Preparation method of DHA molecularly imprinted polymer and application of DHA molecularly imprinted polymer in enrichment and separation of DHA in euphausia superba powder

Abstract

The invention discloses a preparation method of a DHA (docosahexaenoic acid) molecularly imprinted polymer and application of the DHA molecularly imprinted polymer in enrichment and separation of DHA in euphausia superba powder. The method comprises the following steps: mixing template molecules, functional monomers, a mediating agent, an initiator and a pore-foaming agent to react to obtain a prepolymer; wherein the template molecule comprises DHA, the functional monomer comprises methacrylic acid, and the mediating agent comprises rare earth ions; reacting the prepolymer with a cross-linking agent to obtain a product; and purifying the product and drying to obtain the DHA molecularly imprinted polymer. According to the embodiment of the invention, the rare earth ions are adopted as mediation, the selectivity and stability of imprinting sites are improved by utilizing the specific coordination effect of the rare earth ions and carboxyl and double bonds in the DHA, the prepared molecularly imprinted polymer has relatively high selectivity, strong adsorption capacity and short adsorption time on the DHA, and when the molecularly imprinted polymer is used as a solid-phase extraction adsorbent, the adsorption efficiency of the DHA is greatly improved. The requirement of keeping a relatively high recovery rate of DHA in the euphausia superba powder with a complex substrate can be met.

Description

Technical Field

[0001] The present application relates to the technical field of DHA extraction, and in particular to a method for preparing a DHA molecularly imprinted polymer and its application in the enrichment and separation of DHA from Antarctic krill meal. Background Art

[0002] Docosahexaenoic acid (DHA) is a long-chain polyunsaturated fatty acid in the omega-3 family. It is widely found in marine organisms, such as deep-sea fish, microalgae, and some marine mammals. DHA is present in high concentrations in neuronal cell membrane phospholipids and plays many physiological roles, including regulating membrane fluidity, neurotransmitter release, and gene expression.

[0003] In addition, DHA can reduce chronic inflammation, reduce the risk of atherosclerosis, and prevent degenerative diseases in the elderly. The level of DHA in the human body is mainly determined by dietary DHA intake. Fish and fish oil supplements are the main dietary sources of DHA. Therefore, many organizations around the world have issued recommendations for supplementing DHA through diet. The DHA supplement products currently on the market mainly include fish oil capsules, infant formula, and medicines.

[0004] The demand for high-purity DHA in the fields of medicine, infant nutrition, biomaterials, etc. continues to grow.

[0005] Due to the low DHA content in biological samples and the complex matrix, in actual production, it is often necessary to resort to cumbersome extraction processes to obtain DHA with higher purity. At present, the extraction processes mainly include solvent extraction, supercritical fluid extraction (SFE), molecular distillation and silver nitrate complexation. Among them, SFE and silver nitrate complexation are the most widely used. However, SFE is limited in industrial application due to its large equipment investment and high operating pressure. Silver nitrate complexation has strong specificity, good separation effect and high product purity, but silver nitrate is corrosive and difficult to recover, which limits its widespread application. Therefore, the development of efficient, highly selective and environmentally friendly DHA enrichment and separation materials has important commercial value. Summary of the Invention

[0006] The purpose of this application is to provide a method for preparing a DHA molecularly imprinted polymer and its application in the enrichment and separation of DHA from Antarctic krill meal, so as to prepare a DHA molecularly imprinted polymer that has the specific recognition ability for DHA and can also improve the adsorption performance of DHA.

[0007] The technical solution of the present application is: in the first aspect, the present application provides a method for preparing a DHA molecularly imprinted polymer, the method comprising:

[0008] A prepolymer is obtained by reacting a mixed template molecule, a functional monomer, a mediator, an initiator and a porogen; wherein the template molecule includes DHA, the functional monomer includes methacrylic acid, and the mediator includes a rare earth ion;

[0009] reacting the prepolymer with a cross-linking agent to obtain a product;

[0010] The product is purified and dried to obtain a DHA molecularly imprinted polymer.

