CN106883360B - Functionalized stimuli-responsive polymers and methods for their preparation - Google Patents

Abstract

The present invention relates to a functionalized stimulus-responsive polymer and a preparation method thereof. The polymer is obtained by controllable polymerization of two radicals through two free radicals. The obtained amphiphilic block polymer has a furan functional group at the end that can be functionalized and modified, and a main chain with a reducible responsive disulfide bond. The outer layer of the hydrophilic shell of the nanomaterial prepared from this polymer can be modified in situ by the Diels-Alder reaction. dissociation of its nanostructures in the presence of This polymer material has great potential application value in the field of intelligent drug delivery.

Description

Functionalized stimuli-responsive polymers and methods for their preparation

technical field

The present invention relates to a functionalized stimulus-responsive polymer and a preparation method thereof.

Background technique

Smart polymer materials are a new class of materials developed rapidly in the 21st century. Because it imitates the living system, when the physical, chemical and even biological stimulation signals of the external environment are sensed, certain properties of the polymer itself, such as shape, hydration state, surface energy, penetration rate or recognition ability, will change in response. . Combined with the development of nanotechnology, polymer smart nanomaterials constructed by integrating the response behavior of polymer intelligence and the characteristics of nanoscale materials are one of the fastest growing high-tech cutting-edge functional materials in recent years. Green energy storage materials and other fields have broad application potential, especially in the fields of drug intelligent delivery and other fields. With the help of polymer nanomaterials as carriers of therapeutic active ingredients, it is no longer impossible to deliver organic molecular drugs, load specific proteins, and gene drugs. In the past, the requirements for carrier-based polymer nanomaterials were relatively simple, as long as they were non-toxic, good biocompatibility and the ability to simply encapsulate active ingredients. With the development of science, people have higher and higher requirements for the design of polymer nanomaterials, and the development of intelligence and multi-functionality has become the mainstream research and application direction. The realization of the intelligentization of nano-polymer carriers is mainly considered in the following two aspects:

1. The surface can be functionalized. Substances with different functional properties, such as targeting molecules, proteins, antibodies, etc., can be effectively introduced on the surface of polymer nanomaterials coated with active ingredients, so as to realize various functional applications of drug-carrying systems and enhance the effect of intelligent delivery. At the same time expand its application field.

2. Endow polymer nanomaterials with the ability to respond intelligently. The intelligent response of polymer materials is triggered by external stimulation, so as to achieve the purpose of timed, fixed-point and quantitative controllable delivery of active ingredients. In the field of preparing stimuli-responsive polymer nanomaterials, a variety of polymer nanomaterials that respond to different stimuli are developed. For example, temperature response, pH response, light response, reduction response, and the like. Among them, the reduction-responsive polymer nano-drug delivery system can make different changes according to the concentration difference of the reducing substance glutathione in different environments (intracellular and extracellular) in the human body to achieve selective intracellular drug delivery. Therefore, such materials It is regarded as one of the polymer carrier materials that can be practically applied on a large scale in the future.

Common polymer carrier-based nanomaterials often only have a single stimuli-responsive property. To truly realize the smart delivery properties of nano-polymer nanomaterials, functional modification and stimuli-responsive properties must be organically combined to give full play to nanopolymerization. The real application value of biological nanomaterials in the field of intelligent drug delivery/release.

SUMMARY OF THE INVENTION

One of the objects of the present invention is to provide a functionalized stimulus-responsive polymer. The polymer is an amphiphilic block polymer with furan functional groups at the end and disulfide bonds in the main chain.

The second objective of the present invention is to provide a preparation method of the polymer nanomaterial.

