An amphiphilic block copolymer, and a method for preparing and using the same

Abstract

The application relates to an amphiphilic block copolymer and a preparation method and application thereof, the amphiphilic block copolymer has a general structure formula as shown in (I), the amphiphilic block copolymer provided by the application is terminated by Boc-phenylalanine for polymer terminal hydroxyl groups, the stability of the micelles formed is obviously improved in and out of the body, the amphiphilic block copolymer can be made into a drug loading system together with an antitumor drug and a pharmaceutically acceptable auxiliary material, and has a higher application prospect.

Description

Technical Field

[0001] This invention belongs to the field of biopolymer synthesis, specifically relating to an amphiphilic block copolymer and its micelles preparation method, and its application in drugs for treating tumor diseases. Background Technology

[0002] Polymer micelles are a type of nanomedicine delivery system developed in recent years, primarily targeting poorly soluble drugs. Polymer micelle delivery systems can significantly improve drug solubility, reduce drug toxicity and side effects, thereby increasing therapeutic doses. The drug is encapsulated in a core, preventing degradation and inactivation. To date, amphiphilic block copolymers remain the most important material for micelle formation. However, in FDA-approved drug delivery systems, the number of synthetic polymeric excipients that have truly undergone human testing and proven high safety is still very limited, primarily consisting of polyethylene glycol (PEG) and lactide / glycolic acid copolymer (PLGA). These two types of polymers and their copolymers are also being used as excipients in numerous other ongoing clinical trials.

[0003] Currently, polymer micelles using mPEG-PDLLA as a carrier are relatively mature. Depending on the molecular weight of PEG and the mPEG / PLA ratio, copolymers with different structures and molecular weights can be formed. These copolymers are amphiphilic; when forming micelles in solution, the outer layer of the micelle is composed of hydrophilic mPEG segments, and the core is composed of hydrophobic PLA segments. This property of the copolymer material can be used to solubilize some poorly soluble drugs. However, existing technologies have the following problems: First, because the terminal hydroxyl groups in mPEG-PDLLA have a certain degree of hydrophilicity, it is difficult to form a strong interaction with hydrophobic drugs, affecting the encapsulation of drugs by the micelles; second, the intermolecular forces between drug molecules and the hydrophobic chains of the copolymer are weak, making the drug easily dissolve in the micelle core; third, the formed copolymer drug micelles have poor stability. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide an amphiphilic block copolymer by capping the terminal hydroxyl groups of mPEG-PDLLA with Boc-L-phenylalanine, thereby increasing the interaction between the hydrophobic segments and the drug in the copolymer, thus improving the encapsulation ability of the copolymer for the drug when forming micelles in the aqueous phase, and thereby improving the stability of the drug-loaded micelles.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: an amphiphilic block copolymer, referring to tert-butoxycarbonylphenylalanine-terminated methoxy polyethylene glycol-polylactide block copolymer (abbreviated as mPEG-PDLLA-Phe(Boc)), having the following general structural formula:

[0006]

[0007] Where m = 44-45; n = 6-12.

[0008] The molecular formula of the amphiphilic block copolymer is CH3O(C2H4O). m (C6O4H8) n C 14 H 18 NO4; the average molecular weight is 2600-6000, of which the molecular weight of the polyethylene glycol monomethyl ether segment is 2000 and the molecular weight of the polylactic acid segment is 800-4000.

[0009] A method for preparing an amphiphilic block copolymer includes the following steps:

[0010] 1) Take polyethylene glycol monomethyl ether (mPEG) and D,L-lactide, add stannous octoate catalyst, and melt polymerize at 110℃~180℃ for 4~24 hours under nitrogen protection. Pour the obtained product into an organic solvent to crystallize, dry, and obtain intermediate mPEG-PDLLA.

[0011] Preferably, the amount of stannous octoate catalyst added is 1‰ to 10‰ of the weight of D,L-lactide.

[0012] Preferably, the organic solvent is selected from one or a mixture of two or more of anhydrous ethanol, dichloromethane, ethyl acetate, n-hexane, and anhydrous diethyl ether.

[0013] 2) Dissolve Boc-L-phenylalanine in ethyl acetate and react it with tert-butyloxycarbonyl-L-phenylalanine tert-butyl anhydride in the presence of an acid-binding agent for 5-48 h at 0-50 °C. Filter and rotary evaporate to obtain tert-butyloxycarbonyl-L-phenylalanine tert-butyl anhydride.

[0014] Preferably, the acid-binding agent is selected from triethylamine, N,N-diisopropylethylamine, tripropylamine, pyridine, potassium carbonate, sodium carbonate, and sodium hydroxide.

