Molecularly imprinted electrochemical sensor, preparation method thereof and application of molecularly imprinted electrochemical sensor in detecting chloramphenicol

Abstract

The invention discloses a molecularly imprinted electrochemical sensor as well as a preparation method and application thereof in detecting chloramphenicol. The molecularly imprinted electrochemical sensor comprises a substrate electrode, a copper-based metal organic framework material-graphene composite layer, a chitosan layer and a chloramphenicol molecularly imprinted polymer layer which are sequentially stacked, the preparation method comprises the following steps: 1) forming a copper-based metal organic framework material-graphene composite layer on the surface of the substrate electrode; 2) forming a chitosan layer on the surface of the copper-based metal organic framework material-graphene composite layer; and 3) forming a chloramphenicol molecularly imprinted polymer layer on the surface of the chitosan layer. The molecularly imprinted electrochemical sensor has good electron transmissibility, reproducibility, stability, specificity and sensitivity, the preparation method is simple, and the molecularly imprinted electrochemical sensor can be used for detecting chloramphenicol in food, and is rapid in detection, wide in detection range, low in detection limit, stable in performance and suitable for large-scale industrial application.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical detection, and in particular to a molecular imprinting electrochemical sensor, a preparation method thereof, and an application thereof in detecting chloramphenicol. Background Art

[0002] Chloramphenicol is a broad-spectrum, antibacterial antibiotic synthesized entirely in vitro. It achieves its antibacterial effect by binding to bacterial ribosomal subunits, inhibiting and disrupting protein synthesis. Chloramphenicol is not only highly effective but also inexpensive, making it widely used in the treatment and prevention of infectious diseases in humans and animals. However, pathological experiments have shown that chloramphenicol has serious side effects. Long-term use or short-term overdose of chloramphenicol in humans may lead to major diseases such as leukemia and aplastic anemia. Furthermore, chloramphenicol is difficult to degrade naturally when exposed to the natural environment, producing significant ecotoxicity. It can eventually accumulate in humans and other organisms through the food chain, ultimately causing serious diseases. Therefore, the detection of chloramphenicol is crucial and is related to food safety.

[0003] Currently, the main methods used for chloramphenicol detection include gas chromatography, ion chromatography, high-performance liquid chromatography, high-performance liquid chromatography-tandem mass spectrometry, capillary electrophoresis, enzyme-linked immunosorbent assay (ELISA), and fluorescence. These methods offer advantages such as high sensitivity and reliability, but they also suffer from a number of drawbacks, including expensive instrumentation, complex procedures, the need for specialized personnel, high testing costs, and the inability to conduct on-site testing, making them difficult to fully meet practical application needs. Molecularly imprinted electrochemical sensor analysis technology offers advantages such as high sensitivity, good specificity, strong anti-interference ability, high stability, low cost, and the ability to detect small molecules. Compared to these methods, it offers broader application prospects.

[0004] Therefore, it is of great significance to develop a reliable, simple, rapid, low-cost, highly sensitive molecularly imprinted electrochemical sensor suitable for the detection of chloramphenicol. Summary of the Invention

[0005] The purpose of the present invention is to provide a molecular imprinting electrochemical sensor and a preparation method thereof and an application thereof in detecting chloramphenicol.

[0006] The technical solution adopted by the present invention is:

[0007] A molecular imprinting electrochemical sensor comprises a base electrode, a copper-based metal organic framework material-graphene composite layer, a chitosan layer and a chloramphenicol molecular imprinting polymer layer which are stacked in sequence.

[0008] Preferably, the substrate electrode is a glassy carbon electrode.

[0009] Preferably, the mass ratio of the copper-based metal-organic framework material to the graphene in the copper-based metal-organic framework material-graphene composite layer is 1:0.5-1.5.

[0010] Preferably, the inorganic metal center in the copper-based metal organic framework material is a copper ion, and the organic ligand is trimesic acid (H3BTC).

