Preparation method and application of MXene-based electro-polymerization molecularly imprinted polymer

Abstract

The invention discloses a preparation method of an MXene-based electro-polymerization molecularly imprinted polymer and application of the MXene-based electro-polymerization molecularly imprinted polymer in detection of sulfadimethoxine content. The preparation method comprises the steps of synthesis of an MXene-MOF composite material, preparation of the MXene-based electro-polymerization molecularly imprinted polymer and the like. The electrochemical detection of the SDM is realized by electrically polymerizing a layer of molecularly imprinted polymer on the surface of the MXene-based composite material. When SDM exists in a detection environment, an imprinting cavity with specific recognition capability is combined with the SDM through acting forces such as hydrogen bonds and the like, so that the electron transfer rate is hindered, and the current value is reduced. The quantitative detection of the SDM is realized by analyzing the relationship between the logarithm of the concentration of the SDM and the delta I current change value. The method has a wide concentration detection range and a low detection limit, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the preparation of a MXene-based electropolymerized molecularly imprinted polymer and its application in the detection of sulfadimethoxine, belonging to the technical field of new material preparation and veterinary drug residue detection. Background Art

[0002] Traditional molecularly imprinted polymers (MIPs) form a highly cross-linked network polymer on the surface of a material through direct cross-linking of functional monomers and cross-linking agents. After removing the template, binding sites with a shape and structure complementary to the template are generated. The imprinted material is then dispersed and applied to the electrode surface. This method results in uneven distribution and poor stability on the electrode, limiting the performance of electrochemical sensors. However, modifying nanomaterials on the electrode and combining them with electropolymerization to form MIPs is a viable approach to improving the performance of MIP electrochemical sensors.

[0003] Sulfonamides (SAs), a class of broad-spectrum antimicrobial drugs, offer advantages such as stability and affordability. However, frequent consumption of foods containing SA residues can lead to excessive accumulation in the body, causing serious damage to the urinary and hematopoietic systems. Currently, commonly used methods for detecting SDM (sulfadimethoxine) include high-performance liquid chromatography and liquid chromatography-mass spectrometry. However, these methods suffer from complex and expensive instrumentation, require specialized personnel, have long detection times, and lack sensitivity. Therefore, the development of rapid and accurate SDM detection methods is crucial for ensuring food safety. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that traditional molecular imprinting polymerization has problems such as uneven distribution on the electrode surface, poor stability and poor detection sensitivity.

[0005] In order to solve the above problems, the present invention provides the following solutions: A method for preparing a MXene-based electropolymerized molecularly imprinted polymer comprises the following steps: Step 1: Synthesis of MXene-MOF composite materials: Dopamine hydrochloride (DA), MXene, Eu 3+ , 1,3,5-benzenetricarboxylic acid, and terephthalic acid are dispersed in a mixture of N,N-dimethylformamide (DMF) and H2O to obtain a mixed solution; after ultrasonic dispersion, the solution is placed in a reactor and heated, and centrifuged and washed with N,N-dimethylformamide (DMF) and deionized water. The washed precipitate is then vacuum dried to obtain a MXene-MOF composite material; Step 2: Preparation of MXene-based electropolymerized molecularly imprinted polymers: The MXene-MOF composite material obtained in step 1 is prepared into a dispersion with water and then drop-coated on the surface of a glassy carbon electrode (GCE) and dried to obtain an electrode modified with the MXene-MOF composite material; Pyrrole, SDM, and tetrabutylammonium perchlorate (TBAP) were dissolved in acetonitrile solvent to prepare a polymerization solution, and nitrogen was blown to remove dissolved oxygen; the modified electrode was then inserted into the polymerization solution to electropolymerize pyrrole by cyclic voltammetry; the modified electrode was then immersed in a sodium hydroxide solution for elution to remove the SDM template; the resulting electrode was repeatedly washed with ultrapure water to obtain a MXene-based electropolymerized molecularly imprinted polymer.

