Molecularly imprinted composite core-shell adsorption material as well as preparation method and application thereof

Abstract

The invention relates to a molecularly imprinted composite core-shell adsorption material as well as a preparation method and application thereof.The molecularly imprinted composite core-shell adsorption material takes a covalent organic framework material as a core and takes sterigmatocystin as a template molecule to synthesize a molecularly imprinted polymer shell; the prepared molecularly imprinted composite core-shell adsorption material is uniform in spherical morphology, is beneficial to batch synthesis, is better in reproducibility, and has excellent chemical stability and high specific selectivity; the prepared molecularly imprinted composite core-shell adsorption material has specific sterigmatocystin imprinting holes, and high-specificity and high-sensitivity adsorption and enrichment of sterigmatocystin can be realized.

Description

Technical Field

[0001] The invention belongs to the field of new materials, and in particular relates to a molecular imprinting composite core-shell adsorption material and a preparation method and application thereof. Background Art

[0002] For decades, biotoxins have increasingly become a focus of food safety and environmental health concerns due to their easy and widespread spread and "low-dose but high toxicity" characteristics. According to the Centers for Disease Control and Prevention (CDC), 4.5 billion people in developing countries may be exposed to aflatoxins in their daily diet for a long time. The Food and Agriculture Organization of the United Nations (FAO) estimates that 25% of the world's crops are contaminated by mycotoxins during growth or storage. Due to their lipophilicity and potential for bioaccumulation, these biotoxins are highly toxic, and there is an urgent need to develop effective enrichment and quantification methods.

[0003] Nanoporous materials usually form a periodically arranged network framework crystalline structure through bonding, combining the advantages of inorganic and organic materials, with the advantages of designable structural types, adjustable chemical versatility, low density, permanent pores, ultra-high specific surface area, etc., and have broad application prospects in the field of adsorption and enrichment of biological toxins. Molecularly imprinted polymers are a type of polymer biomimetic material with strong molecular recognition ability, with the advantages of simple preparation, designability, excellent selectivity, low preparation cost and good stability, etc., and can be used as selective adsorption materials to separate and enrich target substances from complex matrices. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a molecular imprinting composite core-shell adsorption material and a preparation method and application thereof.

[0005] The technical scheme adopted by the present invention is: a method for preparing a molecularly imprinted composite core-shell adsorption material, which uses a surface imprinting method, takes a covalent organic framework material as a core, and uses a stericidal toxin as a template molecule to synthesize a molecularly imprinted polymer shell to obtain a molecularly imprinted composite core-shell adsorption material.

[0006] Preferably, the specific steps are as follows:

[0007] Step 1: Dissolve 1,3,5-tri(4-aminophenyl)benzene and 2,5-divinyl-1,4-benzenedicarbaldehyde in acetonitrile, mix well, add acetic acid and mix well, and the product obtained by reaction at room temperature is COF;

[0008] Step 2: Add 1,8-dihydroxyanthraquinone to a mixed solution of acetonitrile and water, stir until completely dissolved, add functional monomers, crosslinking agents and ammonia water to the system, and the ratio of functional monomers, crosslinking agents and ammonia water is 1:4:10; after mixing evenly, add the acetonitrile solution of COF prepared in step 1, remove oxygen from the entire reaction system, and stir the reaction overnight; the resulting precipitate is the molecular imprinting composite core-shell adsorption material.

[0009] Preferably, in step 1,3,5-tris(4-aminophenyl)benzene is used in an amount of 70.2 mg, 2,5-divinyl-1,4-benzenedicarbaldehyde is used in an amount of 40.2 mg, the volume of acetonitrile is 25 mL, and the volume of acetic acid is 3.5 mL.

[0010] Preferably, in step 2, the functional monomer is a silane coupling agent, the cross-linking agent is tetraethoxysilane; the ratio of the silane coupling agent, tetraethoxysilane and ammonia water is 1:4:10; and the mass of COF is 100 mg.

[0011] Preferably, the volume ratio of acetonitrile and water in the mixed solution is 5:1.

[0012] The molecularly imprinted composite core-shell adsorption material is prepared by the method for preparing the molecularly imprinted composite core-shell adsorption material.

