Star-shaped beta-poly(malic acid) and a preparation method and application thereof

Abstract

The application discloses star-shaped beta-poly(malic acid) and a preparation method and application thereof, and belongs to the technical field of high polymer materials.The star-shaped beta-poly(malic acid) disclosed by the application is a brand-new poly(malic acid) derivative, has unique physical and chemical properties and special three-dimensional structure, and has a reduced degradation speed, so that the star-shaped beta-poly(malic acid) can effectively prevent being prematurely removed in a body.When the star-shaped beta-poly(malic acid) is used as a drug carrier, the star-shaped beta-poly(malic acid) can not only have good biocompatibility and rich modifiable functional groups of linear poly(malic acid), but also slow down the metabolic clearance rate in the body, prolong the in-vivo circulation of the drug, and has good potential application value in drug delivery, polymer material modification and tissue engineering.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a biodegradable polymer material and its preparation method, and more specifically to a star-shaped β-polymalic acid, its preparation method, and its application. Background Technology

[0002] β-Polymalic acid (PMLA) is an aliphatic polyester with malic acid as its sole monomer. It exhibits excellent water solubility and biocompatibility. In vivo, PMLA degrades into smaller malic acid molecules, which are then metabolized into carbon dioxide and water, without accumulating toxicity. Furthermore, compared to other pharmaceutical polymers, each structural unit of PMLA contains a carboxyl group, allowing for covalent bonding of functional groups such as drugs, tracer molecules, and targeting groups. Therefore, PMLA is an excellent drug carrier material.

[0003] The polymalic acid currently being studied is a linear polymalic acid with a single chain segment. It degrades too quickly, which can easily lead to premature drug release when used as a drug carrier. It also causes polymalic acid to be metabolized too quickly in vivo, which is not conducive to the accumulation of drugs at the target site. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a star-shaped β-polymalic acid, its preparation method and application, so as to solve the technical problems of low molecular weight and poor degradation performance of existing star-shaped polymalic acid.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] This invention discloses a star-shaped β-polymalic acid, which has polybenzoic acid as the core and β-polymalic acid or its derivatives as the arms.

[0007] The number of arms is 3-6, and the number of malic acid structural units contained in each arm is 10-100.

[0008] Preferably, it includes three-armed polymalic acid, four-armed polymalic acid, and six-armed polymalic acid; wherein, the structural formula of the three-armed polymalic acid is as follows:

[0009]

[0010] The structural formula of the four-armed polymalic acid is as follows:

[0011]

[0012] The structural formula of the six-armed polymalic acid is as follows:

[0013]

[0014] Where n = 10 to 100.

[0015] Preferably, the polybenzoic acid includes pyromellitic acid, pyromellitic tetracarboxylic acid, or phenylhexacarboxylic acid.

[0016] Preferably, the derivatives of β-polymalic acid include methyl ester, ethyl ester, butyl ester, and benzyl ester derivatives of β-polymalic acid.

[0017] This invention also discloses a method for preparing the above-mentioned star-shaped β-polymalic acid, comprising the following steps:

[0018] 1) Prepare polybenzoic acid-tetraethylammonium or polycarboxylic acid-naphthalene potassium initiator solution systems;

[0019] 2) Place the initiator solution obtained in step 1) into a reactor, remove the solvent by vacuum, add the polymerization monomer under a nitrogen atmosphere, react after vacuuming, and obtain a solid product.

[0020] 3) Add one drop of concentrated hydrochloric acid to the solid product solution in acetone to terminate the reaction, then add cold diethyl ether to precipitate the product, and collect the solid product, namely star-shaped polybenzyl malate.

[0021] 4) Dissolve star-shaped polymethyl malate in a solvent, add palladium on carbon catalyst, and react with hydrogen gas until the amount of hydrogen gas no longer decreases. Filter to remove the palladium on carbon catalyst, evaporate to remove the solvent, and obtain star-shaped β-polymalic acid.

[0022] Preferably, in step 1), the polybenzoic acid-tetraethylammonium initiator solution system is an initiator system formed by tribenzoic acid, tribenzoic acid or hexabenzoic acid and tetraethylammonium hydroxide or tetramethylammonium hydroxide; the polybenzoic acid-potassium naphthalene initiator solution system is an initiator system formed by tribenzoic acid, tribenzoic acid or hexabenzoic acid and potassium naphthalene.

[0023] Preferably, the molar ratio of the polymerizable monomer to the initiator is (10-1000):1.

