Preparation method and application of molecularly imprinted polymer for specifically adsorbing delta-tocopherol

Abstract

The invention relates to the technical field of molecularly imprinted polymers, in particular to a preparation method and application of a molecularly imprinted polymer capable of specifically adsorbing delta-tocopherol, and the preparation method comprises the following steps: S1, preparing a polymerizable deep eutectic solvent: S1-1, synthesizing guaiacol, methacryloyl chloride and triethylamine into guaiacol methacrylate, and adding the guaiacol methacrylate into the polymerizable deep eutectic solvent; the preparation method comprises the following steps: mixing choline chloride and guaiacol methacrylate to obtain Poly-DES1; s1-2, choline chloride, urea and fatty acid are mixed, and Poly-DES2 is obtained; s2, preparing a molecularly imprinted polymer: S2-1, forming a pre-assembly system by using the Fe3O4 (at) SiO2-NH2 magnetic nano particles, Poly-DES1 and delta-tocopherol; s2-2, Poly-DES2 and azodiisobutyronitrile are added into the pre-assembled system, and a polymer is obtained; s2-3, obtaining a molecularly imprinted polymer; the molecularly imprinted polymer is applied to separation of delta-tocopherol; a benzene ring of guaiacol and a benzene ring of delta-tocopherol are utilized to generate a powerful pi-pi accumulation effect, and the guaiacol benzene ring is high in electron cloud density, so that the delta-tocopherol can be specifically adsorbed.

Description

Technical Field

[0001] This invention relates to the field of molecularly imprinted polymer technology, specifically to a method for preparing and applying molecularly imprinted polymers that specifically adsorb δ-tocopherol. Background Technology

[0002] δ-Tocopherol is the most potent antioxidant homologue in the vitamin E family (antioxidant capacity: δ > γ > β > α). Its benzene ring structure contains one methyl group (α contains three methyl groups), and its side chain is a saturated hydrocarbon group. It exhibits unique effects in inhibiting lipid peroxidation, anti-liver cancer, and anti-inflammation. However, in natural mixed tocopherols, δ-tocopherol accounts for only 5%–15% (the remainder is mainly α-tocopherol > 70%), and the chemical structures of the homologues are highly similar (differences only in the number / position of methyl groups on the benzene ring and the double bonds in the side chain), making precise enrichment difficult using traditional separation methods. High-purity δ-tocopherol has special applications in functional foods, cosmetics, and drug carriers, but most products on the market are mixed tocopherols (purity < 50%) or single α-tocopherols (content > 90%). With a deepening understanding of the importance of δ-tocopherol and other non-α-tocopherols, their application prospects in biomedicine and pharmacology are widely regarded as promising. Therefore, developing high-purity δ-tocopherol separation technology to meet market demand for specific tocopherol homologues is of great practical significance.

[0003] Molecular imprinting technology (MIT) is a technique that mimics the key-and-lock matching process to prepare polymers with specific recognition capabilities for specific target molecules. The target molecule (template molecule) and functional monomers interact through covalent bonds, hydrogen bonds, ionic bonds, van der Waals forces, etc., to form a complex. This complex then undergoes a polymerization reaction under the action of a crosslinking agent, forming a polymer with a specific spatial structure and functional groups. After polymerization, the template molecule is removed from the polymer using appropriate methods, leaving cavities in the polymer that match the shape, size, and functional group distribution of the template molecule. These cavities have a high degree of specificity in recognizing template molecules, distinguishing structurally similar compounds, and exhibit good chemical and thermal stability, allowing for use under various environmental conditions. Compared to traditional adsorbents, they have unique advantages, such as high selectivity, high adsorption capacity, and ease of regeneration.

[0004] While traditional molecular imprinting techniques have improved selectivity to some extent, they still have certain drawbacks: 1. Insufficient recognition selectivity: The interaction between traditional functional monomers and δ-tocopherol lacks sufficient specificity, making it difficult to effectively distinguish other tocopherol homologues, resulting in limited purity improvement; 2. Environmentally unfriendly: The preparation process uses a large amount of toxic organic solvents as porogens, posing environmental pollution and safety hazards; 3. Poor material practicality: Polymers are usually micron-sized powders, resulting in large pressure drops during column operation and difficulties in solid-liquid separation, easily causing material loss and operational inconvenience; 4. Low mass transfer efficiency: High internal mass transfer resistance of polymers leads to slow adsorption-desorption processes and long separation cycles.