[0013] Application of molecular imprinted composite core-shell adsorbent materials in the adsorption or enrichment of Aspergillus sterigmatotoxin.

[0014] Preferably, it is used for the selective adsorption and efficient enrichment of Aspergillus toxin in food samples or environmental sample pollutants.

[0015] The advantages and positive effects of the present invention are as follows: the prepared molecularly imprinted composite core-shell adsorption material has a uniform spherical morphology, is conducive to batch synthesis and has better reproducibility, and has excellent chemical stability and high specific selectivity. The molecularly imprinted composite core-shell adsorption material is prepared by the reaction ratio and conditions in the method, and the molecularly imprinted composite core-shell adsorption material obtained by the reaction has the best adsorption performance;

[0016] Molecularly imprinted composite core-shell adsorbents can achieve efficient adsorption and enrichment of food hazardous substances, opening up a new way for the detection of food hazardous substances; the acquisition of molecularly imprinted composite core-shell adsorbents can expand innovative and advanced food safety and nutrition analysis methods and research concepts, and has important leading significance for further strict monitoring and control of hazardous substances in food and promoting the application of analytical chemistry methodology based on advanced functional materials in food safety and human health science. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a scanning electron micrograph of the molecularly imprinted composite core-shell adsorption material;

[0018] Figure 2 This is a transmission electron microscopy image of the molecularly imprinted composite core-shell adsorption material;

[0019] Figure 3 To characterize the stability of molecularly imprinted composite core-shell adsorption materials;

[0020] Figure 4 To study the specificity of molecularly imprinted composite core-shell adsorption materials;

[0021] Figure 5 This paper studies the adsorption kinetics and adsorption equilibrium of spherical covalent organic framework materials. DETAILED DESCRIPTION

[0022] The embodiments of the present invention are described below with reference to the accompanying drawings.

[0023] The present invention relates to a molecular imprinting composite core-shell adsorption material, a preparation method and an application thereof. The molecular imprinting composite core-shell adsorption material uses a covalent organic framework material as a core, uses sterigmatocystin as a template molecule, and synthesizes a molecular imprinting polymer shell. The prepared molecular imprinting composite core-shell adsorption material has specific sterigmatocystin imprinting pores, can achieve high specificity and high sensitivity adsorption and enrichment of sterigmatocystin, provides a prospective method for the pretreatment and determination of trace harmful substances in complex sample matrices, and can be used for the selective adsorption and efficient enrichment of sterigmatocystin in food and environmental pollutants.

[0024] Molecular imprinting technology is a technology developed to mimic the recognition mechanism of antibodies and antigens through specific recognition of target molecules. The synthesized polymers have the characteristics of low cost, high adsorption efficiency, high affinity and specificity, and reusability, and are widely studied by scholars in different fields. Covalent organic frameworks are connected to organic monomers through strong covalent bonds. Their interesting properties such as diverse main chain structures, ultra-high specific surface area, low crystal density and adjustable pore size make them ideal for various applications such as catalysis, sensing, adsorption and chromatographic separation. Therefore, this method intends to combine the two to form a multifunctional sample pretreatment platform that has the excellent performance of both, making up for the current lack of biotoxin enrichment, and is also crucial for the application of advanced functional materials in the field of environmental protection.

[0025] When preparing the molecularly imprinted composite core-shell adsorption material, a spherical covalent organic framework material with strong adsorption and large specific surface area is first prepared by a one-pot reaction at room temperature, and then a molecularly imprinted polymer shell is synthesized by a surface imprinting method with the covalent organic framework material as the core and Aspergillus sterigmatocystis as the template molecule; the specific preparation method is as follows:

[0026] Step 1: Dissolve 1,3,5-tri(4-aminophenyl)benzene and 2,5-divinyl-1,4-benzenedicarbaldehyde in acetonitrile, sonicate for 1 minute, add acetic acid and vortex vigorously until mixed evenly, place in a centrifuge tube for reaction at room temperature for 72 hours, wash the obtained product three times with ethanol / water, dry in a vacuum oven at 60°C for 12 hours, and collect the yellow powder product, which is COF;