[0011] Preferably, the copper-based metal organic framework material is prepared by a preparation method comprising the following steps:

[0012] i) dispersing a copper salt and polyvinylpyrrolidone (PVP) in a solvent to prepare a copper salt solution, and dispersing trimesic acid in a solvent to prepare a trimesic acid solution;

[0013] ii) adding the trimesic acid solution dropwise to the copper salt solution, allowing the solution to stand for aging, and then separating, purifying and drying the product to obtain a copper-based metal organic framework material.

[0014] Preferably, the molar ratio of the copper salt to trimesic acid in step i) is 1:0.5-2.5.

[0015] Preferably, the copper salt in step i) is at least one of copper nitrate and copper chloride.

[0016] Preferably, the solvent in step i) is methanol.

[0017] Preferably, the purification in step ii) comprises washing the product with ethanol and water multiple times.

[0018] Preferably, the drying in step ii) is carried out at a temperature of 50° C. to 70° C., and the drying time is 10 h to 15 h.

[0019] Preferably, the polymer in the chloramphenicol molecularly imprinted polymer layer is at least one of poly-o-phenylenediamine and polyaniline.

[0020] A method for preparing the molecularly imprinted electrochemical sensor as described above comprises the following steps:

[0021] 1) dispersing a copper-based metal-organic framework material and graphene in a solvent to prepare a dispersion liquid, and then coating the dispersion liquid on the surface of a base electrode and drying it to form a copper-based metal-organic framework material-graphene composite layer;

[0022] 2) coating the chitosan solution on the surface of the copper-based metal-organic framework material-graphene composite layer and drying the chitosan solution to form a chitosan layer;

[0023] 3) Immersing the substrate electrode treated in step 2) in a monomer-chloramphenicol solution for electropolymerization, and then removing the chloramphenicol to form a chloramphenicol molecularly imprinted polymer layer, thereby obtaining a molecularly imprinted electrochemical sensor.

[0024] Preferably, the solvent in step 1) is at least one of isopropanol and water.

[0025] Preferably, the dispersion method in step 1) is ultrasonic dispersion.

[0026] Preferably, the total content of the copper-based metal organic framework material and graphene in the dispersion in step 1) is 0.5 mg / mL to 2.5 mg / mL.

[0027] Preferably, the mass percentage of chitosan in the chitosan solution in step 2) is 1.5% to 2.5%.

[0028] Preferably, the molar ratio of the monomer to the chloramphenicol in the monomer-chloramphenicol solution in step 3) is 1 to 6:1.

[0029] Preferably, the monomer in step 3) is at least one of o-phenylenediamine and aniline.

[0030] Preferably, the electropolymerization in step 3) includes the following operations: using the substrate electrode treated in step 2) as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum electrode as the counter electrode, performing cyclic voltammetry scanning, with a scanning voltage range of 0V to 0.8V, a scanning number of 10 to 30 cycles, and a scanning rate of 40mV / s to 60mV / s.

[0031] Preferably, the step 3) of removing chloramphenicol comprises the following operations: first soaking in a methanol-acetic acid solution, and then rinsing with water.

[0032] Preferably, the volume ratio of methanol to acetic acid in the methanol-acetic acid solution is 8 to 10:1.

[0033] A method for detecting chloramphenicol comprises the following steps:

[0034] a) immersing the molecularly imprinted electrochemical sensor in a chloramphenicol solution for incubation to obtain an incubated molecularly imprinted electrochemical sensor;

[0035] b) using the incubated molecularly imprinted electrochemical sensor and the unincubated molecularly imprinted electrochemical sensor as working electrodes, respectively, and then forming a three-electrode system with a reference electrode and a counter electrode; then immersing the three-electrode system in a test solution for electrochemical testing; and calculating the chloramphenicol content in the test solution based on the change in the electrochemical signal.