[0005] Therefore, this invention designs a molecularly imprinted polymer that specifically adsorbs δ-tocopherol for the separation of δ-tocopherol. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for preparing and applying a molecularly imprinted polymer that specifically adsorbs δ-tocopherol.

[0007] A method for preparing a molecularly imprinted polymer that specifically adsorbs δ-tocopherol includes the following steps: S1. Preparation of polymerizable deep eutectic solvent S1-1. Guaiacrylol, methacryloyl chloride, and triethylamine are reacted in an ice bath at 0-5°C and an inert atmosphere for 12-16 hours to synthesize guaiacol methacrylate. Choline chloride is then mixed with the guaiacol methacrylate in a molar ratio of 1:1-2 at 60-70°C and stirred until a homogeneous and transparent liquid is formed to obtain Poly-DES1. S1-2. Choline chloride, urea and fatty acids are stirred at 70-80℃ for 2-3 hours in a molar ratio of 1:1 to 2:1 to obtain Poly-DES2. S2. Preparation of molecularly imprinted polymers S2-1. Fe3O4@SiO2-NH2 magnetic nanoparticles were ultrasonically dispersed in Poly-DES1 at a solid-liquid ratio of 0.5~1g:1L for 10~15min. Then, δ-tocopherol template molecules with a mass ratio of 1:4~8 to Fe3O4@SiO2-NH2 magnetic nanoparticles were added. The mixture was stirred at 250~350rpm for 8~12h under nitrogen protection at 40~50℃ to form a pre-assembled system. S2-2, Poly-DES2 and azobisisobutyronitrile are added to the pre-assembled system, and the mixture is reacted at a constant temperature of 65~75℃ for 18~24h under nitrogen protection to obtain the polymer; The volume ratio of Poly-DES2 to Poly-DES1 is 1:0.9~1.1, and the amount of azobisisobutyronitrile added is 0.5~1% of the total mass of the pre-assembled system and Poly-DES2. S2-3. After the reaction is complete, the polymer is separated by an external magnetic field with an intensity of 0.2~0.5T and the supernatant is discarded. The polymer is washed several times with anhydrous ethanol and deionized water, then eluted with an eluent, and then washed with ethanol until neutral. The polymer is dried to constant weight in a vacuum drying oven at 60℃ to obtain a molecularly imprinted polymer with a core-shell structure.

[0008] Furthermore, in S1-2, the fatty acid is acrylic acid.

[0009] Note: Polymerizable acrylic acid is used to form a stable and durable polymer, which enhances the stability of the core-shell structure.

[0010] Furthermore, in S2-1, the purity of the template molecule δ-tocopherol is ≥99.0%.

[0011] Note: The fewer impurities, the stronger the specific recognition performance of the molecularly imprinted polymer with the material to be identified; the stronger the polymerization, the better the separation effect.

[0012] Furthermore, in S2-3, the eluent is a mixture of methanol and acetic acid in a volume ratio of 9:1.

[0013] Note: Methanol and acetic acid have good solubility and volatility, which can quickly elute the polymer from the stationary phase.

[0014] Furthermore, the average particle size of the core layer of the molecularly imprinted polymer is 10-50 nm, and the thickness of the shell layer is 5-50 nm.

[0015] Note: A relatively thin shell reduces the time required for δ-tocopherol to reach the recognition site, allowing the adsorption process to reach equilibrium more quickly and improving the efficiency of adsorption separation.

[0016] Furthermore, in S1-1, before the guaiacol undergoes an ice bath reaction, the guaiacol is first activated by benzene ring activation, as follows: Guaiacin was microwave-activated at a power of 600-700W for 10-15 minutes, with CO2 as the activation medium during the activation process. 2,6-Dihydroxytoluene and ethanol solution were mixed at a solid-liquid ratio of 1g:10-12ml to obtain a 2,6-dihydroxytoluene solution. The pH of the 2,6-dihydroxytoluene solution was then adjusted to 4-5 using a pH adjuster. After heating to 40-50℃, microwave-activated guaiacol was added to the 2,6-dihydroxytoluene solution at a liquid-solid ratio of 10-15ml:1g, and stirring was continued for 1-2 hours. The solution was then centrifuged, filtered, washed, and dried to obtain activated guaiacol.

