A method for preparing a bowl-shaped imprinted polymer adsorbent by asymmetric action-induced silicon-based imprinting droplets and application thereof

Abstract

The application belongs to the technical field of molecular recognition adsorption separation functional material preparation, and discloses a method for preparing a bowl-shaped imprint polymer adsorbent by asymmetric action induced silicon-based imprint droplets and application thereof. The application uses 9-vinyladenine 9-VA as a functional monomer, beta-thymidine as a functional monomer, and forms silicon-based imprint droplets after pre-assembly and hydrolysis of 3-(trimethoxysilyl) methyl propyl methacrylate. Subsequently, ellipsoidal iron oxide particles are synthesized, and the surface of the ellipsoidal iron oxide particles is modified by using PVP as a seed, and the silicon-based imprint droplets are polymerized under the condition of magnetic stirring. Due to the centrifugal force, the mass of the iron oxide particles is much larger than that of the polymer droplets, and the iron oxide particles will drag the polymer droplets to deform and form a larger depression under the action of the asymmetric force. AIBN is added to initiate polymerization and solidification, and the composite bowl-shaped imprint polymer particles containing the iron oxide particles are prepared, which are used for realizing high-selectivity adsorption and separation of dT.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of preparation of molecular recognition adsorption separation functional materials, and particularly relates to a bowl-shaped imprint polymer particle adsorbent synthesized by one-step method of asymmetric force induced silicon-based imprinting droplets and separation application thereof. BACKGROUND

[0002] Molecular imprinting polymers (MIPs) are specific adsorbents prepared by simulating antigen-antibody action, also known as "artificial antibodies". By polymerization of functional monomers and cross-linking agents in the presence of template molecules, specific binding cavities complementary to templates in function, size and shape are prepared. The performance of molecular imprinting polymers is affected by many factors in the preparation process. In addition to the selection of template molecules and functional monomers, the cross-linking agent also plays an important role. The cross-linking agent is used to solidify the space around the template molecule and the functional monomer, forming a highly cross-linked polymer network, and after the template molecule is removed, it can still effectively retain the recognition ability for the template molecule. This requires the selected cross-linking agent to have good chemical stability, as well as moderate rigidity and flexibility. At the same time, the amount of cross-linking agent directly affects the cross-linking degree of the molecular imprinting polymer, and then affects the binding force and selectivity of the polymer to the template molecule. When the cross-linking degree is too low, the polymer network formed will be relatively loose, resulting in poor stability of the imprinting site, which is easy to be damaged in the removal process of the template molecule. But when the cross-linking degree is too high, the formed polymer will have too high rigidity and hydrophobicity, thereby hindering the binding of the template molecule to the imprinting site.

[0003] In recent years, with the increasing variety of silane coupling agents, silicon-based imprinting materials have developed rapidly. Sol-gel method is to hydrolyze and condense silane alkoxyl group (Si(OR)n, R = alkyl, such as Me, Et, Pr, etc.) as a molecular precursor, forming an inorganic network based on silica. Compared with flexible polymers, silica has a highly cross-linked rigid structure, has the potential for high shape selectivity, and can form fine imprinting sites. Silica expands very little in the presence of solvents and has excellent thermal stability. These characteristics also enable it to maintain the shape and size of the imprinting cavity. However, SiO2 particles are often solid spherical particles, resulting in fewer molecular imprinting sites. Therefore, the preparation of carrier materials with large specific surface area is crucial to improve the imprinting effect.

[0004] Based on the unique sol-gel process, many studies have shown that the shape of silica can be greatly controlled in the sol stage. There are many methods for the synthesis of materials with different morphologies by sol-gel method, including hydrothermal method, micellar assembly method, phase separation method and the like. However, most of these methods involve complex preparation process and harsh reaction conditions, for example, the use of toxic solvents or strong acids, which will affect or destroy the imprint assembly process. Therefore, it is urgent to develop a simple and mild means to regulate the morphology of silicon-based imprint. The asymmetric action induces the deformation of droplets, which is common in nature, for example, in the process of water droplet falling, the asymmetric gravity and frictional resistance will shape the water droplet into streamline to reduce air resistance. Similarly, when blowing bubbles, the soap film will also be deformed under the action of single direction force. Inspired by this, the present application designs a simple, mild and fast means to construct bowl-shaped imprint composite nanoparticles. SUMMARY

