CN109880148B - Preparation of surface imprinting material and application of surface imprinting material in glutamic acid enantiomer resolution - Google Patents
Preparation of surface imprinting material and application of surface imprinting material in glutamic acid enantiomer resolution Download PDFInfo
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Abstract
The invention discloses a preparation method of a surface imprinting material and application thereof in splitting a glutamic acid enantiomer, wherein graft polymerization of a functional monomer sodium styrene sulfonate is implemented on the surface of a primary amine resin microsphere; then, by utilizing the hydrogen bond interaction between the grafted macromolecular chain PSSS and acidic amino acid glutamic acid molecules, constructing a L-glutamic acid (L-Glu) chiral cavity on the surface of the primary amine resin microsphere by adopting a surface imprinting method, carrying out molecular imprinting of the L-Glu to prepare the imprinted material MIP-PSSS/PSA, and taking the D-glutamic acid (D-Glu) as a reference substance, deeply investigating the recognition characteristic of the imprinted material MIP-PSSS/PSA on the template molecules L-Glu and the resolution performance of glutamic acid raceme. The imprinted material MIP-PSSS/PSA provided by the invention has good recognition selectivity and binding affinity to the template molecule L-Glu, and also has good desorption performance.
Description
Technical Field
The invention relates to a preparation method of a surface imprinting material and application thereof in glutamic acid enantiomer resolution, belonging to the field of imprinting materials.
Background
In 1972, Wulff first synthesized molecularly imprinted polymers, which developed a breakthrough with the creation of covalent and non-covalent types, such as Wulffg (SARHON A. Uber die and wendung von enzymanalog gebauuetten polymerzur racem-attrenung [ J ]. Angew Chem, 1972,84 (8): 364 and 364.), Mosbach (Ardeadr, Mosbach K. Synthesis of substrate-selective polymers by host-guest polymerization [ J ]. Makromol Chem, 1981, 182: 687 and 692 ]). Molecularly imprinted polymers have many advantages such as strong selectivity, simple preparation, strong environmental tolerance, and wide practicality, and thus have been widely used in the fields of chromatographic separation, solid-phase extraction, sensors, drug release, and the like. But there are few reports on the application to the separation of amino acids. The separation method of amino acid includes chemical resolution, crystallization, enzyme method, membrane separation and chromatography (including chiral ligand exchange chromatography, high performance liquid chromatography, gas chromatography and capillary electrophoresis). Some separation methods have narrow application range, some separation methods have high cost and some separation methods have complex process, and some chromatography methods are limited in the field of analytical chemistry and cannot realize rapid, efficient and large-scale separation although the selectivity is good and the separation efficiency is high (particularly chiral ligand exchange chromatography). Therefore, achieving efficient resolution of chiral enantiomers is a very challenging problem.
The molecular imprinting technology is to select target molecules as template molecules, combine functional polymer monomers with complementary functions on the structure with the template molecules through covalent bonds or non-covalent bonds, then add a cross-linking agent for cross-linking reaction, elute the template molecules after the reaction is finished, and leave a cross-linked polymer with fixed cavity shapes and sizes and fixed arrangement functional groups. The surface molecularly imprinted polymer has specific binding affinity and recognition selectivity for the template molecule. Are known as specific recognition materials that mimic biological receptors. The research tries to introduce the novel surface molecular imprinting technology into the molecular imprinting of amino acid, construct chiral holes on the surface of matrix particles, and prepare a high-performance solid phase extractant so as to realize the efficient resolution of amino acid enantiomers on the level of molecular configuration.
Disclosure of Invention
The invention aims to provide a preparation method of a surface imprinting material and application thereof in splitting a glutamic acid enantiomer.