[0024] Preferably, in step 2), the reaction temperature is 20–70°C and the reaction time is 6–168 h.

[0025] Preferably, in step 2), the polymerization monomer is selected as β-benzyloxycarbonyl-β-propiolactone, which is synthesized from L-aspartic acid or L-malic acid.

[0026] This invention also discloses the application of the above-mentioned star-shaped β-polymalic acid as a drug carrier material.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The star-shaped β-polymalic acid disclosed in this invention is a novel polymalic acid derivative. A star polymer is a branched polymer composed of multiple linear polymers connected at the same central point. Compared to linear polymers of the same molecular weight, star polymers possess a three-dimensional spherical structure and a smaller hydrodynamic volume. Furthermore, due to their different spatial structure, star polymers degrade more slowly than their linear counterparts. The star-shaped polymalic acid synthesized in this invention exhibits unique physicochemical properties and a special three-dimensional structure, resulting in a slower degradation rate and effectively preventing premature clearance in vivo. Therefore, when the star-shaped β-polymalic acid of this invention is used as a drug carrier, in addition to possessing the good biocompatibility and abundant modifiable functional groups of linear polymalic acids, it can also slow down their in vivo metabolic clearance rate, prolonging drug circulation. It has significant potential applications in drug delivery, polymer material modification, and tissue engineering.

[0029] The synthesis method disclosed in this invention uses a polycarboxylic acid initiator to synthesize star-shaped polymalic acid with 3 to 8 different numbers of branches and chain lengths of 2kDa to 100kDa through anionic ring-opening polymerization. The resulting polymalic acid is then used as a carrier to prepare drug-loaded nanoparticles for the delivery of antitumor drugs. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the water-soluble star-shaped polymalic acid structure of the present invention;

[0031] Figure 2 The synthetic route for the pyromellitic acid-tetraethylammonium initiator;

[0032] Figure 3 The synthetic route for three-armed polymalic acid;

[0033] Figure 4 The 1H NMR spectrum of the three-armed polymalic acid;

[0034] Figure 5 The infrared absorption spectrum of the three-armed polymalic acid is shown.

[0035] Figure 6 The GPC spectrum of the four-armed polymalic acid;

[0036] Figure 7 The nuclear magnetic resonance spectrum of the 3-arm-PMLA-DOX graft;

[0037] Figure 8 The degradation curves are for linear polymalic acid and three-armed polymalic acid. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0039] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] The present invention will now be described in further detail with reference to the accompanying drawings:

[0041] See Figure 1 The figure shows a schematic diagram of the structure of the star-shaped β-polymalic acid of the present invention. The figure includes three types of star-shaped β-polymalic acid, namely three-armed polymalic acid, four-armed polymalic acid and six-armed polymalic acid.

[0042] The number of β-polymalic acid structural units (monomers) contained in the arms of the aforementioned star-shaped polymalic acid is 10 to 1000, corresponding to a molecular weight of 11.6 to 116 kDa.

[0043] The method for synthesizing star-shaped β-polymalic acid disclosed in this invention includes the following steps:

[0044] 1) Preparation of polybenzoic acid-tetraethylammonium or polybenzoic acid-naphthalene potassium initiation system;

[0045] The synthetic route for the trimesolic acid-tetraethylammonium initiator is as follows: Figure 2 As shown;

[0046] 2) First, add the initiator solution to the reactor, remove the solvent by evacuation, purge with nitrogen, then add the monomer β-benzyloxycarbonyl-β-propiolactone, evacuate to approximately 0.15 mmHg, and react at a certain temperature to obtain a solid. After the reaction stops, add acetone to dissolve the solid, then add one drop of concentrated hydrochloric acid, followed by cold diethyl ether, and collect the white solid, which is star-shaped polybenzyl malate. See the synthetic route for details. Figure 3 ;

[0047] 3) Dissolve the obtained white solid in dioxane, add dry palladium on carbon catalyst, and react with hydrogen gas until the amount of hydrogen gas no longer decreases;

[0048] 4) Filter to remove palladium on carbon, evaporate to remove solvent, and obtain star-shaped β-polymalic acid.

[0049] Preferably, the initiator in step 1) is a polybenzoic acid-tetraethylammonium initiating system formed by tribenzoic acid, tetrabenzoic acid, benzohexacarboxylic acid and tetraethylammonium hydroxide or tetramethylammonium hydroxide, or a polybenzoic acid-naphthalene potassium initiating system formed by polybenzoic acid and potassium naphthalene.

