CN104017126A - Tocopherol molecularly imprinted fluorescent polymer and preparation method and application thereof - Google Patents

Abstract

The invention relates to a preparation method of a molecularly imprinted fluorescent polymer of tocopherol, which comprises the following steps: taking tocopherol as a template molecule, adding quantum dot fluorescent nanomaterials, adopting a functional monomer capable of forming a hydrogen bond with the template molecule, and adding a crosslinking agent In the presence of an initiator, thermal polymerization is carried out to obtain a fluorescent polymer, and then the tocopherol in the polymer is removed to obtain the tocopherol molecularly imprinted fluorescent polymer. The molecularly imprinted fluorescent polymer prepared by the present invention has the advantages of regular shape, high mechanical strength, good selective adsorption effect, and good physical and chemical properties, and can be used to separate, purify, and enrich tocopherol from complex food matrices such as oil and rice. have a broad vision of application.

Description

A kind of tocopherol molecularly imprinted fluorescent polymer and its preparation method and application

technical field

The invention relates to the technical field of molecularly imprinted polymers, in particular to a tocopherol molecularly imprinted fluorescent polymer and a preparation and application method thereof.

Background technique

Tocopherol, also known as vitamin E, is a derivative of dihydrobenzofuran-6-ol, a fat-soluble vitamin with high biological activity, high safety, and easy absorption by the human body. Pure tocopherol is an odorless viscous light yellow liquid, easily soluble in alcohol, ether, acetone, benzene, chloroform and other organic solvents and oils, but insoluble in water. Its melting point is 2.5-3.5°C, its density (25°C) is 0.95g/cm ³ , and its boiling point is 200-220°C under the molecular distillation condition of 66.7pa. Tocopherol is relatively stable to heat, and will not be destroyed even at a high temperature of 200°C. Natural tocopherol has antioxidant effect, it not only has the effect of interrupting oxidative free radicals, but also can quench singlet oxygen. Tocopherol is one of the widely used antioxidants.

Molecular imprinting technology is a technology developed in the past 20 years that specifically selects a specific molecule (template molecule), and is regarded as a new type of specific affinity technology. Polymers prepared by this technique are called molecularly imprinted polymers. Because molecularly imprinted polymers can specifically bind to template molecules, the preparation method is simple, they can be used repeatedly, they have high mechanical strength and good stability, molecularly imprinted polymers have been widely used in chromatographic columns, solid phase extraction, and membrane extraction in recent years. , materials for artificial antibodies and sensors.

Quantum dots are three-dimensional clusters, which are composed of a limited number of atoms, and the size is on the order of nanometers. The physical behavior of this three-dimensional system, such as optical and electrical properties, is similar to atoms, so it is called "artificial atoms". Quantum dots are generally spherical or quasi-spherical, with a particle size of 1 to 10 nm. They are aggregates of atoms and molecules at the nanometer scale. Quantum dot fluorescent materials are a class of nanomaterials that have been widely studied in recent years. Due to their unique photoluminescent properties (good photostability, long fluorescence lifetime, adjustable fluorescence emission wavelength, and high quantum yield), High sensitivity and large specific surface area make them play an increasingly important role as fluorescent probes in the fields of biomarkers, biodetection, and bioimaging.

Therefore, it is hoped to provide a molecularly imprinted fluorescent polymer of tocopherol, which combines the traditional molecular imprinted technology with a new type of quantum dot fluorescent nanomaterial, so as to realize the rapid detection technology of the target molecule-tocopherol, which is fast, simple and practical. Strong and other advantages.

Contents of the invention

The problem to be solved by the present invention is to provide a molecularly imprinted tocopherol fluorescent polymer with simple preparation process, high mechanical strength, good physical and chemical properties, and strong selective adsorption capacity, as well as its preparation method and application.

In order to solve the above technical problems, the technical solution adopted in the present invention is: a tocopherol molecularly imprinted fluorescent polymer, using tocopherol as a template molecule, adding quantum dot fluorescent nanomaterials, and using functional monomers that can form hydrogen bonds with template molecules , in the presence of cross-linking agent and initiator, thermal polymerization reaction preparation.

Preferably, the functional monomer is methacrylic acid; the tocopherol is α-tocopherol; and the quantum dot fluorescent nanomaterial is CdSe/ZnS quantum dots.

Preferably, the crosslinking agent is ethylene glycol dimethacrylate; the initiator is azobisisobutyronitrile.

The present invention also provides a method for preparing the above-mentioned tocopherol molecularly imprinted fluorescent polymer, comprising the following preparation steps:

1) Preparation of molecularly imprinted fluorescent polymer: dissolve tocopherol, quantum dots and functional monomers in chloroform solution and stir for 20 to 40 minutes, preferably 30 minutes, add crosslinking agent and initiator, and blow nitrogen gas for 5 to 5 minutes 20min, preferably 10min, thermally polymerize in a water bath at 40-80°C for 12 to 36 hours, preferably in a water bath at 60°C for 20 hours, to obtain a milky white blocky polymer, grind it fully in a mortar and pass through a sample sieve, It is preferably a 200-mesh sampling sieve to obtain a powdery product;

2) Removal of template molecules: Soxhlet extraction of template molecules with methanol solution, repeated operations until no template molecules can be detected, vacuum drying to constant weight, to obtain tocopherol molecularly imprinted fluorescent polymers.