[0005] The present application takes 9-vinyladenine (9-VA) as a functional monomer and beta-thymidine (dT) as a template molecule, and forms a silicon-based imprint droplet after pre-assembly and hydrolysis of 3-(trimethoxysilyl) methyl propyl methacrylate. Then ellipsoidal iron oxide particles are synthesized, and after modification of the surface of the particles using PVP, the particles are used as seeds to polymerize with the hydrolyzed silicon-based imprint droplets under magnetic stirring. Due to the effect of centrifugal force, the mass of the iron oxide particles is much greater than that of the polymer droplets, and under the action of asymmetric force, the iron oxide particles will drag the polymer droplets to deform and form a larger depression. After adding AIBN to initiate polymerization and solidification, composite bowl-shaped imprint polymer particles containing iron oxide particles are prepared, which are used to realize high selective adsorption and separation of dT.

[0006] To achieve the above technical purpose, the technical scheme adopted by the present application is:

[0007] The present application provides a method for preparing bowl-shaped imprint polymer adsorbent by asymmetrically inducing silicon-based imprint droplets, and evaluates the performance of MIP-Fe2O3-MPS adsorbent in selectively adsorbing and separating dT molecules by using dT simulation solution. The method comprises the following steps:

[0008] (1) Preparation of ellipsoidal iron oxide particles (alpha-Fe2O3)

[0009] First, a sodium hydroxide solution is prepared, and under strong magnetic stirring, it is slowly dropped into anhydrous ferric chloride solution. After mixing uniformly, potassium sulfate solution is added. After stirring uniformly, it is moved to an oven, and after a period of reaction, it is taken out, washed with acetone and water, centrifuged and collected, and dried in a vacuum drying box to obtain alpha-Fe2O3.

[0010] (2) Preparation of PVP-modified alpha-Fe2O3 particles

[0011] α-Fe2O3 was ultrasonically dispersed in deionized water, and then polyvinylpyrrolidone PVP was added to the dispersion, and the PVP was fully dissolved and uniformly coated on the surface of the iron oxide particles by fully stirring, and the α-Fe2O3 / PVP particles were dried to obtain α-Fe2O3 / PVP particles for standby use.

[0012] (3) Preparation of a hydrolysis solution of 3-(trimethoxysilyl) methyl propyl methacrylate (MPS)

[0013] Deionized water was placed in a beaker, and N2 was introduced after adding MPS, and stirring was performed at a certain speed until the mixed solution was transparent and uniform, to obtain a hydrolysis solution of MPS for standby use.

[0014] (4) Preparation of a pre-assembly solution of a template molecule and a functional monomer

[0015] An appropriate amount of a functional monomer 9-vinyladenine (9-VA) and a template molecule β-thymidine (dT) were weighed and dissolved in deionized water, and the pre-assembly solution was obtained after assembly under the conditions of room temperature and light shielding for standby use.

[0016] (5) Preparation of a bowl-shaped imprinted polymer composite particle (MIP-Fe2O3-MPS)

[0017] The hydrolysis solution of MPS and the α-Fe2O3 / PVP particles were mixed, and after stirring at a certain speed, an ammonia solution was added, and after reaction at room temperature, the pre-assembly solution prepared in step (4) was added, and stirring was continued to fully mix; finally, azobisisobutyronitrile (AIBN) was added, and the mixture was placed in an oven for reaction, and after the reaction was completed, the particles were subjected to fractional centrifugal cleaning to remove the secondary nucleation particles. The product after centrifugation was washed with an HCl eluent to remove the template molecule, until no dT was detected in the eluent by a UV-visible spectrophotometer; finally, the purified MIP-Fe2O3-MPS was placed in a vacuum drying oven for drying.

[0018] Similarly, a bowl-shaped non-imprinted polymer composite particle (NIP-Fe2O3-MPS) was synthesized in parallel without adding dT.

[0019] In step (1), the amount ratio of the sodium hydroxide solution, the anhydrous ferric chloride solution and the potassium sulfate solution was (5-15) mL:(5-15) mL:1 mL; wherein the concentration of the sodium hydroxide solution was 5M, the concentration of the anhydrous ferric chloride solution was 2M, and the concentration of the potassium sulfate solution was 0.2M; the reaction temperature was 100°C, and the reaction time was 4-8 days.

