Preparation method for starch hydrogel microspheres

Abstract

Provided in the present application is a preparation method for starch hydrogel microspheres, belonging to the technical field of embolic microsphere manufacturing. The preparation method for starch hydrogel microspheres comprises the following steps: adding a first crosslinking agent to a starch solution and mixing to obtain an aqueous phase solution; adding an oil phase solution to the aqueous phase solution and mixing to obtain a mixed liquid; and adding a second crosslinking agent to the mixed liquid and mixing for reaction to obtain the starch hydrogel microspheres. The starch hydrogel microspheres prepared by the method feature such advantages as long in-vivo degradation time and adjustable degradation time, and can be applied to a wide range of disease types.

Description

A method for preparing starch hydrogel microspheres

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411661882.6, filed on November 19, 2024, entitled "A Method for Preparing Starch Hydrogel Microspheres", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of embolization microsphere manufacturing technology, and more specifically, to a method for preparing starch hydrogel microspheres. Background Technology

[0004] Embolizing materials are commonly used in the medical field to block blood or fluid in blood vessels or other organs. They solidify in the blood or fluid they come into contact with, forming a solid-like substance that blocks fluid flow. Embolizing materials generally possess good biocompatibility, bioabsorption, and other biological and physical properties to suit their specific medical application environments. Vascular embolization has a wide range of applications, including the treatment of vascular lesions such as ruptured blood vessels, arteriovenous malformations, aneurysms, and arteriovenous fistulas, as well as diseases such as hyperemia, tumor-like lesions, and organ dysfunction. In short, regardless of the lesion, as long as vascular embolization can achieve the clinical therapeutic goal without damaging important tissues or organ functions, and the patient can tolerate the post-embolization reactions, vascular embolization can be considered as a treatment option.

[0005] Currently, the most widely used embolization materials in China are PVA microspheres and gelatin sponge particles. However, the non-degradable nature of PVA microspheres, leading to permanent implantation, can cause persistent inflammation and other side effects, significantly impacting patients' willingness to choose embolization. Gelatin sponge particles (Ailikang), made from pigskin gelatin, are insoluble in water but biodegradable in vivo, making them a medium-term embolization material with a complete degradation time of 14-90 days. While gelatin sponge particles offer patients a biodegradable embolization option, their animal-derived origin and the presence of formaldehyde cross-linking agents with toxic side effects make them a less universally applicable choice.

[0006] Based on this, since existing embolization materials all have their own defects, technicians thought of using starch from natural plant sources to prepare embolization materials. However, the starch embolization microspheres prepared by existing processes have the problem of too short in vivo degradation cycle (usually no more than 24 hours), resulting in a limited number of applicable diseases.

[0007] Application content

[0008] The purpose of this application is to provide a method for preparing starch hydrogel microspheres. The starch hydrogel microspheres prepared by this method have the advantages of long in vivo degradation time and adjustable degradation time, and can be applied to a wide range of disease types.

[0009] The embodiments of this application are implemented as follows:

[0010] This application provides a method for preparing starch hydrogel microspheres, comprising the following steps:

[0011] A first cross-linking agent is added to a starch solution and mixed to obtain an aqueous solution; an oil phase solution is added to the aqueous solution and mixed to obtain a mixed liquid; a second cross-linking agent is added to the mixed liquid and the mixture reacts to obtain starch hydrogel microspheres.

[0012] In the above technical solution, the crosslinking agent is added in two steps during the preparation of starch hydrogel microspheres. Specifically, the first crosslinking agent is added during the formation of the aqueous solution, and the second crosslinking agent is added to the system after the aqueous and oil phases are mixed. This specific feeding method of the crosslinking agent enables the prepared starch hydrogel microspheres to have a longer in vivo degradation time. At the same time, the in vivo degradation time of the prepared starch hydrogel microspheres can be adjusted by adjusting the mass ratio of the first and second crosslinking agents, thereby matching more disease types.

[0013] In some alternative embodiments, the mass ratio of the first crosslinking agent to the second crosslinking agent is 1:(0.4~1.5).