In order to achieve the above purpose of the invention, the amphiphilic block polymer of the present invention is synthesized from a styrene-based monomer (VBOEG) containing a polyethylene glycol short chain and a monomer containing a cholesterol moiety through two living controllable polymerization. , in which VBOEG monomer is polymerized by Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT) to obtain a hydrophilic block polymer, and the end functional modification is introduced into Atom Transfer Radical Polymerization (Atom Transfer Radical Polymerization) containing disulfide bonds. Radical Polymerization, ATRP) initiating group to achieve the target amphiphilic block polymer by ATRP polymerization of acrylate monomers containing cholesterol. On this basis, the polymer spherical nanomaterials were prepared by the solvent replacement method. The specific reaction formula is:

According to above-mentioned reaction mechanism, the present invention adopts following technical scheme as follows:

A functionalized stimulus-responsive polymer is characterized in that the structural formula of the polymer is:

Among them, m=10～30; n=10～90.

A method for preparing the above-mentioned functionalized stimulus-responsive polymer, characterized in that the specific steps of the method are:

a. Dissolve chain transfer agent, styrene monomer containing polyethylene glycol short chain and azobisisobutyronitrile in dioxane in a molar ratio of 1:(20~50):(0.1~0.3) , after sealing, carry out dewatering and deoxidizing operation, and then stir and react at 60～80℃ for 12～36 hours, after the reaction is finished, precipitating and purifying in solvent and ether to obtain hydrophilic block polymer PVBOEG.

b. Dissolve PVBOEG and n-hexylamine obtained in step a in dichloromethane at a molar ratio of 1: (5～50), carry out water and oxygen removal operations, and stir the reaction at room temperature for 10 to 24 hours. After the reaction is completed, remove the solvent , precipitating and purifying in ether to obtain the polymer product PVBOEG-SH with a thiol group at the end.

c. Dissolve the above product PVBOEG-SH and the ATRP small molecule initiator containing disulfide bonds in methanol at a molar ratio of 1:10-50, stir and react at room temperature for 16-24 hours, then precipitate and purify in diethyl ether to obtain the target ATRP macroinitiator PVBOEG-SS-Br.

d. Under an inert atmosphere, combine the PVBOEG-SS-Br, cuprous bromide, cholesterol-containing monomer and pentamethyldiethylenetriamine obtained in step c according to 1:(2~5):(20~100 ): (2～5) molar ratio is dissolved in toluene, after dewatering and deoxygenating operation, at 70～80 ℃ temperature, stirring and reacting for 18～48 hours; after the completion of the reaction, remove the copper salt in the product. The stimuli-responsive polymer that can be functionalized with the target polymer was obtained after precipitation purification in methanol and vacuum drying.

；含有聚乙二醇短链的苯乙烯类单体的化学结构式如下：

；含有双硫键的ATRP小分子引发剂的化学结构式如下：

；所述含胆固醇基元的单体的化学结构式如下：

。The structural formula of the chain transfer agent is:

; The chemical structural formula of styrene monomers containing polyethylene glycol short chains is as follows:

; The chemical structural formula of the ATRP small molecule initiator containing disulfide bonds is as follows:

; The chemical structural formula of the monomer containing cholesterol is as follows:

.

The polymer nanomaterial prepared by using the functionalized stimulus-responsive polymer of the present invention has a particle size within 30-500 nm, uniform distribution and regular shape. The specific steps of the preparation method are as follows: dissolving the functionalized stimulus-responsive polymer in a certain amount of tetrahydrofuran to prepare a solution of 0.1wt%-1wt%, and slowly dissolving 1-3 times the volume of deionized water. Add dropwise to the polymer solution. It is then dialyzed through a dialysis bag (molecular weight cut-off 3500 Da). Finally, an aqueous solution of polymer spherical nanomaterials is obtained.

The functionalized stimulus-responsive polymer of the present invention has a specific functionalized furan functional group at the end, and the hydrophilic block and the hydrophobic block are connected by a reduction-responsive disulfide bond. Therefore, it has both functionalized modification ability and reduction stimulus response ability in the same polymer system. The surface of the polymer nanomaterials prepared by the solvent replacement method can be modified with various functionalities as required. As an active ingredient carrier material, it also has the ability to respond intelligently to release. This polymer material has a huge potential application in the field of intelligent drug delivery. value.