[0050] Preferably, the monomer mentioned in step 2) is β-benzyloxycarbonyl-β-propiolactone. It is synthesized using L-aspartic acid or L-malic acid as a starting material.

[0051] The molar ratio of the monomer initiator is 10:1 to 1000:1.

[0052] The reaction temperature is 20–70°C.

[0053] The reaction time is 6 hours to 7 days.

[0054] Example 1

[0055] A method for preparing a star-shaped three-armed polymalic acid includes the following steps:

[0056] 1) Weigh 1 mmol of trimesic acid, dissolve it in ethanol, and add 3 mmol of 10% aqueous solution of tetraethylammonium hydroxide under N2 protection in an ice-water bath. React for 1 hour in an ice-water bath. Dry to obtain a white solid, quickly dissolve it in 10 mL of anhydrous ethanol, and store at low temperature for later use.

[0057] 2) Measure 10 μL of the initiator solution and add it to the reaction flask. Remove the solvent under vacuum until a solid precipitates. Under N2 protection, add 10 mmol of β-benzyloxycarbonyl-β-propiolactone. After the reaction stops, the polymer dissolves in acetone. Add one drop of concentrated hydrochloric acid, then add a large amount of diethyl ether to precipitate the solid. Dry under vacuum to obtain three-arm polybenzyl malate (3-arm-PBM).

[0058] 3) The dried 3-arm-PBM was dissolved in dioxane to prepare a 5% wt solution. Pd / C catalyst was added in proportion, hydrogen was introduced, and hydrogenation reaction was carried out at room temperature. After stirring until the hydrogen no longer decreased, palladium on carbon was filtered, the filtrate was concentrated, the polymer was precipitated in diethyl ether, dried, dialyzed in deionized water for 24 h, and lyophilized to obtain three-arm polymalic acid (3-arm-PMLA).

[0059] The proton NMR spectrum of the prepared three-armed polymalic acid is shown below. Figure 4 As shown, the infrared absorption spectrum is as follows: Figure 5 As shown.

[0060] Example 2

[0061] A method for preparing a star-shaped three-armed polymalic acid includes the following steps:

[0062] 1) The initiator preparation is the same as in Example 1.

[0063] 2) Measure 2 μL of initiator solution and add it to the reaction flask. Remove the solvent under vacuum until a solid precipitates. Under N2 protection, add 10 mmol of β-benzyloxycarbonyl-β-propiolactone. After the reaction stops, the polymer dissolves in acetone. Add one drop of concentrated hydrochloric acid, then add a large amount of diethyl ether to precipitate the solid. Dry under vacuum to obtain three-arm polybenzyl malate (3-arm-PBM).

[0064] 3) The hydrogenation process of 3-arm-PBM is the same as in Example 1.

[0065] Example 3

[0066] A method for preparing a star-shaped four-armed polymalic acid includes the following steps:

[0067] 1) Weigh 1 mmol of pyromellitic acid, dissolve it in ethanol, and add 4 mmol of 10% aqueous solution of tetraethylammonium hydroxide in an ice-water bath under N2 protection. React for 1 hour in an ice-water bath. Dry to obtain a white solid, quickly dissolve it in 10 mL of anhydrous ethanol, and store at low temperature for later use.

[0068] 2) The polymerization process is the same as in Example 1, yielding four-arm polybenzyl malate (4-arm-PBM).

[0069] 3) The hydrogenation process is the same as in Example 1, yielding four-arm polymalic acid (4-arm-PMLA).

[0070] The GPC spectrum of the prepared four-armed polymalic acid is as follows: Figure 6 As shown.

[0071] Example 4

[0072] A method for preparing a star-shaped six-armed polymalic acid includes the following steps:

[0073] 4) Weigh 1 mmol of benzenehexane, dissolve it in ethanol, and add 6 mmol of 10% aqueous solution of tetraethylammonium hydroxide in an ice-water bath under N2 protection. React for 1 hour in an ice-water bath. Dry to obtain a white solid, quickly dissolve it in 10 mL of anhydrous ethanol, and store at low temperature for later use.

[0074] 5) The polymerization process is the same as in Example 1, yielding six-arm polybenzyl malate (6-arm-PBM).

[0075] 6) The hydrogenation process is the same as in Example 1, yielding six-arm polymalic acid (6-arm-PMLA).

[0076] Example 5

[0077] Application of astrocytomalic acid as a drug carrier

[0078] Taking the three-armed polymalic acid obtained in Example 1 as an example, it is prepared into a drug carrier, including the following steps:

[0079] 1) Dissolve 1 mmol each of 3-arm-PMLA, EDC·HCl and N-hydroxysuccinimide (NHS) in DMSO and react at room temperature for 6 h to activate the carboxyl group on star PMLA.