[0017] Note: Microwave activation is carried out in a CO2 medium, which can efficiently excite molecular motion, partially break weak chemical bonds, promote the redistribution of electron clouds in the benzene ring, and increase the electron density and planarity of the aromatic ring. 2,6-Dihydroxytoluene has strong electron-donating hydroxyl groups (ortho-substitution). Under weakly acidic conditions, its phenolic hydroxyl groups are highly protonated and can form electron donor-acceptor complexes with guaiacol through hydrogen bonds or dipole interactions, thereby increasing the electron cloud density of guaiacol and further strengthening the π-π stacking interaction between the benzene ring of guaiacol and the benzene ring of δ-tocopherol.

[0018] Furthermore, the pH adjuster is a hydrochloric acid solution with a mass fraction of 5-10%.

[0019] Note: Hydrochloric acid solution is highly acidic, and pH adjustment is rapid and thorough. The amount used is relatively small, saving costs.

[0020] Application of molecularly imprinted polymers prepared by any of the methods described above in the separation of δ-tocopherol.

[0021] Furthermore, the method for separating δ-tocopherol is as follows: A tocopherol mixture with a purity of 90% was prepared into a tocopherol concentration of 10-50 mg / L using an ethanol / n-hexane mixture with a volume ratio of 3:7. Molecularly imprinted polymer was added to the solution at a solid-liquid ratio of 0.1-0.5 g / L. The mixture was shaken and adsorbed at room temperature for 0.8-1.2 h. Then, it was separated by an external magnetic field of 0.3-0.5 T for 3-5 min to obtain the polymer with saturated adsorption. Add eluent to the adsorbed saturated polymer at a solid-liquid ratio of 1g:100~200ml, shake at room temperature for 30~60min, and then separate again by an external magnetic field of 0.3~0.5T for 3~5min. Collect the eluent and rotary evaporate it to obtain δ-tocopherol.

[0022] Explanation: By utilizing the specific adsorption of molecularly imprinted polymers and the magnetic separation effect of Fe3O4@SiO2-NH2 magnetic nanoparticles, δ-tocopherol can be rapidly and efficiently separated from tocopherol mixtures.

[0023] Compared with existing methods for separating δ-tocopherol, the advantages of this invention are: (1) In this invention, the choline chloride-guaiacol methacrylate composition is used as a functional monomer, mainly for the prepolymerization stage. The benzene ring of guaiacol and the benzene ring of δ-tocopherol produce a strong π-π stacking effect. Due to the high electron cloud density of the benzene ring of guaiacol, this effect has a strong specificity and can effectively distinguish δ-tocopherol from other homologues. The phenolic hydroxyl and methoxy groups of guaiacol can both serve as hydrogen bond sites, forming a stable and specific hydrogen bond network with the phenolic hydroxyl groups of δ-tocopherol, firmly "locking" the template molecule. The double bond of guaiacol methacrylate directly participates in the polymerization. The urea is permanently and precisely fixed around the imprinted cavities. The choline chloride-urea-fatty acid composition is used as a multifunctional crosslinking porogen, mainly in the polymerization reaction stage. Urea is a strong hydrogen bond donor / acceptor and can form a typical DES with choline chloride. Its addition can effectively reduce the viscosity of the entire DES system, which is beneficial to the mass transfer of reactants and the uniformity of polymerization. After polymerization, urea is eluted, leaving abundant pores. The hydrophobic long chain of fatty acid can adjust the overall hydrophilic-hydrophobic balance of the polymer, making it more compatible with the hydrophobic side chain of δ-tocopherol, which helps to improve the adsorption capacity.

[0024] (2) This invention adds Fe3O4@SiO2-NH2 magnetic nanoparticles to the molecularly imprinted polymer to endow the material with surface active functional groups, which can form hydrogen bonds (-NH2···HO-) with the phenolic hydroxyl groups of δ-tocopherol, or enhance the adsorption capacity through electrostatic interaction (with the quaternary ammonium cations in DES), while providing "anchoring sites" for the preparation of the molecularly imprinted polymer (ring-opening reaction with the epoxy groups of the crosslinking agent); therefore, by using aminated Fe3O4@SiO2 nanoparticles as the magnetic core and combining them with the shell of the above-mentioned DES-based molecularly imprinted polymer, a composite material with both superparamagnetism and specific recognition function is created. This solves the pain points of difficult separation and cumbersome operation of traditional adsorption materials, and realizes rapid and efficient solid-liquid separation of δ-tocopherol. Attached Figure Description