[0020] In step (2), the amount ratio of the α-Fe2O3 ellipsoidal particles and PVP was 1 mg:(0.8-1.2) mg; wherein the molecular weight of PVP was K30.

[0021] In step (3), the ratio of the MPS and deionized water is 1 mL : (15-25) mL; the nitrogen gas is introduced for 30 min; and the stirring speed is 600 rpm.

[0022] In step (4), the ratio of the dT, 9-VA and deionized water is 1 mmol : (0.9-1.2) mmol : (40-60) mL. The nitrogen gas is introduced for 30 min, and the assembly is performed at room temperature for 12 h in the dark.

[0023] In step (5), the ratio of the α-Fe2O3 / PVP particles, the MPS hydrolysis solution, the pre-assembly solution, AIBN and the ammonia solution is (5-15) mg : (5-15) mL : (8-12) mL : (15-25) mg : 1 mL; and the concentration of the ammonia solution is 37% wt.

[0024] In step (5), the stirring speed is 400-1200 rpm.

[0025] In step (5), the reaction is performed at room temperature for 30-40 min, or in an oven at 80°C for 12 h.

[0026] In step (5), the speed of the fractional centrifugal washing is 1000-5000 rpm; and the pH of the HCl eluent is 3.0.

[0027] The MIP-Fe2O3-MPS adsorbent prepared in the application is used for selective adsorption and separation of dT.

[0028] Compared with the prior art, the application has the following beneficial effects:

[0029] By virtue of the particularity of the sol-gel method, the silicon-based imprint droplets are constructed in the sol stage to ensure stable assembly of the template molecules and the functional monomers, and the density difference between the iron oxide particles and the silicon-based imprint droplets is used to construct an asymmetric action to induce the silicon-based imprint droplets to deform, so that a mild, simple and fast means is provided to construct the bowl-shaped imprint composite nanoparticles. On the one hand, the complex reaction process and the influence and damage of the stimulating reagents on the imprint assembly are avoided, so that the integrity of the imprint sites is ensured. On the other hand, the simple synthesis steps facilitate further optimization of the influence of the crosslinking density on the selectivity, so that high-selective adsorption and separation of dT are realized. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1SEM image of the bowl-shaped imprinted polymer composite particles prepared in Example 1 at 30 min growth time (a5); for comparison, the morphologies at growth time of (a1) 0 min; (a2) 5 min; (a3) 15 min; (a4) 25 min.

[0031] Figure 2 TEM image of MIP-Fe2O3-MPS prepared in Example 1.

[0032] Figure 3 SEM images and contact angles of the bowl-shaped imprinted polymer composite particles MIP-Fe2O3-MPS prepared in Example 1 after modification of iron oxide with PVP K30 (b1 and b2), and for comparison, SEM images and contact angles of polymers prepared with other molecular weight of PVP K17 (a1 and a2), PVP K90 (c1 and c2) and PVA 403 (d1 and d2).

[0033] Figure 4 Infrared spectra of MIP-Fe2O3-MPS prepared in Test Example 2 with different amount of 9-VA.

[0034] Figure 5 Single component adsorption results of MIP-Fe2O3-MPS and NIP-Fe2O3-MPS prepared in Example 1 for dT, AMP, dA, dC, dG and 5-FC.

[0035] Figure 6 Adsorption capacity and imprinting factor of MIP-Fe2O3-MPS and NIP-Fe2O3-MPS prepared in Test Example 2 as a function of 9-VA amount.

[0036] Figure 7 Regeneration ability analysis of MIP-Fe2O3-MPS and NIP-Fe2O3-MPS by seven consecutive adsorption / desorption cycles in Test Example 3. DETAILED DESCRIPTION

[0037] In order to make the skilled in the art understand the technical solutions of the present application better, the technical solutions of the present application are further described below in combination with specific examples and drawings.

