Embolism microsphere with wrinkled surface and preparation method of embolism microsphere

Abstract

The invention relates to embolism microspheres with wrinkled surfaces and a preparation method of the embolism microspheres, and belongs to the technical field of medical instruments. The method comprises the following steps: dissolving a high-molecular polymer in water to prepare a high-molecular polymer solution; mixing and reacting the high-molecular polymer solution and a cross-linking agent to obtain a modified polymer solution; adding a water-soluble monomer and an initiator into the modified polymer solution, and mixing to obtain a water-phase solution; under a stirring state, adding the water phase solution into the oil phase solution containing the dispersing agent to obtain a water-in-oil reversed-phase suspension polymerization system; keeping a stirring state, and carrying out heating polymerization, purification and collection on the water-in-oil reversed-phase suspension polymerization system to obtain wet microspheres; standing the wet microspheres in an organic solvent, and removing the organic solvent to obtain transition microspheres; transferring the transition-state microspheres into a vacuum drying oven for drying to obtain dry-state microspheres; and soaking the dry microspheres in water to obtain the embolism microspheres with wrinkled surfaces. The method can improve the drug loading rate and drug loading capacity of the embolization microspheres.

Description

Technical Field

[0001] The present application relates to the technical field of medical devices, and in particular to an embolic microsphere with a wrinkled surface and a preparation method thereof. Background Art

[0002] As an emerging embolic material, embolic microspheres have received more and more attention. Different microspheres can be prepared according to the different properties of the carrier materials: such as polyvinyl alcohol microspheres, calcium alginate microspheres, chitosan microspheres, polyethylene glycol microspheres and polystyrene microspheres. With the clinical application of embolic microspheres, embolic microspheres with certain functions have become the future research direction, such as drug-loaded microspheres, imaging microspheres, radioactive microspheres, degradable microspheres, etc. Among them, drug-loaded microspheres not only block the blood circulation and nutrient supply of cancer tumors, but also continuously treat patients by loading different drugs in a long-term sustained release manner.

[0003] In the clinical application of drug-loaded microspheres, the drug loading rate and loading amount are the most important. A fast drug loading rate can reduce preoperative preparation time and improve efficiency; a large drug loading amount can use a smaller number of microspheres to achieve the same drug loading effect. However, most microspheres currently have problems such as slow drug loading rate and low drug loading amount. In addition, the microspheres currently available on the market have a 20-30% particle size shrinkage after drug loading, which will cause small-size microspheres to further shrink after drug loading and leak from the blood vessels at the lesion site, causing the risk of ectopic embolism. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the embodiments of the present application includes providing an embolic microsphere with a wrinkled surface and a preparation method thereof, so as to improve the drug loading performance of the embolic microsphere and reduce the particle size shrinkage ratio of the microsphere after drug loading.

[0005] The embodiment of the present application is implemented as follows:

[0006] In a first aspect, an embodiment of the present application provides a method for preparing embolic microspheres with wrinkled surfaces, comprising: S1. dissolving a polymer in water to prepare a polymer solution; mixing the polymer solution and a cross-linking agent to obtain a modified polymer solution; adding a water-soluble monomer and an initiator to the modified polymer solution to obtain an aqueous solution; S2. adding the aqueous solution to an oil phase solution containing a dispersant under stirring to obtain an oil-in-water reverse suspension polymerization system; maintaining the stirring state, heating, polymerizing, purifying and collecting the oil-in-water reverse suspension polymerization system to obtain wet microspheres; S3. placing the wet microspheres in an organic solvent, removing the organic solvent to obtain transitional microspheres; S4. transferring the transitional microspheres to a vacuum drying oven for drying to obtain dry microspheres; S5. soaking the dry microspheres in water to obtain embolic microspheres with wrinkled surfaces.

[0007] In the above technical scheme, the present application prepares embolic microspheres with wrinkles on the surface by post-processing the synthesized wet microspheres, including dehydration and swelling of the microspheres, so as to improve the drug loading rate and drug loading amount of the embolic microspheres. Among them, the dehydration treatment is to fully replace the moisture of the synthesized wet microspheres with an organic solvent and vacuum drying to achieve the extraction of moisture in the wet microspheres, so that wrinkles are generated on the surface of the dry microspheres, and even after swelling, a large number of wrinkles can still be retained; and because wrinkles are formed on the surface of the microspheres, the specific surface area is increased, that is, the contact area with the drug is increased, so that the drug loading rate is increased and the drug loading amount is increased; at the same time, the microspheres prepared by the preparation method are in a contracted state, and the particle size shrinks less after drug loading, which is stable and controllable.

[0008] In a second aspect, an embodiment of the present application provides an embolic microsphere with a wrinkled surface, which is prepared by the above-mentioned preparation method, and the embolic microsphere has wrinkles on the surface in a wet state.