[0014] In the above technical solution, the ratio of the mass of the first crosslinking agent to the mass of the second crosslinking agent is limited to a specific range, so that the in vivo degradation time of the prepared starch hydrogel microspheres can be adjusted within a large range, so as to be applicable to more types of diseases.

[0015] In some alternative implementations, the mass of the first crosslinking agent is greater than the mass of the second crosslinking agent.

[0016] In the above technical solution, the mass of the first crosslinking agent is set to be greater than the mass of the second crosslinking agent, so that the in vivo degradation time of the prepared starch hydrogel microspheres can be greater than 7 days, which is particularly suitable for diseases that require long-term embolization.

[0017] In some alternative implementations, the mass of the first crosslinking agent is less than the mass of the second crosslinking agent.

[0018] In the above technical solution, the mass of the first crosslinking agent is set to be less than the mass of the second crosslinking agent, so that the in vivo degradation time of the prepared starch hydrogel microspheres can be less than 7 days (e.g., 2 to 5 days), which is particularly suitable for diseases that require short-acting embolization.

[0019] In some alternative implementations, the first crosslinking agent and / or the second crosslinking agent includes a phosphate crosslinking agent.

[0020] Optionally, the phosphoric acid crosslinking agent includes sodium trimetaphosphate and / or sodium tripolyphosphate.

[0021] Optionally, the phosphoric acid crosslinking agent is sodium trimetaphosphate.

[0022] Optionally, the phosphoric acid crosslinking agent is sodium tripolyphosphate.

[0023] Optionally, the phosphoric acid crosslinking agent is a mixture of sodium tripolyphosphate (STMP) and sodium tripolyphosphate (STPP).

[0024] In the above technical solution, the first crosslinking agent and / or the second crosslinking agent are phosphate crosslinking agents. Since this type of crosslinking agent has low toxicity, it can be well adapted to natural plant starch, so that the prepared starch hydrogel microspheres have good biocompatibility.

[0025] Furthermore, the phosphoric acid crosslinking agent uses a mixture of sodium trimetaphosphate and sodium tripolyphosphate, which has the advantage of better crosslinking effect.

[0026] In some alternative embodiments, the mass ratio of sodium trimetaphosphate to sodium tripolyphosphate in the mixture is 10:(0.8~1.2).

[0027] In the above technical solution, limiting the mass ratio of the two crosslinking agents in the mixture to a specific range can achieve a better crosslinking effect.

[0028] In some alternative embodiments, the mass ratio of starch to the first crosslinking agent in the aqueous solution is 10:(1~2).

[0029] In the above technical solution, the mass ratio of starch and the first crosslinking agent in the aqueous solution is limited to a specific range so that the two have a more suitable mass ratio in the aqueous phase, thereby making the prepared starch hydrogel microspheres have the advantages of good sphericity and being less prone to aggregation.

[0030] In some alternative embodiments, the starch concentration in the starch solution is 8-12 g / mL.

[0031] In the above technical solution, the mass concentration of starch in the starch solution is limited to a specific range. A suitable concentration can better mix and disperse with the crosslinking agent, so that the prepared starch hydrogel microspheres have the advantages of good sphericity and are not easy to agglomerate.

[0032] In some alternative embodiments, the preparation step of the oil phase solution includes adding an emulsifier to a mixed solvent of cyclohexane and n-decane and mixing them to obtain an oil phase solution.

[0033] In the above technical solution, a mixed system of cyclohexane and n-decane is used as a solvent in the process of preparing the oil phase solution, which can better dissolve and disperse the emulsifier, thereby achieving a better emulsification effect after the oil phase and water phase are mixed.

[0034] In some alternative embodiments, the volume ratio of cyclohexane to n-decane in the mixed solvent is 1:(0.8~1.2).

[0035] In the above technical solution, the volume ratio of cyclohexane and n-decane in the mixed solvent is limited to a specific range so that the two have a more suitable volume ratio in the miscible system, thereby better dissolving and dispersing the emulsifier, and thus achieving a better emulsification effect after the oil phase and water phase are mixed. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope.