[0036] Preferably, the incubation in step a) is carried out at room temperature (25°C±5°C) and the incubation time is 5 min to 35 min.

[0037] Preferably, the reference electrode in step b) is an Ag / AgCl electrode.

[0038] Preferably, the counter electrode in step b) is a platinum electrode.

[0039] Principle of the present invention: The copper-based metal organic framework material (high porosity, regular octahedral shape, stable structure, and simple synthesis) in the molecularly imprinted electrochemical sensor of the present invention has good chemical stability and a large specific surface area, which is conducive to the loading and combination of subsequent materials. Graphene has excellent electrical conductivity and a large specific surface area. Combining it with the copper-based metal organic framework material can enhance the conductivity of the electrode and provide a larger attachment area for the chloramphenicol molecularly imprinted polymer layer, which is conducive to improving the specificity of chloramphenicol detection. Chitosan helps to fix the copper-based metal organic framework material and graphene material, and can also increase their specific surface area, mechanical stability and durability, and reduce swelling. The present invention incubates chloramphenicol on the molecularly imprinted electrochemical sensor, allowing the chloramphenicol to enter the cavity on its surface (chloramphenicol molecularly imprinted polymer layer), thereby changing the electron transfer ability of its surface. The chloramphenicol content in the test solution is calculated by measuring the change in the electrochemical signal before and after incubation of the chloramphenicol.

[0040] The beneficial effects of the present invention are as follows: the molecular imprinting electrochemical sensor of the present invention has good electron transfer, reproducibility, stability, specificity and sensitivity, and its preparation method is simple. It can be used for the detection of chloramphenicol in food, with rapid detection, wide detection range, low detection limit and stable performance, and is suitable for large-scale industrial application.

[0041] Specifically:

[0042] 1) The molecularly imprinted electrochemical sensor of the present invention has good electron transport properties and can effectively transfer the electrons generated during the reaction, thereby realizing the detection of chloramphenicol with a fast reaction speed;

[0043] 2) The molecularly imprinted electrochemical sensor of the present invention has good reproducibility, stability, specificity and sensitivity, and is suitable for the detection of chloramphenicol in food;

[0044] 3) The molecularly imprinted electrochemical sensor of the present invention can be used for the detection of chloramphenicol in food, with rapid detection, a wide detection range and a low detection limit (within the concentration range of 0.1 μM to 10 μM, the DPV current peak I p It is linearly related to the logarithmic change of chloramphenicol concentration. p The relationship between the logarithmic value of chloramphenicol concentration and the p =-14.471lgC CAP +143.617, the correlation coefficient is R 2=0.9960, the detection limit is 0.02μM; in the concentration range of 10μM to 200μM, the DPV current peak I p It is linearly related to the change of chloramphenicol concentration. p The relationship between the concentration of chloramphenicol and p =-0.186C CAP +128.827, correlation coefficient is R 2 =0.9969), the sensor has stable performance and has a very broad application prospect;

[0045] 4) The molecularly imprinted electrochemical sensor of the present invention has a simple preparation method and low production cost, and is suitable for large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Differential pulse voltammograms of the molecularly imprinted electrochemical sensor of Example 1 with and without incubation of chloramphenicol.

[0047] Figure 2 The differential pulse voltammograms and the constructed linear relationship diagram of the molecularly imprinted electrochemical sensor of Example 1 incubated with different concentrations of chloramphenicol.

[0048] Figure 3 The DPV current peak value I of the molecularly imprinted electrochemical sensor of Example 1 incubated with chloramphenicol, oxytetracycline, gentamicin sulfate, streptomycin sulfate, neomycin sulfate, tetracycline and a mixture thereof p Signal change diagram.

[0049] Figure 4 The DPV current peak value I of the molecularly imprinted electrochemical sensor of Example 1 incubated with chloramphenicol after storage at 4°C for different time periods p Signal change diagram.

