CN108976361B

CN108976361B - Preparation method and application of single-hole hollow boron affinity imprinted polymer

Info

Publication number: CN108976361B
Application number: CN201810420400.6A
Authority: CN
Inventors: 白雪; 潘建明; 王盼; 贾强
Original assignee: Jiangsu University
Current assignee: Hefei Jiuzhou Longteng Scientific And Technological Achievement Transformation Co ltd
Priority date: 2018-05-04
Filing date: 2018-05-04
Publication date: 2020-11-20
Anticipated expiration: 2038-05-04
Also published as: CN108976361A

Abstract

The invention relates to a preparation method and application of a single-hole hollow boron affinity imprinted polymer, in particular to a method for preparing a single-hole hollow boron affinity molecularly imprinted polymer by distillation-precipitation polymerization, belonging to the technical field of preparation of biomedical functional materials; firstly, the surface of a polystyrene ball template with a carboxyl end capping is coated by DPP through initiating polymerization by a 4-vinylphenylboronic acid monomer; in addition, in the DPP process, the generation of pores in the polymer shell is induced by the accompanied microphase separation effect and the symmetrical volume contraction of the shell material, and the single-pore hollow boron affinity imprinted polymer can be obtained by etching the porous polymer shell through THF; then sealing the single-hole hollow boron affinity imprinted polymer in a dialysis bag for selectively separating and purifying LTL; the single-hole hollow boron affinity imprinted polymer prepared by the invention overcomes the problems of low adsorption and separation kinetics, small saturation capacity, poor selectivity and the like of the conventional common molecular imprinted adsorbent to LTL.

Description

Preparation method and application of single-hole hollow boron affinity imprinted polymer

Technical Field

The invention relates to a preparation method and application of a single-hole hollow boron affinity imprinted polymer, in particular to a method for preparing a single-hole hollow boron affinity molecularly imprinted polymer by distillation-precipitation polymerization, and belongs to the technical field of preparation of biomedical functional materials.

Background

Luteolin (LTL) is a natural flavone compound, has strong antioxidant activity, and can inhibit proliferation of tumor cells, and induce tumor cell failure and even death. Peanut shell and Chinese herbal medicine of Compositae contain abundant natural luteolin. Therefore, the extraction and selective separation and purification of luteolin from natural products have important scientific and economic significance. At present, the extraction method of luteolin in peanut shells is more, and mainly comprises the steps of selecting a solvent for extraction under the assistance of ultrasonic, microwave and other means, wherein the common solvents comprise hot water, alkali liquor, methanol, ethanol, acetone, ethyl acetate and the like. The luteolin crude extract obtained after extraction has more components, is a complex system with different chemical scales, forms and multiple components coexisting, and can be applied to links such as health care products, clinical treatment and the like only by further separating, purifying and removing impurities.

The common separation and purification methods mainly comprise an acid precipitation method, a thin layer chromatography method, a column chromatography method, a gradient extraction method, a macroporous resin adsorption separation method and the like. These processes, although each having unique advantages, also have their limitations, among which the common drawbacks are poor process selectivity and low purity of the product obtained. Therefore, establishing and perfecting a new method for selectively identifying, separating and purifying luteolin in the peanut shell extracting solution, increasing the product yield and obtaining higher purity are the problems which need to be solved at present.

Molecular Imprinted Polymers (MIPs) are a new type of polymeric material with molecular recognition capability, also known as artificial antibodies. Generally, a specific functional monomer is selected or designed and synthesized according to the structure of a template molecule; assembling template molecules and functional monomers to form multiple action points, and memorizing the action through a cross-linking polymerization process; after the template molecules are removed, cavities complementary to the size, shape and functional groups of the template molecules are left in the polymer network, and the cavities can be selectively recombined with the template molecules to realize the specific recognition of the target object.