[0037] Figure 1 is a process flow diagram of a method for preparing starch hydrogel microspheres according to an embodiment of this application;

[0038] Figure 2 is an optical microscope image of the starch hydrogel microspheres provided in Example 1 of this application;

[0039] Figure 3 is an optical microscope image of the starch hydrogel microspheres provided in Example 2 of this application;

[0040] Figure 4 is an optical microscope image of the starch hydrogel microspheres provided in Comparative Example 1 of this application;

[0041] Figure 5 is an optical microscope image of the starch hydrogel microspheres provided in Comparative Example 2 of this application;

[0042] Figure 6 is an optical microscope image of the starch hydrogel microspheres provided in Comparative Example 3 of this application;

[0043] Figure 7. In vivo degradation test results provided by control group 1 of this application;

[0044] Figure 8. In vivo degradation test results provided by control group 2 of this application;

[0045] Figure 9 shows the in vivo degradation test results provided in Example 1 of this application;

[0046] Figure 10 shows the in vivo degradation test results provided in Example 2 of this application;

[0047] Figure 11 shows the in vivo degradation test results provided in Comparative Example 1 of this application. Embodiments of the present invention

[0048] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0049] The following is a detailed description of a method for preparing starch hydrogel microspheres according to an embodiment of this application.

[0050] This application provides a method for preparing starch hydrogel microspheres, comprising the following steps:

[0051] A first cross-linking agent is added to a starch solution and mixed to obtain an aqueous solution; an oil phase solution is added to the aqueous solution and mixed to obtain a mixed liquid; a second cross-linking agent is added to the mixed liquid and the mixture reacts to obtain starch hydrogel microspheres.

[0052] In this application, the crosslinking agent is added in two steps during the preparation of starch hydrogel microspheres. Specifically, the first crosslinking agent is added during the formation of the aqueous solution, and the second crosslinking agent is added to the system after the aqueous and oil phases are mixed. This specific gradient feeding method of the crosslinking agent enables the prepared starch hydrogel microspheres to have a longer in vivo degradation time. At the same time, the in vivo degradation time of the prepared starch hydrogel microspheres can be adjusted by adjusting the mass ratio of the first and second crosslinking agents, thereby matching more disease types.

[0053] It should be noted that "the crosslinking agent adopts this specific gradient feeding method, which enables the prepared starch hydrogel microspheres to have a longer in vivo degradation time." The longer degradation time is compared with the existing starch hydrogel microspheres with an in vivo degradation time of less than 24 hours.

[0054] It should be noted that the preparation process of the starch solution can be carried out in accordance with conventional methods in the field, such as adding starch and sodium hydroxide to distilled water and stirring under heating conditions until a transparent paste is formed.

[0055] It should be noted that the method of adding the first crosslinking agent and / or the second crosslinking agent is not limited. For example, it can be in solid form or in liquid form. In the embodiments of this application, it is added in liquid form, for example, in an aqueous solution of 0.2~0.25 g / mL.

[0056] It is understood that after the mixing reaction step, there are also steps of settling, filtering, washing and sieving in sequence, and each step can be performed in accordance with conventional practices in the art.

[0057] It should be noted that the mass ratio of the first crosslinking agent and the second crosslinking agent is not limited and can be adjusted according to actual needs.

[0058] As an example, the mass ratio of the first crosslinking agent to the second crosslinking agent is 1:(0.4~1.5), for example, but not limited to, any one of the mass ratios of 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 and 1:1.5, or any range between the two.

[0059] In this embodiment, the ratio of the mass of the first crosslinking agent to the mass of the second crosslinking agent is limited to a specific range, so that the in vivo degradation time of the prepared starch hydrogel microspheres can be adjusted within a large range, so as to be applicable to more types of diseases.

[0060] As an example, the mass of the first crosslinking agent is greater than the mass of the second crosslinking agent.

[0061] In this embodiment, the mass of the first crosslinking agent is set to be greater than the mass of the second crosslinking agent, so that the in vivo degradation time of the prepared starch hydrogel microspheres can be greater than 7 days, which is particularly suitable for diseases that require long-term embolization.