[0050] Figure 5 This is a graph showing the difference in DPV peak values before and after elution of the molecularly imprinted electrochemical sensor prepared by mixing the copper-based metal-organic framework and graphene in different proportions in Example 3.

[0051] Figure 6 Cyclic voltammograms of different modified electrodes. DETAILED DESCRIPTION

[0052] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0053] Example 1:

[0054] A molecular imprinting electrochemical sensor, the preparation method of which is as follows:

[0055] 1) The copper-based metal organic framework material and graphene (Gr) were ultrasonically dispersed in anhydrous ethanol, the mass ratio of the copper-based metal organic framework material and graphene was 1:1, and the mass volume ratio of the copper-based metal organic framework material and anhydrous ethanol was 1 mg:1 mL, and then placed in a vacuum drying oven at 60 ° C for 12 h to prepare a mixed material, and then the mixed material was ultrasonically dispersed in an isopropanol-water mixed solvent (the volume ratio of isopropanol and water was 1:1) to prepare a total content of the copper-based metal organic framework material and graphene of 1 mg / mL The dispersion was prepared by adding 5 μL of the dispersion and coating the surface of a circular glassy carbon electrode with a diameter of 3 mm (the glassy carbon electrode was pretreated as follows: the glassy carbon electrode was polished into a mirror surface with Al2O3 powder with a particle size of 0.3 μm and Al2O3 powder with a particle size of 0.05 μm, rinsed with distilled water, and then ultrasonically cleaned in distilled water and anhydrous ethanol for 2 minutes each, rinsed with distilled water, and then dried at room temperature), and dried at room temperature to form a copper-based metal organic framework material-graphene composite layer;

[0056] 2) coating 2 μL of a 2% chitosan solution on the surface of the copper-based metal-organic framework material-graphene composite layer and drying at room temperature to form a chitosan layer;

[0057] 3) The glassy carbon electrode treated in step 2) was immersed as a working electrode in 10 mL of phosphate buffer (0.1 mol / L, pH = 6) with a concentration of 10 mmol / L of o-phenylenediamine and a concentration of 2 mmol / L of chloramphenicol. An Ag / AgCl electrode was used as a reference electrode and a platinum electrode was used as a counter electrode to form a three-electrode system. Cyclic voltammetry was then performed with a scanning voltage range of 0 V to 0.8 V, 20 scans, and a scan rate of 50 mV / s. The glassy carbon electrode was then removed and soaked in a methanol-acetic acid solution (the volume ratio of methanol to acetic acid was 9:1) for 20 minutes, then rinsed with water, and dried at room temperature to obtain a molecularly imprinted electrochemical sensor.

[0058] Note:

[0059] The preparation method of the copper-based metal organic framework material is as follows:

[0060] i) dispersing 0.004 mol of Cu(NO3)2·3H2O and 0.445 g of polyvinylpyrrolidone (PVP; number average molecular weight 58,000 g / mol) in 50 mL of methanol to prepare a copper salt solution, and dispersing 0.002 mol of trimesic acid (H3BTC) in 50 mL of methanol to prepare a trimesic acid solution;

[0061] ii) The trimesic acid solution was added dropwise to the copper salt solution at a rate of 1 drop / s. After the addition, the mixture was stirred for 10 minutes, allowed to stand at room temperature for 24 hours, and centrifuged. The solid was washed three times with anhydrous ethanol and three times with distilled water, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain a copper-based metal-organic framework material (denoted as Cu-MOF).