The boron affinity technology is a new method for enriching and separating cis-dihydroxy compound by using substituted boric acid, and makes the boron atom in boric acid group under the alkaline environment complex with hydroxide ion in environment so as to make the hybridization state of boron atom be from planar sp²Hybrid conversion to tetrahedral sp³Hybridization is carried out, the tetrahedral boric acid negative ions can carry out covalent reaction with ortho-dihydroxy in cis-dihydroxy molecules to generate five-membered or six-membered cyclic ester, and when the environment is changed into an acid environment, two co-esters formed by esterification of the cyclic ester compoundThe valence bond is reversibly hydrolyzed to release the cis-dihydroxy compound. In the boron affinity process, the binding of cis-dihydroxy structure is performed by tetrahedral boric acid anions. Boron affinity techniques have been used for the isolation and purification of polysaccharides, glycoproteins and the like, based on the specific recognition of dihydroxy compounds by boronic acids and the ability to release them in response to pH. However, the preparation of the single-hole hollow boron affinity imprinted polymer and the application of the single-hole hollow boron affinity imprinted polymer in the separation and purification of luteolin are not reported.

Disclosure of Invention

The invention aims to solve the problems of low adsorption and separation kinetics, small saturation capacity, poor selectivity and the like of the conventional common molecular imprinting adsorbent on LTL, adopts a distillation-precipitation polymerization (DPP) technology, coats a boron affinity imprinted polymer by taking carboxyl-terminated polystyrene as a hard template, and removes the template to obtain a single-hole hollow boron affinity imprinted polymer (H-PAVM). The invention discusses a pore forming mechanism based on microphase separation and shell material symmetric volume shrinkage; discloses the performance of selectively adsorbing and separating the luteolin.

Firstly, initiating polymerization by utilizing a 4-vinylphenylboronic acid monomer through a DPP (dipeptidyl peptidase) technology to coat the surface of a polystyrene ball template with a carboxyl end capping; in addition, during the distillation-precipitation polymerization, the generation of pores in the polymer shell is induced by the accompanied microphase separation effect and the symmetrical volume contraction of the shell material, and the single-pore hollow boron affinity imprinted polymer can be obtained by THF etching of the porous polymer shell.

In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:

the invention firstly provides a single-hole hollow boron affinity imprinted polymer, which has the advantages of 300 nm, hydrophilicity and dispersibility.

The invention also provides a synthesis method of the single-hole hollow boron-compatible imprinted polymer, namely the single-hole hollow boron-compatible LTL polymer microsphere (H-PAVM), which specifically comprises the following steps:

(1) synthesis of carboxyl terminated polystyrene (CPS) beads:

adopts two-step soap-free polymerization synthesis: firstly, adding 10 mL of acidic aqueous solution of ammonium persulfate into 50 mL of aqueous solution of styrene to initiate styrene polymerization to obtain monodisperse Polystyrene (PS) beads with the size of about 220 nm, carrying out polymerization reaction under nitrogen atmosphere, polymerizing for 3 hours at 70 ℃, and then polymerizing for 0.5 hour at 80 ℃; then, gradually adding acrylic acid, styrene and ammonium persulfate into the colloidal solution, wherein the amount of the acrylic acid is 0.3-1.5g, and further polymerizing for 3-8 hours at the temperature of 50-90 ℃; finally, carboxyl terminated polystyrene (CPS) beads with a diameter of 400 nm were obtained by centrifugation and washing with water and ethanol.

Wherein the mass ratio of the acrylic acid to the styrene to the ammonium persulfate is 20: 200: 1;

the molar ratio of the styrene to the ammonium persulfate is 1: 1.

(2) Synthesis of single-hole hollow boron affinity imprinted polymer microspheres (H-PAVM):

3-7 mL of CPS beads (7 mg/mL), 30-60 mg of acrylamide (AA), 10-20 mg of 4-vinylphenylboronic acid (VPBA), 10-30 mg of LTL, 170-. The slow prepolymerization is carried out by free radical initiation at 40-60 ℃ for 10-15 hours, followed by polymerization/crosslinking reaction at 50-80 ℃ for 20-28 hours and further aging of the product at 70-100 ℃ for 4-8 hours. Then, core-shell structure microspheres PAVM with a single pore are obtained by centrifugation and ethanol washing. Finally, the CPS core was dissolved out of the wells with tetrahydrofuran and LTL template molecules were removed with a mixed solvent of methanol/acetic acid (8: 2, v/v) to prepare single-well hollow boron affinity imprinted microspheres (H-PAVM).