The invention adopts a ' grafting-out ' method to graft sodium polystyrene sulfonate (SSS) on the surface of a primary amine resin microsphere to prepare a grafted particle MIP-SSS/PSA, wherein an enantiomer L-Glu of glutamic acid is taken as a template molecule, N, N ' -Methylene Bisacrylamide (MBA) is taken as a cross-linking agent, a novel surface molecular imprinting technology is adopted, and the surface molecular imprinting of the L-Glu is implemented on the surface of silica gel grafted with PSSS. The prepared MIP-SSS/PSA material has obvious identification selectivity and good binding affinity to L-Glu due to the fact that a large number of chiral imprinting holes of the L-Glu are distributed in the polymer thin layer on the surface of the MIP-SSS/PSA material; these chiral cavities have poor binding capacity and low binding capacity for D-Glu due to mismatch in steric structure and site of action with the other enantiomer, D-Glu. For the racemic solution of the two enantiomers, MIP-SSS/PSA showed good resolution performance. Because the imprinted pores of MIP-SSS/PSA are distributed in the polymer film layer on the surface of the particle, the L-Glu in the combined pores has good elution performance, and the regeneration and the reuse of the imprinted material are facilitated.
The invention provides a preparation method of a surface imprinting material, which comprises the steps of grafting a functional monomer Sodium Styrene Sulfonate (SSS) onto the surface of a primary amine resin microsphere by adopting a ' grafting-out ' method in a solution polymerization system to prepare a functional grafted particle PSSS/PSA, and adopting a novel molecular surface imprinting technology to perform molecular imprinting on a macromolecular PSSS grafted on the surface of the primary amine resin microsphere by taking L-Glu of one enantiomer of glutamic acid (Glu) as a template molecule and N, N ' -Methylene Bisacrylamide (MBA) as a cross-linking agent to prepare the L-Glu molecular surface imprinting material MIP-PSSS/PSA. The other enantiomer D-Glu of glutamic acid is taken as a contrast, the identification performance of MIP-PSSS/PSA on L-Glu molecules is deeply researched by adopting a static method and a dynamic method, and the feasibility of adopting a molecular surface imprinting material to separate the amino acid enantiomer is intensively explored.
The preparation method of the surface imprinting material comprises the following steps:
(1) activating the polystyrene primary amine resin microspheres:
adding 50mL-100mLN, N-dimethylformamide solution into 20g-40g of dried primary amine resin microspheres, soaking at 20-30 ℃ for 12-14 hours, then carrying out suction filtration, and putting into a vacuum oven for drying treatment, thus activating amino groups on the surfaces of the primary amine resin microspheres;
(2) graft polymerizing sodium p-styrenesulfonate on the surface of primary amine resin microspheres:
adding 0.1g-0.3g of activated primary amine resin microspheres into a four-neck flask, adding 40mL-45mL of solvent, 0.2500-0.3500g of SSS, introducing nitrogen for 20-40min, stirring and heating by using a water bath kettle, and adding 0.04-0.08g of initiator ammonium persulfate to start reaction when the temperature reaches 50 ℃; repeatedly washing with distilled water for many times after the reaction is finished for 6-10h, soaking with distilled water for 22-26h, filtering, and drying with a vacuum oven at 40-60 ℃ for 22-26h to obtain the grafted particle PSSS/PSA;
(3) preparing molecular surface imprinting material MIP-PSSS/PSA:
the surface imprinting of the L-glutamic acid molecule is carried out in a non-aqueous medium by adopting a method of synchronously carrying out graft polymerization and cross-linking imprinting: dissolving 0.3-0.5g of monomer SSS and 0.005-0.02g of template molecule glutamic acid in 70mL of solvent, allowing the two to interact for 6-10h, and transferring the solution into a four-neck flask provided with a reflux condenser tube, a stirrer and a thermometer; adding 1-3g of modified primary amine resin ball PSA, adding 0.1-0.2g of initiator ammonium persulfate and 0.1-0.2g of cross-linking agent MBA, stirring and introducing nitrogen for 20-40min, so that on one hand, air in a reaction system is removed, and on the other hand, anionic monomer SSS in the system and glutamic acid molecules are fully reacted with each other; heating to 50 ℃ and carrying out graft polymerization and crosslinking reaction for 4-8h under the stirring condition; and after the reaction is finished, filtering while the mixture is hot, and then soaking and washing the imprinted microspheres for multiple times by using a NaCl solution with the concentration of 2 mol/L to remove template molecules, and drying the template molecules in vacuum to constant weight to obtain the imprinted microsphere MIP-PSSS/PSA.