Description of drawings

Fig. 1 is the ¹ HNMR spectrum of the block polymer PVBOEG-SS-PAChol of the present invention.

FIG. 2 is a GPC curve diagram of the molecular weight change of the block polymer PVBOEG-SS-PChol of the present invention after being acted on with dithiothreitol for different times.

Figure 3 is a TEM photograph of spherical nanomaterials prepared from the block polymer PVBEOG-SS-PAChol of the present invention.

Detailed ways

Preferred embodiments of the present invention are described in detail as follows:

Example 1:

(1) In a dry 25 mL Schlenk reaction flask, add styrene monomer containing polyethylene glycol short chain (3.65 g), Furan-RAFT reagent (95.5 mg), azobisisobutyronitrile (8.8 mg) and 5 mL of dioxane. After sealing with a rubber stopper, the reaction flask was immersed in a preheated 65 ^o C oil bath after dehydration and deoxygenation, and heated and stirred for 24 hours. After the reaction, the solvent was removed by rotary evaporation, and the product was purified by precipitation in 40 mL of ether to obtain the product PVBOEG.

(2) PVBOEG (700 mg), n-hexylamine (90 mg), and 3 mL of dichloromethane were added to a 10 mL reaction flask, and after water and oxygen removal operations were performed. Stir for 24 hours. After removal of the solvent by rotary evaporation, three precipitations in 40 mL of ether gave the product PVBOEG-SH. Add PVBOEG-SH and small molecule ATRP initiator, 3 mL methanol to a 10 mL Schlenk reaction flask. After stirring for 24 hours, the solvent was removed by rotary evaporation, purified by precipitation in 40 mL of ether for three times, and the target macroinitiator PVBOEG-SS-Br was obtained after vacuum drying.

(3) Put PVBOEG-SS-Br (60 mg), cuprous bromide (3.2 mg), and monomer containing cholesterol moiety (373 mg) into a dry 10 mL Schlenk reaction tube, under nitrogen protection, put five A solution of methyldiethylenetriamine (5.2 mg) in toluene (0.6 mL) was added to the reaction tube. After dehydration and deoxygenation, the reaction tube was immersed in a preheated 80 ^o C oil bath and stirred for 24 hours. After the reaction is over, use an overbased alumina column to remove copper salts in the product. It was purified by precipitation in methanol, and the target polymer was obtained after vacuum drying. See Figure 1 for NMR.

Embodiment 2:

In this example, dithiothreitol was selected as the reducing agent to explore the reduction response ability of the block polymer. The specific implementation process is as follows: The block polymer (2 mg) and dithiothreitol (2.5 mg) were dissolved in dichloromethane (1 mL). After the system was deoxygenated, the stirring reaction was started. Samples were taken for molecular weight testing by gel permeation chromatography of the tetrahydrofuran phase at 24 hours and 8 hours after the start of the reaction, respectively. See Figure 2. Compared with the original polymer, after the reaction of PVBOEG-SS-PAChol with dithiothreitol for 24 hours, the peak time was delayed, and the disulfide bond was broken, resulting in a decrease in the molecular weight of the polymer. After 48 hours of reaction, the molecular weight of the polymer decreased and the block polymer was decomposed into two homopolymers. This demonstrates the ability of the block polymer to respond to reducing environments.

Embodiment three:

A polymer spherical nanomaterial prepared by a solvent replacement method. The specific implementation process is as follows: the above-mentioned amphiphilic block polymer (0.5 mg) was dissolved in tetrahydrofuran (1 mL) to prepare a solution, and deionized water (1 mL) was added to the polymer solution at a drop rate of 10 μL/min. middle. During the dropwise addition, the solution was continuously shaken to mix evenly until the deionized water was added dropwise. Then, it was dialyzed through a dialysis bag (molecular weight cut-off of 3500 Da), and finally an aqueous solution of polymer spherical nanomaterials was obtained. The microscopic morphology of the polymerized nanomaterials was observed by transmission electron microscopy, see Figure 3, the morphology was spherical in size between 60-100 nm, the size was relatively consistent, and the distribution was uniform.