For comparison, the method for preparing the single-hole hollow boron affinity non-imprinted microsphere H-PAVN is similar to that of H-PAVM except that no template molecule luteolin is added.

Compared with the prior art, the invention has the beneficial effects that:

the boron affinity technology is a special form of reversible covalent binding, and the invention utilizes the cis-diol structure of boric acid and biological molecules to form cyclic ester in an alkaline water medium, and the cyclic ester is subjected to reversible hydrolysis in an acidic medium to release the cis-diol structure. Compared with other luteolin adsorption separation materials, the boric acid polymerization adsorbent has the advantages of better selectivity and good adsorption effect; the preparation process of the material adopts a mild method, the steps are simple, the operation is convenient, the synthesized material is uniform and high in yield, and the effects of separating and enriching LTL and purifying LTL are successfully achieved.

The present invention selects 4-vinylphenylboronic acid (VPBA) as the functional monomer, which can be added to the CPS surface in one step. The size of the hollow spheres and the pores of the surface can be adjusted to some extent according to the reaction conditions. Single-pore hollow MIPs with boronate affinity were prepared by DPP and the prepared H-PAVM was then used for selective isolation and purification of LTL. The H-PAVM has the advantages of large specific surface area, high affinity of boron affinity imprinting sites, excellent binding and releasing kinetics performance, excellent capturing capacity and the like. Therefore, the H-PAVM is an ideal adsorbing material for selectively and reversibly separating the compound containing the cis-diol structure.

Drawings

FIG. 1 is a TEM image of carboxyl-terminated polystyrene microspheres (a), PAVM (b), H-PAVM (c) prepared in example 1.

FIG. 2 shows FT-IR spectra of PS and CPS (a) and PAVM and H-PAVM (b) prepared in example 1.

FIG. 3 is a hydrodynamic diameter and size distribution plot of CPS, PAVM, H-PAVM as determined by Dynamic Light Scattering (DLS) as prepared in example 1.

FIG. 4 shows EDS energy spectra of CPS (a) and H-PAVM (B) prepared in example 1, with peaks of B element of H-PAVM shown in the figure.

FIG. 5 shows XPS spectra for CPS (a) and H-PAVM (b) prepared in example 1.

FIG. 6 is a graph showing the effect of pH conditions on the adsorption capacity of H-PAVM, H-PAVN, and PAVM.

FIG. 7 is a graph showing the adsorption kinetics of H-PAVM, H-PAVN and PAVM.

FIG. 8 shows the results of the verification of the regeneration capability of the H-PAVM, H-PAVN, and PAVM.

FIG. 9 shows the results of the verification of the adsorption capacity and adsorption specificity of H-PAVM and H-PAVN.

Detailed Description

The identification performance evaluation in the embodiment of the invention is carried out according to the following method: this was done using static adsorption experiments. Respectively adding 10 mg of H-PAVM, H-PAVN and PAVM into an LTL stock solution (35 mg/L) with the initial pH of 5.5-8.5 for 12 hours, measuring the content of the adsorbed LTL by using an ultraviolet-visible spectrophotometer, and calculating the adsorption capacity according to the result; after saturated adsorption, selecting other substances with the same structure as LTL as competitive adsorbates to participate in the research of the selective recognition performance of H-PAVM, H-PAVN and PAVM; the adsorption effect of H-PAVM, H-PAVN and PAVM was investigated by adsorption amounts at several different pH values. The pH of the LTL solution was adjusted with 0.1M NaOH or HCl solution.

The invention is further illustrated by the following examples.