[0015] Preferably, the molar ratio is tert-butyloxycarbonyl-L-phenylalanine pentyl anhydride: intermediate mPEG-PDLLA = (1-10):1.

[0016] 3) Take the intermediate mPEG-PDLLA obtained in step 1) and the tert-butoxycarbonyl-L-phenylalanine pentyl anhydride obtained in step 2), add triethylamine and 4-pyrrolidinylpyridine as solvent, and carry out the end-capping reaction at 0-5℃. The crude product is purified with an organic solvent to obtain an amphiphilic block copolymer.

[0017] Preferably, the organic solvent is selected from one or a mixture of two or more of anhydrous ethanol, ethyl acetate, n-hexane, anhydrous diethyl ether, and methyl tert-butyl ether.

[0018] The above synthesis process route is as follows:

[0019]

[0020] This invention provides the application of an amphiphilic block copolymer as a carrier in the preparation of drug-loaded micelles.

[0021] A drug-loaded micelle of an amphiphilic block copolymer is prepared by the following steps: weighing the drug and the above-mentioned amphiphilic block copolymer, dissolving them in ethyl acetate, removing the ethyl acetate by rotary evaporation at 30°C, drying under vacuum at 45°C, adding water and hydrating at 45-50°C and 200 rpm to obtain a drug-loaded micelle solution.

[0022] Preferably, the drug is selected from paclitaxel, docetaxel, cabazitaxel, methotrexate, 5-fluorouracil, cyclophosphamide, doxorubicin, epirubicin, or pirarubicin.

[0023] The beneficial effects of this invention are:

[0024] 1. This invention involves capping the terminal hydroxyl groups of mPEG-PDLLA by grafting hydrophobic Boc-L-phenylalanine, increasing the hydrophobicity of the hydrophobic segments. This capping enhances the interaction between the hydrophobic segments and the drug in the copolymer, thereby improving the drug encapsulation capacity of the polymeric excipient when forming micelles in the aqueous phase, thus improving the stability of the drug-loaded micelles. This improved stability not only facilitates the scaling up of formulations using thin-film hydration processes but also allows for more effective control of product quality and leverages the EPR effect of micelles in vivo, thereby improving drug targeting and ultimately enhancing efficacy.

[0025] 2. The process conditions provided by this invention are not harsh, the process is reasonable and effective, and it has reproducibility and reliability, which can ensure that the product quality meets the requirements.

[0026] 3. The amphiphilic chimeric copolymer provided by this invention is mixed with antitumor drugs to prepare micelles, which greatly improves the solubility of antitumor drugs. The prepared micelles have small particle size, high encapsulation efficiency, and good stability, and have good application prospects.

[0027] 4. This invention improves the compatibility between drug molecules and hydrophobic segments in block copolymers, and increases the intermolecular forces between drug molecules and hydrophobic chains, making the drug less likely to dissolve in the core of micelles.

[0028] 5. This invention introduces Boc-L-phenylalanine. The benzene ring in the introduced hydrophobic group can generate a molecular π-π conjugation effect with the benzene ring in the drug, and the amide bond in Boc-L-phenylalanine can also form hydrogen bonds with the carbonyl group in the drug. This interaction helps to confine the drug within the core of the micelles, thereby increasing the stability of the micelles. Furthermore, phenylalanine is an essential amino acid for the human body, and its combination with the mPEG-PDLLA copolymer has little impact on its biocompatibility.

[0029] 6. The amphiphilic block copolymer tert-butoxycarbonylphenylalanine-terminated methoxy polyethylene glycol-polylactide block copolymer provided by the present invention is a biodegradable material with high biosafety. Attached Figure Description

[0030] Figure 1 The amphiphilic block copolymer mPEG prepared in Example 1 2000 -PDLLA 800 -Phe(Boc) 1H NMR spectrum.

[0031] Figure 2 The amphiphilic block copolymer mPEG prepared in Example 1 2000 -PDLLA 800 The molecular weight and molecular weight distribution system of -Phe(Boc).