[0006] Preferably, in the step 1, dopamine hydrochloride, MXene, Eu 3+ The ratio of 1,3,5-benzenetricarboxylic acid and terephthalic acid is 1-2g; 1-2g; 0.1-1.0g: 1-500mg: 1-500mg; the volume ratio of N,N-dimethylformamide and H2O is 1:2-4:1.

[0007] Preferably, in the step 1, the ultrasonic dispersion time is 5-30 min; the heating temperature in the reactor is 100-140° C., and the heating time is 6-24 h; the vacuum drying temperature is 25-80° C., and the heating time is 5-10 h.

[0008] Preferably, in the step 2, the glassy carbon electrode (GCE) is polished with alumina powder and rinsed before use, and then the polished electrode is ultrasonicated in water and ethanol respectively to obtain a clean bare GCE.

[0009] More preferably, the ultrasonication time of the glassy carbon electrode in water and ethanol is 1-3 minutes.

[0010] Preferably, in step 2, the MXene-MOF composite material is prepared into a dispersion with a concentration of 1-10 mg / mL using water; and the concentrations of pyrrole and tetrabutylammonium perchlorate are 0.1-1.0 mol / L.

[0011] Preferably, in step 2, the parameters of the cyclic voltammetry are set as follows: the polymerization potential is between -0.6 V and +1.2 V, the scan rate is 10-100 mV / s, and a total of 10-20 cycles; and the elution time is 1-5 min.

[0012] The present invention also provides the use of the MXene-based electropolymerized molecularly imprinted polymer prepared by the above preparation method in detecting the content of sulfadimethoxine.

[0013] Preferably, the sample to be tested is crushed and broken, ethyl acetate is added, ultrasonicated at room temperature, homogenized and then centrifuged, the supernatant is taken, the extraction process is repeated, and the supernatants are combined as the sample solution for the final test; the sample solution is dropped onto the surface of the MXene-based electropolymerized molecularly imprinted polymer for incubation, and then the surface is rinsed with deionized water to obtain an electrode, and the electrode is inserted into a K4[Fe(CN)6] / K3[Fe(CN)6] solution containing KCl, and DPV detection is performed. Finally, the current change value obtained is measured, and the content of sulfadimethoxine is calculated through the constructed SDM detection standard curve.

[0014] More preferably, the ratio of the sample to be tested to ethyl acetate is 5-10 g: 10-20 mL; the time for ultrasonication, homogenization, and centrifugation is 5-10 min; the incubation time is 1-4 min; and the parameters of the DPV detection are set as: voltage -0.2~+0.6 V, scan rate 10-100 m / Vs, and pulse radiation value 10-50 mV.

[0015] The present invention provides a method for preparing a MXene-based electropolymerized molecularly imprinted polymer and its application in the detection of sulfadimethoxine. By electropolymerizing on the surface of a material with good conductivity to form an imprinted polymer with specific adsorption for SDM, combined with an electrochemical detection method, high-sensitivity and high-specificity detection of sulfadimethoxine is achieved, with a wide concentration detection range and a low detection limit.

[0016] Compared with the prior art, the present invention has the following technical effects: 1. This invention forms a MXene-MOF composite by loading MOF materials between MXene layers and on their surfaces, preventing MXene aggregation and collapse that can affect its conductivity. Electropolymerization of the MXene composite to form a molecularly imprinted polymer (MIP) overcomes the unevenness and poor stability of conventional MIPs on electrodes.

[0017] 2. The detection system constructed by this invention utilizes the current response of the imprinted cavity formed by the MXene-MOF-based conductive composite material and electropolymerization on the electrode surface, improving the recognition and specificity of sulfadimethoxine in the detection system, overcoming interference from other homologous targets, and improving the sensitivity and specificity of detection. This overcomes the shortcomings of traditional methods and ensures the health and safety of the public's diet.