[0009] In the above technical solution, the embolic microspheres have wrinkles on their surface in a wet state. Therefore, after the microspheres are loaded with drugs, the wrinkles increase the contact area with the drugs, thereby increasing the drug loading rate and the drug loading amount. At the same time, the microspheres are in a contracted state, and the particle size shrinks less after drug loading, which is stable and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0011] Figure 1 The morphology of the embolic microspheres prepared in Example 1 of the present application before and after drug loading; wherein, Figure 1 a is the morphology before drug loading, Figure 1 b is the morphology after drug loading;

[0012] Figure 2 The morphology of the embolic microspheres prepared in Example 2 of the present application before and after drug loading; wherein, Figure 2 a is the morphology before drug loading, Figure 2 b is the morphology after drug loading;

[0013] Figure 3 The morphology of the embolic microspheres prepared in Example 3 of the present application before and after drug loading; wherein, Figure 3 a is the morphology before drug loading, Figure 3 b is the morphology after drug loading;

[0014] Figure 4 The morphology of the embolic microspheres prepared in Example 4 of the present application before and after drug loading; wherein, Figure 4 a is the morphology before drug loading, Figure 4 b is the morphology after drug loading;

[0015] Figure 5 This is a morphology of the embolic microspheres after drug loading prepared in Comparative Example 1 of the present application;

[0016] Figure 6 This is a morphology diagram of the embolic microspheres prepared in Comparative Example 2 of the present application;

[0017] Figure 7 This is a morphology diagram of the embolic microspheres prepared in Comparative Example 4 of the present application;

[0018] Figure 8 These are the drug loading test results of the embolic microspheres prepared in Examples 1-4 and Comparative Examples 1, 3, and 5 of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0020] The following is a detailed description of an embolic microsphere with a wrinkled surface and a preparation method thereof according to an embodiment of the present application.

[0021] The present application provides an embolic microsphere with a wrinkled surface, and the preparation method thereof comprises the following steps:

[0022] Step S1: Preparation of reaction solution

[0023] (1) Preparation of aqueous solution: dissolving a polymer in water to prepare a polymer solution; mixing the polymer solution and a cross-linking agent to obtain a modified polymer solution; adding a water-soluble monomer and an initiator to the modified polymer solution to obtain an aqueous solution.

[0024] The modified polymer solution further comprises an acid catalyst, wherein the acid catalyst includes but is not limited to at least one of hydrochloric acid, sulfuric acid, nitric acid and p-toluenesulfonic acid.

[0025] In the present application, the high molecular polymer includes, but is not limited to, one or more of polyvinyl alcohol, sodium alginate, sodium hyaluronate, sodium hydroxymethyl cellulose and water-soluble chitosan.

[0026] The mass fraction of the polymer in the aqueous solution is 10-25%. By way of example, the mass fraction of the polymer in the aqueous solution includes but is not limited to 10%, 13%, 13.5%, 14%, 14.5%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, and 25%.

[0027] In the present application, the crosslinking agent includes, but is not limited to, one or more of N-(2,2-dimethoxy)-2-methylacrylamide, N-(1-hydroxy-2,2-dimethoxyethyl)-2-acrylamide and N-(2,2-dimethoxy)-2-acrylamide.

[0028] The mass fraction of the cross-linking agent in the aqueous solution is 0.1-0.5%. By way of example, the mass fraction of the cross-linking agent in the aqueous solution includes but is not limited to 0.1%, 0.2%, 0.24%, 0.28%, 0.3%, 0.32%, 0.36%, 0.38%, 0.4%, 0.45%, and 0.5%.

[0029] In the present application, the water-soluble monomer includes, but is not limited to, one or more of sodium 2-acrylamide-2-methylpropane sulfonate, sodium allyl sulfonate, sodium methacrylic acid, sodium methacrylate, acrylamide and sodium acrylate.

[0030] The mass fraction of the water-soluble monomer in the aqueous phase solution is 2-15%. By way of example, the mass fraction of the water-soluble monomer in the aqueous phase solution includes but is not limited to 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 9.5%, 10%, 10.3%, 10.6%, 11%, 12%, 13%, 14%, and 15%.

[0031] In the present application, the initiator includes but is not limited to one or more of ammonium persulfate, sodium persulfate and potassium persulfate.

[0032] The mass fraction of the initiator in the aqueous solution is 0.2-0.8%. As an example, the mass fraction of the initiator in the aqueous solution includes but is not limited to 0.2%, 0.25%, 0.27%, 0.3%, 0.32%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, and 0.8%.

[0033] (2) Preparation of oil phase solution: Dissolve the oil-soluble dispersant in the oily solvent to prepare the oil phase.

[0034] The oil-soluble dispersant includes at least one of cellulose acetate butyrate, Span, Tween, octylphenol polyoxyethylene ether and oleic acid diethanolamide.

[0035] The oily solvent includes but is not limited to at least one of liquid paraffin, n-heptane, butyl acetate, ethyl acetate, methyl acetate and propyl acetate.

[0036] In some embodiments of the present application, the mass percentage of the oil-soluble dispersant in the oil phase solution is 2-5%. As an example, the mass percentage of the dispersant in the oil phase solution includes but is not limited to 2%, 2.5%, 2.7%, 3%, 3.4%, 3.8%, 4%, 4.3%, 4.5%, 4.7%, 5%.