Three-dimensional cavities with spatial structures matched with the spatial structures of L-glutamic acid molecules are left in the polymer MIP-PSSS/PSA obtained in the preparation process, and the cavities can only allow the L-glutamic acid to enter, so that the imprinted material can be used for identifying and selectively adsorbing the L-glutamic acid, and the racemic glutamic acid can be separated.
In the preparation method, in the step (2), the solvent is a mixed solvent of methanol and water, and the volume ratio of the methanol to the water is 5:1-5: 3.
In the preparation method, in the step (2), when the tea is soaked in distilled water, 40-50mL of distilled water is replaced every 4-6 h.
In the preparation method, the dosage of the SSS is 0.4-0.8% of the total mass of all the raw materials; the using amount of the initiator ammonium persulfate is 20-22% of the mass of the monomer.
The invention provides a surface imprinting material prepared by the preparation method.
The invention provides an application of the surface imprinting material in glutamic acid enantiomer resolution.
In order to further examine the identification characteristics of the imprinted material on L-Glu, a competitive adsorption experiment of MIP-PSSS/PSA on L-Glu and D-Glu was carried out, wherein a binary mixed solution (racemic solution and optical rotation of zero) of L-Glu and D-Glu with the concentration of 0.1 g/L was prepared, 50mL of the mixed solution was taken out of a conical flask with a stopper, 0.03 g of imprinted particulate material MIP-PSSS/PSA was added, the mixture was shaken in a constant temperature shaker for 2.5 h to balance the adsorption, the mixture was allowed to stand for separation, the total equilibrium concentration of glutamic acid in the supernatant was determined by spectrophotometry, and the optical rotation and specific optical rotation of the supernatant were determined by a polarimeter. The supernatant was found to have optical rotation in the same direction as that of D-Glu. This result indicates that MIP-PSSS/PSA has more adsorption to L-Glu in the racemic solution, i.e. a resolution effect on both enantiomers. Then the equilibrium concentration of the L-Glu and the D-Glu in the solution is calculated by the formula (1), and then the distribution coefficient of the L-Glu and the D-Glu is calculated by the formula (2).
In the formula (1), CD，e(g/L) and CL，e(g/L) are the equilibrium concentrations of the two enantiomers in the supernatant, [ alpha ]]Is the specific optical rotation of the supernatant [ alpha ]] D, markStandard specific rotation of enantiomer D-Glu, Ce, total of(g/L) is the total equilibrium concentration of the supernatant;
in the formula, Kd(mL•g-1) Is the partition coefficient of a certain enantiomer Ce (mg•mL-1) Is the equilibrium concentration of the enantiomer in the supernatant, Qe (mg•g-1) Is the equilibrium binding capacity of the enantiomer.
From the partition coefficient data of the two enantiomers in the solution, the selectivity coefficient of the imprinted particulate material MIP-PSSS/PSA for L-Glu was calculated according to equation (3).
Wherein k is the selectivity coefficient of the imprinted material MIP-PSSS/PSA to L-Glu relative to the enantiomer D-Glu, and the size of the k value marks the recognition selectivity of the imprinted material MIP-PSSS/PSA to L-Glu.
The invention has the beneficial effects that:
(1) the imprinted material MIP-PSSS/PSA has good recognition selectivity and binding affinity to the template molecule L-Glu, and compared with D-Glu, the recognition selectivity coefficient is 3.97, and the imprinted material MIP-PSSS/PSA shows good resolution performance;
(2) the imprinted material MIP-PSSS/PSA also has good desorption performance, and the desorption rate can reach 98.62% in 13 bed volumes by taking dilute NaOH aqueous solution as eluent;
(3) because the imprinted pores of MIP-SSS/PSA are distributed in the polymer film layer on the surface of the particle, the L-Glu in the combined pores has good elution performance, and the regeneration and the reuse of the imprinted material are facilitated.
Drawings
FIG. 1 is a schematic diagram of the chemical reaction process for preparing MIP-PSSS/PSA as L-Glu imprinted material in example 1.
FIG. 2 is an infrared spectrum of PSA and PSSS/PSA and MIP-PSSS/PSA prepared in example 1.
FIG. 3 shows the binding isotherms of the imprinted material MIP-PSSS/PSA on the two enantiomers in example 2.
FIG. 4 is the isothermal binding line of the non-imprinted material PSSS/PSA of example 2 for the two enantiomers.