[0062] Performance testing:

[0063] 1) The molecularly imprinted electrochemical sensor of this embodiment was immersed in a chloramphenicol solution with a concentration of 10 μM and incubated at room temperature for 30 minutes. The chloramphenicol that did not enter the molecularly imprinted cavity was carefully rinsed with a phosphate buffer solution to obtain an incubated molecularly imprinted electrochemical sensor. The incubated molecularly imprinted electrochemical sensor was used as a working electrode to form a three-electrode system with an Ag / AgCl electrode (reference electrode) and a platinum electrode (counter electrode). The blank control (Black) was a molecularly imprinted electrochemical sensor without incubation of chloramphenicol. Electrochemical tests were then carried out at room temperature. All were in 10 mL of potassium ferricyanide aqueous solution (5 mM [Fe(CN)6] 3- / 4- +0.1M KCl) was used in the test process, and the differential pulse voltammetry (DPV) was used. The obtained differential pulse voltammetry diagram is shown in Figure 1 shown.

[0064] Depend on Figure 1 It can be seen that the DPV current of the electrode before the molecular imprinting electrochemical sensor of this embodiment is incubated with chloramphenicol is 1.69×10 -4 A, while the DPV current of the electrode decreased to 1.44×10 -4 A, calculated △I=0.25×10 -4 A, indicating that the electron transfer ability of the molecularly imprinted electrochemical sensor surface has changed.

[0065] 2) The molecularly imprinted electrochemical sensor of this embodiment was incubated with 10 mL of chloramphenicol solutions at concentrations of 0.1 μM, 0.5 μM, 1 μM, 5 μM, 10 μM, 20 μM, 40 μM, 60 μM, 80 μM, 100 μM and 120 μM, respectively, and then the three-electrode system was assembled to perform the electrochemical test (same as above). The differential pulse voltammogram obtained by the test and the constructed linear relationship diagram are shown in FIG. Figure 2 (a is the differential pulse voltammogram, b and c are the constructed linear relationship diagrams).

[0066] Depend on Figure 2 It can be seen that within the concentration range of 0.1μM to 10μM, the DPV current peak I p It is linearly related to the logarithmic change of chloramphenicol concentration. p The relationship between the logarithmic value of chloramphenicol concentration and the p=-14.471lgC CAP +143.617, correlation coefficient R 2 =0.9960, the detection limit is 0.02μM; in the concentration range of 10μM to 200μM, the DPV current peak I p It is linearly related to the change of chloramphenicol concentration. p The relationship between the concentration of chloramphenicol and p =-0.186C CAP +128.827, correlation coefficient R 2 =0.9969.

[0067] 3) The molecularly imprinted electrochemical sensor of this embodiment was incubated with 10 mL of 1 μM chloramphenicol (denoted as CAP) solution, 1 μM oxytetracycline (denoted as OTC) solution, 1 μM gentamicin sulfate (denoted as GM) solution, 1 μM streptomycin sulfate (denoted as SS) solution, 1 μM neomycin sulfate (denoted as NS) solution, 1 μM tetracycline (denoted as TC) solution and 1 μM mixed solution (the concentrations of CAP, OTC, GM, SS, NS and TC were all 1 μM, denoted as mixed standard), and then the three-electrode system was assembled for electrochemical test (same as above). The DPV current peak value I p Signal changes as shown in the figure Figure 3 shown.

[0068] Depend on Figure 3 It can be seen that the DPV current peak I of the molecularly imprinted electrochemical sensor incubated with oxytetracycline, gentamicin sulfate, streptomycin sulfate, neomycin sulfate, and tetracycline p The degree of signal reduction is much lower than that of the molecularly imprinted electrochemical sensor incubated with the chloramphenicol solution and the mixed solution (mixed standard), indicating that the molecularly imprinted electrochemical sensor of this embodiment has good selectivity.

[0069] 4) The molecularly imprinted electrochemical sensor of this embodiment was placed in a refrigerator at 4°C for 1 day, 3 days, 5 days, 7 days, 14 days and 21 days, and then immersed in 10 mL of 1 μM chloramphenicol solution for incubation. The three-electrode system was then assembled for electrochemical testing (same as above). The DPV current peak value I p Signal diagram Figure 4 shown.

