A rapidly degradable embolization microsphere for knee artery embolization and a preparation method and application thereof

Abstract

The application provides a fast-degradation embolization microsphere for knee artery embolization and a preparation method and application thereof, and belongs to the technical field of medical devices. The microsphere has a gradient crosslinking structure with decreasing crosslinking degrees from outside to inside, and is formed by stepwise crosslinking of starch, an internal crosslinking agent and an external crosslinking agent through reverse phase emulsification; the starch is at least one selected from acid hydrolyzed starch, potato starch and soluble starch; the internal crosslinking agent is polyethylene glycol diglycidyl ether, and the external crosslinking agent is at least one selected from sodium trimetaphosphate and epichlorohydrin; the microsphere is degraded under the condition that the concentration of alpha-amylase is 100-200 U / L and the temperature is 37 DEG C, and the morphology completely disappears within 1 h-48 h; the microsphere maintains a circular morphology within 60 min before degradation, and the morphology is rapidly degraded within 70-90 min, so that the mechanical property and the degradation property of the microsphere are synergistically controlled.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to a rapidly degradable embolic microsphere for knee artery embolization, its preparation method, and its application. Background Technology

[0002] In my country, the incidence of symptomatic knee osteoarthritis (KOA) alone is as high as 8.1%. KOA is mainly characterized by pain, stiffness, and limited range of motion in the affected joint. Initially, imipenem / cilastatin sodium (IPM / CS) granules were used clinically to embolize abnormal blood vessels in patients to relieve pain. These antibiotic granules dissolve rapidly in the body and have shown good clinical outcomes. However, IPM / CS granules are not suitable for patients allergic to valproic acid or related antibiotics. Furthermore, because they lack indications for vascular embolization, excessive use can easily lead to antibiotic abuse and also carries the risk of exacerbating kidney damage in patients.

[0003] Subsequently, doctors often use permanent embolization microspheres to embolize the abnormal blood vessels in patients. Normal knee arteries have a rich network of anastomosing vessels, and pathological neovascularization is mostly a diffuse peripheral vascular network, making precise superselection of target vessels difficult. Therefore, the use of permanent embolization microspheres greatly increases the risk of ectopic embolization complications. International clinical studies have shown that 10-15% of patients experience ectopic embolization-related adverse reactions, including skin damage, ischemic edema, and surgical area numbness, indicating a high risk of non-targeted ectopic embolization.

[0004] Currently, there are no microspheres in China that can rapidly degrade after embolization at the vascular site for clinical use. Therefore, developing a simple-to-prepare, rapidly degradable microsphere for this application has significant clinical value.

[0005] Chinese invention patent CN113694248B discloses an embolic microsphere based on soluble starch, its preparation, and its application. This embolic microsphere is prepared by reverse-phase suspension polymerization of soluble starch, olefin polar monomers, initiators, and crosslinking agents. The continuous phase consists of an oil phase and a surfactant, while the dispersed phase comprises soluble starch, olefin polar monomers, initiators, and crosslinking agents. This invention obtains embolic microspheres by crosslinking olefin polar monomers with soluble starch via free radical grafting. The embolic microspheres exhibit a rich porous structure with pores extending into the interior, resulting in a large specific surface area. Furthermore, the surface of the embolic microspheres possesses numerous hydrophilic polar groups, enabling electrostatic adsorption of drugs and achieving a good sustained-release effect. However, this patent uses conventional crosslinking agents (epichlorohydrin, N,N'-methylenebisacrylamide, etc.) for overall crosslinking, forming a homogeneous crosslinked network that lacks time-controlled characteristics. Additionally, the introduction of olefin monomers and initiators poses a risk of residue buildup. Summary of the Invention

[0006] The purpose of this invention is to propose a rapidly degradable embolization microsphere for knee artery embolization, its preparation method and application. It has high biosafety and achieves synergistic regulation of the mechanical properties and degradation properties of the microsphere. It is suitable for the clinical needs of "temporarily occluding pathological neovascularization first and then rapidly degrading to restore blood flow" in knee artery embolization. Different degradation cycles can be selected according to clinical use.

[0007] The technical solution of this invention is implemented as follows:

[0008] This invention provides a rapidly degradable embolic microsphere for knee artery embolization. The microsphere has a gradient cross-linking structure with decreasing cross-linking degree from the outside to the inside, and is formed by stepwise cross-linking of starch, an internal cross-linking agent, and an external cross-linking agent through reverse emulsification. The starch is selected from at least one of acid-hydrolyzed starch, potato starch, and soluble starch. The internal cross-linking agent is polyethylene glycol diglycidyl ether, and the external cross-linking agent is selected from at least one of sodium trimetaphosphate and epichlorohydrin. The microsphere is degraded at an α-amylase concentration of 100-200 U / L and at 37°C, and its morphology completely disappears within 1-48 hours. The microsphere maintains a spherical morphology for the first 60 minutes of degradation and undergoes rapid morphological degradation within 70-90 minutes.

[0009] As a further improvement of the present invention, the microspheres do not break at a 70% compression rate and pass the injection test via a 1.7F microcatheter.