[0037] Step S2: Microsphere synthesis

[0038] Under stirring, the aqueous phase solution is added to the oil phase solution containing the dispersant to obtain an oil-in-water reverse suspension polymerization system; the oil-in-water reverse suspension polymerization system is heated, polymerized, purified and collected while maintaining stirring to obtain wet microspheres.

[0039] The temperature of the heating polymerization is 65-85°C, and the time is 10-15 hours. As an example, the temperature of the heating polymerization includes but is not limited to 65°C, 70°C, 75°C, 80°C, 85°C; 65°C; the time of the heating polymerization includes but is not limited to 10h, 11h, 12h, 13h, 14h, 15h.

[0040] In the present application, when the aqueous phase solution is added to the oil phase solution containing the dispersant, a catalyst may also be added to react to accelerate the reaction rate and promote the synthesis of microspheres.

[0041] By way of example, the catalyst includes, but is not limited to, at least one of hydrochloric acid, sulfuric acid, nitric acid, and p-toluenesulfonic acid.

[0042] Step S3: Replacement of water with organic solvent

[0043] The wet microspheres in step S2 are immersed in an organic solvent, and the organic solvent is removed to obtain transitional microspheres.

[0044] Optionally, the organic solvent includes a first organic solvent and a second organic solvent;

[0045] Specifically, the steps are as follows:

[0046] S11. Slowly add the first organic solvent to the wet microspheres prepared in step (2) under stirring, stop stirring and let stand for a first period of time.

[0047] S12. After the microspheres are completely settled, the supernatant is slowly poured out, and the second organic solvent is added again, and the mixture is allowed to stand for a second period of time so that the water in the wet microspheres is completely replaced, and then the second organic solvent is removed to obtain transitional microspheres;

[0048] The second time period is greater than the first time period.

[0049] Optionally, the second time period t2 and the first time period t1 satisfy t2:t1=(10-30):1.

[0050] In the embodiment of the present application, a large amount of water is removed by standing the organic solvent for a relatively short time, and then a trace amount of water between the microspheres is removed by standing for a relatively long time. In this way, the water on the surface of the synthesized wet microspheres can be efficiently removed to prepare for subsequent processing.

[0051] Among them, the first organic solvent includes but is not limited to one or more of acetone, acetonitrile, methanol and ethanol; the second organic solvent includes but is not limited to one or more of acetone, acetonitrile, methanol and ethanol; optionally, the volume V1 of the first organic solvent and the volume V2 of the second organic solvent satisfy V1:V2=(10~15):1.

[0052] In the embodiment of the present application, the moisture contained in the synthesized wet microspheres is replaced by a secondary organic solvent, wherein the volume of the first organic solvent used for the first time is much larger than the volume of the second organic solvent used for the second time, thereby reducing the volume of the organic solvent used for the second time and facilitating preparation for subsequent processing.

[0053] As an example, the first time period is 30 to 60 minutes, and the second time period is 10 to 15 hours. The first time period includes but is not limited to 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, and 60 minutes; the second time period includes but is not limited to 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, and 15 hours.

[0054] The present application can replace the moisture between the wet microspheres by using the first organic solvent, and the first time period is 30 to 60 minutes, and the moisture between the wet microspheres is replaced efficiently in a short time; the second organic solvent is used to further replace the moisture on the surface of the wet microspheres, so it takes a second time period (10 to 15 hours) for a longer replacement. Therefore, the present application can fully replace the moisture of the wet microspheres through the secondary organic solvent replacement.

[0055] Step S4: Vacuum drying

[0056] Transferring the transition state microspheres in step S3 to a vacuum drying oven for drying to obtain dry microspheres;

[0057] Optionally, in the present application, drying includes: drying the transition state microspheres at a first temperature for a third period of time, and then reducing the temperature to a second temperature for a fourth period of time to obtain dry microspheres; wherein the first temperature is greater than the second temperature.

[0058] The transition state microspheres in the present application are vacuum dried twice at different temperatures, firstly at a higher temperature for a period of time to achieve the preforming of the wrinkles on the microsphere surface, and then at a lower temperature for a period of time to finalize the wrinkle morphology on the microsphere surface, thereby producing an effective and stable wrinkle morphology.

[0059] In the present application, the moisture content of the dry microspheres is less than 5%, which is conducive to the stable shaping of the wrinkled morphology of the microspheres.

[0060] The present application first performs high-temperature drying at a first temperature and then reduces the temperature to a second temperature for relatively low-temperature drying, thereby achieving the extraction of moisture from the microspheres, achieving a dry ball moisture content of less than 5%, and thereby allowing the dry microspheres to still retain a large amount of wrinkles after swelling. Due to the presence of surface wrinkles, the particle size shrinkage of the microspheres after drug loading is relatively small (less than 7%), and the particle size shrinkage is stable.

[0061] As an example, the first temperature is 80-90°C, and the second temperature is 50-60°C.

[0062] As an example, the third time period t3 is 1 to 2 hours, and the fourth time period t4 is 2 to 4 hours.

