Core-shell structured micellar microspheres and preparation method and use thereof

Abstract

The present invention belongs to the technical field of medicine, and particularly relates to a core-shell structured micelle microsphere and its preparation method and use. The core-shell structured micelle microsphere of the present invention has an outer shell composed of amphiphilic lipid, an inner shell composed of hydrophilic chain polymer, and a core of drug molecules wrapped in a network structured copolymer. The double-layer shell structure can realize effective drug delivery, reduce drug loss during delivery, and improve drug utilization rate, and the wrapped drug molecules can be used as the core to realize sustained drug release. The present invention also optimizes the core-shell material, and selects amphiphilic phospholipid as the outer shell, thereby improving biocompatibility and drug delivery efficiency, and selects hydrophilic chain polymer as the inner shell, thereby effectively preventing drug burst release, and selects mPEG-PLGA block copolymer as the one for wrapping drug molecules, thereby further preventing drug burst release and realizing control over drug release rate, which can meet the complex needs of practical use.

Description

[Technical field]

[0001] The present invention relates to the technical field of medicine, in particular to the field of composite materials for coated catheters under IPC classification number A61L29 / 12, specifically to core-shell structured micellar microspheres and the preparation method and use thereof. [Background technology]

[0002] Microsphere formulations are a new dosage form developed in recent years, which is formed by dispersing drugs in a matrix material to form spherical particles, and can be administered by injection or interventional surgery. After administration, the microsphere framework degrades and erodes, allowing the encapsulated drug molecules to diffuse, which can provide sustained or delayed release effects. At present, there are various microsphere formulations with different structures, such as porous structure, core-shell structure, and solid structure.

[0003] In particular, interventional therapy with expandable balloons is widely used clinically, but in order to realize targeted chemotherapy, drug coating is usually applied to the surface of the expandable balloon. However, whether it is an injection or a drug coating on an expandable balloon, there is a problem that the drug is lost in the blood before reaching the target location, and the bioavailability of the drug is greatly reduced. In addition, most of the microsphere preparations carry drugs by intermolecular forces such as electrostatic action, so the bond is not tight enough, and the surface of the microsphere may also contain some drug parts, which leads to the occurrence of burst release phenomenon, which may cause adverse reactions, as well as the drug release period is too short to achieve long-term therapeutic effect. Therefore, the development of microspheres with stable structure and excellent sustained release effect is urgently needed in the field of medicine.

[0004] The prior art CN105106174B discloses core-shell bilayer microspheres prepared with copolymers of polyketal and poly(lactic acid-co-glycolic acid), which can solve the phenomenon of burst release; however, the microspheres are large, have high requirements for injection conditions, are not suitable for drug coating on expandable balloons, and have a low drug release rate, resulting in low drug bioavailability. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the objective of the present invention is to provide a core-shell structured micellar microsphere which has high drug availability, is easy to prepare, has a small particle size, has a wide range of application, and can realize long-term sustained release of drugs.

[0006] Meanwhile, the object of the present invention is to further provide a method for preparing micellar microspheres with core-shell structure, which has mild conditions and a simple process.

[0007] Meanwhile, the object of the present invention is to further provide a use of said core-shell structured micellar microspheres.

[0008] In order to achieve the above object of the invention, the present invention uses the following technical solutions:

[0009] A micellar microsphere having a core-shell structure, wherein the core of the micellar microsphere having the core-shell structure is a plurality of drug molecules encapsulated in a copolymer, the shell of the micellar microsphere having the core-shell structure is, from the inside to the outside, a chain polymer layer and a lipid layer, the copolymer has a network structure, and the chain polymer layer is a network structure formed by intermolecular forces of the chain polymer.

[0010] Preferably, the particle size of the core-shell micellar microspheres is 1 to 10 μm.

[0011] Preferably, the lipid layer is composed of amphipathic lipids, the hydrophilic end of which faces into the shell and the lipophilic end faces outwardly of the shell.

[0012] More preferably, the amphiphilic lipid is soy lecithin.