[0038] The performance evaluation in the specific implementation of the present application is carried out according to the following method:

[0039] A certain amount of adsorbent is added to 2 mL of PBS solution with a certain initial concentration of β-thymidine (dT) (pH = 7.4). After the adsorbent is in contact with the test solution for 12 h, the dT solution is removed from the membrane to remove the suspended adsorbent. The concentration of dT in the filtrate is detected by ultraviolet visible spectrophotometry (UV-vis), and the equilibrium adsorption capacity at the corresponding concentration is calculated according to the detection result; a certain amount of adsorbent is added to 2 mL of dT solution with an initial concentration of 300 μmol / L, which is taken out at a certain time gradient, and the adsorption capacity is calculated according to the UV-vis detection result, which is used to study the kinetic performance of the MIP-Fe2O3-MPS adsorbent. In order to test the selective performance of the adsorbent in extracting dT, several nucleoside compounds with similar structures and properties are selected, such as 2-deoxyadenosine (dA), 2-deoxyguanosine (dG), 2-deoxycytidine (dC), 5-fluorocytidine (5-FC) and adenosine monophosphate (APM) as selective adsorbents to study the recognition performance of the adsorbent.

[0040] In order to verify that the adsorbent can still maintain good dT selectivity in complex matrix samples, river water is used as an actual sample for analysis. The actual sample and the spiked sample are prepared in phosphate buffer, and a certain amount of adsorbent is added to 2.0 mL of the actual sample and the spiked sample. After adsorption for 2.0 h, the concentrations of the samples in the filtrate are determined by HPLC, and the adsorption capacity is calculated according to the determination results, which is used to study the selective recognition and separation ability of MIP-Fe2O3-MPS in complex actual samples.

[0041] The application will be further described below in conjunction with specific implementation examples.

[0042] Example 1:

[0043] (1) Preparation of ellipsoidal iron oxide particles (α-Fe2O3)

[0044] First, 100 mL of 5M sodium hydroxide solution is prepared, and under strong magnetic stirring, it is slowly dropped into 100 mL of 2M anhydrous ferric chloride solution. After mixing evenly, 10 mL of 0.2M potassium sulfate solution is added. After stirring evenly, it is moved to a 100℃ oven, and after 7 days of reaction, it is taken out, washed with acetone and water, centrifuged and dried in a vacuum drying box.

[0045] (2) Preparation of PVP modified α-Fe2O3 particles

[0046] 100 mg of oven-dried α-Fe2O3 ellipsoidal particles are weighed into a 20 mL glass bottle, 10 mL of deionized water is added, and after ultrasonic dispersion, 100 mg of polyvinylpyrrolidone PVP (K30) is added. Stir well to make it evenly cover the surface of the iron oxide particles, dry to obtain α-Fe2O3 / PVP particles, and reserve for use.

[0047] (3) Preparation of 3-(trimethoxysilyl)propyl methacrylate (MPS) hydrolysis solution

[0048] 60 mL of deionized water was measured into a beaker, and 3 mL of MPS solution was added after N2 was bubbled for 30 min. The stirring speed was kept at 600 rpm until the mixture was dissolved and became transparent and uniform. The MPS hydrolysis solution was obtained and ready for use.

[0049] (4) Preparation of pre-assembly solution of template molecule and functional monomer

[0050] 0.2 mmol of functional monomer 9-vinyladenine (9-VA) and 0.2 mmol of template molecule β-thymidine (dT) were weighed and dissolved in 10 mL of deionized water. After N2 was bubbled for 30 min, the assembly was carried out at room temperature for 12 h in the dark.

[0051] (5) Preparation of bowl-shaped imprinted polymer composite particles MIP-Fe2O3-MPS

[0052] 10 mL of MPS hydrolysis solution was taken into a 100 mL flask, and 10 mg of α-Fe2O3 / PVP particles were added. After stirring at a speed of 1000 rpm until the mixture was uniformly mixed, 1 mL of ammonia solution (NH3, 37% wt) was added dropwise. The reaction was carried out at room temperature for 30 min at a certain stirring speed, and then 10 mL of pre-assembly solution was added and stirred for another 30 min. Finally, 20 mg of azobisisobutyronitrile (AIBN) was added, and the mixture was placed in an oven at 80°C for 12 h. After the reaction was completed, the particles were fractionally cleaned to remove the secondary nucleated particles. The product after centrifugation was eluted with pH = 3.0 HCl to remove the template molecule, until no dT was detected in the eluate by ultraviolet-visible spectrophotometry. Finally, the purified MIP-Fe2O3-MPS was placed in a vacuum drying oven for drying.

[0053] Similarly, bowl-shaped non-imprinted polymer composite particles NIP-Fe2O3-MPS were synthesized in parallel without the addition of dT.