[0063] Among them, during the first drying, the first temperature is controlled within the range of 80-90°C, and the third time period t3 is controlled within 1-2h. On the one hand, the microspheres can still retain a large amount of wrinkled morphology after swelling; on the other hand, it is more conducive to improving the mechanical properties, drug loading rate and drug loading amount of the microspheres. When the first temperature is higher than 80°C and the drying time is greater than 2h, the surface of the prepared microspheres has wrinkles, and as the first temperature increases, the degree of wrinkles on the surface of the microspheres increases. However, when the first temperature is higher than 90°C, the microspheres formed are too strong and hard as a whole, which will hinder the entry of loaded drugs, thereby affecting the drug loading performance. Similarly, as the drying time increases, the strength of the microspheres will increase, but the compression elasticity will decrease, resulting in a slower drug loading rate and a reduced drug loading amount of the microspheres. This is because the microspheres formed due to the long drying time are too strong and hard as a whole, which hinders the entry of loaded drugs, thereby affecting the drug loading performance.

[0064] Step S5: Microsphere swelling

[0065] The dried microspheres in step S4 are immersed in water to obtain polyvinyl alcohol embolic microspheres with wrinkled surfaces.

[0066] As an example, purified water (1000 mL) was added to a container containing dry microspheres and soaked for 0.5 to 2 hours to obtain embolic microspheres with wrinkled surfaces.

[0067] The embodiment of the present application discloses a preparation method of wet microspheres with smooth surface generated by reverse suspension polymerization, replacing water with an organic solvent twice and vacuum drying twice at different temperatures to obtain a dry microsphere with a wrinkled surface morphology, which is then placed in water to swell and still exhibits a wrinkled morphology; compared with wet microspheres synthesized in a conventional post-treatment process, which still exhibit a smooth morphology after vacuum drying and then swell in water, the embolic microspheres synthesized in the present application have a stable wrinkled morphology on the surface, an increased specific surface area, and an increased drug loading capacity, and at the same time, the particle size shrinkage rate after drug loading is low, and the particle size of the microspheres is stable and controllable.

[0068] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0069] Example 1

[0070] This embodiment provides an embolic microsphere with a wrinkled surface, and the preparation method thereof comprises the following steps:

[0071] (1) Preparation of aqueous solution

[0072] 100 g of polyvinyl alcohol was added to 500 mL of water, and the temperature was raised to 95°C and stirred to dissolve to form a uniform solution; then 2.00 g of (N-(2,2-dimethoxy)-2-methylacrylamide was added, and 30 mL of hydrochloric acid was added after stirring evenly, and the reaction was continued with stirring at 23°C for 15 hours to obtain a polyvinyl alcohol aqueous solution; then, 10 g of 2-acrylamide-2-methylpropanesulfonic acid, 0.3 g of ammonium persulfate and 100 g of polyvinyl alcohol aqueous solution were stirred evenly to form a uniform solution to obtain an aqueous phase solution.

[0073] (2) Preparation of oil phase solution

[0074] 20 g of cellulose acetate butyrate was added to 500 mL of butyl acetate, and the mixture was stirred and dissolved at 40° C. to form a uniform solution to obtain an oil phase.

[0075] (3) Microsphere synthesis

[0076] Under stirring conditions, the aqueous phase solution of step (1) is slowly added dropwise to the oil phase solution of step (2) to form an oil-in-water reverse suspension polymerization system. After the addition is completed, the reaction system is heated to 65° C., and the reverse suspension polymerization reaction begins. After the reaction is continued for 12 hours, stirring and heating are stopped, the reaction system is allowed to stand and the layers are separated. The oil phase is separated, and the microspheres are collected and repeatedly washed to obtain wet microspheres.

[0077] (4) Microsphere dehydration

[0078] Under stirring conditions, 1200 mL of acetone was slowly added to the wet microspheres (600 mL) in step (3), and the stirring was stopped and the mixture was allowed to stand for 30 min to replace the moisture in the wet microspheres with acetone. After the microspheres were completely settled, the supernatant was slowly poured out, and 120 mL of acetone was added again. The mixture was allowed to stand for 15 h to ensure that the moisture in the wet microspheres was completely replaced. After the standing was completed, the acetone was poured out; then, the microspheres were transferred to a vacuum drying oven, first dried at 80° C. for 1 h, and then cooled to 50° C. and dried for 3 h to obtain dry microspheres.

[0079] (5) Microsphere swelling

[0080] Add 1000 mL of purified water into the container containing the dry microspheres and soak for 1 hour to obtain embolic microspheres with wrinkled surfaces.

[0081] Example 2

[0082] This embodiment is basically the same as embodiment 1, except that the first drying time in the vacuum drying oven in step (4) is 2 hours.

[0083] (4) Microsphere dehydration

[0084] Under stirring conditions, 1200 mL of acetone was slowly added to the wet microspheres (600 mL) in step (3), and the stirring was stopped and the mixture was allowed to stand for 30 min to replace the moisture in the wet microspheres with acetone. After the microspheres were completely settled, the supernatant was slowly poured out, and 120 mL of acetone was added again. The mixture was allowed to stand for 15 h to ensure that the moisture in the wet microspheres was completely replaced. After the standing was completed, the acetone was poured out; then, the microspheres were transferred to a vacuum drying oven, first dried at 80° C. for 2 h, and then cooled to 50° C. and dried for 3 h to obtain dry microspheres.