[0032] Figure 3 The amphiphilic block copolymer mPEG prepared in Example 1 2000 -PDLLA 800 Granularity diagram of -Phe(Boc). Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments; it should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0034] Example 1: Amphiphilic block copolymer mPEG 2000 -PDLLA 800 -Phe(Boc)

[0035] (I) The preparation method is as follows:

[0036] 1. Preparation of intermediate mPEG 2000 -PDLLA 800

[0037] Weigh out 10.0g of mPEG 2000In a 100 mL polymerization flask, after dehydration under vacuum stirring at 130 °C for 3 h, 5.0 g of D,L-lactide and 5 mg of stannous octoate were added under nitrogen protection. The reaction vessel was sealed under a vacuum of -0.095 MPa or less, and the reactants were stirred in an oil bath at 130 °C for melt polymerization for 18 h. The reaction was then stopped. After cooling to room temperature, 100 mL of anhydrous ethanol was added to dissolve the reactants. After cooling and crystallization, the solid was filtered to obtain a white solid. After vacuum drying at room temperature for 24 h, 10.03 g of intermediate mPEG was obtained. 2000 -PDLLA 800 .

[0038] NMR calculation of mPEG 2000 -PDLLA 800 The molecular weight was 2839, and mPEG was determined by gel permeation chromatography (GPC). 2000 -PDLLA 800 The number-average molecular weight and molecular weight distribution coefficient were 4088 and 1.11, respectively.

[0039] 2. Preparation of tert-butyloxycarbonyl-L-phenylalanine pentyl anhydride

[0040] In a 100 mL three-necked round-bottom flask, add Boc-L-phenylalanine / anhydrous ethyl acetate solution (2.16 g Boc-L-phenylalanine dissolved in 20 mL anhydrous ethyl acetate) and 0.83 g triethylamine. After stirring to dissolve, cool to -10 to 0 °C. Add 1.0 g tert-butyloxycarbonyl chloride dropwise, stir the reaction at 0 to 10 °C for 2 h, and continue stirring at room temperature for 1 h. Filter to remove insoluble matter, and remove the solvent by rotary evaporation at -0.09 MPa under reduced pressure at 35 to 40 °C to obtain a white solid, tert-butyloxycarbonyl-L-phenylalanine tert-butyl anhydride (Boc-Phe-OCOC(CH3)3).

[0041] 3. End-capping reaction

[0042] Add 5.33 g of mPEG to a 100 mL three-necked round-bottom flask. 2000 -PDLLA 800 Add 60 mL of dichloromethane, stir to dissolve, then add the Boc-Phe-OCOC(CH3)3 obtained in step 2, cool the system to 0-5℃, add 1.35 g of triethylamine and 0.20 g of 4-pyrrolidinylpyridine, stir the resulting mixture at 0-5℃ for 1 h, then continue stirring at room temperature for 24 h, remove the solvent by rotary evaporation under reduced pressure, and the obtained polymer is the crude product mPEG-PDLLA-Phe(Boc).

[0043] The crude product was dissolved in 25 mL of anhydrous ethanol, then frozen at -10°C to crystallize, and filtered. Another 25 mL of anhydrous ethanol was added to dissolve the solution, which was then frozen at -10°C to crystallize and filtered again. The resulting filter cake was dried under vacuum at room temperature for 24 hours to obtain 3.77 g of a white solid, which was the amphiphilic block copolymer mPEG. 2000 -PDLLA 800 -Phe(Boc) finished product.

[0044] NMR calculation of mPEG 2000 -PDLLA 800 -Phe(Boc) has a molecular weight of 3122, and GPC was used to determine the mPEG. 2000 -PDLLA 800 The number-average molecular weight and molecular weight distribution coefficient of -Phe(Boc) are 4445 and 1.09, respectively.

[0045] (II) Characterization

[0046] See NMR spectrum Figure 1 , H1-NMR(DCCl3): 1.38-1.41(-C-CH3), 1.55-1.56(CH-CH3), 3.38(0-CH3), 3.55-3. 76 (O-CH2-C); 4.26-4.30 (O-CH2CH2-O); 5.16-5.22 (O=C-CH(C)-O) 7.16-7.28 (≡CH).

[0047] See GPC diagram Figure 2 The test results are as follows: Mp = 4628, Mn = 4445, Mw = 4827, Mz = 5268, Mz+1: 5791, PDI = 1.09.

[0048] See particle size diagram Figure 3 The test results are as follows: average particle size = 20.1 nm, dispersion index PDI = 0.142, D50 = 18.7 nm, D90 = 30.4 nm.

[0049] Example 2: Amphiphilic block copolymer mPEG 2000 -PDLLA 1200 -Phe(Boc)

[0050] The preparation method is as follows:

[0051] 1. Preparation of intermediate mPEG 2000 -PDLLA 1200

[0052] Weigh out 8.50g mPEG 2000In a 100 mL polymerization flask, after dehydration under vacuum stirring at 130 °C for 3 h, 6.80 g of D,L-lactide and 7 mg of stannous octoate were added under nitrogen protection. The reaction vessel was sealed under a vacuum of -0.095 MPa or less, and the reactants were stirred in an oil bath at 130 °C for melt polymerization for 18 h. The reaction was then stopped. After cooling to room temperature, 85 mL of anhydrous ethanol was added to dissolve the solid. After cooling and crystallization, the solid was filtered to obtain a white solid. After vacuum drying at room temperature for 24 h, 9.91 g of intermediate mPEG was obtained. 2000 -PDLLA 1200 .