[0054] Figure 1Figure 5 is a SEM image of the bowl-shaped imprinting polymer composite nanoparticles MIP-Fe203-MPS prepared in Example 1, and the growth of the composite nanoparticles at different growth times is also compared: (a1) 0 min; (a2) 5 min; (a3) 15 min; (a4) 25 min. The droplets of silane are first spherical particles with a particle size of about 200 nm in the absence of contact between the droplets and the iron oxide particles, and as the silane condensation reaction proceeds, the droplets of silane on the surface of the iron oxide particles gradually grow larger and begin to grow asymmetrically under the action of asymmetric force. After 15 min, the droplets of silane on one side of the iron oxide particles are pulled by the asymmetric force and form a cavity, and as the asymmetric force continues to act, the cavity gradually grows away from the iron oxide particles, and ultimately a bowl-shaped composite nanoparticle with a single opening is obtained after 30 min.

[0055] Figure 2 Figure 6 is a TEM image of the MIP-Fe203-MPS prepared in Example 1, which also confirms the bowl-shaped structure of the material.

[0056] Figure 3 Figure 7 is a SEM image and contact angle of the composite nanoparticles prepared in Example 1 after modification of the iron oxide using PVP K30, and SEM images and contact angles of the composite nanoparticles prepared after modification of the iron oxide using K17, K90 and PVA403 are also compared. As the K value increases, the molecular weight of the PVP gradually increases, the viscosity also gradually increases, and the hydrophobicity also gradually increases. As can be seen from the figure, when the molecular weight is small, the asymmetric force generated is small, and only hollow composite nanoparticles can be obtained, while when the molecular weight is too large, the influence of the viscosity gradually dominates, tightly connecting the iron oxide particles and the droplets, hindering the relative movement, so that bowl-shaped particles cannot be obtained, and due to the large viscosity, numerous particles accumulate and aggregate. The use of K30 can well obtain bowl-shaped composite nanoparticles.

[0057] Example 2

[0058] (1) Preparation of ellipsoidal iron oxide particles (a-Fe203)

[0059] First, 50 mL of a 5M sodium hydroxide solution was prepared, and under strong magnetic stirring, it was slowly added dropwise into 50 mL of a 2M anhydrous iron chloride solution. After mixing well, 10 mL of a 0.2M potassium sulfate solution was added. After stirring well, it was moved to a 100°C oven, and after 4 days of reaction, it was taken out, washed with acetone and water, centrifuged and collected, and dried in a vacuum drying oven.

[0060] (2) Preparation of PVP-modified a-Fe203particles

[0061] Take 100 mg of dried α-Fe2O3 ellipsoidal particles into a 20 mL glass bottle, add 10 mL of deionized water, after ultrasonic dispersion, add 80 mg of polyvinylpyrrolidone PVP, fully stir to make it evenly cover the surface of the iron oxide particles. Dry the α-Fe2O3 / PVP particles and reserve for use.

[0062] (3) Preparation of 3-(trimethoxysilyl) methyl propyl methacrylate (MPS) hydrolysis solution

[0063] Measure 45 mL of deionized water into a beaker, after 30 min of N2 bubbling, add 3 mL of MPS solution, keep the stirring speed at 600 rpm until the mixture is dissolved and presents a transparent and uniform state, get the MPS hydrolysis solution and reserve for use.

[0064] (4) Preparation of template molecule and functional monomer pre-assembly solution

[0065] Take 0.18 mmol of functional monomer 9-vinyladenine (9-VA) and 0.2 mmol of template molecule β-thymidine (dT) and dissolve them in 8 mL of deionized water, after 30 min of N2 bubbling, assemble at room temperature for 12 h in the dark.

[0066] (5) Preparation of bowl-shaped imprinting polymer composite particles MIP-Fe2O3-MPS

[0067] Take 5 mL of MPS hydrolysis solution into a 100 mL flask, add 5 mg of α-Fe2O3 / PVP particles, after stirring and mixing uniformly at a speed of 1000 rpm, add 1 mL of ammonia solution (NH3, 37% wt), keep a certain stirring speed and react at room temperature for 30 min, then add 8 mL of pre-assembly solution and continue stirring for 30 min. Finally, add 15 mg of azobisisobutyronitrile (AIBN) and place the mixture in an oven at 80°C for 12 h, after the reaction is completed, the particles are washed and the secondary nucleation particles are removed. The centrifuged product is eluted with pH = 3.0 HCl to remove the template molecule, until no dT is detected in the eluent by ultraviolet-visible spectrophotometer. Finally, the purified MIP-Fe2O3-MPS is placed in a vacuum drying oven.