[0085] Example 3

[0086] This embodiment is basically the same as embodiment 1, except that the first drying temperature in the vacuum drying oven in step (4) is 90°C.

[0087] (4) Microsphere dehydration

[0088] Under stirring conditions, 1200 mL of acetone was slowly added to the wet microspheres (600 mL) in step (3), and the stirring was stopped and the mixture was allowed to stand for 30 min to replace the moisture in the wet microspheres with acetone. After the microspheres were completely settled, the supernatant was slowly poured out, and 120 mL of acetone was added again. The mixture was allowed to stand for 15 h to ensure that the moisture in the wet microspheres was completely replaced. After the standing was completed, the acetone was poured out; then, the microspheres were transferred to a vacuum drying oven, first dried at 90° C. for 1 h, and then cooled to 50° C. and dried for 3 h to obtain dry microspheres.

[0089] Example 4

[0090] This embodiment is basically the same as embodiment 1, except that in step (4), the first drying temperature in the vacuum drying oven is 90° C. and the drying time is 2 h.

[0091] (4) Microsphere dehydration

[0092] Under stirring conditions, 1200 mL of acetone was slowly added to the wet microspheres (600 mL) in step (3), and the stirring was stopped and the mixture was allowed to stand for 30 min to replace the moisture in the wet microspheres with acetone. After the microspheres were completely settled, the supernatant was slowly poured out, and 120 mL of acetone was added again. The mixture was allowed to stand for 15 h to ensure that the moisture in the wet microspheres was completely replaced. After the standing was completed, the acetone was poured out; then, the microspheres were transferred to a vacuum drying oven, first dried at 90° C. for 2 h, and then cooled to 50° C. and dried for 3 h to obtain dry microspheres.

[0093] Comparative Example 1

[0094] This comparative example is basically the same as Example 1, except that there is no first drying step in step (4).

[0095] (4) Microsphere dehydration

[0096] Under stirring conditions, 1200 mL of acetone was slowly added to the wet microspheres (600 mL) in step (3). After stopping stirring, the mixture was allowed to stand for 30 min to replace the moisture in the wet microspheres with acetone. After the microspheres were completely settled, the supernatant was slowly poured out, and 120 mL of acetone was added again. The mixture was allowed to stand for 15 h to ensure that the moisture in the wet microspheres was completely replaced. After the standing was completed, the acetone was poured out. Subsequently, the microspheres were transferred to a vacuum drying oven and dried at 50° C. for 3 h to obtain dry microspheres.

[0097] Comparative Example 2

[0098] This comparative example is basically the same as Example 1, except that the first drying temperature in the vacuum drying oven in step (4) is 70°C.

[0099] (4) Microsphere dehydration

[0100] Under stirring conditions, 1200 mL of acetone was slowly added to the wet microspheres (600 mL) in step (3), and the stirring was stopped and the mixture was allowed to stand for 30 min to replace the moisture in the wet microspheres with acetone. After the microspheres were completely settled, the supernatant was slowly poured out, and 120 mL of acetone was added again. The mixture was allowed to stand for 15 h to ensure that the moisture in the wet microspheres was completely replaced. After the standing was completed, the acetone was poured out; the microspheres were then transferred to a vacuum drying oven, first dried at 70° C. for 1 h, and then cooled to 50° C. for drying for 3 h to obtain dry microspheres.

[0101] Comparative Example 3

[0102] This comparative example is basically the same as Example 1, except that in step (4), the first drying temperature in the vacuum drying oven is 100°C.

[0103] (4) Microsphere dehydration

[0104] Under stirring conditions, 1200 mL of acetone was slowly added to the wet microspheres (600 mL) in step (3), and the stirring was stopped and the mixture was allowed to stand for 30 min to replace the moisture in the wet microspheres with acetone. After the microspheres were completely settled, the supernatant was slowly poured out, and 120 mL of acetone was added again. The mixture was allowed to stand for 15 h to ensure that the moisture in the wet microspheres was completely replaced. After the standing was completed, the acetone was poured out; then, the microspheres were transferred to a vacuum drying oven, first dried at 100° C. for 1 h, and then cooled to 50° C. and dried for 3 h to obtain dry microspheres.

[0105] Comparative Example 4

[0106] This comparative example is basically the same as Example 1, except that in step (4), the first drying time in the vacuum drying oven is 0.5 h.

[0107] (4) Microsphere dehydration

[0108] Under stirring conditions, 1200 mL of acetone was slowly added to the wet microspheres (600 mL) in step (3), and the stirring was stopped and the mixture was allowed to stand for 30 min to replace the moisture in the wet microspheres with acetone. After the microspheres were completely settled, the supernatant was slowly poured out, and 120 mL of acetone was added again. The mixture was allowed to stand for 15 h to ensure that the moisture in the wet microspheres was completely replaced. After the standing was completed, the acetone was poured out; the microspheres were then transferred to a vacuum drying oven, first dried at 80° C. for 0.5 h, and then cooled to 50° C. for drying for 3 h to obtain dry microspheres.