[0053] NMR calculation of mPEG 2000 -PDLLA 1200 The molecular weight is 3186, and the mPEG was determined by GPC. 2000 -PDLLA 1200 The number-average molecular weight and molecular weight distribution coefficient were 4608 and 1.09, respectively.

[0054] 2. Preparation of tert-butyloxycarbonyl-L-phenylalanine pentyl anhydride

[0055] In a 100 mL three-necked round-bottom flask, add Boc-L-phenylalanine / anhydrous ethyl acetate solution (3.04 g Boc-L-phenylalanine dissolved in 20 mL anhydrous ethyl acetate) and 1.16 g triethylamine. After stirring to dissolve, cool to -10 to 0 °C. Add 1.39 g tert-butyloxycarbonyl chloride dropwise, stir the reaction at 0 to 10 °C for 2 h, and then continue stirring at room temperature for 1 h. Filter to remove insoluble matter, and remove the solvent by rotary evaporation at -0.09 MPa under reduced pressure at 35 to 40 °C to obtain a white solid, tert-butyloxycarbonyl-L-phenylalanine tert-butyl anhydride (Boc-Phe-OCOC(CH3)3).

[0056] 3. End-capping reaction

[0057] Add 9.20 g of mPEG to a 100 mL three-necked round-bottom flask. 2000 -PDLLA 1200 Add 50 mL of dichloromethane, stir to dissolve, then add the Boc-Phe-OCOC(CH3)3 obtained in step 2, cool the system to 0-5℃, add 1.16 g of triethylamine and 0.20 g of 4-pyrrolidinylpyridine, stir the resulting mixture at 0-5℃ for 1 h, then continue stirring at room temperature for 24 h, remove the solvent by rotary evaporation under reduced pressure, and the obtained polymer is the crude product mPEG-PDLLA-Phe(Boc).

[0058] The crude product was dissolved in 75 mL of anhydrous ethanol, then frozen at -10 °C for crystallization and filtered. Another 75 mL of anhydrous ethanol was added to dissolve the solution, which was then frozen at -10 °C for crystallization and filtered again. The resulting filter cake was dried under vacuum at room temperature for 24 h to obtain 9.10 g of a white solid, which was the amphiphilic block copolymer mPEG. 2000 -PDLLA 1200 -Phe(Boc) finished product.

[0059] NMR calculation of mPEG 2000 -PDLLA 1200 -Phe(Boc) has a molecular weight of 3433, and GPC was used to determine the mPEG. 2000 -PDLLA 1200 The number-average molecular weight and molecular weight distribution coefficient of -Phe(Boc) are 4825 and 1.09, respectively.

[0060] Example 3: Amphiphilic block copolymer mPEG 2000 -PDLLA 1500 -Phe(Boc)

[0061] The preparation method is as follows:

[0062] 1. Preparation of intermediate mPEG 2000 -PDLLA 1500

[0063] Weigh out 10.0g of mPEG 2000 In a 100 mL polymerization flask, after dehydration under vacuum stirring at 130 °C for 3 h, 11.0 g of D,L-lactide and 11 mg of stannous octoate were added under nitrogen protection. The reaction vessel was sealed under a vacuum of -0.095 MPa or less, and the reactants were stirred in an oil bath at 130 °C for melt polymerization for 18 h. The reaction was then stopped. After cooling to room temperature, 100 mL of anhydrous ethanol was added to dissolve the reactants. After cooling and crystallization, the solid was filtered to obtain a white solid. After vacuum drying at room temperature for 24 h, 12.38 g of intermediate mPEG was obtained. 2000 -PDLLA 1500 .

[0064] NMR calculation of mPEG 2000 -PDLLA 1500 The molecular weight is 3491, and the mPEG was determined by GPC. 2000 -PDLLA 1500 The number-average molecular weight and molecular weight distribution coefficient of -Phe(Boc) are 4460 and 1.10, respectively.