Example 1: synthesis of single-hole hollow LTL-imprinted polymer microspheres

Carboxyl terminated polystyrene (CPS) beads were synthesized using a two-step soap-free polymerization: first, 10 mL of an acidic aqueous solution of ammonium persulfate was added to 50 mL of an aqueous solution of styrene to initiate polymerization of styrene, resulting in monodisperse PS beads having a size of about 220 nm. The polymerization was carried out under nitrogen atmosphere, and was carried out at 70 ℃ for 3 hours and at 80 ℃ for 0.5 hour. Then, 0.9 g of acrylic acid, 9.0 g of styrene and 0.045 g of ammonium persulfate were gradually added to the above colloidal solution, and further polymerized at 70 ℃ for 5 hours. Finally, the carboxyl terminated polystyrene (CPS) beads were isolated by centrifugation and washing with water and ethanol.

5 mL of CPS microspheres (7 mg/mL), 48 mg of acrylamide (AA), 15 mg of 4-vinylphenylboronic acid (VPBA), 20 mg of LTL, 192 mg of Ethylene Glycol Dimethacrylate (EGDMA) and 8 mg of Azobisisobutyronitrile (AIBN) were dissolved in 50 mL of acetonitrile, and the reaction system was stirred during polymerization at a magnetic stirring speed of 700 rpm in order to ensure uniform dispersion of the CPS beads. In the first step, a slow prepolymerization at 43 ℃ for 12 hours was carried out by free radical initiation. Subsequently, the polymerization/crosslinking reaction was carried out at 60 ℃ for 24 hours, and the product was further aged at 85 ℃ for 6 hours. Finally, PAVM microspheres with single pores were obtained by centrifugation and ethanol washing. Single-pore hollow boron affinity imprinted polymeric microspheres (H-PAVM) were prepared by removing the PS core with tetrahydrofuran and further removing the LTL template molecule with a mixed solvent of methanol/acetic acid (8: 2, v/v).

FIG. 1a is a TEM image of the carboxyl-terminated polystyrene microspheres with a particle size of 220 nm synthesized by soap-free copolymerization in this example, the PS particles as the template are uniform and highly monodisperse, and the aqueous dispersion thereof cast on the silicon wafer forms a hexagonal lattice after drying in a room temperature environment.

FIG. 1b is a TEM image of the prepared PAVM, the core-shell microsphere sample having uniform shell thickness, diameter of 300 nm, highly smooth surface and spherical morphology confirmed by the poly (AA-co-VPBA) shell formed by selective polymerization of the monomer, rather than by irregular aggregation of the polymer on the surface of the PS beads.

FIG. 1c shows TEM images of the obtained single-pore H-PAVM microspheres after removal of the PS particles, the synthesized material is uniform and the yield is high.

FIG. 2 shows FT-IR spectra of PS and CPS (a) and PAVM and H-PAVM (b) prepared in this example. As can be seen from fig. 2a, the modified PS nanoparticles are at 1750 cm due to the stretching vibration of the C = O bond compared to the unmodified PS^-1And 1710 cm^-1With an absorption band. Next, 3419 cm of the spectrum of PAVM and H-PAVM in FIG. 2b^-1The characteristic absorption peaks in the vicinity are stretching vibrations of-OH and-NH-. Furthermore, 2948 cm in the sample of FIG. 2b^-1、2860 cm^-1And 1465 cm^-1The peak of (a) is attributed to the stretching vibration and bending vibration of C-H. At 1731 cm^-1A sharp peak was observed in the vicinity of the peak, which was C = O stretching vibration, and was attributed to the ester bond of AA. At 1618 cm^-1And 1454 cm^-1The characteristic peaks in the vicinity are respectively attributed to the N-H in-plane bending vibrationAnd C-N stretching vibrations, which can be observed in PAVM and H-PAVM spectra. Furthermore, 1371 cm in PAVM and H-PAVM^-1A new absorption peak was observed, confirming the presence of-B (OH) in the polymer chain₂Group, indicating that boronic acid groups have been successfully introduced.

FIG. 3 is a graph showing hydrodynamic diameter and size distribution of CPS (a), PAVM (b), H-PAVM (c) prepared in this example, as measured by Dynamic Light Scattering (DLS). The hydrodynamic diameter (Dh) of the CPS is about 220 nm (FIG. 3 a), which is close to the size measured by TEM. FIGS. 3b and 3c show that the hydrodynamic diameter of PAVM and H-PAVM is increased to 300 nm, demonstrating that PAVM and H-PAVM have hydrophilicity and excellent dispersion, which is beneficial for trapping LTL in aqueous samples.