[0109] Comparative Example 5

[0110] This comparative example is basically the same as Example 1, except that the first drying time in the vacuum drying oven in step (4) is 3 hours.

[0111] (4) Microsphere dehydration

[0112] Under stirring conditions, 1200 mL of acetone was slowly added to the wet microspheres (600 mL) in step (3), and the stirring was stopped and the mixture was allowed to stand for 30 min to replace the moisture in the wet microspheres with acetone. After the microspheres were completely settled, the supernatant was slowly poured out, and 120 mL of acetone was added again. The mixture was allowed to stand for 15 h to ensure that the moisture in the wet microspheres was completely replaced. After the standing was completed, the acetone was poured out; the microspheres were then transferred to a vacuum drying oven, first dried at 80° C. for 3 h, and then cooled to 50° C. for drying for 3 h to obtain dry microspheres.

[0113] Test example

[0114] In this test example, the water content of the dry microspheres provided in the examples and comparative examples of the present application was tested; the mechanical properties, appearance and drug loading performance of the swollen embolic microspheres were tested.

[0115] 1. Water content of dry microspheres:

[0116] Test method: Use the drying loss method to detect the water content in the dry microspheres. Weigh the weight m of the weighing dish that has been dried to a constant weight, add the dry microspheres into it, and weigh the weight m1. Open the bottle cap, place it in an oven, dry it at 105°C for 2 hours, cover the bottle cap and cool it in a dryer for 0.5 hours (to room temperature), and weigh it; open the bottle cap again, place it in an oven, dry it at 105°C for 1 hour, cover the bottle cap and cool it in a dryer for 0.5 hours (to room temperature), and weigh it. Until the difference between two consecutive weighings does not exceed 0.3 mg, record the weight as m2, perform 2 parallel operations, and take the average value as the final result. Water content % = (m1-m2) / (m1-m)*100%. The above test results are shown in Table 1.

[0117] Table 1

[0118] Group First drying temperature / ℃ First drying time / h Water content / % Example 1 80 1 4.92 Example 2 80 2 4.39 Example 3 90 1 4.21 Example 4 90 2 3.04 Comparative Example 1 / / 9.67 Comparative Example 2 70 1 8.88 Comparative Example 3 100 1 2.75 Comparative Example 4 80 0.5 8.67 Comparative Example 5 80 3 3.36

[0119] By comparing the moisture content results of Example 1, Example 3, Comparative Example 2 and Comparative Example 3, it can be seen that, under the same other conditions, as the drying temperature increases, the moisture content of the dry microspheres after drying will decrease. Combined with the following appearance inspection, it can be known that at a temperature of 70°C, the microspheres are smooth in surface after swelling, and at a temperature of 80°C and above, the microspheres are wrinkled in surface after swelling; by comparing the moisture content results of Example 1, Example 2, Comparative Example 4 and Comparative Example 5, it can be seen that, under the same other conditions, as the drying time increases, the moisture content of the dry microspheres after drying will decrease. Combined with the following appearance inspection, it can be known that at a drying time of 0.5h, the microspheres are smooth in surface after swelling, and at a drying time of 1h and above, the microspheres are wrinkled in surface after swelling; in Comparative Example 1, since the first drying step was not performed, the moisture content of the microspheres was higher than 5%, and the microspheres were smooth in surface after swelling; when the moisture content of the dry microspheres was lower than 5%, embolic microspheres with wrinkled surface would be formed after swelling.

[0120] 2. Mechanical properties test:

[0121] Test method: Spread the microspheres (250 μm) on a glass slide, place them under the probe of a texture analyzer (TA-XT PlusC), and select the Hold Compression mode for testing. The test results are shown in Table 2.

[0122] Table 2

[0123] Group Drying temperature / ℃ Drying time / h Strength / g Compression elasticity / % Example 1 80 1 99.803 66.14 Example 2 80 2 108.385 62.35 Example 3 90 1 115.735 60.39 Example 4 90 2 122.315 59.62 Comparative Example 1 / / 82.573 71.83 Comparative Example 2 70 1 84.556 70.98 Comparative Example 3 100 1 168.128 41.46 Comparative Example 4 80 0.5 85.329 70.65 Comparative Example 5 80 3 150.263 45.88

[0124] It can be seen from the mechanical property results of Example 1, Example 3, Comparative Example 2 and Comparative Example 3 that, under the same conditions, with the increase of drying temperature, the strength of the microspheres will increase, and the compression elasticity will decrease; when the drying temperature is 100°C in Comparative Example 3, the microspheres have too high strength, poor compression elasticity, and poor mechanical properties. It can be seen from the mechanical property results of Example 1, Example 2, Comparative Example 4 and Comparative Example 5 that, under the same conditions, with the increase of drying time, the strength of the microspheres will increase, and the compression elasticity will decrease; when the drying time is 3h in Comparative Example 5, the microspheres have too high strength, poor compression elasticity, and poor mechanical properties.