[0065] 2. Preparation of tert-butyloxycarbonyl-L-phenylalanine pentyl anhydride

[0066] In a 100 mL three-necked round-bottom flask, add Boc-L-phenylalanine / anhydrous ethyl acetate solution (2.16 g Boc-L-phenylalanine dissolved in 20 mL anhydrous ethyl acetate) and 0.83 g triethylamine. After stirring to dissolve, cool to -10 to 0 °C. Add 1.0 g tert-butyloxycarbonyl chloride dropwise, stir the reaction at 0 to 10 °C for 2 h, and continue stirring at room temperature for 1 h. Filter to remove insoluble matter, and remove the solvent by rotary evaporation at -0.09 MPa under reduced pressure at 35 to 40 °C to obtain a white solid, tert-butyloxycarbonyl-L-phenylalanine tert-butyl anhydride (Boc-Phe-OCOC(CH3)3).

[0067] 3. End-capping reaction

[0068] Add 5.0 g mPEG to a 100 mL three-necked round-bottom flask. 2000 -PDLLA 1500 Add 50 mL of dichloromethane, stir to dissolve, then add the Boc-Phe-OCOC(CH3)3 obtained in step 2, cool the system to 0-5℃, add 0.63 g of triethylamine and 0.093 g of 4-pyrrolidinylpyridine, stir the resulting mixture at 0-5℃ for 1 h, then continue stirring at room temperature for 24 h, remove the solvent by rotary evaporation under reduced pressure, and the obtained polymer is the crude product mPEG-PDLLA-Phe(Boc).

[0069] The crude product was dissolved in 50 mL of anhydrous ethanol, then frozen at -10 °C for crystallization and filtered. Another 50 mL of anhydrous ethanol was added to dissolve the solution, which was then frozen at -10 °C for crystallization and filtered again. The resulting filter cake was dried under vacuum at room temperature for 24 h to obtain 4.72 g of a white solid, which was the amphiphilic block copolymer mPEG. 2000 -PDLLA 1500 -Phe(Boc) finished product.

[0070] NMR calculation of mPEG 2000 -PDLLA 1500 -Phe(Boc) has a molecular weight of 3845, and its mPEG content was determined by GPC. 2000 -PDLLA 1500 The number-average molecular weight and molecular weight distribution coefficient of -Phe(Boc) are 4896 and 1.07, respectively.

[0071] Example 4: Amphiphilic block copolymer mPEG 2000 -PDLLA 1700 -Phe(Boc)

[0072] The preparation method is as follows:

[0073] 1. Preparation of intermediate mPEG 2000 -PDLLA 1700

[0074] Weigh out 10.0g of mPEG 2000 In a 100 mL polymerization flask, after dehydration under vacuum stirring at 130 °C for 3 h, 12.0 g of D,L-lactide and 12 mg of stannous octoate were added under nitrogen protection. The reaction vessel was sealed under a vacuum of -0.095 MPa or less, and the reactants were stirred in an oil bath at 130 °C for melt polymerization for 18 h. The reaction was then stopped. After cooling to room temperature, 100 mL of anhydrous ethanol was added to dissolve the reactants. After cooling and crystallization, the solid was filtered to obtain a white solid. After vacuum drying at room temperature for 24 h, 3.1 g of intermediate mPEG was obtained. 2000 -PDLLA 1700 The yield was 59.61%.

[0075] NMR calculation of mPEG 2000 -PDLLA 1700 The molecular weight is 3654, and the mPEG was determined by GPC. 2000 -PDLLA 1700 The number-average molecular weight and molecular weight distribution coefficient were 4710 and 1.09, respectively.

[0076] 2. Preparation of tert-butyloxycarbonyl-L-phenylalanine pentyl anhydride

[0077] In a 100 mL three-necked round-bottom flask, add Boc-L-phenylalanine / anhydrous ethyl acetate solution (2.16 g Boc-L-phenylalanine dissolved in 20 mL anhydrous ethyl acetate) and 0.83 g triethylamine. After stirring to dissolve, cool to -10 to 0 °C. Add 1.0 g tert-butyloxycarbonyl chloride dropwise, stir the reaction at 0 to 10 °C for 2 h, and continue stirring at room temperature for 1 h. Filter to remove insoluble matter, and remove the solvent by rotary evaporation at -0.09 MPa under reduced pressure at 35 to 40 °C to obtain a white solid, tert-butyloxycarbonyl-L-phenylalanine tert-butyl anhydride (Boc-Phe-OCOC(CH3)3).

[0078] 3. End-capping reaction

[0079] Add 5.01 g mPEG to a 100 mL three-necked round-bottom flask. 2000 -PDLLA 1700 Add 50 mL of dichloromethane, stir to dissolve, then add the Boc-Phe-OCOC(CH3)3 obtained in step 2, cool the system to 0-5℃, add 0.63 g of triethylamine and 0.093 g of 4-pyrrolidinylpyridine, stir the resulting mixture at 0-5℃ for 1 h, then continue stirring at room temperature for 24 h, remove the solvent by rotary evaporation under reduced pressure, and the obtained polymer is the crude product mPEG-PDLLA-Phe(Boc).