[0025] Figure 1 This is a comparison chart of the results of Investigation 1 of this invention; Figure 2 This is a comparison chart of the results of Investigation 2 of this invention; Figure 3 This is a comparison chart of the results of Investigation 3 of this invention. Detailed Implementation

[0026] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0027] Example 1: A method for preparing a molecularly imprinted polymer that specifically adsorbs δ-tocopherol, comprising the following steps: S1. Preparation of polymerizable deep eutectic solvent S1-1. Guaiacrylol, methacryloyl chloride, and triethylamine were reacted in an ice bath at 3°C ​​and an inert atmosphere for 14 h to synthesize guaiacol methacrylate. Choline chloride was then mixed with the guaiacol methacrylate in a molar ratio of 1:1.5:1.2 at 65°C and stirred until a homogeneous and transparent liquid was formed to obtain Poly-DES1. S1-2. Choline chloride, urea and fatty acid (i.e. acrylic acid) are stirred at 70-80°C for 2-3 hours in a molar ratio of 1:1.5:1 to obtain Poly-DES2. S2. Preparation of molecularly imprinted polymers S2-1. Fe3O4@SiO2-NH2 magnetic nanoparticles were ultrasonically dispersed in Poly-DES1 at a solid-liquid ratio of 0.5~1g:1L for 10~15min at 150W. Then, δ-tocopherol template molecule with a purity of 99.5% and a mass ratio of 1:6 to Fe3O4@SiO2-NH2 magnetic nanoparticles was added. The mixture was stirred at 250~350rpm for 8~12h at 40~50℃ under nitrogen protection to form a pre-assembled system. The preparation method of the Fe3O4@SiO2-NH2 magnetic nanoparticles is as follows: 2.78 g FeCl3·6H2O and 1.39 g FeCl2·4H2O were dissolved in 30 ml of water, and N2 was bubbled into the water to purge the air. The mixture was then heated in a water bath to 60 °C. 5 mL of 25% NaOH solution was added to the water to obtain the reaction solution. The mixture was stirred at 300 rpm for 30 min. Heating was stopped when the reaction solution turned black. The mixture was stirred and cooled to room temperature (25 °C). The obtained product was then separated and washed with deionized water until neutral, and then washed twice with anhydrous ethanol. Finally, it was vacuum dried at 60 °C for 12 h to obtain Fe3O4 magnetic nanoparticles. Fe3O4 magnetic nanoparticles were dispersed in an ethanol-water solution with a solid-liquid ratio of 1 g:1 L and ammonia solution with a volume ratio of 3:1. 10 wt% tetraethyl orthosilicate and 26 wt% ammonia solution were added to coat the Fe3O4 magnetic nanoparticles. The mixture was reacted at 60 °C for 12 hours to form Fe3O4@SiO2. After washing and drying with 0.1 M dilute hydrochloric acid, the Fe3O4@SiO2 was ultrasonically dispersed in anhydrous toluene with a solid-liquid ratio of 1 g:0.15 L and reacted with 250 μL of 3-aminopropyltriethoxysilane. The mixture was stirred and heated to 70 °C for 10 hours under nitrogen protection. After the reaction was complete, the mixture was cooled to room temperature. The nanoparticles were separated by an external magnetic field and washed repeatedly with toluene, ethanol, and deionized water. The mixture was then vacuum dried to obtain Fe3O4@SiO2-NH2 magnetic nanoparticles. S2-2, Poly-DES2 and azobisisobutyronitrile were added to the pre-assembled system, and the mixture was reacted at 70°C for 20 h under nitrogen protection to obtain the polymer; The volume ratio of Poly-DES2 to Poly-DES1 was 1:1, and the amount of azobisisobutyronitrile added was 0.8% of the total mass of the pre-assembled system and Poly-DES2. S2-3. After the reaction is complete, the polymer is separated using an external magnetic field with an intensity of 0.4T, and the supernatant is discarded. The polymer is washed several times with anhydrous ethanol and deionized water, and then eluted with an eluent consisting of a mixture of methanol and acetic acid in a volume ratio of 9:1. The polymer is then washed with a 70% ethanol solution until neutral and dried to constant weight in a vacuum drying oven at 60°C to obtain a core-shell structured molecularly imprinted polymer with an average core particle size of 30 nm and a shell thickness of 25 nm.