[0018] 3. The linear range of the logarithm of the sulfadimethoxine concentration and the ΔI current change value established in the present invention is 5×10 -8 ~5×10 -4 g / kg, with a wide detection range and a detection limit LOD of 2.24×10 -9 g / kg. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scanning electron microscope image of the MXene-MOF composite material; Figure 2 Cyclic voltammetry (CV) curves of different modified electrodes in K4[Fe(CN)6] / K3[Fe(CN)6] solutions; Figure 3 The differential pulse voltammetry (DPV) curves of different modified electrodes in K4[Fe(CN)6] / K3[Fe(CN)6] solutions; Figure 4 The schematic diagram of the detection method of sulfadimethoxine based on molecularly imprinted polymer electrochemical sensor; Figure 5 Standard curve of sulfadimethoxine detection based on molecularly imprinted polymer electrochemical sensor; Figure 6 Analyze the data of the anti-interference performance of the constructed detection system; Figure 7 In the figure a and b, respectively, the DPV characterizations of the MXene-based electropolymerized molecularly imprinted polymers prepared in Examples 1 and 2 before and after the addition of 100 µg / kg sulfadimethoxine. DETAILED DESCRIPTION

[0020] To make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0021] The preparation process of MXene used in Example 1-2 is as follows: first, LiF is added at 9 mol·L -1 Dissolve it in HCl and react in water for 30 minutes. Then add Ti3AlC2 (aluminum titanium carbide, total amount added is 50g / L) slowly in batches and react in water for 48 hours. -1 The product was centrifuged and washed with HCl and distilled water until the pH value of the supernatant was greater than 6, and then placed in a vacuum drying oven and dried at 40 °C to obtain MXene.

[0022] Example 1 Preparation of a MXene-based electropolymerized molecularly imprinted polymer and its application in the detection of sulfadimethoxine. The specific steps are as follows: Step 1, synthesis of MXene-MOF composite material: 1g DA, 1g MXene, 300mg Eu 3+, 80 mg of 1,3,5-benzenetricarboxylic acid, and 80 mg of terephthalic acid were mixed. Then, 80 mL of DMF aqueous solution (DMF:water volume ratio of 7:3) was added. Ultrasonic dispersion was performed for 15 minutes, and the mixture was heated in a reactor at 120°C for 12 hours. After centrifugation and washing with DMF and deionized water, the mixture was vacuum dried at 60°C for 10 hours.

[0023] Figure 1 This is a scanning electron microscope image of the MXene-MOF composite material.

[0024] Figure 2 、 3 These are the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) curves of different modified electrodes in K4[Fe(CN)6] / K3[Fe(CN)6] solution.

[0025] Step 2, preparation of MXene-based electropolymerized molecular imprinted polymer: 8 μL of 4 mg / mL MXene-MOF composite material solution was applied to the GCE surface and dried at 37 °C for 15 min to obtain the modified electrode MXene-MOF / GCE.

[0026] Next, a mixture of 0.1 mol / L pyrrole, 5 mmol / L SDM, and 0.1 mol / L TBAP was prepared in acetonitrile solvent to obtain a polymer solution. N2 was blown for 10 minutes to remove dissolved oxygen. The modified electrode MXene-MOF / GCE was then placed in the polymerization solution to electropolymerize pyrrole by CV, with the polymerization potential between -0.6 V and +1.2 V, a scan rate of 50 mV / s, and 10 cycles. The modified electrode was then immersed in 0.1 mol / L sodium hydroxide solution for 4 minutes to remove the SDM molecular template. The resulting electrode was repeatedly washed with ultrapure water and is represented here as MIP / MXene-MOF / GCE. When SDM is present in the detection system, the electron transfer between the electrode and the solution is hindered, resulting in a decrease in the current value.

[0027] In this embodiment, the sample to be tested is fish meat.