[0080] The crude product was dissolved in 50 mL of anhydrous ethanol, then frozen at -10 °C for crystallization and filtered. Another 50 mL of anhydrous ethanol was added to dissolve the solution, which was then frozen at -10 °C for crystallization and filtered again. The resulting filter cake was dried under vacuum at room temperature for 24 h to obtain 4.53 g of a white solid, which was the amphiphilic block copolymer mPEG. 2000 -PDLLA 1700 -Phe(Boc) finished product.

[0081] NMR calculation of mPEG 2000 -PDLLA 1700 -Phe(Boc) has a molecular weight of 4078, and mPEG was determined by GPC. 2000 -PDLLA 1700 The number-average molecular weight and molecular weight distribution coefficient of -Phe(Boc) are 5208 and 1.07, respectively.

[0082] Example 5: Amphiphilic block copolymer mPEG 2000 -PDLLA 2600 -Phe(Boc)

[0083] The preparation method is as follows:

[0084] 1. Preparation of intermediate mPEG 2000 -PDLLA 2600

[0085] Weigh out 5.0g of mPEG 2000 In a 100 mL polymerization flask, after dehydration by vacuum stirring at 130 °C for 3 h, 10.3 g of D,L-lactide and 10 mg of stannous octoate were added under nitrogen protection. The reaction vessel was sealed under a vacuum of -0.095 MPa or less, and the reactants were stirred in an oil bath at 130 °C for melt polymerization for 18 h. The reaction was then stopped. After cooling to room temperature, 100 mL of anhydrous ethanol was added to dissolve the reactants. After cooling and crystallization, the solid was filtered to obtain a white solid. After vacuum drying at room temperature for 22 h, 11.4 g of intermediate mPEG was obtained. 2000 -PDLLA 2600 The yield was 74.53%.

[0086] NMR calculation of mPEG 2000 -PDLLA 2600 The molecular weight is 4656, and the mPEG was determined by GPC. 2000 -PDLLA 2600 The number-average molecular weight and molecular weight distribution coefficient were 5606 and 1.09, respectively.

[0087] 2. Preparation of tert-butyloxycarbonyl-L-phenylalanine pentyl anhydride

[0088] In a 100 mL three-necked round-bottom flask, add a Boc-L-phenylalanine / anhydrous ethyl acetate solution (2.16 g Boc-L-phenylalanine dissolved in 20 mL anhydrous ethyl acetate) and 0.83 g triethylamine. After stirring to dissolve, cool to -10 to 0 °C. Add 1.0 g tert-butyloxycarbonyl-L-phenylalanine tert-butyloxycarbonyl-L-phenylalanine tert-butyloxycarbonyl-OOCOC(CH3)3.

[0089] 3. End-capping reaction

[0090] Add 5.01 g mPEG to a 100 mL three-necked round-bottom flask. 2000 -PDLLA 2600 Add 50 mL of dichloromethane, stir to dissolve, then add the Boc-Phe-OCOC(CH3)3 obtained in step 2, cool the system to 0-5℃, add 0.63 g of triethylamine and 0.09 g of 4-pyrrolidinylpyridine, stir the resulting mixture at 0-5℃ for 1 h, then continue stirring at room temperature for 24 h, remove the solvent by rotary evaporation under reduced pressure, and the obtained polymer is the crude product mPEG-PDLLA-Phe(Boc).

[0091] The crude product was dissolved in 50 mL of anhydrous ethanol, then frozen at -10 °C to crystallize, and filtered. Another 50 mL of anhydrous ethanol was added to dissolve the solution, which was then frozen at -10 °C to crystallize and filtered again. The resulting filter cake was dried under vacuum at room temperature for 24 h to obtain 4.78 g of a white solid, which was the amphiphilic block copolymer mPEG. 2000 -PDLLA 2600 -Phe(Boc) finished product.

[0092] NMR calculation of mPEG 2000 -PDLLA 2600 -Phe(Boc) has a molecular weight of 4926, and GPC determination shows that the mPEG content is... 2000 -PDLLA 2600 The number-average molecular weight and molecular weight distribution coefficient of -Phe(Boc) are 6059 and 1.06, respectively.

