response value and the carcinoembryonic antigen concentration of a molecularly imprinted electrochemical sensor (MIP / CS / CoMOF-IL / SPCE). Detailed Implementation Example 1

[0041] A molecularly imprinted electrochemical sensor with a CoMOF-IL sensitive membrane modified electrode includes a working electrode with a flexible material as a substrate. A CoMOF-IL sensitive membrane, a chitosan membrane, a crosslinking agent and target protein insulating layer, and a poly(o-phenylenediamine) molecularly imprinted layer are sequentially connected to the surface of the flexible electrode. The poly(o-phenylenediamine) molecularly imprinted layer has imprinted holes of the target protein.

[0042] The working electrode is a flexible screen-printed electrode assembled from carbon nanotubes (provided by Qingdao Botan Technology Co., Ltd.), with polyethylene terephthalate as the flexible substrate material. The sensitive membrane is a CoMOF-IL composite material, which is a three-dimensional rod-shaped membrane synthesized by a one-step hydrothermal method. It has a large specific surface area and good electrocatalytic performance, and will be used in the experiment to increase the contact area with the analyte. The ionic liquid selected is 1-benzyl-3-methylimidazolium tetrafluoroborate. Based on the strong electrochemical interaction between the ionic liquid and the cobalt-based MOF, and the improvement of the dispersion of the cobalt-based MOF by the ionic liquid, the combination of the ionic liquid and the cobalt-based MOF provides an efficient platform for sensitive electrochemical sensing.

[0043] The chitosan membrane serves as a modified electrode, and a uniform and dense membrane is formed on the modified electrode using an electrodeposition method. Compared with the drop-coating method for synthesizing chitosan membranes, the chitosan membrane formed by this method provides a more regular amino group arrangement, which is beneficial for connecting cross-linking agents to increase the amount of carcinoembryonic antigen loaded as the template protein.

[0044] The cross-linking agent and the insulating layer of the target protein immobilize the target protein. The non-electroactive carcinoembryonic antigen protein is cross-linked onto the chitosan membrane modification layer using the cross-linking agent glutaraldehyde. After the carcinoembryonic antigen protein is modified onto the electrode surface, it acts as an insulating film, hindering electron transport.

[0045] The poly(o-phenylenediamine) molecularly imprinted layer provides imprinted sites for the target protein carcinoembryonic antigen (CEA). The o-phenylenediamine monomer and template protein are pre-assembled via hydrogen bonds. While the monomer polymerizes on the electrode surface, the template protein embeds into the polymer membrane, thereby introducing selective recognition sites into the polymer membrane. The thickness of the poly(o-phenylenediamine) molecularly imprinted layer can be determined by the number of scanning cycles, and the conductivity state of the membrane and the redox reactions occurring during polymerization can be visually reflected by cyclic voltammetry.

[0046] The insulating layer is a cross-linking layer between a cross-linking agent and a target protein. After polymerizing the poly(o-phenylenediamine) molecular imprinted layer, the target protein is eluted to form imprinted vacancies.

[0047] The target protein is carcinoembryonic antigen (CEA). Example 2

[0048] 1) Weigh 1.245 g of cobalt acetate tetrahydrate (C4H6CoO4·4(H2O), 1.05 g of 1,3,5-pyromellitic acid (H3BTC), and 0.59 g of benzimidazole (BIm) and dissolve them in N,N-dimethylformamide (DMF). Then, stir the above solution and pour it into a high-pressure reactor for high-temperature reaction to obtain cobalt-based MOF materials.

[0049] 2) Weigh out 0.002 g·mL -1 1-Benzyl-3-methylimidazolium tetrafluoroborate and 0.01 g·mL -1 Cobalt-based MOFs were dispersed in water, and the mixture was then continuously stirred in an oil bath and allowed to stand. The resulting dispersion was filtered through a filter membrane, dried, and the CoMOF-IL composite material was collected.

[0050] 3) Sonicate the CoMOF-IL composite material to disperse it evenly, take 15 μL and drop it onto the electrode surface, and let it dry naturally to complete the preparation of the flexible electrode modified with CoMOF-IL composite material.

[0051] The specific steps for preparing the carcinoembryonic antigen (CEA) molecularly imprinted electrochemical sensor in this invention are as follows:

[0052] 4) Add 0.25 mg·mL -1 CS was dropped onto the electrode surface and electrodeposition was performed using a constant potential: -0.5V for 100s. After drying at room temperature, CS / Co MOF-IL / MWCNTs / SPCE was obtained.

[0053] 5) Add 2.5% glutaraldehyde solution to the surface of the modified electrode, activate it at room temperature, wash it with water and air dry.

[0054] 6) Then take 50 μg·mL -1 Carcinoembryonic antigen was dropped onto the electrode surface, reacted at room temperature first, and then placed in a refrigerator at 4°C to continue the reaction. Afterwards, the electrode was washed with phosphate solution to remove excess protein.