FIG. 5 is a graph showing the dynamic adsorption profile of the non-imprinted material PSSS/PSA in example 2 on the glutamic acid enantiomer.
FIG. 6 is a dynamic binding curve of the imprinted material MIP-PSSS/PSA on the glutamic acid enantiomer in example 2.
FIG. 7 is a graph showing the elution profile in example 4.
Detailed Description
The present invention is further illustrated by, but is not limited to, the following examples.
The primary amine resin of the invention has sulfonic acid functional groups after being modified and grafted by Sodium Styrene Sulfonate (SSS). In the process of cross-linking imprinting, because hydrogen bond interaction force exists between the sulfonate and the amino and the oxygen atom on the hydroxyl of glutamic acid, a binding site with specific binding performance can be formed. After the template molecules are washed away, three-dimensional cavities with spatial structures matched with the spatial structures of the L-glutamic acid molecules are left in the polymer, and the MIP-PSSS/PSA material with the L-Glu molecularly imprinted surface is formed.
Example 1: preparation of molecular surface imprinted material MIP-PSSS/PSA
The preparation process specifically comprises the following steps:
(1) activating the polystyrene primary amine resin microspheres:
adding 100mL of N, N-dimethylformamide solution into 30g of dried primary amine resin microspheres, soaking at the temperature of 30 ℃ for 12h, then carrying out suction filtration, and putting into a vacuum oven for drying treatment, thus activating amino groups on the surfaces of the primary amine resin microspheres;
(2) graft polymerizing sodium p-styrenesulfonate on the surface of primary amine resin microspheres:
0.2g of activated primary amine resin microspheres was added to a four-necked flask, and 42mL of solvent (V) was addedMethanol：VWater (W)=5:2), 0.2887g (0.6235% of the total mass) of SSS, introducing nitrogen for 30min, starting stirring and heating by using a water bath kettle, adding 0.0600g of initiator ammonium persulfate (20.78% of the mass of the monomer) when the temperature reaches 50 ℃ and starting reaction; and after 8h of reaction, repeatedly washing with distilled water for many times, soaking in distilled water for 24h (continuously changing water), performing suction filtration, and drying in a vacuum oven at the temperature of 50 ℃ for 24h to obtain the grafted particle PSSS/PSA.
The grafting amount of the grafted microparticles was determined using acid-base titration: soaking PSSS/PSA with a certain volume of hydrochloric acid for 8h to ensure that the hydrochloric acid fully reacts with amino groups on the surface of the primary amine resin spheres, titrating the residual hydrochloric acid with standard NaOH, and calculating the grafting degree of the PSSS/PSA by a formula. The grafting amount obtained under this protocol was 120 mg/g.
(3) Preparing molecular surface imprinting material MIP-PSSS/PSA:
the surface imprinting of the L-glutamic acid molecule is carried out in a non-aqueous medium by adopting a method of synchronously carrying out graft polymerization and cross-linking imprinting: 0.5232 monomer SSS and 0.01g template molecule glutamic acid are dissolved in 70mL solvent, and after the mutual action of the solvent and the solvent is carried out for 6 to 10 hours, the solvent is moved into a four-neck flask provided with a reflux condenser tube, a stirrer and a thermometer; adding 1.2g of modified primary amine resin ball PSA, adding 0.136 g of initiator ammonium persulfate and 0.1565g of cross-linking agent MBA, stirring and introducing nitrogen for 30min, on one hand, removing air in a reaction system, and on the other hand, enabling an anionic monomer SSS in the system to fully react with glutamic acid molecules; heating to 50 ℃ and carrying out graft polymerization and crosslinking reaction for 6 hours under the stirring condition; and after the reaction is finished, filtering while the mixture is hot, and then soaking and washing the imprinted microspheres for multiple times by using a NaCl solution with the concentration of 2 mol/L to remove template molecules, and drying the template molecules in vacuum to constant weight to obtain the imprinted microsphere MIP-PSSS/PSA.
The principle of the preparation process is shown in figure 1.