Preferably, in step 1), the molar ratio of tocopherol, quantum dots, functional monomers, crosslinking agent and initiator is 1:0.05:2-16:20-30:0.12-0.37.

Preferably, in step 1), the molar ratio of tocopherol, quantum dots, functional monomer, crosslinking agent and initiator is 1:0.05:8:25:0.27.

The present invention also provides an application of the above-mentioned tocopherol molecularly imprinted fluorescent polymer in separating, purifying or enriching tocopherol from complex food matrices.

The solution containing tocopherol is selectively and specifically adsorbed to the molecularly imprinted fluorescent polymer of tocopherol, so as to achieve the purpose of purifying and rapidly detecting the tocopherol.

The advantages and positive effects that the present invention has are:

1), the molecularly imprinted fluorescent polymer prepared by the method of the present invention has the advantages of regular shape, high mechanical strength, good refinement performance, good selective adsorption effect, etc., and can be used for separation from complex food matrices such as oil and rice, Purification and enrichment of tocopherol has broad application prospects.

2), the preparation method of the molecularly imprinted fluorescent polymer in the present invention is simple, the process is scientific, the cost is low, the operation is simple, the reaction conditions are mild and easy to control, and it can specifically and selectively separate and quickly detect tocopherol, which provides a basis for subsequent applications. The preparation method is simple and convenient, and is suitable for large-scale popularization and application.

Detailed ways

The present invention combines molecular imprinting technology with quantum dot fluorescent nanomaterials to synthesize materials with highly selective adsorption of tocopherol. The specific preparation steps are as follows:

1) Preparation of molecularly imprinted fluorescent polymer: Dissolve 1 mmol of template molecule tocopherol and 0.05 mmol of quantum dots and functional monomers in 5.25 mL of chloroform solution and stir for 30 minutes, add cross-linking agent, 45 mg of initiator, and degas , Thermally polymerized in a water bath at 60°C for 20 hours to obtain a milky white blocky polymer, which was fully ground in a mortar and passed through a 200-mesh sieve to obtain a powder product;

2) Removal of template molecules: Soxhlet extraction of template molecules with methanol solution, repeated operations until no template molecules can be detected, vacuum drying to constant weight, and finally a tocopherol molecularly imprinted fluorescent polymer with uniform particle size.

Seven specific examples are provided, and the specific amounts of template molecules tocopherol, quantum dots, functional monomers, and cross-linking agents in Examples 1 to 7 are shown in Table 1:

Table I

Take 10 mL of the tocopherol solution with a concentration of 1.0×10 ^-4 mol L ^-1 , add 20 mg of the molecularly imprinted fluorescent polymers prepared in different molar ratios in Examples 1 to 4 above, and measure the tocopherol in the precipitate under different conditions concentration, calculate the adsorption capacity of the polymer, and the imprinting factor. The experimental results are shown in Table 2. As the molar ratio increases, the fluorescence change of the molecularly imprinted fluorescent polymer to tocopherol first decreases and then increases. Molecule: functional monomer = 1:8 is the largest. When the molar ratio is low, a complete recognition site cannot be formed, and multi-site binding between the functional monomer and the template molecule cannot be realized; when the molar ratio is high, the functional monomer is excessive, which will lead to enhanced non-specific adsorption; therefore, the template molecule is selected : functional monomer = 1: 2 ~ 1: 16 is the best molar ratio for synthesis, and template molecule: functional monomer = 1: 8 is the best molar ratio for synthesis.

Table II

Take 10 mL of the tocopherol solution with a concentration of 1.0×10 ^-4 mol L ^-1 , add 20 mg of the molecularly imprinted fluorescent polymers prepared in different molar ratios in the above-mentioned Examples 5 to 7, shake and absorb for a certain period of time, and then centrifuge ( 5000rpm, 10min), measure the concentration of tocopherol in the precipitation under different conditions, calculate the adsorption capacity of the polymer, and the imprinting factor, the experimental results are shown in Table 3, with the increase of the molar ratio, the effect of molecularly imprinted fluorescent polymer on the growth The fluorescence of phenol decreased first and then increased, and the maximum was when template molecule: crosslinking agent = 1:25. When the molar ratio is low, solid molecularly imprinted fluorescent polymers cannot be formed; when the molar ratio is high, the cross-linking agent is excessive, which will cause the diameter of the synthesized polymer to be too large, and the excessive cross-linking agent encapsulating quantum dots will lead to quantum dots Fluorescence decreases, thereby affecting the sensitivity of detection. Therefore, choosing template molecule: crosslinking agent = 1:20-1:30 is the best synthetic molar ratio, and selecting template molecule: crosslinking agent = 1:25 is the best synthetic molar ratio.