[0011] In one embodiment of the above-mentioned method for preparing the DHA molecularly imprinted polymer, the structural formula of the DHA is:

[0012]

[0013] In one embodiment of the above-mentioned method for preparing DHA molecularly imprinted polymer, the molar ratio of the template molecule, the functional monomer and the initiator is 1:(2-6):(1-4).

[0014] In one embodiment of the above-mentioned method for preparing DHA molecularly imprinted polymer, the initiator comprises at least one of azobisisobutyronitrile and azobisisoheptanenitrile; and / or,

[0015] The mediator includes one or more of silver acetate, europium acetate, cobalt acetate, and lanthanum chloride; and / or,

[0016] The porogen includes a mixture of methanol and acetonitrile or a mixture of methanol and n-butanol.

[0017] In one embodiment of the above-mentioned method for preparing DHA molecularly imprinted polymer, in the mixture of methanol and acetonitrile, the volume ratio of methanol to acetonitrile is (0-5):(5-0);

[0018] In the mixture of methanol and n-butanol, the volume ratio of methanol to n-butanol is (0-5):(5-0).

[0019] In one embodiment of the above-mentioned method for preparing the DHA molecularly imprinted polymer, the reaction of the mixed template molecule, the functional monomer, the mediator, the initiator and the porogen to obtain the prepolymer comprises:

[0020] Mix the template molecule, functional monomer, mediator, initiator and porogen and then sonicate for 5-10 minutes;

[0021] The mixture is allowed to stand for 30 to 60 minutes to perform a prepolymerization reaction to obtain a prepolymer.

[0022] In one embodiment of the above-mentioned method for preparing DHA molecularly imprinted polymer, the cross-linking agent includes at least one of ethylene glycol dimethacrylate and triester trimethacrylate.

[0023] In one embodiment of the above-mentioned method for preparing the DHA molecularly imprinted polymer, the reaction of the prepolymer with the cross-linking agent to obtain the product is carried out in a water bath;

[0024] The water bath heating temperature is 50-70° C., and the reaction time is 10-24 hours.

[0025] In one embodiment of the above-mentioned method for preparing DHA molecularly imprinted polymer, the reaction of the prepolymer with a cross-linking agent to obtain a product is carried out in a closed environment.

[0026] In a second aspect, the present application provides a use of a DHA molecularly imprinted polymer prepared by the preparation method of a DHA molecularly imprinted polymer as described in any one of the first aspects in the enrichment and separation of DHA in Antarctic krill meal.

[0027] The advantages of the present application are: 1. Rare earth ions are used as a mediator, and the specific coordination effect of rare earth ions with carboxyl groups and double bonds in DHA is utilized to improve the selectivity and stability of the imprinted sites. The prepared molecularly imprinted polymer has high selectivity for DHA, strong adsorption capacity, and short adsorption time. When used as a solid-phase extraction adsorbent, it can meet the requirements of maintaining a high recovery rate of DHA in Antarctic krill meal with a complex matrix; 2. The present application has low cost, simple experimental operation, and easy-to-control reaction conditions. The prepared molecularly imprinted polymer is used as a filler for solid-phase extraction, which can achieve efficient separation and enrichment of DHA in Antarctic krill meal. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 is a scanning electron micrograph of molecularly imprinted polymer;

[0030] Figure 2 This is a comparison chart of the adsorption effects of DHA molecularly imprinted polymers prepared using different mediators in the preparation method of DHA molecularly imprinted polymers provided in the examples of this application;

[0031] Figure 3 This is a comparison chart of the adsorption effect of the molecularly imprinted polymer before and after adding europium acetate in the preparation method of the DHA molecularly imprinted polymer provided in the examples of the present application;

[0032] Figure 4This is a comparison chart of the adsorption effect of MIP / NIP on samples with different loading concentrations;

[0033] Figure 5 Schematic diagram of the identification mechanism and extraction apparatus;