The infrared spectrum was measured by KBr pellet method to confirm the structural change. The infrared spectrum is shown in FIG. 2. From the spectra, it can be seen that 1650cm-1The characteristic absorption peak of double bond indicates that the substrate fails to react completely, 3400cm-1Is NH23750cm of the stretching vibration peak of-1Is the stretching vibration peak of N-H, 1678cm-1The peak is the absorption peak of the amide carbonyl group in the range of 1576cm-1The peak at which the amide N-H undergoes in-plane bending absorption vibration is derived from MBA in the crosslinked copolymer, 1460cm-1And 1410cm-1Characteristic absorption peaks of methylene and methine respectively show that double bonds in primary amine spheres and monomer SSS undergo addition polymerization reaction, and 1190cm-1Having sulfonic acid group-SO3-The characteristic absorption peak of (A) is obviously strengthened, which indicates that the monomer is successfully grafted to the surface of the primary amine microsphere.
Example 2: examination of the recognition Performance of MIP-PSSS/PSA on two enantiomers, L-Glu and D-Glu
1. Determination of isothermal bonding Performance
The binding performance of the surface imprinted material MIP-PSSS/PSA to two enantiomers of glutamic acid is determined by respectively adopting a static method and a dynamic method. Similarly, binding performance was determined by first determining the kinetic behavior of MIP-PSSS/PSA binding to L-Glu and D-Glu, determining when binding reaches equilibrium (also around 2 h).
(1) Static method: respectively placing 50mL of L-Glu solution with concentration changing from 0.03 to 0.30 g/L into a plurality of conical bottles with stoppers at a constant temperature of 30 DEG CAdding about 0.03 g of accurately weighed imprinted particulate material MIP-PSSS/PSA, oscillating for 2h in a constant temperature oscillator to balance the binding, standing for layering to obtain supernatant, measuring the equilibrium concentration of L-Glu in the supernatant by spectrophotometry according to a formula (1), and calculating the equilibrium binding capacity Q of MIP-PSSS/PSA to L-Glu according to a formula (4)e(mg/g) and plotting the equilibrium binding capacity versus the equilibrium concentration, i.e. isothermal binding curve.
C in formula (4)0(g/L)，C e(g/L) is the concentration of L-Glu in the solution before and after adsorption respectively; v (mL) is the volume of the adsorption solution, and m (g) is the mass of the blotting material MIP-PSSS/PSA. According to the same method, the equilibrium binding capacity of the MIP-PSSS/PSA material of the L-Glu molecular engram material to the other enantiomer D-Glu is determined, and an isothermal binding curve is drawn.
(2) Dynamic method: at room temperature, 1.5 g of MIP-SSS/PSA was swollen in water and packed in a glass tube with an inner diameter of 10 mm to make the Bed Volume (Bed Volume, BV) of the packed column 2 mL. The solution of L-Glu with the concentration of 0.1 g/L is heated for 4 BV.h-1The flow rate of the mixed solution is countercurrent and passes through a packed column, the effluent liquid is collected at intervals of 1 BV, the concentration of L-Glu in the effluent liquid is measured, a dynamic binding curve is drawn, and the leakage binding capacity and the saturation binding capacity of MIP-PSSS/PSA to the L-Glu are calculated by utilizing the concentration of the effluent liquid and the volume number of the bed. The dynamic binding curve of the imprinted material MIP-SSS/PSA to D-Glu was determined and plotted using the same method.
2. Identification characteristics of MIP-PSSS/PSA and binding Properties to two enantiomers
Combining isotherms with dynamic binding curves
Isothermal adsorption experiments on two enantiomers L-Glu and D-Glu in an aqueous medium were performed by using a static method and a dynamic method, respectively, using a grafted particulate material MIP-PSSS/PSA and a L-Glu molecularly imprinted material MIP-PSSS/PSA.