[0070] Depend on Figure 4 It can be seen that the molecular imprinting electrochemical sensor of this embodiment was incubated for 1 day, 3 days, 5 days, 7 days, 14 days and 21 days after being stored in the refrigerator. The DPV current peak value I pThe signal changes were 98.98%, 97.33%, 96.12%, 94.63%, 89.55% and 85.09%, respectively, indicating that the molecularly imprinted electrochemical sensor of this embodiment has good stability.

[0071] 5) The molecularly imprinted electrochemical sensor of this embodiment was incubated with 10 mL of milk diluent (chloramphenicol added at concentrations of 1 μM and 100 μM, respectively) and honey diluent (chloramphenicol added at concentrations of 1 μM and 100 μM, respectively), and then a three-electrode system was assembled to perform an electrochemical test (same as above). The feasibility test results of the molecularly imprinted electrochemical sensor in actual samples are shown in the following table:

[0072] Table 1 Feasibility test results of molecular imprinting electrochemical sensors in actual samples

[0073]

[0074]

[0075] As shown in Table 1, the spiked recovery rate of the molecular imprinting electrochemical sensor of this embodiment in milk is 100.50% to 111.24%, with a relative standard deviation of ≤9.50%. The spiked recovery rate in honey is 100.86% to 108.15%, with a relative standard deviation of ≤6.31%. This shows that the molecular imprinting electrochemical sensor has high sensitivity and can be used for the detection of chloramphenicol in food.

[0076] Example 2:

[0077] A molecularly imprinted electrochemical sensor is prepared in the same manner as in Example 1, except that the volume of "phosphate buffer containing 10 mmol / L o-phenylenediamine and 2 mmol / L chloramphenicol" in step 3) is replaced with "phosphate buffer containing 8 mmol / L o-phenylenediamine and 2 mmol / L chloramphenicol".

[0078] After testing (testing method is the same as that of Example 1), the selectivity, stability and sensitivity of the molecular imprinting electrochemical sensor of this example are very close to those of the molecular imprinting electrochemical sensor of Example 1.

[0079] Example 3:

[0080] A molecularly imprinted electrochemical sensor is prepared in the same manner as in Example 1, except that the mass ratio of the copper-based metal organic framework material to the graphene in step 1) is adjusted from 1:1 to 1:0.5-2.5.

[0081] Performance test (test method is the same as in Example 1):

[0082] In this embodiment, the molecularly imprinted electrochemical sensor prepared by mixing copper-based metal organic framework and graphene in different proportions was tested for the difference in DPV peak values before and after elution. Figure 5 shown.

[0083] Depend on Figure 5 It can be seen that when the mass ratio of copper-based metal-organic framework and graphene is 1:1, the DPV current is the largest and the signal amplification effect of the molecular imprinting sensor is the best.

[0084] Comparative Example:

[0085] A molecularly imprinted electrochemical sensor is prepared in the same manner as in Example 1, except that the volume of "phosphate buffer containing 10 mmol / L o-phenylenediamine and 2 mmol / L chloramphenicol" in step 3) is replaced with "phosphate buffer containing 10 mmol / L o-phenylenediamine".

[0086] Performance test (test method is the same as in Example 1):

[0087] The cyclic voltammograms of different modified electrodes are shown in Figure 2. Figure 6 (GCE is a glassy carbon electrode, Cu-MOF / Gr / GCE is a glassy carbon electrode containing a copper-based metal organic framework material-graphene composite layer, o-PD-CAP / Cu-MOF / Gr / GCE is the molecular imprinting electrochemical sensor of Example 1 without eluting the chloramphenicol template molecule after electropolymerization of the molecular imprinting membrane, o-PD / Cu-MOF / Gr / GCE is the molecular imprinting electrochemical sensor of Example 1 after eluting the chloramphenicol template molecule, NIP / Cu-MOF / Gr / GCE is a molecular imprinting electrochemical sensor of the comparative example; Cu-MOF is a copper-based metal organic framework material, Gr is graphene, o-PD is poly-o-phenylenediamine, CAP is chloramphenicol, and NIP is a polymer layer without adding a CAP template).