[0068] Similarly, bowl-shaped non-imprinting polymer composite particles NIP-Fe2O3-MPS are synthesized in parallel without adding dT.

[0069] Example 3

[0070] (1) Preparation of ellipsoidal iron oxide particles (α-Fe2O3)

[0071] First, 150 mL of 5M sodium hydroxide solution was prepared, and it was slowly dropped into 150 mL of 2M anhydrous ferric chloride solution under strong magnetic stirring. After mixing well, 10 mL of 0.2M potassium sulfate solution was added. After stirring well, it was moved to a 100°C oven, and after 8 days of reaction, it was taken out, washed with acetone and water, centrifuged, and dried in a vacuum drying box.

[0072] (2) Preparation of PVP-modified α-Fe2O3 particles

[0073] 100 mg of oven-dried α-Fe2O3 ellipsoidal particles were weighed into a 20 mL glass bottle, 10 mL of deionized water was added, and after ultrasonic dispersion, 120 mg of polyvinylpyrrolidone PVP was added, and it was stirred well to evenly cover the surface of the iron oxide particles. The α-Fe2O3 / PVP particles were dried and prepared for use.

[0074] (3) Preparation of 3-(trimethoxysilyl) methyl propyl methacrylate (MPS) hydrolysis solution

[0075] 75 mL of deionized water was measured into a beaker, and after 30 min of N2 bubbling, 3 mL of MPS solution was added, and stirring was maintained at 600 rpm until the mixed solution was transparent and uniform. The MPS hydrolysis solution was prepared and ready for use.

[0076] (4) Preparation of template molecule and functional monomer pre-assembly solution

[0077] 0.24 mmol of functional monomer 9-vinyladenine (9-VA) and 0.2 mmol of template molecule β-thymidine (dT) were dissolved in 12 mL of deionized water, and after 30 min of N2 bubbling, the assembly was carried out at room temperature for 12 h in the dark.

[0078] (5) Preparation of bowl-shaped imprint polymer composite particles MIP-Fe2O3-MPS

[0079] 15 mL of MPS hydrolysis solution was taken into a 100 mL flask, 15 mg of PVP-modified α-Fe2O3 ellipsoidal particles were added, and after stirring well at 1000 rpm, 1 mL of ammonia solution (NH3, 37% wt) was added dropwise. After 30 min of reaction at room temperature with a certain stirring speed, 12 mL of pre-assembly solution was added, and stirring was continued for 30 min. Finally, 25 mg of azobisisobutyronitrile (AIBN) was added, and the mixture was placed in an 80°C oven for 12 h. After the reaction was completed, the particles were fractionally washed to remove the secondary nucleation particles. The centrifuged product was eluted with pH = 3.0 HCl to remove the template molecule, and dT was not detected in the eluent by ultraviolet-visible spectrophotometry. Finally, the purified MIP-Fe2O3-MPS was dried in a vacuum drying box.

[0080] Similarly, bowl-shaped non-imprinted polymer composite particles NIP-Fe2O3-MPS were synthesized in parallel without adding dT.

[0081] Test Example 1:

[0082] Selecting β-thymidine (dT), 2-deoxycytidine (dC), 2-deoxyguanosine (dG) and 2'-deoxyadenosine (dA), 5-fluorocytidine (5-FC) and adenosine monophosphate (AMP) as selective adsorbates, solutions of the above six compounds were prepared with a concentration of 300 μmol / L, 5 mL of each was added to a centrifuge tube, and after oscillation at room temperature for 12.0 hours, the adsorbent was collected by centrifugation, and then the concentration of the compound in the filtrate was determined by ultraviolet-visible spectroscopy (UV-vis), the adsorption capacity was calculated, and the results were obtained Figure 5 It can be found that the adsorption capacity of MIP-Fe2O3-MPS and NIP-Fe2O3-MPS obtained in Example 1 for template molecule dT (70.79 μmol / g) is significantly higher than that of the other five competitors. That is, the specific adsorption recognition effect of MIP-Fe2O3-MPS is in the order of dT > dC > dG > 5-FC > AMP > dA. Although they have similar molecular structures and functional groups to dT, the adsorption capacity and selectivity of MIP-Fe2O3-MPS for the competitors are still much lower than that of dT, because they do not match the size of the imprinted cavity in shape and size. This shows that the molecular imprinting technology plays a very important role in improving the selective recognition ability of the adsorbent, and MIP-Fe2O3-MPS has good selective recognition ability for dT.