[0080] 2) Add 3 mmol of doxorubicin, stir overnight at room temperature in the dark, and after the reaction is complete, dialyze to remove the solvent and small molecules, and freeze dry to obtain the 3-arm-PMLA-DOX graft.

[0081] The nuclear magnetic resonance spectrum of the prepared 3-arm-PMLA-DOX graft is as follows: Figure 7 As shown.

[0082] The star-shaped three-armed polymalic acid obtained in Example 1 and ordinary linear polymalic acid were subjected to degradation experiments. Both were dissolved separately in PBS buffer solution with a pH of 7.2–7.4, and 0.1% sodium azide was added to inhibit bacterial growth. The solutions were shaken at a constant temperature of 37°C. A small amount of solution was taken every three days, and its molecular weight (weight-average molecular weight Mw) was determined by gel chromatography. The degradation curves obtained by plotting time on the x-axis and normalized molecular weight (determined molecular weight / initial molecular weight) on the y-axis are shown below. Figure 8 As shown in the figure, 3-arm-PMLA exhibits similar degradation behavior to linear PMLA, but its degradation rate is significantly lower than that of PMLA.

[0083] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A star-shaped β-polymalic acid, characterized in that, This star-shaped β-polymalic acid has polybenzoic acid as its core and β-polymalic acid or its derivatives as its arms; the derivatives of β-polymalic acid are methyl ester, ethyl ester, butyl ester or benzyl ester of β-polymalic acid; The number of arms is 3-6, and the number of malic acid structural units contained in each arm is 10-100.

2. The star-shaped β-polymalic acid according to claim 1, characterized in that, Including three-armed polymalic acid, four-armed polymalic acid and six-armed polymalic acid; The structural formula of the three-armed polymalic acid is as follows: ； The structural formula of the four-armed polymalic acid is as follows: ； The structural formula of the six-armed polymalic acid is as follows: ； Where n = 10~100.

3. The star-shaped β-polymalic acid according to claim 1, characterized in that, Polybenzoic acids include pyromellitic acid, pyromellitic tetracarboxylic acid, or phenylhexacarboxylic acid.

4. The method for preparing star-shaped β-polymalic acid according to any one of claims 1 to 3, characterized in that, Includes the following steps: 1) Prepare a polybenzoic acid-tetraethylammonium initiator solution system or a polybenzoic acid-naphthalene potassium initiator solution system; 2) Place the initiator solution obtained in step 1) in a reactor, remove the solvent by vacuum, add the polymerization monomer under a nitrogen atmosphere, react after vacuuming, and obtain a solid product. 3) Dissolve the solid product in acetone, add a drop of concentrated hydrochloric acid to terminate the reaction, then add cold diethyl ether to precipitate the product, and collect the solid product, namely star-shaped polybenzyl malate. 4) Dissolve star-shaped polymethyl malate in a solvent, add palladium catalyst on carbon, and react with hydrogen gas until the amount of hydrogen gas no longer decreases. Filter to remove the palladium catalyst on carbon, evaporate to remove the solvent, and obtain star-shaped β-polymalic acid.

5. The method for preparing star-shaped β-polymalic acid according to claim 4, characterized in that, In step 1), the polybenzoic acid-tetraethylammonium initiator solution system is an initiator system formed by pyromellitic acid, pyromellitic tetracarboxylic acid or hexacarboxylic acid and tetraethylammonium hydroxide or tetramethylammonium hydroxide; the polybenzoic acid-potassium naphthalene initiator solution system is an initiator system formed by pyromellitic acid, pyromellitic tetracarboxylic acid or hexacarboxylic acid and potassium naphthalene.

6. The method for preparing star-shaped β-polymalic acid according to claim 4, characterized in that, The molar ratio of monomer to initiator is (10~1000):

1.

7. The method for preparing star-shaped β-polymalic acid according to claim 4, characterized in that, In step 2), the reaction temperature is 20~70 ℃ and the reaction time is 6 h~168 h.

8. The method for preparing star-shaped β-polymalic acid according to claim 4, characterized in that, In step 2), the polymerization monomer is selected as β-benzyloxycarbonyl-β-propiolactone, which is synthesized from L-aspartic acid or L-malic acid.

9. The use of the star-shaped β-polymalic acid as described in claim 1 or 2 as a drug carrier material.

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