[0125] 3. Appearance:

[0126] Test method: Spread the embolic microspheres on a glass slide and place them under a video display system (VHX-950F) microscope to observe and record their appearance.

[0127] Figure 1 The morphology of the embolic microspheres prepared in Example 1 of the present application before and after drug loading; wherein, Figure 1 a is the morphology before drug loading, Figure 1 b is the morphology after drug loading; Figure 2 The morphology of the embolic microspheres prepared in Example 2 of the present application before and after drug loading; wherein, Figure 2 a is the morphology before drug loading, Figure 2 b is the morphology after drug loading; Figure 3 The morphology of the embolic microspheres prepared in Example 3 of the present application before and after drug loading; wherein, Figure 3 a is the morphology before drug loading, Figure 3 b is the morphology after drug loading; Figure 4 The morphology of the embolic microspheres prepared in Example 4 of the present application before and after drug loading; wherein, Figure 4 a is the morphology before drug loading, Figure 4 b is the morphology after drug loading; Figure 5 This is a morphology of the embolic microspheres after drug loading prepared in Comparative Example 1 of the present application; Figure 6 This is a morphology diagram of the embolic microspheres prepared in Comparative Example 2 of the present application; Figure 7 This is the morphology of the embolic microspheres prepared in comparative example 4 of this application; please refer to Figure 1-Figure 7 。

[0128] It can be seen from the morphological results of Example 1, Example 3 and Comparative Example 2 that, under the same conditions, with the increase of drying temperature, the wrinkle degree of the microsphere surface increases; when the drying temperature in Comparative Example 2 is 70°C, the surface of the microsphere is smooth and wrinkle-free after swelling. It can be seen from the morphological results of Example 1, Example 2 and Comparative Example 4 that, under the same conditions, with the increase of drying time, the wrinkle degree of the microsphere surface increases; when the drying time in Comparative Example 4 is 0.5h, the surface of the microsphere is smooth and wrinkle-free after swelling; and since Comparative Example 1 has not undergone the first stage of high-temperature drying treatment, when the moisture content of the dry ball is greater than 5%, the surface of the microsphere is smooth and wrinkle-free after swelling.

[0129] The moisture content of the microspheres in the dry state in Comparative Examples 1, 2, and 4 is greater than 5%, resulting in the wrinkles on the surface of the dry ball being restored to a smooth state due to swelling; while the moisture content of the microspheres in the dry state in Examples 1, 2, 3, and 4 is less than 5%, and the wrinkles on the surface of the dry ball still retain a large number of wrinkles even after swelling.

[0130] 4. Drug loading rate test:

[0131] Test method: The embolic microspheres (250 μm, 2 mL) prepared in Examples 1-4 and Comparative Examples 1, 3, and 5 were mixed with doxorubicin (20 mg / mL, 4 mL), and samples were taken at regular intervals. The residual amount of doxorubicin in the supernatant was tested by HPLC, and the drug loading was calculated. The test results of drug loading rate are shown in Table 3.

[0132] Table 3

[0133]

[0134] By comparing the drug loading rate results of Example 1, Example 3 and Comparative Example 3, it can be seen that, under the same other conditions, as the first drying temperature increases from 80°C to 90°C, the drug loading rate of the microspheres will become faster; from 90°C to 100°C, the drug loading rate of the microspheres will slow down. This is because the microspheres formed by excessively high temperatures are too strong and hard as a whole, which hinders the entry of loaded drugs, thereby affecting the drug loading performance. By comparing the drug loading rate results of Example 1, Example 2 and Example 5, it can be seen that, under the same other conditions, as the first drying time increases from 1h to 2h, the drug loading rate of the microspheres will become faster; from 2h to 3h, the drug loading rate of the microspheres will slow down. This is because the microspheres formed by excessively long drying time are too strong and hard as a whole, which hinders the entry of loaded drugs, thereby affecting the drug loading performance.

[0135] 5. Maximum drug loading test:

[0136] Test method: Microspheres (250 μm, 1 mL) were mixed with doxorubicin (20 mg / mL, 4 mL), samples were taken at regular intervals, and the residual amount of doxorubicin in the supernatant was tested by HPLC, and the drug loading was calculated. Figure 8 and as shown in Table 4 below.

[0137] Table 4

[0138] Group Drying temperature / ℃ Drying time / h Maximum drug loading per milliliter of microspheres / mg Example 1 80 1 38.06 Example 2 80 2 38.29 Example 3 90 1 40.28 Example 4 90 2 41.42 Comparative Example 1 / / 35.57 Comparative Example 3 100 1 33.67 Comparative Example 5 80 3 34.12

[0139] By comparing the drug loading results of Example 1, Example 3 and Comparative Example 3, it can be seen that, under the same other conditions, as the first drying temperature increases from 80°C to 90°C, the drug loading of the microspheres will increase; from 90°C to 100°C, the drug loading of the microspheres will decrease. This is because the microspheres formed by excessively high temperatures are too strong and hard as a whole, which hinders the entry of loaded drugs, thereby affecting the drug loading performance. By comparing the drug loading results of Example 1, Example 2 and Example 5, it can be seen that, under the same other conditions, as the first drying time increases from 1h to 2h, the drug loading of the microspheres will increase; from 2h to 3h, the drug loading of the microspheres will decrease. This is because the microspheres formed by excessively long drying time are too strong and hard as a whole, which hinders the entry of loaded drugs, thereby affecting the drug loading performance.