[0013] The core-shell micellar microsphere according to the present invention has an outer layer made of amphiphilic lipids, which are arranged in such a manner that the hydrophilic end faces the inside of the shell and the lipophilic end faces the outside of the shell, and on the one hand, it has affinity with the hydrophilic inner layer, and can form a dense bilayer structure to prevent the drug molecules in the core from diffusing; on the other hand, during preparation, it can form a bilayer spherical shell in the solvent with the help of similar polarity, so the preparation process is simple. On the one hand, when the lipophilic end faces the outside of the shell, the polarity difference with the blood is large, and the outside of the shell can form a hydrophobic surface, which can prevent the drug molecules from diffusing in the blood, which can reduce the loss of the drug during delivery and improve the bioavailability of the drug; on the other hand, when the microsphere comes into contact with the vascular wall, the lipophilic end has a good affinity with the cell membrane, especially because the structure of the phospholipid is similar to that of the cell membrane, which makes the affinity better; and the affinity between the lipid layer and the cell membrane opens the drug delivery passage, realizes the release of the drug, and further improves the utilization rate of the drug. In particular, when the core-shell structured micellar microspheres of the present invention are used as a drug coating for an expandable drug balloon, the expansion of the balloon will bring the microspheres into contact with the vascular wall at the target site, and the affinity of the lipid layer with the cell membrane will ensure retention of the drug at the target site, improving targeting and reducing damage to healthy tissues and adverse reactions.

[0014] Preferably, the chain polymer is a hydrophilic chain polymer and includes one or more of PEG (polyethylene glycol), hyaluronic acid, chitosan, iopromide, shellac, tannic acid, polylactide, and PLGA (poly(lactic-co-glycolic acid)).

[0015] Preferably, the mass fraction of the drug molecules in the core-shell micellar microspheres is 30% to 50%.

[0016] Preferably, the mass ratio of the lipid layer to the chain polymer layer is 1 to 5:1.

[0017] The present invention selects a network structure formed by hydrophilic chain polymer as the inner shell of the micellar microsphere with core-shell structure, which has affinity with the hydrophilic end of the amphiphilic lipid layer, and in addition to forming a double-layered spherical shell, when the microsphere has affinity with the vascular wall, the drug will be released after the chain polymer is decomposed, preventing the burst release of the drug and achieving the effect of sustained or delayed release. The inventor creatively expresses that the particle size and external shape of the microsphere can be controlled by adjusting the weight ratio of lipid to hydrophilic chain polymer. The present invention specifically selects the weight ratio of lipid to hydrophilic chain polymer to be 1-5:1, and obtains a core-shell structure micellar microsphere with regular shape, particle size of 10+0.5 μm or less, and suitable dimensions, so that the microsphere can be used as a drug coating for an expandable drug balloon, and the application range is expanded. At the same time, when the microspheres of the present invention can be used as a drug coating for an expandable drug balloon, it overcomes the drawback that the hydrophilic chain polymer absorbs water, the drug coating easily peels off from the surface of the balloon, and excess coating remains on the balloon, resulting in low drug utilization.

[0018] Preferably, the copolymer is selected from one or more of mPEG-PLGA block copolymers, PEG-PLGA block copolymers, and PEG-hyaluronic acid copolymers.

[0019] Preferably, the mass fraction of mPEG (methoxypolyethylene glycol) in the mPEG-PLGA block copolymer is 0.1 to 5.0%, more preferably 1%.

[0020] Preferably, the mass fraction of mPEG in the mPEG-PLGA block copolymer is 550-2,000, and the number average molecular weight of PLGA is 5,000-60,000.

[0021] Specifically, the present invention selects a network structure formed by a block copolymer composed of mPEG with a number average molecular weight of 550-2000 and PLGA with a number average molecular weight of 5000-60000, which encases drug molecules and releases the drug as the drug decomposes at the target site, and further realizes the adjustment of the drug release rate. The inventor unexpectedly invents that the higher the mPEG ratio, the faster the drug release rate; when the mPEG ratio is more than 5wt%, the drug release rate is relatively fast and may even cause burst release; when the mPEG ratio is 1wt%, the drug is released rapidly in the early stage, causing an increase in blood drug concentration, and the drug release rate slows down in the later stage, releasing almost continuously for 90 days; when the mPEG ratio is 0.1wt%, the drug release rate of the microspheres slows down and becomes almost linear, achieving an almost uniform and stable release. Based on this creative invention, the core-shell structured micellar microspheres of the present invention can be endowed with different drug release rate characteristics by adjusting the mPEG ratio of the mPEG-PLGA block copolymer, so as to meet various complex requirements in clinical practice.