[0093] Example 6: A drug-loaded micelle of an amphiphilic block copolymer

[0094] The preparation method is as follows:

[0095] Weigh out 0.25g of paclitaxel and 1.25g of the mPEG prepared in Example 2. 2000 -PDLLA 1200After adding 50 mL of ethyl acetate and stirring until completely dissolved, the ethyl acetate was removed by rotary evaporation at 30 °C. After 30 min, the vacuum was turned to the lowest level and the mixture was vacuum dried at 45 °C for 2 h. Then, 35 mL of water was added and the mixture was hydrated at 45 °C and 200 rpm for 4.5 min to obtain the drug-loaded micelle solution. The results are shown in Table 1.

[0096] Example 7: A drug-loaded micelle of an amphiphilic block copolymer

[0097] The preparation method is as follows:

[0098] Weigh out 0.25g of paclitaxel and 1.25g of the mPEG prepared in Example 1. 2000 -PDLLA 800 -Phe(Boc), after adding 50 mL of ethyl acetate and stirring until completely dissolved, the ethyl acetate was removed by rotary evaporation at 30 °C. After 30 min, the vacuum degree was turned to the lowest level and the mixture was vacuum dried at 45 °C for 2 h. Then, 50 mL of water was added and the mixture was hydrated at 50 °C and 200 rpm for 5.5 min to obtain the drug-loaded micelle solution. The results are shown in Table 1.

[0099] Example 8: A drug-loaded micelle of an amphiphilic block copolymer

[0100] The preparation method is as follows:

[0101] Weigh out 0.25g of paclitaxel and 1.25g of the mPEG prepared in Example 2. 2000 -PDLLA 1200 -Phe(Boc), after being completely dissolved in 50 mL of ethyl acetate by stirring, the ethyl acetate was removed by rotary evaporation at 30 °C. After 30 min, the vacuum was turned to the lowest level and the mixture was vacuum dried at 45 °C for 2 h. Then, 50 mL of water was added and the mixture was hydrated at 50 °C and 200 rpm for 4.5 min to obtain the drug-loaded micelle solution. The results are shown in Table 1.

[0102] Example 9: A drug-loaded micelle of an amphiphilic block copolymer

[0103] The preparation method is as follows:

[0104] Weigh out 0.25g of paclitaxel and 1.25g of the mPEG prepared in Example 3. 2000 -PDLLA 1500 -Phe(Boc), after adding 50mL of ethyl acetate and stirring until completely dissolved, the ethyl acetate was removed by rotary evaporation at 30℃. After 30min, the vacuum degree was turned to the lowest level and the mixture was vacuum dried at 45℃ for 2h. Then, 50mL of water was added and the mixture was hydrated at 50℃ and 200rpm for 21min to obtain the drug-loaded micelle solution. The results are shown in Table 1.

[0105] Example 10: A drug-loaded micelle of an amphiphilic block copolymer

[0106] The preparation method is as follows:

[0107] Weigh out 0.25g of paclitaxel and 1.25g of the mPEG prepared in Example 4. 2000 -PDLLA 1700 -Phe(Boc), after adding 50mL of ethyl acetate and stirring until completely dissolved, the ethyl acetate was removed by rotary evaporation at 30℃. After 30min, the vacuum was turned to the lowest level and dried under vacuum at 45℃ for 2h. Then, 50mL of water was added and hydrated at 50℃ and 200rpm for 47min to obtain the drug-loaded micelle solution. The results are shown in Table 1.

[0108] Example 11: A drug-loaded micelle of an amphiphilic block copolymer

[0109] The preparation method is as follows:

[0110] Weigh out 0.25g of paclitaxel and 1.25g of the mPEG prepared in Example 5. 2000 -PDLLA 2600 -Phe(Boc), after adding 50mL of ethyl acetate and stirring until completely dissolved, remove the ethyl acetate by rotary evaporation at 30℃. After 30min, turn the vacuum to the lowest level and dry under vacuum at 45℃ for 2h. Add 50mL of water and hydrate at 50℃ and 200rpm for 70min to obtain the drug-loaded micelle solution. In this example, the hydration was not complete after 70min and was too poor to be placed. The results are shown in Table 1.

[0111] Table 1. Results of particle size and drug loading tests

[0112]

[0113]

[0114] Table 1 summarizes the following:

[0115] (1) Comparing Example 6 and Example 8, it can be seen that the micelles prepared in Example 8 using the end-capping excipient mPEG-PDLLA-Phe(Boc) did not show significant changes in particle size distribution, encapsulation efficiency, and drug loading within 24 hours of being placed at 37°C; however, the micelles prepared in Example 6 using the unend-capping excipient mPEG-PDLLA showed significant changes in particle size distribution after 8 hours of being placed at 37°C, characterized by a significant increase in PDI, a wider particle size distribution range, and a decrease in particle uniformity. Therefore, the micelles prepared by the end-capping polymer excipient mPEG-PDLLA-Phe(Boc) of this invention have better stability.