[0034] Figure 6 This is the recovery result of the actual spiked sample of DHA. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] As described in the background, molecular imprinting technology (MIT) in the prior art is based on a principle similar to the "lock and key" model. Template molecules are covalently or non-covalently bound to functional monomers, and under the action of a cross-linking agent, a polymer network with specific recognition sites for the target molecule is formed. These polymers are known as molecularly imprinted polymers (MIPs). These polymers have a high degree of recognition and selectivity for the template molecule and are currently widely used in the pre-treatment of solid-phase extraction of target molecules in various complex matrices. These applications include the separation, enrichment, and detection of protein markers in blood samples, aflatoxins in traditional Chinese medicines, and trace paralytic shellfish neurotoxins in marine products, achieving extraction results similar to or better than commercially available extraction materials. However, in most of the reported literature, there are few studies on the use of MIPs for DHA extraction and separation. Only a few reports use oleic acid or palmitic acid as templates and allylthiourea as functional monomers to prepare MIPs, which can be used for the extraction and separation of OA and PA from palmitic acid distillate waste; or use succinic acid (SCA) as a template molecule, methacrylic acid as a functional monomer, and silver nitrate as a chelating agent to prepare MIPs for the extraction and separation of SCA, but the purity and recovery rate are not excellent.

[0037] To address the above-mentioned problems, the present application creatively proposes a method for preparing a DHA molecularly imprinted polymer and its application in the enrichment and separation of DHA from Antarctic krill meal. Rare earth ions are used as a medium, and the specific coordination effect of rare earth ions with carboxyl groups and double bonds in DHA is utilized to improve the selectivity and stability of the imprinted sites. The prepared molecularly imprinted polymer has high selectivity for DHA, strong adsorption capacity, and short adsorption time. When used as a solid-phase extraction adsorbent, it can meet the requirements of maintaining a high recovery rate of DHA in Antarctic krill meal with a complex matrix.

[0038] This will be described below in conjunction with specific embodiments.

[0039] Specifically, the present invention provides a method for preparing a DHA molecularly imprinted polymer, the method comprising:

[0040] S1. Mixing a template molecule, a functional monomer, a mediator, an initiator and a porogen to react to obtain a prepolymer; wherein the template molecule includes DHA, the functional monomer includes methacrylic acid, and the mediator includes a rare earth ion.

[0041] S2. reacting the prepolymer with a cross-linking agent to obtain a product.

[0042] S3, purifying the product and drying it to obtain a DHA molecularly imprinted polymer.

[0043] The preparation method of the DHA molecularly imprinted polymer provided in the embodiments of the present application is based on the molecular structural characteristics of DHA and methacrylic acid. The mediating ions in the mediator form an octahedral coordination structure with the carboxylic acid group, and may polarize the conjugated double bond system in the molecule through secondary interactions, which can play a role in supporting and stabilizing the special pores. In the adsorption process of DHA by the prepared DHA molecularly imprinted polymer, the ion-mediated effect not only gives the imprinted cavities the specific recognition ability of the carboxylic acid group, but also may achieve synergistic recognition of the polyene structure through metal-π interaction, thereby improving the adsorption performance.

[0044] In some embodiments, the structural formula of DHA is:

[0045]

[0046] In some embodiments, the molar ratio of the template molecule, the functional monomer, and the initiator is 1:(2-6):(1-4). Alternatively, the molar ratio of the template molecule, the functional monomer, and the initiator can be 1:2:1, 1:2:2, 1:2:3, 1:2:4, 1:3:1, 1:3:3, 1:4:1, 1:4:3, 1:4:4, 1:5:1, 1:5:3, 1:5:4, 1:6:1, 1:6:2, 1:6:4, or any ratio within the above ratio range.

[0047] In some embodiments, the initiator includes at least one of azobisisobutyronitrile and azobisisoheptanenitrile.

[0048] The mediator includes one or more of silver acetate, europium acetate, cobalt acetate, and lanthanum chloride.

[0049] The porogen includes a mixture of methanol and acetonitrile or a mixture of methanol and n-butanol.