[0022] Meanwhile, the present invention provides a method for preparing the above-mentioned core-shell structured micellar microspheres, the method comprising: Step S1: dissolving the drug and the copolymer in an organic solvent A, mixing uniformly, dissolving sufficiently, and leaving the mixture to stand for 2 to 8 hours to obtain a mixed solution a; Step S2 of dissolving lipids and linear polymers in solvent B and mixing them uniformly to obtain a mixed solution b; Step S3: adding the mixed solution a to the mixed solution b and mixing them uniformly to obtain a core-shell structured micellar microsphere solution; Step S4: drying and precipitating the core-shell structured micellar microspheres to obtain core-shell structured micellar microspheres; Includes.

[0023] Preferably, the drug is selected from one or more of rapamycin, rapamycin derivatives, taxol, heparin and hirudin.

[0024] Preferably, the weight ratio is 20 to 80 parts by weight of the drug, 10 to 70 parts by weight of the lipid, 5 to 60 parts by weight of the chain polymer, and 5 to 60 parts by weight of the copolymer.

[0025] Preferably, the organic solvent A comprises one or more of ethanol, isopropanol, acetone, methylene chloride, chloroform, ethyl acetate, acetonitrile, butyl acetate, ether, and carbon tetrachloride.

[0026] Preferably, the solvent B comprises one or more of methyl alcohol, ethanol, isopropanol, methylene chloride, chloroform, ethyl acetate, acetonitrile, butyl acetate, ether, and carbon tetrachloride.

[0027] Preferably, the organic solvent A and the solvent B are each 10,000 to 25,000 parts by weight.

[0028] Meanwhile, the present invention provides the use of said core-shell structured micellar microspheres, which can be used as drug coating for expandable drug balloons or as injections.

[0029] Preferably, the method for preparing the drug coating includes the steps of: nebulizing the core-shell micellar microsphere solution with ultrasonic waves to form mist droplets; spraying the mist droplets onto the surface of the balloon of the expandable drug balloon catheter with nitrogen; during the spraying process, the solvent evaporates, and the core-shell micellar microspheres adhere to the surface of the balloon to form a drug coating.

[0030] Preferably, the drug coating has a thickness of 1 to 10 microns.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The ash-shell structure micellar microspheres of the present invention have an outer layer composed of amphiphilic lipids, which can prevent the diffusion of drug molecules in the core, and the outside of the shell can form a hydrophobic surface, which can reduce the loss of the drug during delivery and improve the bioavailability of the drug;

[0033] 2. The present invention selects amphiphilic lipids, especially phospholipids, as the outer shell structure, which has excellent affinity with cell membranes, and can realize drug release through affinity with cell membranes, improve drug availability, realize drug retention at the target position, improve targeting, and reduce adverse reactions;

[0034] 3. The present invention selects a network structure formed by a hydrophilic chain polymer as the inner shell of the micellar microsphere with a core-shell structure, which prevents the burst release of the drug and achieves the effect of sustained or delayed release;

[0035] 4. The inventors have found that by adjusting the weight ratio of lipid to hydrophilic chain polymer, the particle size and external shape of the microspheres can be controlled. In particular, when a weight ratio of specific lipid to hydrophilic chain polymer of 1-5:1 is selected, micellar microspheres with regular shape and particle size of 10+0.5 μm or less can be obtained, expanding the application range of micellar microspheres with core-shell structure.

[0036] 5. The present invention specifically selects a network structure formed by a specific molecular weight mPEG-PLGA block copolymer to encapsulate drug molecules and achieve sustained release of the drug;

[0037] 6. The present invention creatively explores the relationship between the mPEG content of mPEG-PLGA block copolymer and the drug release rate of the resulting core-shell micellar microspheres, and by adjusting the mPEG content of mPEG-PLGA block copolymer, different drug release rate characteristics can be imparted, so as to meet various complex requirements in clinical practice. [Brief description of the drawings]

[0038] [Figure 1] 1 is a scanning electron microscope photograph of the core-shell micellar microspheres in Example 2. [Diagram 2] 1 is a topography photograph of the core-shell micellar microspheres in Example 2 taken by an optical microscope. [Diagram 3] 1 is a topography photograph of a core-shell structured micellar microsphere in Comparative Example 1 taken by an optical microscope. [Figure 4] Schematic of a drug molecule (green) encapsulated in an mPEG-PLGA block copolymer (black). [Diagram 5] FIG. 2 is a schematic diagram of the cross-sectional structure of a micellar microsphere having a core-shell structure according to the present invention. [Figure 6] FIG. 1 is a graph showing the change in drug release rate over time for core-shell micellar microspheres prepared by mPEG-PLGA block copolymers having mPEG mass fractions of 0.1% (Example 1), 1% (Example 2), and 5% (Example 3). [Figure 7] FIG. 2 is a curve showing the change in drug release rate over time for core-shell micellar microspheres prepared by an mPEG-PLGA block copolymer having an mPEG mass fraction of 9% (Comparative Example 2). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] The parts in the examples refer to parts by weight. Example 1