[0028] Place 5g of ground fish (accurate to 0.01g) in a 50mL centrifuge tube. Add 15mL of ethyl acetate and sonicate for 10 minutes. Homogenize with a homogenizer at 10,000 rpm for 3 minutes. Centrifuge the extract at 4,000 rpm for 5 minutes. Collect the supernatant. Repeat the extraction process again, and combine the supernatants. Add this supernatant dropwise to the detection system constructed in step 2 of Example 1. Measure the change in current (ΔI) before and after incubation. Calculate the spiked recovery of SDM in the fish sample using the constructed standard curve for Sulfamethoxazole detection.

[0029] Figure 6This figure shows the anti-interference performance of the constructed detection system. The detection targets are SDM (sulfadimethoxine), SMD (sulfadimethoxine), ST (sulfathiazole), TC (tetracycline), and CAP (chloramphenicol). As can be seen from the figure, when the constructed detection method is applied to other structural analogs and common veterinary drugs such as sulfadimethoxine, sulfathiazole, tetracycline, and chloramphenicol, even at a concentration five times that of sulfadimethoxine, no significant change in the current variation value is observed. This demonstrates that the detection method constructed by the present invention has good specificity and sensitivity for sulfadimethoxine.

[0030] Example 2 A preparation method of a MXene-based electropolymerized molecularly imprinted polymer comprises the following steps: Step 1: Synthesis of MXene-MOF composite material: 1g DA, 2g MXene, 300mg Eu 3+ , 70 mg of 1,3,5-benzenetricarboxylic acid, and 70 mg of terephthalic acid were mixed. Then, 80 mL of DMF aqueous solution (DMF:water volume ratio of 7:3) was added. Ultrasonic dispersion was performed for 15 minutes, and the mixture was heated in a reactor at 120°C for 12 hours. After centrifugation and washing with DMF and deionized water, the mixture was vacuum dried at 60°C for 10 hours.

[0031] Step 2: Preparation of MXene-based electropolymerized molecular imprinted polymer: 8 μL of 4 mg / mL MXene-MOF composite material solution was applied to the GCE surface and dried at 37 °C for 15 min to obtain the modified electrode MXene-MOF / GCE.

[0032] Next, a polymer solution was prepared in acetonitrile with a mixture of 0.075 mol / L pyrrole, 5 mmol / L SDM, and 0.1 mol / L TBAP. N2 was purged for 10 minutes to remove dissolved oxygen. The modified MXene-MOF / GCE electrode was then placed in the polymerization solution and subjected to CV electropolymerization of pyrrole. The polymerization potential ranged from -0.6 V to +1.2 V, with a scan rate of 50 mV / s and 15 cycles. The modified electrode was then immersed in 0.1 mol / L sodium hydroxide solution for 4 minutes to remove the SDM molecular template. The resulting electrode was repeatedly rinsed with ultrapure water and is denoted here as MIP / MXene-MOF / GCE.

[0033] Figure 7 In the figure a and b, respectively, the DPV characterizations of the MXene-based electropolymerized molecularly imprinted polymers prepared in Examples 1 and 2 before and after the addition of 100 μg / kg sulfadimethoxine.

Claims

1. A method for preparing a MXene-based electropolymerized molecularly imprinted polymer, characterized in that: The following steps are involved: Step 1: Synthesis of MXene-MOF composite materials: Dopamine hydrochloride, MXene, Eu 3+ , 1,3,5-benzenetricarboxylic acid, and terephthalic acid are dispersed in a mixture of N,N-dimethylformamide and H2O to obtain a mixed solution; after ultrasonic dispersion, the solution is placed in a reactor and heated, and the solution is centrifuged and washed with N,N-dimethylformamide and deionized water. The washed precipitate is then vacuum dried to obtain a MXene-MOF composite material; Step 2: Preparation of MXene-based electropolymerized molecularly imprinted polymers: The MXene-MOF composite material obtained in step 1 is prepared into a dispersion with water and then drop-coated on the surface of the glassy carbon electrode and dried to obtain an electrode modified with the MXene-MOF composite material; Pyrrole, SDM, and tetrabutylammonium perchlorate were dissolved in acetonitrile solvent to prepare a polymerization solution, and nitrogen was blown to remove dissolved oxygen; the modified electrode was then inserted into the polymerization solution to electropolymerize pyrrole by cyclic voltammetry; the modified electrode was then immersed in a sodium hydroxide solution for elution to remove the SDM template; the resulting electrode was repeatedly washed with ultrapure water to obtain a MXene-based electropolymerized molecularly imprinted polymer.