[0083] Test Example 2:

[0084] A series of bowl-shaped imprinted composite nanoparticles were prepared by adding 0.1, 0.2, 0.3, 0.4, 0.6 mmol of 9-VA respectively, while maintaining the ratio of template molecule to functional monomer unchanged, to change the ratio of functional monomer to crosslinking agent MPS in the reaction system.

[0085] Under the same conditions, bowl-shaped non-imprinted composite nanoparticles were prepared without adding template molecules.

[0086] Figure 4 The chemical functional groups on the surface of MIP-Fe2O3-MPS were studied by Fourier infrared spectroscopy. By comparing the addition of different amounts of functional monomer 9-VA, the intensity of the O-H stretching vibration peak gradually increased with the increase of the amount of 9-VA modified, which confirmed that the MIPs were successfully grown into Fe2O3-MPS.

[0087] 5 mL of 300 μmol / L β-thymidine dT in PBS (pH = 7.4) was added to a centrifuge tube, and 5 mg of the adsorbent prepared in Example 1 was added. After the adsorbent was contacted with the test solution for 12.0 h, the dT solution was passed through the membrane to remove the suspended adsorbent. The concentration of dT in the filtrate was detected by UV-vis, and the adsorption capacity and imprint factor were calculated according to the results to obtain Figure 6 As can be seen from the figure, the adsorption capacity increases with the increase of the amount of functional monomer 9-VA. However, with the increase of the amount of 9-VA, the imprint factor shows a trend of first increasing and then decreasing. When 0.3 mmol of 9-VA is added, the imprint factor reaches 3.85. When the amount of 9-VA is increased to 0.4 mmol, the imprint factor begins to decrease.

[0088] Test Example 3:

[0089] For the regeneration of the adsorbent, MIP-Fe2O3-MPS and NIP-Fe2O3-MPS obtained in Example 1 were subjected to seven cycles of adsorption / desorption experiments. 2.0 mg of MIP-Fe2O3-MPS was added to a centrifuge tube containing 2.0 mL of PBS solution (pH = 7.4) with a dT concentration of 300 μmol / L. After 12.0 h of oscillation, the concentration of dT in the solution was detected, and the adsorption capacity Q e (μmol / g) was calculated. After each adsorption, the adsorbed MIP-Fe2O3-MPS was eluted with a pH = 3.0 HC1 solution at room temperature for 12.0 h. Then the regenerated adsorbent was washed to neutral with deionized water and used for the next adsorption / desorption cycle after drying. As shown in Figure 7 shown, in the first three cycles, the adsorption capacity and the imprint factor did not decrease significantly, and after seven cycles, the adsorption capacity of MIP-Fe2O3-MPS for dT decreased from the initial 46.515 μmol / g to 40.368 μmol / g, which still maintained 87% of the initial adsorption capacity, and the imprint factor did not decrease significantly, indicating that the sites of MIP-Fe2O3-MPS were relatively stable and had good reusability.