[0040] This embodiment provides a core-shell micellar microsphere, the core of which is a plurality of drug molecules encapsulated in a network-structured copolymer, and the shell of which is a network structure formed of chain polymer layers and a lipid layer in order from the inside to the outside.

[0041] The lipid layer is composed of soy lecithin, the hydrophilic end of the soy lecithin facing into the shell and the lipophilic end facing out of the shell;

[0042] the chain polymer is PEG;

[0043] The mass ratio of the lipid layer to the network structure formed by the chain polymer is 3:2;

[0044] the drug molecule is a rapamycin molecule;

[0045] the mass fraction of the drug molecules in the core-shell micellar microsphere is 40%;

[0046] The copolymer is an mPEG-PLGA block copolymer, in which the molecular weight of mPEG is 550, the molecular weight of PLGA is 60000, and the mass fraction of mPEG is 0.1%. The mPEG-PLGA block copolymer is purchased from Yinchuang Special Chemical (Shanghai) Co., Ltd.

[0047] An embodiment of the present invention further provides a method for preparing the above-mentioned core-shell structured micellar microspheres, the method comprising: Step S1: dissolving 40 parts of rapamycin and 60 parts of mPEG-PLGA block copolymer in 20,000 parts of acetone, mixing uniformly, dissolving sufficiently, and leaving for 6 hours to obtain a mixed solution a; Step S2: dissolving 60 parts of soybean lecithin and 40 parts of PEG in 20,000 parts of ethyl acetate and mixing uniformly to obtain a mixed solution b; Step S3: adding the mixed solution a to the mixed solution b and mixing them uniformly to obtain a core-shell structured micellar microsphere solution; Step S4: spraying the core-shell structured micelle microsphere solution, drying and precipitating to obtain core-shell structured micelle microspheres; Includes.

[0048] This embodiment further provides the use of the above core-shell structured micellar microspheres, which can be used as drug coating of expandable drug balloons or as injections;

[0049] The method for preparing the drug coating includes the steps of ultrasonically atomizing the core-shell micellar microsphere solution to form mist droplets, and spraying the mist droplets onto the surface of the balloon of an expandable drug balloon catheter with nitrogen, during which the solvent evaporates and the core-shell micellar microspheres adhere to the surface of the balloon to form a drug coating.

[0050] The drug coating has a thickness of 10 microns. Example 2

[0051] This example further provides a core-shell structured micellar microsphere and its preparation method and use, the embodiment of which is the same as that of Example 1, with the following differences: the mass fraction of mPEG in the mPEG-PLGA block copolymer is 1%, and the mPEG-PLGA block copolymer is purchased from Yinchuang Special Chemical (Shanghai) Co., Ltd.

[0052] The particle size of the micellar microspheres of the core-shell structure of this example is 2.5 to 10.5 μm. A scanning electron micrograph is shown in FIG. 1, and a topography photograph taken by an optical microscope is shown in FIG. Example 3

[0053] This example further provides a core-shell structured micellar microsphere and its preparation method and use, the embodiment of which is the same as that of Example 1, with the following differences: the mass fraction of mPEG in the mPEG-PLGA block copolymer is 5%, and the mPEG-PLGA block copolymer is purchased from Yinchuang Special Chemical (Shanghai) Co., Ltd. Comparative Example 1

[0054] This example further provides a core-shell structured micellar microsphere and its preparation method and use, the embodiment of which is the same as that of Example 2, with the following differences: the mass ratio of the lipid layer to the network structure formed by chain polymer is 1:3, and its optical microscope topography photograph is shown in Figure 3. Comparative Example 2

[0055] This comparative example further provides the core-shell structured micellar microspheres and its preparation method and use, the embodiment of which is the same as that of Example 2, with the following differences: the mass fraction of mPEG in the mPEG-PLGA block copolymer is 9%, and the mPEG-PLGA block copolymer is purchased from Jinan Jufukai Biological Technology Co., Ltd.