[0062] As an example, the mass of the first crosslinking agent is less than the mass of the second crosslinking agent.

[0063] In this embodiment, the mass of the first crosslinking agent is set to be less than the mass of the second crosslinking agent, so that the in vivo degradation time of the prepared starch hydrogel microspheres can be less than 7 days (e.g., 2 to 5 days), which is particularly suitable for diseases requiring short-acting embolization.

[0064] It should be noted that the types of the first crosslinking agent and / or the second crosslinking agent are not limited and can be adapted to meet actual needs.

[0065] As an example, the first crosslinking agent and / or the second crosslinking agent may include phosphate crosslinking agents.

[0066] As an example, phosphate crosslinking agents include sodium trimetaphosphate and / or sodium tripolyphosphate.

[0067] As an example, a phosphoric acid crosslinking agent is sodium trimetaphosphate.

[0068] As an example, a phosphoric acid crosslinking agent is sodium tripolyphosphate.

[0069] As an example, a phosphoric acid crosslinking agent is a mixture of sodium trimetaphosphate and sodium tripolyphosphate.

[0070] In this embodiment, the first crosslinking agent and / or the second crosslinking agent are phosphate crosslinking agents. Since these crosslinking agents have low toxicity, they can be well adapted to natural plant starch, so that the prepared starch hydrogel microspheres have good biocompatibility.

[0071] In this embodiment, the phosphoric acid crosslinking agent is a mixture of sodium trimetaphosphate and sodium tripolyphosphate, which has the advantage of better crosslinking effect.

[0072] As an example, in the mixture, the mass ratio of sodium trimetaphosphate to sodium tripolyphosphate is 10:(0.8~1.2), for example, but not limited to any one of the mass ratios of 10:0.8, 10:0.9, 10:1, 10:1.1 and 10:1.2 or any range between the two.

[0073] In this embodiment, limiting the mass ratio of the two crosslinking agents in the mixture to a specific range can achieve a better crosslinking effect.

[0074] As an example, in the aqueous solution, the mass ratio of starch to the first crosslinking agent is 10:(1~2), for example, but not limited to any one of the mass ratios of 10:1, 10:1.1, 10:1.2, 10:1.3, 10:1.4, 10:1.5, 10:1.6, 10:1.7, 10:1.8, 10:1.9 and 10:2, or any range between the two.

[0075] In this embodiment, the mass ratio of starch to the first crosslinking agent in the aqueous solution is limited to a specific range so that the two have a suitable mass ratio in the aqueous phase, thereby giving the prepared starch hydrogel microspheres the advantages of good sphericity and low agglomeration.

[0076] As an example, in a starch solution, the mass concentration of starch is 8 to 12 g / mL, for example, but not limited to any one of the mass concentrations of 8 g / mL, 9 g / mL, 10 g / mL, 11 g / mL and 12 g / mL or any range between two.

[0077] In this embodiment, the mass concentration of starch in the starch solution is limited to a specific range. A suitable concentration can better mix and disperse with the crosslinking agent, so that the prepared starch hydrogel microspheres have the advantages of good sphericity and are not easy to agglomerate.

[0078] As an example, the preparation steps of the oil phase solution include: adding an emulsifier to a mixed solvent of cyclohexane and n-decane and mixing them to obtain an oil phase solution.

[0079] In this embodiment, a mixture of cyclohexane and n-decane is used as a solvent during the preparation of the oil phase solution. This mixture can effectively dissolve and disperse the emulsifier, thereby achieving a better emulsification effect after the oil and water phases are mixed.

[0080] As an example, in the mixed solvent, the volume ratio of cyclohexane to n-decane is 1:(0.8~1.2), for example, but not limited to any one of the volume ratios of 1:0.8, 1:0.9, 1:1, 1:1.1 and 1:2, or any range between the two.

[0081] In this embodiment, the volume ratio of cyclohexane and n-decane in the mixed solvent is limited to a specific range so that the two have a more suitable volume ratio in the miscible system, thereby better dissolving and dispersing the emulsifier, and thus achieving a better emulsification effect after the oil phase and water phase are mixed.