Claims

1. A method for the preparation of a bowl-shaped imprinted polymer adsorbent by asymmetric action-induced silica-based imprinting droplets, characterized by, It comprises the following steps: (1) Preparation of ellipsoidal iron oxide particles α-Fe2O3 First, prepare a sodium hydroxide solution, slowly drop it into the anhydrous ferric chloride solution under strong magnetic stirring, add the potassium sulfate solution after mixing evenly, stir evenly and then move it to the oven, take it out after a period of reaction, wash it with acetone and water, collect it by centrifugation and dry it in a vacuum drying box to obtain α-Fe2O3; (2) Preparation of α-Fe2O3 particles modified by PVP Ultrasonically disperse α-Fe2O3 in deionized water, then add polyvinylpyrrolidone PVP to the dispersion, fully stir to dissolve PVP completely and evenly cover the surface of the iron oxide particles, dry to obtain α-Fe2O3 / PVP particles, and reserve them for use; (3) Preparation of 3-(trimethoxysilyl) methyl propyl methacrylate MPS hydrolysis solution Put deionized water in a beaker, introduce N2, then add MPS, keep stirring at a certain speed until the mixed solution is transparent and uniform, obtain the MPS hydrolysis solution, and reserve it for use; (4) Preparation of pre-assembly solution of template molecules and functional monomers Dissolve a certain amount of functional monomer 9-vinyladenine 9-VA and template molecule β-thymidine dT in deionized water, introduce N2, assemble at room temperature in the dark, and obtain the pre-assembly solution, and reserve it for use; (5) Preparation of bowl-shaped imprinted polymer composite particles (MIP-Fe2O3-MPS) Mix the MPS hydrolysis solution and α-Fe2O3 / PVP particles, stir at a certain speed until they are mixed evenly, then add an ammonia solution, keep stirring at a certain speed at room temperature, then add the pre-assembly solution prepared in step (4) and continue stirring to mix thoroughly, finally add azobisisobutyronitrile AIBN and put the mixture in an oven to react, after the reaction is completed, the particles are separated by centrifugation to remove the secondary nucleation particles, the template molecules are removed by washing the centrifuged product with HCl eluent until no dT is detected in the eluent by ultraviolet-visible spectrophotometry, and finally the purified MIP-Fe2O3-MPS is dried in a vacuum drying box.

2. The method of asymmetrically action-induced silicon-based imprinting droplet preparation of a bowl-shaped imprinted polymer adsorbent according to claim 1, characterized in that, In step (1), the amount ratio of the sodium hydroxide solution, the anhydrous ferric chloride solution and the potassium sulfate solution is (5-15) mL:(5-15) mL:1 mL; the concentration of the sodium hydroxide solution is 5M, the concentration of the anhydrous ferric chloride solution is 2M, and the concentration of the potassium sulfate solution is 0.2M; the reaction temperature is 100℃, and the reaction time is 4-8 days.

3. The method of claim 1 for the preparation of asymmetrically acting induced-silica-based imprint droplet bowls of imprinted polymer adsorbents, characterized in that, In step (2), the amount ratio of the α-Fe2O3 ellipsoidal particles and PVP is 1 mg:(0.8-1.2) mg; the molecular weight of PVP is K30.

4. The method of claim 1 for the preparation of asymmetrically acting induced-silica-based imprint droplet bowls of imprinted polymer adsorbents, characterized in that, In step (3), the amount ratio of MPS and deionized water is 1 mL:(15-25) mL; the nitrogen introduction time is 30 min; and the stirring speed is 600 rpm.

5. The method of claim 1, wherein the asymmetrically acting inducible silica-based imprint droplet preparation bowl-shaped imprinted polymer adsorbent is characterized by, In step (4), the amount ratio of dT, 9-VA and deionized water is 1 mmol:(0.9-1.2) mmol:(40-60) mL; the nitrogen introduction time is 30 min; and the assembly time in the dark at room temperature is 12 h.

6. The method of asymmetrically acting on an induced-silica-based imprint droplet to prepare a bowl-shaped imprinted polymer adsorbent according to claim 1, wherein, In step (5), the amount ratio of the α-Fe2O3 / PVP particles, the MPS hydrolysis solution, the pre-assembly solution, AIBN and the ammonia solution is (5-15) mg:(5-15) mL:(8-12) mL:(15-25) mg:1 mL; wherein the concentration of the ammonia solution is 37%wt.

7. The method of claim 1, wherein the asymmetrically acting inducible silica-based imprint droplet preparation bowl-shaped imprinted polymer adsorbent is characterized by, In step (5), the stirring speed is 400-1200 rpm.

8. The method of claim 1, wherein the asymmetrically acting inducible silica-based imprint droplet preparation bowl-shaped imprinted polymer adsorbent is characterized by, In step (5), the reaction time at room temperature is 30-40 min; the reaction temperature in the oven is 80°C, and the reaction time is 12 h.

9. The method of claim 1, wherein the asymmetrically acting inducible silica-based imprint droplet preparation bowl-shaped imprinted polymer adsorbent is characterized by, In step (5), the speed of the fractional centrifugal washing is 1000-5000 rpm, and the pH of the HCl eluent is 3.

0.

10. Use of the MIP-Fe2O3-MPS adsorbent prepared by the method of any one of claims 1-9 for the selective adsorption separation of dT.

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