[0055] 7) In a solution containing 5 mmol·L -1 10 mmol·L of o-phenylenediamine -1 Electropolymerization was carried out in phosphate buffer solution: cyclic voltammetric electropolymerization was performed for 30 cycles in a potential range of 0 to +0.8 V at a scan rate of 50 mV / s.

[0056] 8) The obtained imprinted polymer electrode was rinsed with ultrapure water and immersed in 0.5 mol·L⁻¹ water. -1 The template molecule carcinoembryonic antigen was removed by immersion in acetic acid solution for 15 minutes, denoted as MIP / CS / Co MOF-IL / MWCNTs / SPCE.

[0057] 9) As a control group, non-imprinted polymers (NIPs) were prepared according to the same procedure, except that the template molecule carcinoembryonic antigen was not added during the polymerization process. This was denoted as NIP / CS / Co MOF-IL / MWCNTs / SPCE. Example 3

[0058] Detection was performed using the carcinoembryonic antigen molecularly imprinted electrochemical sensor prepared in Example 2:

[0059] 1) Immerse the modified electrode in 10 mmol·L⁻¹ water. -1 In a phosphate solution, electrochemical voltammetry and electrochemical impedance spectroscopy were then performed on each modified electrode to obtain the corresponding cyclic voltammetry and electrochemical impedance spectroscopy.

[0060] 2) The prepared electrochemical sensor was immersed in a solution containing 0, 0.0001, 0.01, 0.1, 1, 5, and 10 ng·mL⁻¹ -1 The carcinoembryonic antigen (CEA) standard solution was measured using differential pulse voltammetry, and the CEA solubility was plotted against the differential pulse voltammetric response. (See attached diagram.) Figure 4 As shown, the peak current value corresponds to the carcinoembryonic antigen concentration in the range of 0.0001–10 ng·mL. -1 The reaction exhibited a good linear relationship within the specified range, with the linear regression equation being I = 3.09 Log C (ng / mL) + 19.87 (R²). 2 =0.991). Compared with the results of other methods for detecting carcinoembryonic antigen in the literature, this work has a wider linear range and a lower detection limit, and is more sensitive for practical trace detection.

[0061] 3) Lysozyme, human serum albumin, and human immunoglobulin G were selected as coexisting proteins in human serum as carcinoembryonic antigen to determine the selectivity of the molecularly imprinted electrochemical sensor modified with a cobalt-based MOF / ionic liquid sensitive membrane.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A molecularly imprinted electrochemical sensor of a cobalt-based MOF / ionic liquid sensitive film modified electrode, comprising a working electrode, characterized in that, The flexible material is used as a substrate, and a cobalt-based MOF / 1-benzyl-3-methyl imidazole tetrafluoroborate ionic liquid composite sensitive film, a chitosan film, a crosslinking agent and target protein insulation layer and a poly-o-phenylenediamine molecular imprinting layer are sequentially connected on the surface of the flexible electrode, the crosslinking agent and target protein insulation layer is obtained by crosslinking non-electrically active carcinoembryonic antigen protein to the chitosan film modification layer through a crosslinking agent glutaraldehyde, and the poly-o-phenylenediamine molecular imprinting layer has imprinting sites of target protein carcinoembryonic antigen, o-phenylenediamine monomers are pre-assembled with template protein carcinoembryonic antigen through hydrogen bonds, the monomers are polymerized on the surface of the electrode, and at the same time, the template protein is embedded in the polymer film, and after elution, the imprinting sites are formed.

2. The molecularly imprinted electrochemical sensor according to claim 1, wherein, The working electrode is a flexible screen-printed electrode assembled by carbon nanotubes, and polyethylene terephthalate is used as a flexible substrate material; the composite sensitive film is a cobalt-based MOF / ionic liquid composite, and the composite sensitive film is in a three-dimensional rod shape and is synthesized by one-step hydrothermal method, and the ionic liquid is 1-benzyl-3-methyl imidazole tetrafluoroborate.

3. The molecularly imprinted electrochemical sensor according to claim 1, wherein, The chitosan film is a modification layer, and a stable film with original properties is formed on the modified electrode by an electrodeposition method.