[0082] It should be noted that the type of emulsifier is not limited and can be selected and set according to the conventional methods in this field, such as emulsifier OP-4.

[0083] It should be noted that for processes or steps in starch hydrogel microspheres that are not specifically described or limited, they can be set according to conventional methods in the field.

[0084] As an example, the process flow diagram of the preparation method of starch hydrogel microspheres is exemplarily shown in Figure 1.

[0085] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0086] Example 1

[0087] This application provides a method for preparing starch hydrogel microspheres, comprising the following steps:

[0088] Add 10 g of starch and 1 g of sodium hydroxide to 100 mL of distilled water and heat and stir until a transparent paste forms. Let it stand and cool for later use. Take 25 mL of the starch solution and add 7 mL of an aqueous solution containing 1.4 g of STMP and 0.14 g of STPP while stirring. Stir until fully dissolved to obtain an aqueous phase solution. Add 0.5 g of emulsifier (OP-4) to 100 mL of a mixed solvent (cyclohexane and n-decane in a volume ratio of 1:1) and stir to obtain an oil phase solution. Add the oil phase solution to the aqueous phase solution and stir to obtain a mixed liquid. Add 3 mL of an aqueous solution containing 0.6 g of STMP and 0.06 g of STPP to the mixed liquid and stir to react at room temperature (25 °C) for 24 h. After the reaction is complete, allow it to stand, filter, wash (wash three times with ethyl acetate to remove oil phase impurities), and sieve to obtain starch hydrogel microspheres.

[0089] Example 2

[0090] This application provides a method for preparing starch hydrogel microspheres, comprising the following steps:

[0091] Add 10 g of starch and 1 g of sodium hydroxide to 100 mL of distilled water and heat and stir until a transparent paste forms. Let it stand and cool for later use. Take 25 mL of the starch solution and add 7 mL of an aqueous solution containing 1.4 g of STMP and 0.14 g of STPP while stirring. Stir until fully dissolved to obtain an aqueous phase solution. Add 0.5 g of emulsifier (OP-4) to 100 mL of a mixed solvent (cyclohexane and n-decane in a volume ratio of 1:1) and stir to obtain an oil phase solution. Add the oil phase solution to the aqueous phase solution and stir to obtain a mixed liquid. Add 10 mL of an aqueous solution containing 2 g of STMP and 0.2 g of STPP to the mixed liquid and stir to react at room temperature (25 °C) for 24 h. After the reaction is complete, allow to stand, filter, wash (wash three times with ethyl acetate to remove oil phase impurities), and sieve to obtain starch hydrogel microspheres.

[0092] Example 3

[0093] This application provides a method for preparing starch hydrogel microspheres, comprising the following steps:

[0094] Add 10 g of starch and 1 g of sodium hydroxide to 100 mL of distilled water and heat and stir until a transparent paste forms. Let it stand and cool for later use. Take 25 mL of the starch solution and add 7 mL of an aqueous solution containing 1.4 g of STMP and 0.14 g of STPP while stirring. Stir until fully dissolved to obtain an aqueous phase solution. Add 0.5 g of emulsifier (OP-4) to 100 mL of a mixed solvent (cyclohexane and n-decane in a volume ratio of 1:1) and stir to obtain an oil phase solution. Add the oil phase solution to the aqueous phase solution and stir to obtain a mixed liquid. Add 5 mL of an aqueous solution containing 1 g of STMP and 0.1 g of STPP to the mixed liquid and stir to react at room temperature (25 °C) for 24 h. After the reaction is complete, allow it to stand, filter, wash (wash three times with ethyl acetate to remove oil phase impurities), and sieve to obtain starch hydrogel microspheres.