[0027] Step 2: Add 1 mmol of 1,8-dihydroxyanthraquinone to a mixed solution of 25 mL of acetonitrile and 5 mL of water, and stir with a magnetic stirrer until completely dissolved, add functional monomer (silane coupling agent), crosslinking agent (tetraethoxysilane) and ammonia water to the system, and the ratio of functional monomer (silane coupling agent), crosslinking agent (tetraethoxysilane) and ammonia water is 1:4:10; after mixing evenly, add 3 mL of COF acetonitrile solution, continuously pass nitrogen through the entire reaction system for 15 minutes to remove oxygen, seal the flask and stir the reaction at room temperature overnight; the obtained precipitate is washed 3 times with methanol and water, and then eluted with a Soxhlet extraction apparatus, the eluent is composed of acetone and acetic acid (9:1, v / v), and the eluted product is the molecular imprinting composite core-shell adsorption material.

[0028] The prepared molecular imprinting composite core-shell adsorption material has uniform morphology, can selectively adsorb Aspergillus toxin, has strong specificity and high sensitivity, and provides a promising sample pretreatment material for food safety analysis. In view of the problem that the matrix of biological toxin samples is complex and the content is extremely low, the traditional analysis method developed is mainly based on chromatography / mass spectrometry methods assisted by sample pretreatment, including liquid-liquid extraction, microwave-assisted extraction, immunoaffinity extraction, solid phase extraction, magnetic solid phase extraction, etc. These sample pretreatment technologies have their own advantages, but the adsorption specificity of the target is weak, the purification effect is not ideal, and the matrix effect is strong, which affects the accuracy and sensitivity of the analysis and detection results. The molecular imprinting composite core-shell adsorption material prepared by the present invention has the advantages of good chemical stability and strong specificity, and can achieve efficient enrichment and convenient control of target pollutants.

[0029] The scheme of the present invention is described below in conjunction with the accompanying drawings, wherein the experimental methods without specific operating steps are all carried out in accordance with the corresponding product instructions, and the instruments, reagents, and consumables used in the examples can all be purchased from commercial companies unless otherwise specified.

[0030] Example 1: Preparation of molecularly imprinted composite core-shell adsorption material

[0031] A spherical covalent organic framework material with strong adsorption and large specific surface area was prepared by a one-pot reaction at room temperature. 70.2 mg of 1,3,5-tris(4-aminophenyl)benzene and 40.2 mg of 2,5-divinyl-1,4-benzenedicarbaldehyde were dissolved in 25 mL of acetonitrile, ultrasonicated for 1 minute, 3.5 mL of acetic acid was added and vortexed vigorously until the mixture was uniform, and then placed in a centrifuge tube for reaction at room temperature for 72 hours. The obtained product was washed three times with ethanol / water, dried at 60°C in a vacuum drying oven for 12 hours, and the yellow powder product was collected as COF.

[0032] Then, the molecular imprinting polymer shell was synthesized by surface imprinting method with covalent organic framework material as the core and adenomatous toxin as the template molecule. 1mmol 1,8-dihydroxyanthraquinone was added to a mixed solution of 25mL acetonitrile and 5mL water and stirred with a magnetic stirrer until completely dissolved. Next, 468μL functional monomer (silane coupling agent), 1120.05μL cross-linking agent (tetraethoxysilane) and 333μL ammonia water were added to the system. After mixing evenly, 3mL COF (100mg) acetonitrile solution was added. Subsequently, nitrogen was continuously passed through the entire reaction system for 15min to remove oxygen. Finally, the flask was sealed and stirred at room temperature overnight. The resulting precipitate was washed three times with methanol and water, and then eluted with a Soxhlet extraction apparatus, and the eluent consisted of acetone and acetic acid (9:1, v / v); the eluted product was the molecularly imprinted composite core-shell adsorption material COF@MIP.

[0033] The prepared molecular imprinted composite core-shell adsorption material was photographed by scanning electron microscope and transmission electron microscope to observe its structure. Figure 1 and Figure 2 As shown. Figure 1 Scanning electron microscopy images show that the prepared adsorption material has a uniform morphology. Figure 2 It can be seen from the transmission electron microscopy image that the particle size of the prepared molecularly imprinted composite core-shell structure is about 700nm.

[0034] The prepared molecular imprinted composite core-shell adsorption material was tested for stability. An appropriate amount of the composite material to be tested was weighed and placed in the sample tank. After compaction, it was placed in the instrument to detect the change in sample mass during the heating process. The scanning temperature range was 25-550°C. The test results were as follows: Figure 3 As shown, it proves its good stability.