[0050] Preferably, the volume ratio of methanol to acetonitrile in the mixture of methanol and acetonitrile is (0-5):(5-0); the volume ratio of methanol to n-butanol in the mixture of methanol and n-butanol is (0-5):(5-0).

[0051] In some embodiments, the reaction of the mixed template molecules, functional monomers, mediators, initiators and pore-forming agents to obtain the prepolymer comprises:

[0052] The mixed template molecules, functional monomers, mediators, initiators and pore-forming agents are ultrasonically treated for 5-10 minutes;

[0053] The mixture is allowed to stand for 30-60 minutes to perform the prepolymerization reaction to obtain the prepolymer. Optionally, the ultrasonic treatment time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, or any point value within the above range. The standing time can be 30 minutes, 35 minutes, 40 minutes, 46 minutes, 50 minutes, 52 minutes, 57 minutes, 60 minutes, or any point value within the above range.

[0054] In some embodiments, the crosslinking agent comprises at least one of ethylene glycol dimethacrylate and trimethyl triacrylate.

[0055] In some embodiments, the reaction of the prepolymer and the crosslinking agent to obtain the product is performed under water bath heating; the temperature of the water bath heating is 50-70℃, and the reaction time of the reaction is 10-24 hours. Optionally, the temperature of the water bath heating can be 50℃, 52℃, 55℃, 57℃, 60℃, 63℃, 66℃, 70℃, or any point value within the above range, and the reaction time of the reaction can be 10 hours, 11 hours, 13 hours, 15 hours, 17 hours, 19 hours, 20 hours, 22 hours, 24 hours, or any point value within the above range.

[0056] In some embodiments, the reaction of the prepolymer and the crosslinking agent to obtain the product is performed in a closed environment.

[0057] In some embodiments, the purification comprises elution of the product to remove unreacted substances.

[0058] The application also provides an application of the DHA molecularly imprinted polymer prepared by the preparation method of the DHA molecularly imprinted polymer according to any one of the above embodiments in the enrichment and separation of DHA in Antarctic krill powder.

[0059] The preparation method of the DHA molecularly imprinted polymer provided in the examples of the present application uses rare earth ions as a medium and utilizes the specific coordination effect of rare earth ions with carboxyl groups and double bonds in DHA to improve the selectivity and stability of the imprinted sites. The prepared molecularly imprinted polymer has high selectivity for DHA, strong adsorption capacity, and short adsorption time. When used as a solid-phase extraction adsorbent, it can meet the requirements of maintaining a high recovery rate of DHA in Antarctic krill meal with a complex matrix. The method is low in cost, simple in experimental operation, and easy to control reaction conditions. The prepared molecularly imprinted polymer is used as a filler for solid-phase extraction and can achieve efficient separation and enrichment of DHA in Antarctic krill meal.

[0060] The solution of this application will be described in detail below with reference to the accompanying drawings and various embodiments.

[0061] Example 1: This example provides a method for preparing a DHA molecularly imprinted polymer, comprising:

[0062] 0.06 mmol of DHA, 0.06 mmol of silver acetate, 0.24 mmol of methacrylic acid, and 0.04 g of azobisisobutyronitrile were added to a vial. 4 mL of methanol was added to dissolve the mixture, followed by 4 mL of acetonitrile. After sonication for 5 minutes, the mixture was allowed to stand at room temperature for 30 minutes to prepolymerize. 0.96 mmol of ethylene glycol dimethacrylate was then added, mixed thoroughly, and the cap was tightened. The interface was sealed with parafilm, and the entire vial was wrapped with plastic wrap. The entire vial, below the cap, was immersed in a water bath set at 65°C for 12 hours. After the reaction, the reaction product was transferred to a centrifuge tube, shaken with methanol for 3 hours, centrifuged at 5000 rpm for 10 minutes, and the supernatant removed. This step was repeated three times. A methanol-acetic acid (9:1) eluent was then added, shaken for 3 hours, centrifuged at 5000 rpm for 10 minutes, and the supernatant removed. This step was repeated five times. The eluted MIP was dried by forced air at 60° C. for 8 h to obtain DHA molecularly imprinted polymer-MIP solid particles.