4. The molecularly imprinted electrochemical sensor of claim 1, wherein, The target protein is carcinoembryonic antigen.

5. A method for preparing the molecularly imprinted electrochemical sensor according to claim 1, characterized by, The preparation method comprises the following steps: 1) a certain amount of cobalt acetate tetrahydrate is dispersed in N,N-dimethylformamide, then a certain amount of 1,3,5-benzenetricarboxylic acid and benzimidazole is mixed with the above solution, continuous stirring is performed, then the mixed solution is poured into a high-pressure reaction kettle for high-temperature reaction, the solution is naturally cooled at room temperature, and a purple precipitate is collected by centrifugation, and after washing and drying, a cobalt-based MOF is obtained; 2) a certain amount of 1-benzyl-3-methyl imidazole tetrafluoroborate is added to a cobalt-based MOF aqueous dispersion, then continuous stirring is performed in an oil bath, and then the dispersion is filtered by using a filter membrane, and the product is dried in a vacuum drying box to obtain a cobalt-based MOF / ionic liquid composite; 3) a certain amount of cobalt-based MOF / ionic liquid composite suspension is added dropwise to the surface of a dried flexible electrode, and the electrode is dried at room temperature; 4) a chitosan film is deposited on the surface of the flexible electrode by using an electrodeposition method; The electrodeposition process is performed by using a constant potential mode, and after the electrodeposition is completed, the electrode is quickly washed with ultrapure water and dried for standby; 5) a certain amount of glutaraldehyde solution is added dropwise to the surface of the modified electrode, the electrode is activated at room temperature, and then washed with water and dried; 6) then a certain amount of carcinoembryonic antigen is added dropwise to the surface of the electrode, the electrode is first reacted at room temperature, and then placed in a refrigerator at 4 DEG C for continuous reaction, and then washed with a phosphate solution; 7) an electro-polymerization reaction is performed in a phosphate buffer solution containing a certain concentration of o-phenylenediamine; 8) the obtained imprinted polymer electrode is washed with ultrapure water and immersed in an eluent to remove the template molecule carcinoembryonic antigen.

6. The preparation method according to claim 5, characterized in that: in step 1), the molar ratio of cobalt acetate tetrahydrate, 1,3,5-benzenetricarboxylic acid and benzimidazole is in the range of 1:0.5:1 to 1:2:

1. The concentration ratio of 1-benzyl-3-methylimidazole tetrafluoroborate to cobalt-based MOF in step 2) is 1:5; 2 mg·mL -1 5 ~ 20 μL of the cobalt-based MOF / ionic liquid composite suspension on the surface of the electrode The electrodeposition conditions in Step 4) are as follows: 0.25 mg mL -1 The chitosan solution is added dropwise to the surface of the electrode sheet, and electrodeposition is performed at a constant potential of -0.3 to -0.8 V for 50 to 200 seconds. The electro-polymerization condition in step 7) is to introduce nitrogen into the phosphate buffer solution containing 5 mmol·L -1 The phosphate buffer solution of o-phenylenediamine is introduced with nitrogen in the dark to remove oxygen, and the modified electrode is placed in the buffer solution to perform electro-polymerization in the dark, the voltage range is from (-0.2~0.1 V)~(+0.6~+1 V), the scanning rate is 40~60 mV·s -1 , and the scanning number of circles is 20~40 cycles; The eluent in Step 8) is 0.5 mol·L -1 acetic acid solution for 10 to 20 minutes.

7. The preparation method of claim 5, wherein: The molar ratio of cobalt acetate tetrahydrate: 1,3,5-benzenetricarboxylic acid: benzimidazole in step 1) is 1:1:1; The concentration ratio of 1-benzyl-3-methylimidazole tetrafluoroborate to cobalt-based MOF in step 2) is 1:5; 2 mg·mL -1 Cobalt-based MOF / ionic liquid composite suspension 15 μL on the surface of the electrode; The electrodeposition conditions in step 4) were 0.25 mg mL -1 Chitosan solution was dropped onto the electrode sheet surface and electrodeposited at a constant potential: -0.5 V for 100 s; The electro-polymerization condition in step 7) is to add 5 mmol·L -1 The phosphate buffer solution of o-phenylenediamine is purged with nitrogen in the dark to remove oxygen, and the modified electrode is placed in the buffer solution and electro-polymerized in the dark, with a voltage range of 0-0.8, a scanning rate of 50 mV·s -1 , and a scanning number of 30 cycles; The eluent in step 8) was 0.5 mol·L -1 acetic acid solution for 15 minutes.

8. A method for detecting carcinoembryonic antigen (CEA) for non-diagnostic purposes using the molecularly imprinted electrochemical sensor described in claim 1, characterized in that, The method comprises the following steps: The molecularly imprinted electrochemical sensor is placed in a phosphate solution, and then electrochemical voltammetry scanning and alternating current impedance measurement are performed on the electrochemical sensor, and the corresponding cyclic voltammogram and alternating current impedance diagram are obtained after scanning; The molecularly imprinted electrochemical sensor is immersed in a standard solution containing different concentration gradients of carcinoembryonic antigen, and the differential pulse voltammetry is measured, and the carcinoembryonic antigen solubility and the differential pulse voltammetry response value are plotted; Lysozyme, human serum albumin and human immunoglobulin G are selected as coexisting proteins in human serum of carcinoembryonic antigen to determine the selectivity of the molecularly imprinted electrochemical sensor.

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