FIG. 4 shows EDS energy spectra of CPS (a) and H-PAVM (B) prepared in this example, with B element peak of H-PAVM shown in the figure. The presence of elements C and O in CPS, as shown in FIG. 4a, and C, O, N and B in H-PAVM, as seen in FIG. 2B, confirms the successful preparation of boron affinity imprinted polymers.

FIG. 5 is an XPS spectrum of CPS (FIG. 5 a) and H-PAVM (FIG. 5 b) prepared in this example. In FIG. 5a, only two peaks of O1s (531.08 eV) and C1s (282.86 eV) are present in CPS. However, the presence of O1s (531.07 eV), N1s (397.72 eV), C1s (282.86 eV), and B1s (189.76 eV) was observed in H-PAVM, indicating that the phenylboronic acid moiety was successfully incorporated into the polymeric network. These results are consistent with findings in the FT-IR spectra and EDS spectra.

Example 2: synthesis of single-hole hollow LTL-imprinted polymer microspheres:

carboxyl terminated polystyrene (CPS) beads were synthesized using a two-step soap-free polymerization: styrene polymerization was initiated by first adding 10 mL of an acidic aqueous solution of ammonium persulfate to 50 mL of an aqueous solution of styrene to obtain monodisperse PS beads having a size of about 220 nm. The polymerization was carried out under nitrogen atmosphere, and was carried out at 70 ℃ for 3 hours and at 80 ℃ for 0.5 hour. Then, 1.5g of acrylic acid, 15 g of styrene and 0.075 g of ammonium persulfate were gradually added to the above colloidal solution, and further polymerized at 90 ℃ for 8 hours. Finally, the carboxyl terminated polystyrene (CPS) beads were isolated by centrifugation and washing with water and ethanol.

7 mL of CPS microspheres (7 mg/mL), 60 mg of acrylamide (AA), 20 mg of 4-vinylphenylboronic acid (VPBA), 30 mg of LTL, 210 mg of Ethylene Glycol Dimethacrylate (EGDMA) and 10 mg of Azobisisobutyronitrile (AIBN) were dissolved in 70 mL of acetonitrile, and the reaction system was stirred during polymerization at a magnetic stirring speed of 1000 rpm in order to ensure uniform dispersion of the CPS beads. In the first step, a slow prepolymerization at 60 ℃ for 15 hours was carried out by free radical initiation. Subsequently, the polymerization/crosslinking reaction was carried out at 80 ℃ for 28 hours, and the product was further aged at 100 ℃ for 8 hours. Finally, PAVM microspheres with single pores were obtained by centrifugation and ethanol washing. Single-pore hollow boron affinity imprinted polymeric microspheres (H-PAVM) were prepared by removing the PS core with tetrahydrofuran and further removing the LTL template molecule with a mixed solvent of methanol/acetic acid (8: 2, v/v).

Example 3: synthesis of single-hole hollow LTL-imprinted polymer microspheres:

carboxyl terminated polystyrene (CPS) beads were synthesized using a two-step soap-free polymerization: styrene polymerization was initiated by first adding 10 mL of an acidic aqueous solution of ammonium persulfate to 50 mL of an aqueous solution of styrene to obtain monodisperse PS beads having a size of about 220 nm. The polymerization was carried out under nitrogen atmosphere, and was carried out at 70 ℃ for 3 hours and at 80 ℃ for 0.5 hour. Then, 0.3 g of acrylic acid, 3 g of styrene and 0.015 g of ammonium persulfate were gradually added to the above colloidal solution, and further polymerized at 50 ℃ for 3 hours. Finally, the carboxyl terminated polystyrene (CPS) beads were isolated by centrifugation and washing with water and ethanol.