As can be seen from FIGS. 3 and 4, the non-imprinted fine NMIP-PSSS/PSA has equal adsorption effect on the enantiomers of glutamic acid (D-glutamic acid and L-glutamic acid), and the adsorption capacity is as high as 120mg/g, which indicates that the non-imprinted material NMIP-PSSS/PSA has no recognition selectivity on D-glutamic acid and L-glutamic acid. The enantiomers of chiral compounds all have identical chemical formulas and physicochemical properties, differing only in optical rotation. Therefore, hydrogen bonds are formed between the two glutamic acid enantiomers and a macromolecular chain PSSS in the non-imprinted material NMIP-PSSS/PSA, so that the non-imprinted material has stronger adsorption force on D-glutamic acid and L-glutamic acid and has no adsorption selectivity. And the adsorption effect of the imprinted material MIP-PSSS/PSA on D-glutamic acid is much stronger than that of L-glutamic acid. The adsorption amount of L-glutamic acid was reduced from 120mg/g in the right graph to about 48mg/g, while D-glutamic acid remained at a high adsorption amount of about 120 mg/g. The change shows that the surface imprinted material MIP-PSSS/PSA prepared by the experiment has good binding capacity and recognition selectivity on the template molecule L-glutamic acid, but has weak binding capacity on the D-glutamic acid molecule. The reason is that a large number of L-glutamic acid imprinted holes are distributed in a surface polymer thin layer of the imprinted material MIP-PSSS/PSA, and the chiral holes are highly matched with L-glutamic acid molecules in terms of spatial structure and action sites, so that the imprinted material MIP-PSSS/PSA has specific chiral recognition capability on the L-glutamic acid of the template molecules, forms strong binding force and generates high adsorption capacity. But these chiral holes do not match the D-glutamic acid molecule. It is difficult to make it enter the cavity, resulting in a low adsorption amount of D-glutamic acid by MIP-PSSS/PSA. In a word, a static adsorption experiment proves that the surface imprinted material MIP-PSSS/PSA has good chiral recognition capability on the template molecule L-glutamic acid.
FIG. 5 shows the dynamic adsorption curves of the unscented material PSSS/PSA for the two enantiomers of glutamic acid, and FIG. 6 shows the dynamic binding curves of the L-Glu molecularly imprinted material MIP-PSSS/PSA for the two enantiomeric molecules. As can be seen from FIG. 5, for the PSSS/PSA packed column, the breakthrough curves are identical when the two enantiomeric solutions are passed through the column in countercurrent at a flow rate of 4 BV/h, respectively; both solutions began to leak at 29 BV; from FIG. 6, however, it can be seen that the leakage curve for the L-Glu solution is significantly different from the leakage curve for the D-Glu solution for the MIP-PSSS/PSA packed column: (1) the D-Glu solution began to leak at 25 BV, while the L-Glu solution had a leak volume of 38 BV, a difference of 13 BV; (2) the D-Glu solution is completely penetrated at 40BV, and the penetrating volume of the L-Glu solution is 55 BV; the fact of the above dynamic experiment shows again that MIP-SSS/PSA shows obvious recognition selectivity and excellent binding affinity to L-Glu, and in comparison, the recognition and binding capacity to D-Glu is weaker.
Example 3: binding selectivity experiments (enantiomer splitting experiments)
In order to further examine the identification characteristics of the imprinted material on L-Glu, a competitive adsorption experiment of MIP-PSSS/PSA on L-Glu and D-Glu was carried out, wherein a binary mixed solution (racemic solution and optical rotation of zero) of L-Glu and D-Glu with the concentration of 0.1 g/L was prepared, 50mL of the mixed solution was taken out of a conical flask with a stopper, 0.03 g of imprinted particulate material MIP-PSSS/PSA was added, the mixture was shaken in a constant temperature shaker for 2.5 h to balance the adsorption, the mixture was allowed to stand for separation, the total equilibrium concentration of glutamic acid in the supernatant was determined by spectrophotometry, and the optical rotation and specific optical rotation of the supernatant were determined by a polarimeter. The supernatant was found to have optical rotation in the same direction as that of D-Glu. This result indicates that MIP-PSSS/PSA has more adsorption to L-Glu in the racemic solution, i.e. a resolution effect on both enantiomers. Then the equilibrium concentration of the L-Glu and the D-Glu in the solution is calculated by the formula (1), and then the distribution coefficient of the L-Glu and the D-Glu is calculated by the formula (2).
In the formula (1), CD，e(g/L) and CL，e(g/L) are the equilibrium concentrations of the two enantiomers in the supernatant, [ alpha ]]Is the specific optical rotation of the supernatant [ alpha ]] D, markStandard specific rotation of enantiomer D-Glu, Ce, total of(g/L) is the total equilibrium concentration of the supernatant;
in the formula, Kd(mL•g-1) Is the partition coefficient of a certain enantiomer Ce (mg•mL-1) Is the equilibrium concentration of the enantiomer in the supernatant, Qe (mg•g-1) Is the equilibrium binding capacity of the enantiomer.