[0063] Example 2: This example provides a method for preparing a DHA molecularly imprinted polymer, comprising:

[0064] 0.06 mmol of DHA, 0.06 mmol of europium acetate, 0.24 mmol of methacrylic acid, and 0.04 g of azobisisobutyronitrile were added to a vial. 3 mL of methanol was added to dissolve the mixture, followed by 2 mL of acetonitrile. After sonication for 5 minutes, the mixture was allowed to stand at room temperature for 30 minutes to prepolymerize. 0.96 mmol of ethylene glycol dimethacrylate was then added, mixed thoroughly, and the cap was tightened. The interface was sealed with parafilm, and the entire vial was wrapped with plastic wrap. The entire vial, below the cap, was immersed in a water bath set at 65°C for 12 hours. After the reaction, the reaction product was transferred to a centrifuge tube, shaken with methanol for 3 hours, centrifuged at 5000 rpm for 10 minutes, and the supernatant removed. This step was repeated three times. A methanol-acetic acid (9:1) eluent was then added, shaken for 3 hours, centrifuged at 5000 rpm for 10 minutes, and the supernatant removed. This step was repeated five times. The eluted MIP was dried by forced air at 60° C. for 4 h to obtain DHA molecularly imprinted polymer-MIP solid particles.

[0065] Example 3: This example provides a method for preparing a DHA molecularly imprinted polymer, comprising:

[0066] Add 0.06 mmoL of DHA, 0.06 mmoL of europium acetate, 0.24 mmoL of methacrylic acid, and 0.04 g of azobisisobutyronitrile to a vial. Dissolve in 2 mL of methanol, then add 3 mL of acetonitrile. Ultrasonicate for 5 minutes to mix thoroughly, then let stand at room temperature for 30 minutes to prepolymerize. Add 1.2 mmoL of ethylene glycol dimethacrylate, mix thoroughly, and tighten the cap. Wrap the joint with parafilm to seal, and wrap the entire vial with plastic wrap. Submerge the entire vial below the cap in a water bath set at 65°C for 12 hours. After the reaction, the reaction product was transferred to a centrifuge tube, shaken with methanol for 3 hours, centrifuged for 10 minutes (5000 rpm), and the supernatant removed. This step was repeated three times. Then, a methanol-acetic acid (9:1) eluent was added and shaken for 3 hours. Centrifuged for 10 minutes (5000 rpm), the supernatant removed, and this step was repeated five times. The eluted MIP was air-dried at 60°C for 6 hours to obtain DHA molecularly imprinted polymer (MIP) solid particles.

[0067] Comparative Example 1: In this comparative example, a non-imprinted polymer NIP was prepared. The preparation process was the same as that of MIP Example 1. The only difference from Example 1 was that the template molecule DHA was not added.

[0068] Comparative Example 2: In this comparative example, europium acetate was used to prepare MIP. The preparation process was the same as that of MIP Example 1. The only difference from Example 1 was that europium acetate was added instead of silver acetate.

[0069] Comparative Example 3: In this comparative example, MIP was prepared using cobalt acetate. The preparation process was the same as that of MIP Example 1. The only difference from Example 1 was that cobalt acetate was added instead of silver acetate.

[0070] Comparative Example 4: In this comparative example, MIP was prepared using lanthanum chloride. The preparation process was the same as that of MIP Example 1. The only difference from Example 1 was that lanthanum chloride was added instead of silver acetate.

[0071] Comparative Example 5: In this comparative example, europium acetate was not used to prepare MIP. The preparation process of this MIP was the same as that of Example 2, and the only difference from Example 2 was that europium acetate was not added during the process.

[0072] Comparative Example 6: In this comparative example, a non-imprinted polymer NIP was prepared. The preparation process was the same as that of MIP Example 2. The only difference from Example 2 was that no template molecule DH was added.