[0028] Example 2: The molecularly imprinted polymer prepared in Example 1 was applied to the separation of δ-tocopherol, as follows: A tocopherol mixture with a purity of 90% was prepared into a tocopherol concentration of 30 mg / L using an ethanol / n-hexane mixture with a volume ratio of 3:7. Molecularly imprinted polymer was added to the solution at a solid-liquid ratio of 0.3 g / L. The mixture was shaken and adsorbed at room temperature for 1 h. Then, it was separated by an external magnetic field of 0.4 T for 4 min to obtain the polymer with saturated adsorption. Eluent was added to the adsorbed saturated polymer at a solid-liquid ratio of 1g:150ml. The mixture was shaken at room temperature for 45min and then separated again by an external magnetic field of 0.4T for 4min. The eluent was collected and subjected to rotary evaporation in a water bath at 40℃ and a vacuum of -0.085MPa until it was evaporated to dryness and a viscous oily substance appeared. The rotary evaporation was then stopped to obtain δ-tocopherol.

[0029] Example 3: This example differs from Example 1 in that guaiacol, methacryloyl chloride, and triethylamine are reacted in an ice bath at 0-5°C and an inert atmosphere for 12 hours to synthesize guaiacol methacrylate. Choline chloride and the guaiacol methacrylate are mixed and stirred at 60°C in a 1:1 molar ratio until a homogeneous and transparent liquid is formed, yielding Poly-DES1.

[0030] Example 4: This example differs from Example 1 in that guaiacol, methacryloyl chloride, and triethylamine are reacted in an ice bath at 0-5°C and an inert atmosphere for 16 hours to synthesize guaiacol methacrylate. Choline chloride and the guaiacol methacrylate are mixed and stirred at 70°C in a molar ratio of 1:2 until a homogeneous and transparent liquid is formed, yielding Poly-DES1.

[0031] Example 5: This example differs from Example 1 in that choline chloride, urea, and fatty acids are stirred at 70°C for 2 hours in a molar ratio of 1:1:1 to obtain Poly-DES2.

[0032] Example 6: This example differs from Example 1 in that choline chloride, urea, and fatty acids are stirred at 80°C for 3 hours in a molar ratio of 1:2:1 to obtain Poly-DES2.

[0033] Example 7: This example differs from Example 1 in that Fe3O4@SiO2-NH2 magnetic nanoparticles were ultrasonically dispersed in Poly-DES1 at a solid-liquid ratio of 0.5g:1L for 10min. Then, template molecule δ-tocopherol with a mass ratio of 1:4 to Fe3O4@SiO2-NH2 magnetic nanoparticles was added. The mixture was stirred at 250rpm for 8h at 40℃ under nitrogen protection to form a pre-assembled system.

[0034] Example 8: This example differs from Example 1 in that Fe3O4@SiO2-NH2 magnetic nanoparticles were ultrasonically dispersed in Poly-DES1 at a solid-liquid ratio of 1g:1L for 15min. Then, template molecule δ-tocopherol with a mass ratio of 1:8 to Fe3O4@SiO2-NH2 magnetic nanoparticles was added. The mixture was stirred at 350rpm for 12h at 50℃ under nitrogen protection to form a pre-assembled system.

[0035] Example 9: This example differs from Example 1 in that Poly-DES2 and azobisisobutyronitrile are added to the pre-assembled system, and the reaction is carried out at a constant temperature of 65°C for 18 hours under nitrogen protection to obtain the polymer; wherein, the volume ratio of Poly-DES2 to Poly-DES1 is 1:0.9, and the amount of azobisisobutyronitrile added is 0.5% of the total mass of the pre-assembled system and Poly-DES2.

[0036] Example 10: This example differs from Example 1 in that Poly-DES2 and azobisisobutyronitrile (AIBN) are added to the pre-assembled system, and the mixture is reacted at a constant temperature of 75°C for 24 hours under nitrogen protection to obtain the polymer; wherein, the volume ratio of Poly-DES2 to Poly-DES1 is 1:1.1, and the amount of AIBN added is 1% of the total mass of the pre-assembled system and Poly-DES2.