From the partition coefficient data of the two enantiomers in the solution, the selectivity coefficient of the imprinted particulate material MIP-PSSS/PSA for L-Glu was calculated according to equation (3).
Wherein k is the selectivity coefficient of the imprinted material MIP-PSSS/PSA to L-Glu relative to the enantiomer D-Glu, and the size of the k value marks the recognition selectivity of the imprinted material MIP-PSSS/PSA to L-Glu.
Selectivity coefficient of MIP-SSS/PSA for template enantiomer molecules and resolution performance for racemate:
a binary mixed solution (namely racemic solution) with the same concentration of L-Glu and D-Glu is prepared, and a competitive adsorption experiment is carried out by using a blotting material MIP-SSS/PSA. Table 1 shows the partition coefficients K of the two substancesdAnd selectivity coefficient k of MIP-SSS/PSA on template enantiomer L-Glu.
TABLE 1 table of partition and selection coefficients for two amino acids
From the data in Table 1, it can be found that the selectivity coefficient of the imprinted material MIP-SSS/PSA relative to D-Glu is 3.97, indicating that the imprinted material MIP-SSS/PSA has obvious identification selectivity on L-Glu. Obviously, the above competitive experimental data also fully reveal that the imprinted material MIP-SSS/PSA has obvious resolution capability on two enantiomers of glutamic acid.
The selectivity coefficient of MIP-PSSS/PSA for L-glutamic acid molecules is greatest at a temperature of 30 ℃. As the blotting temperature increases, the selectivity coefficient becomes greater; the temperature reaches a maximum of 8.1 when reaching 30 ℃; as temperature continues to rise, the selectivity coefficient decreases instead.
The selectivity coefficient of MIP-PSSS/PSA for L-glutamic acid molecules reaches a maximum of 7.8 when the ratio of monomeric SSS to crosslinker MBA is 5: 1.
When the ratio of the template molecule L-glutamic acid to the monomer SSS is 250: at 1, the selectivity coefficient k of MIP-PSSS/PSA on the template molecules reaches a maximum of 7.8.
A binary mixed solution (namely racemic solution) with the same concentration of L-Glu and D-Glu is prepared, and a competitive adsorption experiment is carried out by using a blotting material MIP-SSS/PSA. Compared with D-Glu, the selectivity coefficient of the imprinted material MIP-SSS/PSA to the L-Glu is 3.97, which shows that the imprinted material MIP-SSS/PSA has obvious identification selectivity to the L-Glu. Obviously, the above competitive experimental data also fully reveal that the imprinted material MIP-SSS/PSA has obvious resolution capability on two enantiomers of glutamic acid.
Example 4: examination of elution Performance
Packing the blotting material MIP-PSSS/PSA which has saturated adsorption of L-Glu and has the mass of 1.1 g into a column, using sodium hydroxide with the concentration of 0.1 mol/L as eluent at room temperature and 4 BV.h-1The flow rate of the mixed solution is passed through a packed column in a countercurrent manner to carry out desorption experiments, the eluate is collected at intervals of 1 BV, the concentration of L-Glu in the eluate is measured, a desorption curve is drawn, and the elution performance of the imprinted material MIP-PSSS/PSA is inspected.
The eluate was passed through a MIP-PSSS/PSA packed column saturated with the blotting material adsorbing L-Glu in countercurrent with 0.1 mol/L sodium hydroxide, and the dynamic analysis curve is shown in FIG. 7.
As can be seen from FIG. 7, the desorption curve is sharp and has no tail, and the desorption rate in 11 bed volumes reaches 97.23 percent and the desorption rate in 13 bed volumes reaches 98.62 percent through calculation. The experimental data fully show that the L-Glu molecules combined in the cavity of the imprinted material MIP-PSSS/PSA have excellent desorption performance due to the fact that the L-Glu molecules are distributed in the polymer thin layer on the surface of the primary amine resin microsphere, and the regeneration and the reuse of the extraction column are facilitated.