[0073] The performance tests of the molecularly imprinted polymers prepared in the above examples and comparative examples are as follows:

[0074] Accurately weigh the dried MIP or NIP prepared in Example 1 (12 mg) into a volumetric flask, add 3 mL of a 0.03 g / mL DHA-n-hexane solution to evenly disperse the polymer. This is used as the MIP or NIP experimental group. The blank group follows the same process except that no MIP or NIP is added. The blank group and the experimental group are placed in a shaker and shaken at room temperature for 3 hours, and then detected by gas chromatograph. Finally, the concentration of the MIP or NIP group is deducted from the concentration of the blank group to obtain the actual adsorption result of the MIP or NIP. The amount of DHA adsorbed at equilibrium (Qe, g / g) is calculated according to formula (1):

[0075]

[0076] Where C0 and C e represent the initial and equilibrium concentrations of the template in the solution (g / mL), V represents the volume of the solution (mL), and M is the mass of the polymer (mg).

[0077] The data of the adsorption experiment were fitted using the Langmuir-Freundlich (LF) model. The formula of the Langmuir-Freundlich (LF) model is formula (2):

[0078]

[0079] where Q max is the apparent maximum number of template binding sites, and K is a constant related to the adsorption energy or net enthalpy (mmol / L).

[0080] The imprinting effect of MIPs was evaluated by the imprinting factor IF:

[0081]

[0082] where Q MI P represents the amount of target molecules bound to MIP, Q NIP Indicates the amount of target molecule bound to NIP.

[0083] The adsorption effects of DHA molecularly imprinted polymers prepared in comparative examples 2, 3 and 4 under the mediation of different rare earth metal ions on DHA are as follows: Figure 2 As shown, under the same adsorption conditions, europium acetate as a mediating substance has a better adsorption effect on DHA, and the adsorption capacity of MIP to the template is much higher than that of NIP, and the imprinting factor IF is 2.86 with high selectivity.

[0084] Compared with Example 2 in which MIP was prepared under the same conditions, the adsorption capacity of the MIP prepared with europium acetate increased significantly compared with Comparative Example 5 in which MIP was prepared without europium acetate, while the adsorption performance of the MIP prepared with europium acetate in Comparative Example 6 decreased, thereby obtaining a larger imprinting factor. Figure 3 shown.

[0085] Application of actual samples:

[0086] Select DHA standard and add n-hexane to prepare a series of DHA-n-hexane mixed standard solutions. Weigh the MIPs or NIPs (200 mg) prepared in Example 3, add it to 6 mL of the above solution, and adsorb it at room temperature for 3 hours. Transfer the adsorbed solution to a solid phase extraction device. Unadsorbed impurities flow out of the column through a 0.45 μm hydrophobic sieve plate under the action of gravity. The adsorbed DHA and MIPs remain above the sieve plate together, separating the sample from the sample solution. Rinse the column with 2 mL of methanol and elute with 3 mL of n-hexane-acetic acid (8:2, v / v). Collect the eluate, determine its content by GC, and calculate the recovery rate based on the standard curve.

[0087] Attachment Figure 4 The figure compares the adsorption of DHA by MIP and NIP under different loading solution concentrations. This shows that under the same adsorption conditions, MIP has a much higher adsorption capacity for the template than NIP, with an imprinting factor (IF) of 6.74, high selectivity, a maximum adsorption capacity of 0.896 g / g, and high extraction efficiency.

[0088] Attachment Figure 5 Schematic diagram of the identification mechanism and solid phase extraction device.

[0089] To investigate whether MIP maintains stable adsorption in the complex matrix of Antarctic krill meal, Antarctic krill oil was extracted from the meal using an organic solvent extraction method (see Hu Mengling, Zhang Shuai, Fang Yi, et al. Determination of fatty acid composition and content in Antarctic krill by solvent extraction-precolumn derivatization-gas chromatography. Analytical Laboratory, 2019, 38(05): 569-574). n-Hexane was added to the extracted oil to prepare a sample solution with a concentration of 0.03 g / mL. The adsorption and elution processes of MIP and NIP in the sample solution were consistent with those of the standard. The adsorption experiment was repeated three times.