[0037] Example 11: This example differs from Example 1 in that, after the reaction, the polymer was separated using an external magnetic field with an intensity of 0.2T, and the supernatant was discarded; the polymer was washed several times alternately with anhydrous ethanol and deionized water, then eluted with an eluent, and then washed with ethanol until neutral. It was then dried in a vacuum drying oven at 60°C to constant weight to obtain a molecularly imprinted polymer with a core-shell structure; the average particle size of the core layer of the molecularly imprinted polymer was 10 nm, and the thickness of the shell layer was 50 nm.

[0038] Example 12: This example differs from Example 1 in that, after the reaction, the polymer was separated using an external magnetic field with an intensity of 0.5T, and the supernatant was discarded; the polymer was washed several times alternately with anhydrous ethanol and deionized water, then eluted with an eluent, and then washed with ethanol until neutral. It was then dried in a vacuum drying oven at 60°C to constant weight to obtain a molecularly imprinted polymer with a core-shell structure; the average particle size of the core layer of the molecularly imprinted polymer was 50 nm, and the thickness of the shell layer was 5 nm.

[0039] Example 13: This example differs from Example 1 in that, in S1-1, before the guaiacol undergoes an ice bath reaction, the guaiacol is first activated with a benzene ring. The method is as follows: Guaiacin was microwave-activated at 650W for 12 min, with CO2 as the activation medium during the activation process. 2,6-Dihydroxytoluene was mixed with an ethanol solution at a solid-liquid ratio of 1 g: 11 ml to obtain a 2,6-dihydroxytoluene solution. The pH of the 2,6-dihydroxytoluene solution was then adjusted to 4.5 using an 8% hydrochloric acid solution. After heating to 45°C, microwave-activated guaiacol was added to the 2,6-dihydroxytoluene solution at a liquid-solid ratio of 12 ml: 1 g, and stirring was continued for 1.5 h. The solution was then centrifuged, filtered, washed, and dried. The centrifugation speed was 500 rpm for 30 s, the washing was done with deionized water, and the drying was carried out at 60°C for 1 h to obtain activated guaiacol.

[0040] Example 14: The difference between this example and Example 13 is that guaiacol was microwave activated for 10 minutes at a power of 600W.

[0041] Example 15: The difference between this example and Example 13 is that guaiacol was activated by microwave at 700W for 15 minutes.

[0042] Example 16: The difference between this example and Example 13 is that 2,6-dihydroxytoluene and ethanol solution were mixed at a solid-liquid ratio of 1g:10ml to obtain a 2,6-dihydroxytoluene solution. The pH of the 2,6-dihydroxytoluene solution was then adjusted to 4 using a pH adjuster and heated to 40°C.

[0043] Example 17: The difference between this example and Example 13 is that 2,6-dihydroxytoluene and ethanol solution were mixed at a solid-liquid ratio of 1g:12ml to obtain a 2,6-dihydroxytoluene solution. The pH of the 2,6-dihydroxytoluene solution was then adjusted to 5 using a pH adjuster and heated to 50°C.

[0044] Example 18: This example differs from Example 13 in that microwave-activated guaiacol is added to a 2,6-dihydroxytoluene solution at a liquid-to-solid ratio of 10 ml: 1 g and the mixture is stirred for 1 hour.

[0045] Example 19: The difference between this example and Example 13 is that microwave-activated guaiacol was added to a 2,6-dihydroxytoluene solution at a liquid-to-solid ratio of 15 ml: 1 g and the mixture was stirred for 2 h.

[0046] Example 20: This example differs from Example 2 in that a tocopherol mixture with a purity of 90% is prepared into a solution with a tocopherol concentration of 10 mg / L. A molecularly imprinted polymer is added to the solution at a solid-liquid ratio of 0.1 g / L. The mixture is shaken and adsorbed at room temperature for 0.8 h. Then, it is separated by an external magnetic field of 0.3 T for 3 min to obtain a polymer that is saturated with adsorption.

[0047] Example 21: The difference between this example and Example 2 is that the tocopherol mixture with a purity of 90% was prepared into a solution with a tocopherol concentration of 50 mg / L. Molecularly imprinted polymer was added to the solution at a solid-liquid ratio of 0.5 g / L. The mixture was shaken and adsorbed at room temperature for 1.2 h. Then, it was separated by an external magnetic field of 0.5T for 5 min to obtain the polymer with saturated adsorption.