[0095] Example 4

[0096] This application provides a method for preparing starch hydrogel microspheres, comprising the following steps:

[0097] Add 10 g of starch and 1 g of sodium hydroxide to 100 mL of distilled water and heat and stir until a transparent paste forms. Let it stand and cool for later use. Take 25 mL of the starch solution and add 7 mL of an aqueous solution containing 1.5 g of STMP while stirring. Stir until fully dissolved to obtain an aqueous phase solution. Add 0.5 g of emulsifier (OP-4) to 100 mL of a mixed solvent (cyclohexane and n-decane in a volume ratio of 1:1) and stir to obtain an oil phase solution. Add the oil phase solution to the aqueous phase solution and stir to obtain a mixed liquid. Add 5 mL of an aqueous solution containing 1 g of STMP to the mixed liquid and stir to react at room temperature (25℃) for 24 h. After the reaction is complete, allow it to stand, filter, wash (wash three times with ethyl acetate to remove oil phase impurities), and sieve to obtain starch hydrogel microspheres.

[0098] Comparative Example 1

[0099] This application provides a comparative example of a method for preparing starch hydrogel microspheres, comprising the following steps:

[0100] Add 10 g of starch and 1 g of sodium hydroxide to 100 mL of distilled water and heat and stir until a transparent paste forms. Let it stand and cool for later use. Take 25 mL of the starch solution and add 7 mL of an aqueous solution containing 1.4 g of STMP and 0.14 g of STPP while stirring. Stir until fully dissolved to obtain an aqueous phase solution. Add 0.5 g of emulsifier (OP-4) to 100 mL of a mixed solvent (cyclohexane and n-decane in a volume ratio of 1:1) and stir to obtain an oil phase solution. Add the oil phase solution to the aqueous phase solution and stir at room temperature (25 °C) for 24 h. After the reaction is complete, allow it to stand, filter, wash (wash three times with ethyl acetate to remove oil phase impurities), and sieve to obtain starch hydrogel microspheres.

[0101] Comparative Example 2

[0102] This application provides a comparative example of a method for preparing starch hydrogel microspheres, comprising the following steps:

[0103] Add 10 g of starch and 1 g of sodium hydroxide to 100 mL of distilled water and heat and stir until a transparent paste forms. Let it stand and cool for later use. Add 0.5 g of emulsifier (OP-4) to 100 mL of mixed solvent (cyclohexane and n-decane in a volume ratio of 1:1) and stir to obtain an oil phase solution. Take 25 mL of starch solution and add the oil phase solution to it while stirring, and stir to obtain a mixed liquid. Then add 7 mL of an aqueous solution containing 1.4 g of STMP and 0.14 g of STPP to the mixed liquid, and stir to react at room temperature (25 °C) for 24 h. After the reaction is complete, allow it to stand, filter, wash (wash three times with ethyl acetate to remove oil phase impurities), and sieve to obtain starch hydrogel microspheres.

[0104] Comparative Example 3

[0105] This application provides a comparative example of a method for preparing starch hydrogel microspheres, comprising the following steps:

[0106] Add 10 g of starch and 1 g of sodium hydroxide to 100 mL of distilled water and heat and stir until a transparent paste forms. Let it stand and cool for later use. Add 0.5 g of emulsifier (OP-4) to 100 mL of mixed solvent (cyclohexane and n-decane in a volume ratio of 1:1) and stir to obtain an oil phase solution. Take 25 mL of starch solution and add the oil phase solution to it while stirring, and stir to obtain a mixed liquid. Then add 17 mL of an aqueous solution containing 3.4 g of STMP and 0.34 g of STPP to the mixed liquid, and stir to react at room temperature (25 °C) for 24 h. After the reaction is complete, allow it to stand, filter, wash (wash three times with ethyl acetate to remove oil phase impurities), and sieve to obtain starch hydrogel microspheres.

[0107] Test case

[0108] 1. Microstructure testing of hydrogel microspheres

[0109] Test method:

[0110] The starch hydrogel microspheres prepared in Examples 1-2 and Comparative Examples 1-3 were numbered, and the microstructure of each sample was then tested.

[0111] The specific testing steps are as follows:

[0112] Take 100 mL of each group of sieved microspheres (300-600 μm) and add 100 mL of physiological saline. After standing and allowing the microspheres to settle and separate into layers, remove the supernatant and add 100 mL of physiological saline again. Repeat the operation three or more times to obtain replacement microspheres with physiological saline as the storage medium. Take pictures with an optical microscope to observe the microstructure of the microspheres.