Claims (6)
1. A surface imprinting material, characterized by: the preparation method comprises the following steps;
the preparation method of the surface imprinting material comprises the following steps:
(1) activating the polystyrene primary amine resin microspheres:
adding 50mL-100mLN, N-dimethylformamide solution into 20g-40g of dried primary amine resin microspheres, soaking at 20-30 ℃ for 12-14 hours, then carrying out suction filtration, and putting into a vacuum oven for drying treatment, thus activating amino groups on the surfaces of the primary amine resin microspheres;
(2) preparing molecular surface imprinting material MIP-PSSS/PSA:
the surface imprinting of the L-glutamic acid molecule is carried out in a non-aqueous medium by adopting a method of synchronously carrying out graft polymerization and cross-linking imprinting: dissolving 0.3-0.5g of monomer sodium styrene sulfonate SSS and 0.005-0.02g of template molecule glutamic acid in 70mL of solvent, allowing the two to interact for 6-10h, and transferring the solution into a four-neck flask provided with a reflux condenser tube, a stirrer and a thermometer; adding 1-3g of activated primary amine resin microsphere PSA, adding 0.1-0.2g of initiator ammonium persulfate and 0.1-0.2g of cross-linking agent MBA, stirring and introducing nitrogen for 20-40min, so that on one hand, air in a reaction system is removed, and on the other hand, anionic monomer SSS in the system and glutamic acid molecules are fully reacted with each other; heating to 50 ℃ and carrying out graft polymerization and crosslinking reaction for 4-8h under the stirring condition; and after the reaction is finished, filtering while the mixture is hot, and then soaking and washing the imprinted microspheres for multiple times by using a NaCl solution with the concentration of 2 mol/L to remove template molecules, and drying the template molecules in vacuum to constant weight to obtain the imprinted microsphere MIP-PSSS/PSA.
2. The surface imprinting material of claim 1, wherein: in the step (2), the solvent is a mixed solvent of methanol and water, and the volume ratio of the methanol to the water is 5:1-5: 3.
3. The surface imprinting material of claim 1, wherein: the dosage of the SSS is 0.4-0.8% of the total mass of all the raw materials; the using amount of the initiator ammonium persulfate is 20-22% of the mass of the monomer.
4. Use of the surface imprinted material of claim 1 for the enantiomeric resolution of glutamic acid.
5. Use according to claim 4, characterized in that: preparing a binary mixed solution of L-Glu and D-Glu with the concentration of 0.1 g/L, putting 50mL of the mixed solution into a conical flask with a plug, adding 0.03 g of imprinted particulate material MIP-PSSS/PSA, oscillating for 2.5 h in a constant-temperature oscillator to balance the adsorption, standing for separation, measuring the total equilibrium concentration of glutamic acid in the supernatant by adopting a spectrophotometry, and measuring the optical rotation and the specific optical rotation of the supernatant by using a polarimeter; the MIP-PSSS/PSA is shown to have more adsorption to the L-Glu in the racemic solution, namely, the resolution effect is generated on the two enantiomers.
6. Use according to claim 5, characterized in that: in application, the distribution coefficient of the L-Glu and the D-Glu satisfies the following relation:
wherein K is the selectivity coefficient of the imprinted material MIP-PSSS/PSA to L-Glu relative to the enantiomer D-Glu, and the size of the K value marks the recognition selectivity of the imprinted material MIP-PSSS/PSA to L-Glu; in the above formula:
wherein, Kd(mL•g-1) Is the partition coefficient of a certain enantiomer Ce (mg•mL-1) Is the equilibrium concentration of the enantiomer in the supernatant, Qe (mg•g-1) Is the equilibrium binding capacity of the enantiomer.
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| CN105693960A (en) * | 2016-03-03 | 2016-06-22 | 华南师范大学 | Method for preparing glutamic acid surface molecularly imprinted polymer silica microspheres |
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| CN101216464A (en) * | 2007-12-29 | 2008-07-09 | 中国农业大学 | Molecular blotting polymer microsphere for detecting malachite green |
| CN103998932A (en) * | 2011-06-29 | 2014-08-20 | 中央研究院 | Capture, purification and release of biological substance using a surface coating |
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