[0090] Attachment Figure 6 The adsorption results of the parallel experiment showed that the recovery rate of DHA in Antarctic krill powder by MIPs exceeded 86%, which was significantly higher than that of NIPs. This shows that MIPs has high selectivity for DHA and can meet the requirements for enrichment of DHA in real samples.

[0091] The present invention provides a method for preparing a molecularly imprinted polymer (MIP). The MIP, prepared using rare earth metals as mediators and methacrylic acid as a functional monomer, is used for the separation and enrichment of DHA. The resulting MIP exhibits high selectivity for DHA, strong adsorption capacity, and a short adsorption time. Its use as a solid-phase extraction adsorbent can achieve high DHA recovery rates even in the complex matrix of Antarctic krill meal. The simple and low-cost preparation method has the potential for further industrial application in DHA enrichment and separation.

[0092] The above embodiments are intended only to illustrate the technical concepts and features of this application. Their purpose is to enable those familiar with the technology to understand the content of this application and implement it accordingly. They are not intended to limit the scope of protection of this application. Any modifications made based on the spirit of the main technical solution of this application shall be included in the scope of protection of this application.

Claims

1. A method for preparing a DHA molecularly imprinted polymer, characterized in that: The method comprises: A prepolymer is obtained by reacting a mixed template molecule, a functional monomer, a mediator, an initiator and a porogen; wherein the template molecule includes DHA, the functional monomer includes methacrylic acid, and the mediator includes a rare earth ion; reacting the prepolymer with a cross-linking agent to obtain a product; The product is purified and dried to obtain a DHA molecularly imprinted polymer.

2. The method for preparing a DHA molecularly imprinted polymer according to claim 1, wherein The structural formula of the DHA is:

3. The method for preparing a DHA molecularly imprinted polymer according to claim 1, wherein The molar ratio of the template molecule, the functional monomer and the initiator is 1:(2-6):(1-4).

4. The method for preparing a DHA molecularly imprinted polymer according to any one of claims 1 to 3, wherein: The initiator comprises at least one of azobisisobutyronitrile and azobisisoheptanenitrile; and / or, The mediator includes one or more of silver acetate, europium acetate, cobalt acetate, and lanthanum chloride; and / or, The porogen includes a mixture of methanol and acetonitrile or a mixture of methanol and n-butanol.

5. The method for preparing the DHA molecularly imprinted polymer according to claim 4, wherein In the mixture of methanol and acetonitrile, the volume ratio of methanol to acetonitrile is (0-5):(5-0); In the mixture of methanol and n-butanol, the volume ratio of methanol to n-butanol is (0-5):(5-0).

6. The method for preparing a DHA molecularly imprinted polymer according to claim 1, wherein The reaction of the mixed template molecule, the functional monomer, the mediator, the initiator and the porogen to obtain the prepolymer comprises: Mix the template molecule, functional monomer, mediator, initiator and porogen and then sonicate for 5-10 minutes; The mixture is allowed to stand for 30 to 60 minutes to perform a prepolymerization reaction to obtain a prepolymer.

7. The method for preparing a DHA molecularly imprinted polymer according to claim 1, wherein The cross-linking agent includes at least one of ethylene glycol dimethacrylate and triester trimethacrylate.

8. The method for preparing a DHA molecularly imprinted polymer according to claim 1, wherein The step of reacting the prepolymer with a crosslinking agent to obtain a product is carried out under heating in a water bath; The water bath heating temperature is 50-70° C., and the reaction time is 10-24 hours.

9. The method for preparing a DHA molecularly imprinted polymer according to claim 8, wherein The step of reacting the prepolymer with a cross-linking agent to obtain a product is carried out in a closed environment.

10. Use of the DHA molecularly imprinted polymer prepared by the preparation method of the DHA molecularly imprinted polymer according to any one of claims 1 to 9 in the enrichment and separation of DHA from Antarctic krill meal.

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