2. The method for preparing a MXene-based electropolymerized molecularly imprinted polymer according to claim 1, wherein: In the step 1, dopamine hydrochloride, MXene, Eu 3+ , 1,3,5-benzenetricarboxylic acid, and terephthalic acid in a ratio of 1-2 g: 1-2 g: 0.1-1.0 g: 1-500 mg: 1-500 mg; and the volume ratio of N,N-dimethylformamide to H2O is 1:2-4:

1.

3. The method for preparing a MXene-based electropolymerized molecularly imprinted polymer according to claim 1, wherein: In the step 1, the ultrasonic dispersion time is 5-30 min; the heating temperature in the reactor is 100-140° C., and the heating time is 6-24 h; the vacuum drying temperature is 25-80° C., and the heating time is 5-10 h.

4. The method for preparing a MXene-based electropolymerized molecularly imprinted polymer according to claim 1, wherein: In the second step, the glassy carbon electrode is polished with alumina powder and rinsed before use, and then the polished electrode is ultrasonicated in water and ethanol respectively to obtain a clean bare GCE.

5. The method for preparing a MXene-based electropolymerized molecularly imprinted polymer according to claim 4, wherein: The ultrasonic time of the glassy carbon electrode in water and ethanol is 1-3 minutes.

6. The method for preparing a MXene-based electropolymerized molecularly imprinted polymer according to claim 1, wherein: In the step 2, the MXene-MOF composite material is prepared into a dispersion with a concentration of 1-10 mg / mL using water; the concentrations of pyrrole and tetrabutylammonium perchlorate are 0.1-1.0 mol / L.

7. The method for preparing a MXene-based electropolymerized molecularly imprinted polymer according to claim 1, wherein: In the step 2, the parameters of the cyclic voltammetry are set as follows: the polymerization potential is between -0.6 V and +1.2 V, the scan rate is 10-100 mV / s, and a total of 10-20 cycles; and the elution time is 1-5 min.

8. Use of a MXene-based electropolymerized molecularly imprinted polymer prepared by the preparation method according to any one of claims 1 to 7 in detecting the content of sulfadimethoxine.

9. The use according to claim 8, characterized in that The sample to be tested was crushed to break the wall, ethyl acetate was added, and the mixture was sonicated at room temperature. The mixture was homogenized and then centrifuged. The supernatant was taken and the extraction process was repeated. The supernatants were combined to serve as the final sample solution for detection. The sample solution was dropwise added to the surface of the MXene-based electropolymerized molecularly imprinted polymer for incubation, and the surface was then rinsed with deionized water to obtain an electrode. The electrode was inserted into a K4[Fe(CN)6] / K3[Fe(CN)6] solution containing KCl for DPV detection. The current change value was finally measured, and the content of sulfadimethoxine was calculated using the constructed SDM detection standard curve.

10. The use according to claim 9, characterized in that The ratio of the sample to be tested to ethyl acetate is 5-10 g: 10-20 mL; the time for ultrasonication, homogenization, and centrifugation is 5-10 min; the incubation time is 1-4 min; and the parameters of the DPV detection are set as: voltage -0.2~+0.6 V, scan rate 10-100 m / Vs, and pulse radiation value 10-50 mV.

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