3 mL of CPS microspheres (7 mg/mL), 30 mg of acrylamide (AA), 10 mg of 4-vinylphenylboronic acid (VPBA), 10 mg of LTL, 170 mg of Ethylene Glycol Dimethacrylate (EGDMA) and 6 mg of Azobisisobutyronitrile (AIBN) were dissolved in 30 mL of acetonitrile, and the reaction system was stirred during polymerization at a magnetic stirring speed of 500 rpm in order to ensure uniform dispersion of the CPS beads. In the first step, a slow prepolymerization at 40 ℃ for 10 hours was carried out by free radical initiation. Subsequently, the polymerization/crosslinking reaction was carried out at 50 ℃ for 20 hours, and the product was further aged at 70 ℃ for 4 hours. Finally, PAVM microspheres with single pores were obtained by centrifugation and ethanol washing. Single-pore hollow boron affinity imprinted polymeric microspheres (H-PAVM) were prepared by removing the PS core with tetrahydrofuran and further removing the LTL template molecule with a mixed solvent of methanol/acetic acid (8: 2, v/v).

Example 4:

10 mg of H-PAVM, H-PAVN, PAVM prepared under the conditions described in example 1 were added to a series of LTL stock solutions (35 mg/L) with an initial pH of 5.5-8.5, respectively, for 24 hours. The final LTL concentration was measured by UV-visible spectrophotometer at 351 nm. The pH of the LTL solution was adjusted with 0.1M NaOH or HCl solution. The experiments were carried out simultaneously in 3 groups. The LTL trapped on the H-PAVM, H-PAVN, PAVM microspheres was then eluted with ethanol and double distilled water (5: 5, V/V; pH = 5.0), the eluent pH was adjusted from 5.5 to 8.5 by adding 0.1M HCl and 0.1M NaOH in water, and the residual concentration of LTL was investigated using a UV-visible spectrophotometer.

The results showed that the adsorption capacity of H-PAVM, H-PAVN, PAVM increased from pH =5.5 to pH =7.5, while the pH decreased from pH 7.5 to 8.5, i.e. the adsorption amount of all three of H-PAVM, H-PAVN, PAVM peaked when the LTL solution had a pH of 7.5 (the results are shown in fig. 6), and thus it was seen that the pH of 7.5 was the optimum adsorption condition.

Example 5:

in order to measure the adsorption performance of the H-PAVM microspheres to LTL, an adsorption equilibrium experiment and an adsorption kinetics experiment were studied in a mixed solvent of ethanol and double distilled water (5: 5, V/V). Based on the best adsorption results of the pH experiment obtained in example 4, the pH of the LTL solution was adjusted to 7.5. In kinetic experiments, 10 mg of H-PAVM microspheres were initially concentrated at 35 mg/LAdding into 10 mL of 35 mg mL^-1And (3) measuring the concentration of the adsorbed LTL solution in the LTL solution at certain time intervals (6.0 min, 15 min, 30 min, 60 min, 120 min, 180 min, 240 min, 360 min, 480 min and 720 min). The temperature of the mixture was maintained at 25 ℃ by means of a thermostatic water bath.

As a result, it was found that the adsorption capacity of H-PAVM rapidly increased in the first 100 min and then remained substantially unchanged, indicating that the binding of H-PAVM to LTL reached a dynamic equilibrium (the results are shown in FIG. 7). To determine the regeneration capacity, the H-PAVM after selective adsorption of LTL was regenerated in the same manner as the template was removed during synthesis of imprinted particles and then re-used for re-absorption of LTL.

In this example, the adsorption and desorption cycle process was repeated five times using H-PAVM, H-PAVN, PAVM. The results show that the H-PAVM only loses 3.3% of its adsorption capacity on average in five cycles, the adsorption capacity of the H-PAVN is reduced by 3.7%, and the average adsorption capacity of the PAVM is reduced by 7.9%, which is attributed to the hollow structure of the H-PAVM. The reason for this result is that the regeneration conditions employed were relatively mild, and the stability of the adsorption sites on the inner and outer surfaces of the H-PAVM microspheres was excellent, which also demonstrates that the H-PAVM microspheres can maintain good regeneration ability in repeated cycles (the results are shown in fig. 8).