[0113] Refer to Figures 2 to 6, where Figure 2 corresponds to Example 1 (scale bar is 400 μm), Figure 3 corresponds to Example 2 (scale bar is 400 μm), Figure 4 corresponds to Example 1 (scale bar is 400 μm), Figure 5 corresponds to Example 2 (scale bar is 400 μm), and Figure 6 corresponds to Example 3 (scale bar is 300 μm).

[0114] As shown in Figures 2-6, the starch hydrogel microspheres prepared according to the preparation method provided in this application have the advantages of good sphericity and good dispersibility. It is particularly important to note that if a crosslinking agent is added only after mixing the aqueous and oil phases, the prepared microspheres exhibit severe agglomeration, making subsequent applications difficult. Furthermore, the agglomeration of microspheres becomes more severe with increasing amounts of crosslinking agent.

[0115] 2. Solid content test of hydrogel microspheres

[0116] Test method:

[0117] The starch hydrogel microspheres prepared in Examples 1-4 and Comparative Examples 1-3 were numbered, and the solid content of each sample was tested.

[0118] The specific testing steps are as follows:

[0119] The moisture content of the microspheres in the 300-600 micrometer range before replacement was tested using a moisture analyzer. The test was repeated three times and the average value was taken to obtain the corresponding solid content. The corresponding test results are statistically summarized in Table 1.

[0120] 3. In vitro degradation time test of hydrogel microspheres

[0121] Test method:

[0122] The starch hydrogel microspheres prepared in Examples 1-4 and Comparative Example 1 were numbered, and the in vitro degradation time of each sample was tested.

[0123] The specific testing steps are as follows:

[0124] Take 2 mL of each group of microspheres that have been replaced with 300-600 micrometers and add them to 18 mL of physiological saline solution containing α-amylase to prepare an enzyme concentration of 500 U / L. Incubate the mixture on a shaker at 37℃. Visually observe the reaction flasks at regular intervals. When the microspheres are no longer visible, take 0.5 mL of the mixture and dilute it to 1 mL for microscopic photography. The time when no microspheres are visible under microscopic photography is considered the time when the microspheres are completely degraded. The corresponding test results are summarized in Table 1.

[0125] 4. In vivo degradation time test of hydrogel microspheres

[0126] Test method:

[0127] The starch hydrogel microspheres prepared in Examples 1-4 and Comparative Example 1 were numbered respectively. Meanwhile, commercially available PVA microspheres (Kerich (Shenzhen) Medical Technology Development Co., Ltd. - non-degradable) and gelatin sponge particles (Ailikang Pharmaceutical Technology Co., Ltd., complete degradation time 14-90 days) were used as control group 1 and control group 2. Then, the in vivo degradation time of each sample was tested and the test results are summarized in Table 1.

[0128] The specific testing steps are as follows:

[0129] Five healthy rabbits were prepared, and the vascular network of the rabbit ears was photographed under a light source (i.e., preoperative photographs of the rabbit ear vascular network were collected). Then, a 22G indwelling needle was inserted into the central artery 4-5 cm from the base of the rabbit ear, from the proximal end to the distal end, in the direction of blood flow. The needle was then removed, and the suspended sample was slowly injected (pulsating injection, 1 mL / min) until obvious injection resistance was observed. When the light source was shone from the back of the ear, the central artery of the rabbit ear turned white and there was no blood flow inside. After the injection, the injection site was pressed to stop the bleeding, and the indwelling needle was removed. The needle insertion site was marked. Then, the vascular network of the rabbit ears was photographed under a light source at 0 h, 2 h, 1 day, 2 days and 7 days after the operation to statistically analyze the degradation state of the sample in the animals.

[0130] It should be noted that if the blood vessels at the rabbit site are completely normal, it means that the sample has been completely degraded; if the blood vessels at the rabbit site are still damaged, it means that the sample has not been completely degraded, and the more severe the damage, the better the embolization effect of the sample (i.e., the more difficult it is to degrade).