Embodiment 4:

In this example, fluorescein 5-maleimide was selected as the model molecule for surface modification to perform in-situ functional modification on the surface of the polymer nanomaterial. The specific implementation process is as follows: Dissolve fluorescein 5-maleimide (0.5 mg) in DMF (30 μL), mix with the aqueous solution of the above nano-spherical material, and remove unreacted fluorescein by dialysis after 12 hours. model molecule. Comparing before and after the reaction, the assembly solution after the reaction obviously has a fluorescent color, which proves that the polymer nanomaterial has the ability to modify the surface of functionalized substances in situ. Polymer carriers with such surface modifications will have great application prospects in the realization of targeted delivery of drug-loading systems.

The embodiments of the present invention have been described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and various changes can also be made according to the purpose of the invention and creation of the present invention. , modification, substitution, combination, and simplification are all equivalent substitution methods, as long as they meet the purpose of the present invention, as long as they do not deviate from the synthesis method of block polymers and the preparation method of spherical nanomaterials and the technical principle of application of the present invention and inventive concept, all belong to the protection scope of the present invention.

Claims (4)

1. A functionalizable stimulus responsive polymer characterized by the structural formula:

wherein m is 10-30; n is 10 to 90.

2. A method for preparing a functionalizable stimuli-responsive polymer, characterized in that the method comprises the following specific steps:

a. and (2) mixing a chain transfer agent, a styrene monomer containing polyethylene glycol short chain and azobisisobutyronitrile according to the weight ratio of 1: (20-50): (0.1-0.3) dissolving in dioxane in a molar ratio, sealing, performing water removal and oxygen removal operation, stirring at the temperature of 60-80 ℃ for reaction for 12-36 hours, removing the solvent by rotary evaporation after the reaction is finished, and precipitating and purifying in ether to obtain a product PVBOEG;

b. and (c) mixing the PVBOEG and the n-hexylamine obtained in the step a according to the proportion of 1: (5-50) dissolving in dichloromethane in a molar ratio, performing water removal and oxygen removal operation, stirring at room temperature for reaction for 10-24 hours, removing the solvent after the reaction is finished, and precipitating and purifying in diethyl ether to obtain a product PVBOEG-SH;

c. the product PVBOEG-SH and ATRP micromolecule initiator containing disulfide bonds are added according to the proportion of 1: dissolving the 10-50 molar ratio in methanol, stirring at room temperature for reaction for 16-24 hours, and then precipitating and purifying in diethyl ether to obtain a target ATRP macromolecular initiator PVBOEG-SS-Br;

d. and c, under an inert atmosphere, mixing the PVBOEG-SS-Br, cuprous bromide, a monomer containing a cholesterol group and pentamethyl diethylenetriamine obtained in the step c according to the weight ratio of 1: (2-5): (20-100): (2-5) dissolving the mixture in toluene in a molar ratio, performing water removal and oxygen removal, and stirring to react for 18-48 hours at the temperature of 70-80 ℃; removing copper salt in the product after the reaction is finished; precipitating and purifying in methanol, and vacuum drying to obtain the target polymer functionalized stimulus responsive polymer.

3. A polymer spherical nano material prepared by using the block polymer as the raw material according to claim 1, wherein the size of the nano microsphere is between 30 and 500 nm; the hydrophilic shell and the hydrophobic core of the nano microsphere are connected by a disulfide bond, and the surface of the nano microsphere is provided with a furan group capable of being functionally modified.

4. A method for preparing nano-microspheres according to claim 3, characterized in that the method comprises the following specific steps: dissolving the amphiphilic block polymer in tetrahydrofuran to prepare 0.1-1 wt% solution, and slowly dripping 1-3 times of volume of deionized water into the polymer solution; and dialyzing with deionized water to obtain the polymer spherical nano material.

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