Example 6:

selective assays were performed by comparing the amount of similar molecular structure rebinding on MIP nanospheres, selecting catechol (CTC), Trichlorophenol (TCP) and Hydroquinone (HDQ) for use as competitive adsorption species. As a result, the final adsorption capacities of the H-PAVM to the single solutions of LTL, TCP, CTC and QRT were found to be 22.01 mg/g, 2.31 mg/g, 2.33 mg/g and 2.71 mg/g, respectively. The final adsorption capacities of H-PAVN on LTL, TCP, CTC and QRT single solutions were 12.95 mg/g, 2.01 mg/g, 2.22 mg/g and 2.61 mg/g, respectively, which indicates that the selective adsorption capacity of H-PAVM on LTL is outstanding and that the selective adsorption capacity of H-PAVM on LTL is very specific (results are shown in FIG. 9).

Claims

1. A preparation method of a single-hole hollow boron affinity imprinted polymer is characterized by comprising the following steps:

(1) synthesis of carboxyl terminated polystyrene (CPS) beads:

firstly, adding an ammonium persulfate acidic aqueous solution into a styrene aqueous solution to initiate styrene polymerization to obtain monodisperse polystyrene beads; then, gradually and uniformly mixing acrylic acid, styrene and ammonium persulfate with the monodisperse polystyrene beads, and further polymerizing to obtain carboxyl-terminated polystyrene (CPS) beads;

dissolving CPS beads, acrylamide, 4-vinylphenylboronic acid, LTL, ethylene glycol dimethacrylate and azobisisobutyronitrile into acetonitrile, and magnetically stirring a reaction system in the polymerization process in order to ensure uniform dispersion of the CPS beads; slow pre-polymerization by free radical initiation followed by polymerization/cross-linking reaction, then further aging of the product; obtaining core-shell structure microspheres PAVM with single pores by centrifugation and ethanol washing; finally, dissolving and removing the CPS nucleus from the hole by tetrahydrofuran, and removing the LTL template molecule by using a methanol/acetic acid mixed solvent to prepare a single-hole hollow boron affinity imprinted microsphere (H-PAVM);

the CPS beads, acrylamide, 4-vinylphenylboronic acid, LTL, ethylene glycol dimethacrylate, azobisisobutyronitrile and acetonitrile were used in amounts of 3-7 mL, 30-60 mg, 10-20 mg, 10-30 mg, 170-210 mg, 6-10 mg and 30-70 mL, respectively.

2. The preparation method of the single-hole hollow boron affinity imprinted polymer according to claim 1, wherein the volume ratio of the styrene aqueous solution to the ammonium persulfate acidic aqueous solution in the step (1) is 5: 1; the polymerization was carried out under nitrogen atmosphere, first at 70 ℃ for 3 hours and then at 80 ℃ for 0.5 hour.

3. The preparation method of the single-hole hollow boron affinity imprinted polymer according to claim 1, wherein the mass ratio of the acrylic acid to the styrene to the ammonium persulfate in the step (1) is as follows: 20: 200: 1; the further polymerization is carried out for 3 to 8 hours at the temperature of between 50 and 90 ℃.

4. The method for preparing a single-hole hollow boron affinity imprinted polymer according to claim 3, wherein the amount of acrylic acid used in step (1) is 0.3 to 1.5 g.

5. The method for preparing the single-hole hollow boron affinity imprinted polymer according to claim 1, wherein the pre-polymerization in the step (2) is slow pre-polymerization at 40-60 ℃ for 10-15 hours.

6. The method for preparing a single-hole hollow boron affinity imprinted polymer according to claim 1, wherein the polymerization/crosslinking reaction in the step (2) is performed at 50-80 ℃ for 20-28 hours.

7. The method for preparing the single-hole hollow boron affinity imprinted polymer according to claim 1, wherein the product is aged at 70-100 ℃ for 4-8 hours in the step (2).

8. The preparation method of any one of claims 1-7, wherein the polymer is 300 nm, and has hydrophilicity and dispersibility.

9. The use of the single-hole hollow boron affinity imprinted polymer of claim 8 for selective adsorption separation of luteolin.