[0131] Refer to Figures 7 to 11, where Figure 7 corresponds to Control Group 1, Figure 8 corresponds to Control Group 2, Figure 9 corresponds to Example 1, Figure 10 corresponds to Example 2, and Figure 11 corresponds to Example 1.

[0132] As shown in Figures 7-11, the test results indicate that in Control Groups 1 and 2, the vascular network in the rabbits was still severely damaged 7 days after surgery, indicating that the blood vessels were still severely blocked (i.e., the sample had not decomposed). In Example 1, the vascular network in the rabbits recovered to normal between 2 and 7 days after surgery, indicating that the in vivo degradation time of the sample in Example 1 was 2-7 days. In Example 2, the damage to the vascular network in the rabbits was somewhat relieved 7 days after surgery compared to 1 day after surgery, but it had not recovered to normal, indicating that the in vivo degradation time of the sample in Example 2 was greater than 7 days. In Comparative Example 1, the vascular network in the rabbits recovered to normal 1 day after surgery, indicating that the in vivo degradation time of the sample in Comparative Example 1 was within 24 hours.

[0133] Table 1

[0134]

[0135] It should be noted that “—” in Table 1 indicates that no test was performed.

[0136] Based on the test results in Table 1 and Figures 2 to 11, it can be seen that the starch hydrogel microspheres prepared according to the preparation method provided in the embodiments of this application have the advantages of good sphericity and good dispersibility, and have a long degradation time in vivo with adjustable specific degradation time, making them suitable for a wide range of diseases.

[0137] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for preparing starch hydrogel microspheres, characterized in that, Includes the following steps: The first cross-linking agent was added to the starch solution and mixed to obtain an aqueous solution; An oil phase solution is added to the aqueous phase solution and mixed to obtain a mixed liquid; A second crosslinking agent is added to the mixed liquid and the mixture is reacted to obtain starch hydrogel microspheres.

2. The method for preparing starch hydrogel microspheres according to claim 1, characterized in that, The mass ratio of the first crosslinking agent to the second crosslinking agent is 1:(0.4~1.5).

3. The method for preparing starch hydrogel microspheres according to claim 2, characterized in that, The mass of the first crosslinking agent is greater than the mass of the second crosslinking agent.

4. The method for preparing starch hydrogel microspheres according to claim 2, characterized in that, The mass of the first crosslinking agent is less than the mass of the second crosslinking agent.

5. The method for preparing starch hydrogel microspheres according to any one of claims 1 to 4, characterized in that, The first crosslinking agent and / or the second crosslinking agent include phosphate crosslinking agents; Optionally, the phosphoric acid crosslinking agent includes sodium trimetaphosphate and / or sodium tripolyphosphate; Optionally, the phosphoric acid crosslinking agent is sodium trimetaphosphate; Optionally, the phosphoric acid crosslinking agent is sodium tripolyphosphate; Optionally, the phosphoric acid crosslinking agent is a mixture of sodium trimetaphosphate and sodium tripolyphosphate.

6. The method for preparing starch hydrogel microspheres according to claim 5, characterized in that, In the mixture, the mass ratio of sodium trimetaphosphate to sodium tripolyphosphate is 10:(0.8~1.2).

7. The method for preparing starch hydrogel microspheres according to any one of claims 1 to 4, characterized in that, In the aqueous solution, the mass ratio of starch to the first crosslinking agent is 10:(1~2).

8. The method for preparing starch hydrogel microspheres according to any one of claims 1 to 4, characterized in that, The starch solution contains starch with a mass concentration of 8-12 g / mL.

9. The method for preparing starch hydrogel microspheres according to any one of claims 1 to 4, characterized in that, The preparation steps of the oil phase solution include: adding an emulsifier to a mixed solvent of cyclohexane and n-decane and mixing them to obtain an oil phase solution.

10. The method for preparing starch hydrogel microspheres according to claim 9, characterized in that, In the mixed solvent, the volume ratio of cyclohexane to n-decane is 1:(0.8~1.2).

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