[0140] 6. Test of shrinkage ratio of microspheres after drug loading:

[0141] Test method: The embolic microspheres before and after drug loading were spread on a glass slide and placed under a microscope of a video display system (VHX-950F) for testing. The particle sizes of 200 microspheres were tested and the average value was taken. The test results are shown in Table 5.

[0142] Table 5

[0143] Group Average diameter before drug loading / μm Average diameter after drug loading / μm Shrinkage ratio / % Example 1 243.49 228.45 6.18 Example 2 250.12 235.71 5.76 Example 3 247.52 233.85 5.52 Example 4 242.63 230.44 5.43 Comparative Example 1 247.10 196.53 20.46

[0144] By comparing the shrinkage ratio results of the embolic microspheres prepared in Examples 1-4 and Comparative Example 1 before and after drug loading, it can be seen that the shrinkage ratio of the embolic microspheres with smooth surfaces after drug loading is about 20%, and the shrinkage ratio of the embolic microspheres with wrinkled surfaces after drug loading is about 6%, and the particle size shrinkage is stable.

[0145] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

Claims

1. A method for preparing embolic microspheres with wrinkled surfaces, characterized in that: include: S1. The polymer is dissolved in water to prepare a polymer solution; the polymer solution and a crosslinking agent are mixed to obtain a modified polymer solution; Adding water-soluble monomers and initiators to the modified polymer solution and mixing to obtain an aqueous phase solution; S2. Under stirring, adding the aqueous solution to the oil phase solution containing the dispersant to obtain an oil-in-water reverse suspension polymerization system; maintaining stirring, heating the oil-in-water reverse suspension polymerization system for polymerization, purification and collection to obtain wet microspheres; S3. placing the wet microspheres in an organic solvent, removing the organic solvent to obtain transition state microspheres; S4. transferring the transition state microspheres to a vacuum drying oven for drying to obtain dry microspheres; S5. Soaking the dry microspheres in water to obtain the polyvinyl alcohol embolic microspheres with wrinkled surfaces.

2. The preparation method according to claim 1, characterized in that: Step S3 includes: Under stirring conditions, adding a first organic solvent to the wet microspheres, stopping stirring and allowing to stand for a first period of time; After removing the supernatant, a second organic solvent is added, the mixture is allowed to stand for a second period of time, and the second organic solvent is removed to obtain the transition state microspheres; wherein, The second time period is greater than the first time period.

3. The preparation method according to claim 2, characterized in that: The first organic solvent includes one or more of acetone, acetonitrile, methanol and ethanol; the second organic solvent includes one or more of acetone, acetonitrile, methanol and ethanol; and / or, The volume V1 of the first organic solvent and the volume V2 of the second organic solvent satisfy V1:V2=(10-15):

1.

4. The preparation method according to claim 2, characterized in that: The second time period t2 and the first time period t1 satisfy t2:t1=(10-30):1; Optionally, the first time period is 30 to 60 minutes, and the second time period is 10 to 15 hours.

5. The preparation method according to claim 1, characterized in that: In step S4, the drying comprises: Drying the transition state microspheres at a first temperature for a third period of time, and then lowering the temperature to a second temperature for a fourth period of time to obtain the dry state microspheres; wherein the first temperature is greater than the second temperature; Optionally, the water content of the dry microspheres is less than 5%.

6. The preparation method according to claim 5, characterized in that: The first temperature is 80°C to 90°C, and the second temperature is 50°C to 60°C.

7. The preparation method according to claim 5, characterized in that: The third time period t3 is 1 to 2 hours, and the fourth time period t4 is 2 to 4 hours.

8. The preparation method according to claim 1, characterized in that: In step S3, the temperature of the heating polymerization is 65 to 85° C. and the time is 10 to 15 hours; and / or, In step S5, the soaking time is 0.5 to 2 hours.

9. The preparation method according to claim 1, characterized in that: The high molecular polymer includes one or more of polyvinyl alcohol, sodium alginate, sodium hyaluronate, sodium hydroxymethyl cellulose and water-soluble chitosan; and / or, the cross-linking agent comprises one or more of N-(2,2-dimethoxy)-2-methylacrylamide, N-(1-hydroxy-2,2-dimethoxyethyl)-2-acrylamide and N-(2,2-dimethoxy)-2-acrylamide; and / or, the water-soluble monomer includes one or more of sodium 2-acrylamide-2-methylpropane sulfonate, sodium allyl sulfonate, sodium methacrylic acid, sodium methacrylate, acrylamide and sodium acrylate; And / or, the initiator includes one or more of ammonium persulfate, sodium persulfate and potassium persulfate.

10. An embolic microsphere with a wrinkled surface, characterized in that: The embolic microspheres are prepared by the preparation method according to any one of claims 1 to 9, and have wrinkles on the surface in a wet state.

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