[0088] Depend on Figure 6 It can be seen that Cu-MOF / Gr / GCE has good conductivity. After being compounded with the molecular imprinting membrane, the cyclic voltammetric performance of o-PD-CAP / Cu-MOF / Gr / GCE decreases significantly due to the non-conductivity of the molecular imprinting membrane itself. However, after elution, the conductivity of o-PD / Cu-MOF / Gr / GCE increases significantly due to the elution of the template molecule CAP. The cyclic voltammetric performance of NIP / Cu-MOF / Gr / GCE without the template molecule CAP is still very poor after elution.

[0089] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A molecularly imprinted electrochemical sensor, characterized in that The composition includes a base electrode, a copper-based metal organic framework material-graphene composite layer, a chitosan layer and a chloramphenicol molecular imprinting polymer layer which are stacked in sequence.

2. The molecularly imprinted electrochemical sensor according to claim 1, characterized in that: The base electrode is a glassy carbon electrode.

3. The molecularly imprinted electrochemical sensor according to claim 1, wherein: The mass ratio of the copper-based metal organic framework material to the graphene in the copper-based metal organic framework material-graphene composite layer is 1:0.5-1.

5.

4. The molecularly imprinted electrochemical sensor according to any one of claims 1 to 3, characterized in that: The inorganic metal center in the copper-based metal organic framework material is a copper ion, and the organic ligand is trimesic acid.

5. The molecularly imprinted electrochemical sensor according to any one of claims 1 to 3, characterized in that: The polymer in the chloramphenicol molecularly imprinted polymer layer is at least one of poly-o-phenylenediamine and polyaniline.

6. A method for preparing a molecularly imprinted electrochemical sensor according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) dispersing a copper-based metal-organic framework material and graphene in a solvent to prepare a dispersion liquid, and then coating the dispersion liquid on the surface of a base electrode and drying it to form a copper-based metal-organic framework material-graphene composite layer; 2) coating the chitosan solution on the surface of the copper-based metal-organic framework material-graphene composite layer and drying it to form a chitosan layer; 3) Immersing the substrate electrode treated in step 2) in a monomer-chloramphenicol solution for electropolymerization, and then removing the chloramphenicol to form a chloramphenicol molecularly imprinted polymer layer, thereby obtaining a molecularly imprinted electrochemical sensor.

7. The preparation method according to claim 6, characterized in that: Step 1) The total content of the copper-based metal organic framework material and graphene in the dispersion is 0.5 mg / mL to 2.5 mg / mL.

8. The preparation method according to claim 6, characterized in that: In step 3), the molar ratio of the monomer to the chloramphenicol in the monomer-chloramphenicol solution is 1 to 6:

1.

9. The preparation method according to claim 6 or 8, characterized in that: Step 3) The electropolymerization includes the following operations: using the substrate electrode treated in step 2) as a working electrode, the Ag / AgCl electrode as a reference electrode, and the platinum electrode as a counter electrode, performing cyclic voltammetry scanning, with a scanning voltage range of 0V to 0.8V, a scanning number of 10 to 30 cycles, and a scanning rate of 40mV / s to 60mV / s.

10. A method for detecting chloramphenicol, characterized in that, The following steps are involved: a) immersing the molecularly imprinted electrochemical sensor according to any one of claims 1 to 5 in a chloramphenicol solution for incubation to obtain an incubated molecularly imprinted electrochemical sensor; b) using the incubated molecularly imprinted electrochemical sensor and the unincubated molecularly imprinted electrochemical sensor as working electrodes, respectively, and then forming a three-electrode system with a reference electrode and a counter electrode; then immersing the three-electrode system in a test solution for electrochemical testing; and calculating the chloramphenicol content in the test solution based on the change in the electrochemical signal.

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