[0116] (2) As can be seen from Examples 7 to 11, when the molecular weight of mPEG-PDLLA-Phe(Boc) is between 3100 and 3900, the prepared drug-loaded micelles have a narrow particle size distribution range, high encapsulation efficiency, and relatively short hydration time. Furthermore, after being placed at 37°C for 24 hours, the particle size distribution, encapsulation efficiency, and drug loading are basically unchanged, indicating that the formed micelles have good stability. When the molecular weight is greater than 4000, the hydration time is longer and the micelle stability is poor.

Claims

1. An amphiphilic block copolymer, characterized in that, The amphiphilic block copolymer refers to a tert-butoxycarbonylphenylalanine-terminated methoxy polyethylene glycol-polyracemic lactide block copolymer, having the general structural formula shown in (I): （I） Where m = 44-45; n = 6-12; the NMR calculation of the amphiphilic block copolymer shows a molecular weight of 3100-3900. The preparation method of the amphiphilic block copolymer includes the following steps: 1) Take polyethylene glycol monomethyl ether and D,L-lactide, add stannous octoate catalyst, and melt polymerize at 110℃~180℃ for 4~24 hours under nitrogen protection. Pour the obtained product into an organic solvent to crystallize, dry, and obtain intermediate mPEG-PDLLA. 2) Dissolve Boc-L-phenylalanine in ethyl acetate and react it with pivaloyl chloride in the presence of an acid-binding agent. The reaction is carried out at 0-50℃ for 5-48 h. After filtration and rotary evaporation, tert-butoxycarbonyl-L-phenylalanine pivaloyl anhydride is obtained. 3) Take the intermediate mPEG-PDLLA obtained in step 1) and the tert-butoxycarbonyl-L-phenylalanine pentyl anhydride obtained in step 2), add triethylamine and 4-pyrrolidinylpyridine as solvent, and carry out the end-capping reaction at 0-5℃. The crude product is purified with an organic solvent to obtain an amphiphilic block copolymer. The purification process involves dissolving the crude product in 25 mL of anhydrous ethanol, freezing it at -10°C to crystallize, filtering, then dissolving it in another 25 mL of anhydrous ethanol, freezing the solution at -10°C to crystallize, filtering, and finally drying the resulting filter cake under vacuum at room temperature for 24 hours to obtain a white solid.

2. The amphiphilic block copolymer according to claim 1, characterized in that, In step 1), the amount of stannous octoate catalyst added is 1‰ to 10‰ of the weight of D,L-lactide.

3. The amphiphilic block copolymer according to claim 1, characterized in that, In step 1), the organic solvent is selected from one or a mixture of two or more of anhydrous ethanol, dichloromethane, ethyl acetate, n-hexane and anhydrous diethyl ether.

4. The amphiphilic block copolymer according to claim 1, characterized in that, In step 2), the acid-binding agent is selected from triethylamine, N,N-diisopropylethylamine, tripropylamine, pyridine, potassium carbonate, sodium carbonate, and sodium hydroxide.

5. The amphiphilic block copolymer according to claim 1, characterized in that, In step 3), the molar ratio is tert-butyloxycarbonyl-L-phenylalanine pentyl anhydride: intermediate mPEG-PDLLA = (1~10):

1.

6. The amphiphilic block copolymer according to claim 1, characterized in that, In step 3), the organic solvent is selected from one or a mixture of two or more of anhydrous ethanol, ethyl acetate, n-hexane, anhydrous diethyl ether and methyl tert-butyl ether.

7. The application of the amphiphilic block copolymer of claim 1 as a carrier in the preparation of drug-loaded micelles.

8. A drug-loaded micelle of an amphiphilic block copolymer, characterized in that, The preparation method includes the following steps: weigh the drug and the amphiphilic block copolymer according to claim 1, dissolve them in ethyl acetate, remove the ethyl acetate by rotary evaporation at 30°C, dry under vacuum at 45°C, add water and hydrate at 45-50°C and 200 rpm to obtain a drug-loaded micelle solution.

9. The amphiphilic block copolymer drug-loaded micelles according to claim 8, characterized in that, The drug is selected from paclitaxel, docetaxel, cabazitaxel, methotrexate, 5-fluorouracil, cyclophosphamide, doxorubicin, epirubicin, or pirarubicin.

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