Table 3 Selection of Polymerization Reaction Crosslinking Agent

Take 20mg of tocopherol molecularly imprinted fluorescent polymer, add 10ml of 1.0×10 ^-4 mol L ^-1 tocopherol solution, mix well, shake and absorb, measure the concentration of tocopherol in the precipitate every 30 minutes, and calculate the different time Unit adsorption of tocopherol by molecularly imprinted fluorescent polymers. The experimental results show that within a certain adsorption time, the adsorption of tocopherol by molecularly imprinted polymers increases with the increase of adsorption time, and when the adsorption time is 7h, the adsorption of tocopherol by molecularly imprinted polymers tends to adsorption equilibrium . It takes a certain amount of time for the template molecules to enter the molecularly imprinted polymer. If the time is too short, the molecularly imprinted polymer cannot absorb enough tocopherol; if the adsorption time is too long, the efficiency will be reduced and even some tocopherol molecules will be desorbed and released. ; Therefore, choose 7-8h as the best adsorption time, and choose the adsorption time as 7h as the best adsorption time.

In order to better prove the beneficial effects of the present invention, seven control groups were specially set up, and 0.05mmol of quantum dots were dissolved in 5.25mL of solvent chloroform, mixed and mixed, and functional monomer A was added according to the values in Table 1. Acrylic acid, crosslinker ethylene glycol dimethacrylate, and initiator azobisisobutyronitrile. After mixing, nitrogen gas was introduced for 10 min, and the reaction system was sealed under nitrogen gas. React at 60°C for 20 hours; after the polymerization reaction, crush, grind, and sieve the synthesized polymer, and then remove template molecules with methanol solution until no template molecules can be detected; dry the polymer from which template molecules have been removed, and finally obtain Molecularly imprinted fluorescent polymer with uniform particle size.

A blank polymer was used to determine the adsorption equilibrium, and the experimental process was the same as the corresponding experimental process in the examples. The results showed that the blank polymers of the seven control groups had no adsorption capacity.

In conclusion, the tocopherol molecularly imprinted fluorescent polymer of the present invention can specifically and selectively separate tocopherol, enrich tocopherol, and provide a basis for subsequent application. The preparation method is simple and convenient, and is suitable for large-scale application.

The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and cannot be considered as limiting the implementation scope of the present invention. All equal changes and improvements made according to the creative scope of the present invention should still belong to the scope covered by this patent.

Claims (7)

1. A tocopherol molecularly imprinted fluorescent polymer, characterized in that: take tocopherol as a template molecule, add quantum dot fluorescent nanomaterials, adopt a functional monomer that can form a hydrogen bond with the template molecule, in the cross-linking agent and initiator In the presence of thermal polymerization reaction preparation. 2. The molecularly imprinted fluorescent polymer of tocopherol according to claim 1, characterized in that: the functional monomer is methacrylic acid; the tocopherol is α-tocopherol; the quantum dot fluorescent nanomaterial is CdSe /ZnS quantum dots. 3. The molecularly imprinted fluorescent polymer of tocopherol according to claim 1 or 2, characterized in that: the crosslinking agent is ethylene glycol dimethacrylate; the initiator is azobisisobutyronitrile. 4. A method for preparing the tocopherol molecularly imprinted fluorescent polymer according to any one of claims 1 to 3, characterized in that: comprising the following preparation steps: 1) Preparation of molecularly imprinted fluorescent polymer: dissolve tocopherol, quantum dots and functional monomers in chloroform solution and stir for 20 to 40 minutes, preferably 30 minutes, add crosslinking agent and initiator, and blow nitrogen gas for 5 to 5 minutes 20min, preferably 10min, thermally polymerize in a water bath at 40-80°C for 12 to 36 hours, preferably in a water bath at 60°C for 20 hours, to obtain a milky white blocky polymer, grind it fully in a mortar and pass through a sample sieve, It is preferably a 200-mesh sampling sieve to obtain a powdery product; 2) Removal of template molecules: Soxhlet extraction of template molecules with methanol solution, repeated operations until no template molecules can be detected, vacuum drying to constant weight, to obtain tocopherol molecularly imprinted fluorescent polymers. 5. The preparation method of the molecularly imprinted fluorescent polymer of tocopherol according to claim 4, is characterized in that: in step 1), the molar ratio of tocopherol, quantum dot, functional monomer, crosslinking agent and initiator is 1 :0.05:2-16:20-30:0.12-0.37. 6. The preparation method of the molecularly imprinted fluorescent polymer of tocopherol according to claim 4 or 5, is characterized in that: in step 1), the molar ratio of tocopherol, quantum dot, functional monomer, crosslinking agent and initiator For 1:0.05:8:25:0.27. 7. The application of the tocopherol molecularly imprinted fluorescent polymer as claimed in claim 1 in the separation, purification or enrichment of tocopherol from complex food matrices.