[0056] Performance Testing

[0057] In the drug release test, the sustained release effect of the core-shell structured micellar microspheres prepared by mPEG-PLGA block copolymers with different mass fractions is verified by animal experiments. In this experiment, a miniature pig animal model is used, and the drug coding in Examples 1 to 3 and Comparative Example 2 is used in the miniature pig body, respectively, and the timing is set to 0 (immediate), 1 day, 7 days, 14 days, 30 days, 60 days, and 90 days. Drug testing is performed on the blood vessels by extracting the pig blood vessel model.

[0058] The experimental subjects were miniature pig animal models weighing approximately 25 to 45 kg.

[0059] The experimental product had a drug content of 1 to 10 μg / mm 2 1 shows drug coating in Examples 1 to 3 and Comparative Example 2.

[0060] The experimental method is as follows.

[0061] (1) Seven porcine animal models were selected for each group, corresponding to the timing of 0 (immediately), 1 day, 7 days, 14 days, 30 days, 60 days, and 90 days, respectively. The balloons of the expandable balloon catheters sprayed with drug coating in Examples 1 to 3 and Comparative Example 2 were implanted into the cardiovascular RCA, LCX, and LAD of the porcine animal models in each group.

[0062] (2) At the timing of 0 (immediately), 1 day, 7 days, 14 days, 30 days, 60 days, and 90 days, the pigs are killed and blood vessels are removed to measure the drug content.

[0063] The experimental results are as follows: Based on the obtained drug content, a drug release curve (see Figures 6 and 7) was drawn, and the drug release rate on the vertical axis is the ratio of the drug content in the vascular wall to the drug content on the balloon surface before implantation. [Explanation of symbols]

[0064] 1. Lipid layer, 2. Chain polymer layer, 3. Drug molecule, 4. Network copolymer.

Claims

1. A core-shell micellar microsphere, wherein the core of the core-shell micellar microsphere is a plurality of drug molecules encapsulated in a copolymer, the shell of the core-shell micellar microsphere is, from the inside to the outside, a chain polymer layer and a lipid layer, the copolymer has a network structure, and the chain polymer layer is a network structure formed by intermolecular forces of the chain polymer.

2. The core-shell micellar microspheres according to claim 1, wherein the particle size of the core-shell micellar microspheres is 1-10 μm.

3. The core-shell structured micellar microsphere of claim 1, characterized in that the lipid layer is composed of amphiphilic lipids, the hydrophilic ends of the amphiphilic lipids facing into the shell and the lipophilic ends facing out of the shell.

4. The core-shell structured micellar microsphere of claim 1, wherein the chain polymer is a hydrophilic chain polymer and includes one or more of PEG, hyaluronic acid, chitosan, iopromide, shellac, tannic acid, polylactide, and PLGA.

5. The core-shell micellar microsphere according to claim 1, wherein the copolymer is selected from one or more of mPEG-PLGA block copolymer, PEG-PLGA block copolymer, and PEG-hyaluronic acid copolymer.

6. The core-shell micellar microsphere according to claim 5, wherein the mass fraction of mPEG in the mPEG-PLGA block copolymer is 0.1-5.0%.

7. The core-shell micellar microsphere according to claim 1, wherein the mass ratio of the lipid layer to the chain polymer layer is 1-5:

1.

8. Step S1: dissolving the drug and copolymer in an organic solvent A, mixing uniformly, dissolving sufficiently, and leaving the mixture to stand for 2 to 8 hours to obtain a mixed solution a; Step S2: dissolving lipids and linear polymers in a solvent B and mixing them uniformly to obtain a mixed solution b; Step S3: adding the mixed solution a to the mixed solution b and mixing them uniformly to obtain a core-shell structured micellar microsphere solution; Step S4: drying and precipitating the core-shell micellar microsphere solution to obtain core-shell micellar microspheres; A method for producing the core-shell structured micellar microspheres according to any one of claims 1 to 7, comprising:

9. Use of the core-shell structured micellar microspheres according to any one of claims 1 to 7 or obtained by the preparation method according to claim 8, characterized in that they are used as drug coatings for expandable drug balloons or as injections.

10. The use of core-shell structured micellar microspheres according to claim 9, characterized in that the thickness of said drug coating is 1-10 microns.

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