[0035] Example 2: Enrichment and adsorption of Aspergillus sterigmatotoxin by molecularly imprinted composite core-shell adsorption materials

[0036] When used, it can be combined with high performance liquid chromatography analysis to achieve selective adsorption and efficient enrichment of aspergillus toxin in food and environmental pollutants. Take 10mg of the prepared molecular imprinting composite core-shell adsorption material, add 5mL of standard solutions of different biological toxins, and prepare samples containing AFG1, AFB1, AFG2, AFB2, ST, DT, DON and ZEN in this embodiment, and ultrasonicate until uniformly dispersed. After incubation in a shaking table for 60 minutes, the supernatant is collected by centrifugation. After the supernatant is blown to dryness with nitrogen, acetonitrile is added for redissolution, and after passing through the membrane, it can be detected in combination with HPLC, where COF@MIP is a prepared molecular imprinting composite core-shell adsorption material, and COF@NIP is a polymer prepared under the same conditions, but without the addition of template molecules.

[0037] The results are as follows Figure 4-5 As shown, Figure 4 This study on the adsorption specificity of spherical covalent organic framework materials showed that the prepared molecularly imprinted composite core-shell adsorption material has selective adsorption for Aspergillus sterigmatotoxin. Figure 5 The adsorption kinetics and adsorption equilibrium studies of spherical covalent organic framework materials showed that the prepared molecularly imprinted composite core-shell adsorption material has efficient adsorption performance for Aspergillus sterigmatotoxin.

[0038] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a molecularly imprinted composite core-shell adsorption material, characterized in that: Through the surface imprinting method, the covalent organic framework material is used as the core and the adenomatous toxin is used as the template molecule to synthesize the molecularly imprinted polymer shell to obtain the molecularly imprinted composite core-shell adsorption material.

2. The method for preparing the molecularly imprinted composite core-shell adsorption material according to claim 1, characterized in that: The specific steps are as follows: Step 1: Dissolve 1,3,5-tri(4-aminophenyl)benzene and 2,5-divinyl-1,4-benzenedicarbaldehyde in acetonitrile, mix well, add acetic acid and mix well, and the product obtained by reaction at room temperature is COF; Step 2: Add 1,8-dihydroxyanthraquinone to a mixed solution of acetonitrile and water, stir until completely dissolved, add functional monomers, crosslinking agents and ammonia water to the system, and the ratio of functional monomers, crosslinking agents and ammonia water is 1:4:10; after mixing evenly, add the acetonitrile solution of COF prepared in step 1, remove oxygen from the entire reaction system, and stir the reaction overnight; the resulting precipitate is the molecular imprinting composite core-shell adsorption material.

3. The method for preparing the molecularly imprinted composite core-shell adsorption material according to claim 2, characterized in that: In step 1, the molar ratio of 1,3,5-tris(4-aminophenyl)benzene to 2,5-divinyl-1,4-benzenedicarbaldehyde is 1:1, the concentration is preferably 8 mol / L, the volume of acetonitrile is 25 mL, and the volume of acetic acid is 3.5 mL.

4. The method for preparing the molecularly imprinted composite core-shell adsorption material according to claim 2, characterized in that: In step 2, the functional monomer is a silane coupling agent, and the cross-linking agent is tetraethoxysilane; the ratio of the silane coupling agent, tetraethoxysilane and ammonia water is 1:4:10; and the amount of COF added is 3 mg / mL.

5. The method for preparing the molecularly imprinted composite core-shell adsorption material according to claim 4, characterized in that: The volume ratio of acetonitrile and water in the mixed solution is 5:

1.

6. The molecularly imprinted composite core-shell adsorption material prepared by the method for preparing the molecularly imprinted composite core-shell adsorption material according to any one of claims 1 to 5.

7. Use of the molecularly imprinted composite core-shell adsorption material according to claim 6 in the adsorption or enrichment of Aspergillus sterigmatotoxin.

8. The use according to claim 7, characterized in that: Used for the selective adsorption and efficient enrichment of Aspergillus toxin in food samples or environmental sample pollutants.

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