[0048] Example 22: The difference between this example and Example 2 is that an eluent was added to the adsorbed saturated polymer at a solid-liquid ratio of 1g:100ml, the mixture was shaken at room temperature for 30min, and then separated again by an external magnetic field of 0.3T for 3min. The eluent was collected and rotary evaporated to obtain δ-tocopherol.

[0049] Example 23: The difference between this example and Example 2 is that an eluent was added to the adsorbed saturated polymer at a solid-liquid ratio of 1g:200ml, the mixture was shaken at room temperature for 60min, and then separated again by an external magnetic field of 0.5T for 5min. The eluent was collected and rotary evaporated to obtain δ-tocopherol.

[0050] Experimental Example: The description of this experimental example is based on the scheme described in Example 2, and aims to illustrate the practical application effect of the present invention.

[0051] The molecularly imprinted polymers prepared in each embodiment were applied to separate δ-tocopherol from a tocopherol mixture. The separation purity and recovery rate of the obtained δ-tocopherol were analyzed by high performance liquid chromatography (HPLC) as experimental results to demonstrate the advantages of the molecularly imprinted polymers obtained in the present invention in the separation of δ-tocopherol.

[0052] Investigation 1: Investigate the effect of the preparation method of molecularly imprinted polymers on the separation purity and recovery rate of δ-tocopherol.

[0053] from Figure 1 The results show that, compared with Examples 1 and 3 to 12, the preparation parameters of Poly-DES1 (too small or too large), Poly-DES2 (too small or too large), the preparation parameters of the pre-assembled system (too small or too large), the preparation parameters of the polymer (too small or too large), and the preparation parameters of the molecularly imprinted polymer (too small or too large) all reduce the separation purity and recovery rate of δ-tocopherol. Therefore, from a comprehensive perspective, the parameters of Example 1 are relatively better.

[0054] Investigation 2: Investigate the effect of guaiacol activation on the separation purity and recovery rate of δ-tocopherol.

[0055] from Figure 2The results show that, compared with Examples 1 and 13-19, the activation of guaiacol enhances the π-π stacking of the benzene ring between guaiacol and δ-tocopherol. As a result, the specific recognition effect of Examples 13-19 is further enhanced compared with Example 1. Therefore, the separation purity and recovery rate of δ-tocopherol in Examples 13-19 are further improved compared with Example 1. Comparing Examples 13 to 19, excessively small or large microwave activation parameters, excessively small or large parameters for preparing the 2,6-dihydroxytoluene solution, and excessively small or large parameters for activating guaiacol with the 2,6-dihydroxytoluene solution all reduce the separation purity and recovery rate of δ-tocopherol. Therefore, from a comprehensive perspective, the parameters in Example 13 are relatively better.

[0056] Investigation 3: Investigate the effect of the application method of molecularly imprinted polymers on the separation purity and recovery rate of δ-tocopherol.

[0057] from Figure 3 The results show that, compared with Examples 2 and 20-23, both excessively small or large parameters of the oscillation adsorption and elution oscillation will reduce the separation purity and recovery rate of δ-tocopherol. Therefore, from a comprehensive perspective, the parameters of Example 13 are relatively better.

[0058] In summary, it can be seen that the molecularly imprinted polymer prepared by this invention can achieve a separation purity of over 95% for δ-tocopherol, and the recovery rate of δ-tocopherol is consistently above 85%.

Claims

1. A method for preparing a molecularly imprinted polymer that specifically adsorbs δ-tocopherol, characterized in that, Includes the following steps: S1. Preparation of polymerizable deep eutectic solvent S1-1. Guaiacrylol, methacryloyl chloride, and triethylamine are reacted in an ice bath at 0-5°C and an inert atmosphere for 12-16 hours to synthesize guaiacol methacrylate. Choline chloride is then mixed with the guaiacol methacrylate in a molar ratio of 1:1-2 at 60-70°C and stirred until a homogeneous and transparent liquid is formed to obtain Poly-DES1. S1-2. Choline chloride, urea and fatty acids are stirred at 70-80℃ for 2-3 hours in a molar ratio of 1:1 to 2:1 to obtain Poly-DES2. S2, Preparation of molecularly imprinted polymers S2-1. Fe3O4@SiO2-NH2 magnetic nanoparticles were ultrasonically dispersed in Poly-DES1 at a solid-liquid ratio of 0.5~1g:1L for 10~15min. Then, δ-tocopherol template molecules with a mass ratio of 1:4~8 to Fe3O4@SiO2-NH2 magnetic nanoparticles were added. The mixture was stirred at 250~350rpm for 8~12h under nitrogen protection at 40~50℃ to form a pre-assembled system. S2-2, Poly-DES2 and azobisisobutyronitrile are added to the pre-assembled system, and the mixture is reacted at a constant temperature of 65~75℃ for 18~24h under nitrogen protection to obtain the polymer; The volume ratio of Poly-DES2 to Poly-DES1 is 1:0.9~1.1, and the amount of azobisisobutyronitrile added is 0.5~1% of the total mass of the pre-assembled system and Poly-DES2. S2-3. After the reaction is complete, the polymer is separated by an external magnetic field with an intensity of 0.2~0.5T and the supernatant is discarded. The polymer is washed several times with anhydrous ethanol and deionized water, then eluted with an eluent, and then washed with ethanol until neutral. The polymer is dried to constant weight in a vacuum drying oven at 60℃ to obtain a molecularly imprinted polymer with a core-shell structure.

2. The method for preparing the molecularly imprinted polymer that specifically adsorbs δ-tocopherol as described in claim 1, characterized in that, In S1-2, the fatty acid is acrylic acid.

3. The method for preparing the molecularly imprinted polymer that specifically adsorbs δ-tocopherol as described in claim 1, characterized in that, In S2-1, the purity of the template molecule δ-tocopherol is ≥99.0%.

4. The method for preparing the molecularly imprinted polymer that specifically adsorbs δ-tocopherol as described in claim 1, characterized in that, In S2-3, the eluent is a mixture of methanol and acetic acid in a volume ratio of 9:

1.

5. The method for preparing the molecularly imprinted polymer that specifically adsorbs δ-tocopherol as described in claim 1, characterized in that, The molecularly imprinted polymer has an average core diameter of 10-50 nm and a shell thickness of 5-50 nm.

6. The method for preparing the molecularly imprinted polymer that specifically adsorbs δ-tocopherol as described in claim 1, characterized in that, In S1-1, before the guaiacol undergoes an ice bath reaction, the guaiacol is first activated by benzene ring activation. The method is as follows: Guaiacin was microwave-activated at a power of 600-700W for 10-15 minutes, with CO2 as the activation medium during the activation process. 2,6-Dihydroxytoluene and ethanol solution were mixed at a solid-liquid ratio of 1g:10-12ml to obtain a 2,6-dihydroxytoluene solution. The pH of the 2,6-dihydroxytoluene solution was then adjusted to 4-5 using a pH adjuster. After heating to 40-50℃, microwave-activated guaiacol was added to the 2,6-dihydroxytoluene solution at a liquid-solid ratio of 10-15ml:1g, and stirring was continued for 1-2 hours. The solution was then centrifuged, filtered, washed, and dried to obtain activated guaiacol.

7. The method for preparing the molecularly imprinted polymer that specifically adsorbs δ-tocopherol as described in claim 1, characterized in that, The pH adjuster is a hydrochloric acid solution with a mass fraction of 5-10%.

8. The application of the molecularly imprinted polymer prepared by the method according to any one of claims 1 to 7 in the separation of δ-tocopherol.

9. The application as described in claim 8, characterized in that, The method for separating δ-tocopherol is as follows: A tocopherol mixture with a purity of 90% was prepared into a tocopherol concentration of 10-50 mg / L using an ethanol / n-hexane mixture with a volume ratio of 3:

7. Molecularly imprinted polymer was added to the solution at a solid-liquid ratio of 0.1-0.5 g / L. The mixture was shaken and adsorbed at room temperature for 0.8-1.2 h. Then, it was separated by an external magnetic field of 0.3-0.5 T for 3-5 min to obtain the polymer with saturated adsorption. Add eluent to the adsorbed saturated polymer at a solid-liquid ratio of 1g:100~200ml, shake at room temperature for 30~60min, and then separate again by an external magnetic field of 0.3~0.5T for 3~5min. Collect the eluent and rotary evaporate it to obtain δ-tocopherol.

Images