[0010] This invention further protects a method for preparing the above-mentioned rapidly degradable embolic microspheres for knee artery embolization, comprising the following steps:

[0011] S1. Dissolve starch in sodium hydroxide solution to prepare starch solution;

[0012] S2. Dissolve the surfactant in the oil phase solvent to prepare the oil phase;

[0013] S3. Add the internal crosslinking agent to the starch solution obtained in step S1, stir until homogeneous, and obtain the aqueous phase;

[0014] S4. Add the aqueous phase obtained in step S3 to the oil phase obtained in step S2, stir and emulsify to obtain a reverse emulsion;

[0015] S5. Add an external crosslinking agent to the reverse emulsion obtained in step S4 to carry out a crosslinking reaction;

[0016] S6. Allow the microspheres to stand and separate into layers, collect the microspheres, wash them with organic solvent and purified water, and then replace them with physiological saline to obtain rapidly degradable embolization microspheres for knee artery embolization.

[0017] As a further improvement of the present invention, in step (1), the concentration of the sodium hydroxide solution is 0.5M-2M, and the mass-volume concentration of the starch solution is 10%-20%.

[0018] As a further improvement of the present invention, in step (2), the surfactant is selected from at least one of Span 80, Span 85 and Tween 80; the oil phase solvent is selected from at least one of isopropyl palmitate, n-butyl acetate, cyclohexane, decane, n-heptane and petroleum ether.

[0019] As a further improvement of the present invention, in step (3), the amount of the internal crosslinking agent added to each 20 mL starch solution is 25 μL-200 μL.

[0020] As a further improvement of the present invention, in step (4), the volume ratio of the aqueous phase to the oil phase is 1:(3-5), and the emulsification time is 5min-30min.

[0021] As a further improvement of the present invention, in step (5), the external crosslinking agent sodium trimetaphosphate is added in the form of sodium trimetaphosphate aqueous solution, wherein the amount of sodium trimetaphosphate added is 0.4g-1.2g, and the reaction conditions are to react at 35℃-45℃ for 2h-4h first, and then at room temperature for 12h-18h.

[0022] As a further improvement of the present invention, in step (6), the organic solvent includes ethyl acetate and ethanol.

[0023] This invention further protects the application of the above-mentioned rapidly degradable embolization microspheres for knee artery embolization in the preparation of knee artery embolization treatment devices.

[0024] The present invention has the following beneficial effects:

[0025] 1. The raw materials of this invention are all plant-derived starch and conventional pharmaceutical cross-linking agents. No non-starch components such as olefin monomers and initiators are introduced, thus avoiding the risk of monomer residue and achieving higher biosafety.

[0026] 2. Although the material is starch polysaccharide, the microspheres prepared by this invention through different combinations of crosslinking agents exhibit compressibility (over 70%) and suitable duct permeability. Preferably, the internal crosslinking agents are polyethylene glycol diglycidyl ether and epichlorohydrin, while the external crosslinking agents are preferably medium- or short-chain crosslinking agents such as sodium trimetaphosphate and epichlorohydrin. This invention achieves synergistic regulation of the mechanical and degradation properties of the microspheres by utilizing the differences in the chemical properties and timing of addition of the internal and external crosslinking agents, without introducing non-starch monomers or adding post-processing steps.

[0027] 3. This invention achieves a controllable degradation cycle by regulating the content of crosslinking agent, resulting in a time-controlled degradation structure driven by "high external and low internal" crosslinking degree. This realizes the time-sequential programming of degradation behavior, which is particularly suitable for the clinical needs of "temporarily occluding pathological neovascularization first and then rapidly degrading to restore blood flow" in knee artery embolism. Different degradation cycles can be selected according to clinical use.

[0028] 4. The microspheres prepared by this invention have different degrees of cross-linking from the outside to the inside. After maintaining a certain volume for a certain period of time, they can be rapidly degraded. Through the combination and ratio of cross-linking agents, the triple performance of high compressibility, high permeability and rapid and controllable degradation has been achieved for the first time in the starch microsphere system.

[0029] 5. Pathological neovascularization in knee osteoarthritis (KOA) is a diffuse peripheral vascular network, interwoven with the rich anastomotic vascular network of the normal knee joint. This invention uses plant-derived starch (avoiding the risks associated with animal-derived gelatin) and, through the aforementioned gradient cross-linking and controllable degradation design, ensures that the microspheres completely degrade within 1-48 hours after embolizing the target vessel (the cross-linking agent ratio is selected according to clinical needs), fundamentally avoiding non-target ectopic vascular embolism caused by permanent microspheres. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a morphological diagram of the microspheres obtained in Example 1 of the present invention.

[0032] Figure 2 This is a morphological diagram of the microspheres obtained in Example 2 of the present invention.

[0033] Figure 3 This is a morphological diagram of the microspheres obtained in Example 3 of the present invention.

[0034] Figure 4 This is a morphological diagram of the microspheres obtained in Example 4 of the present invention.

[0035] Figure 5 This is a morphological diagram of the microspheres obtained in Example 5 of the present invention.

[0036] Figure 6 This is a morphological diagram of the microspheres obtained in Example 6 of the present invention.

[0037] Figure 7 This is a morphological diagram of the microspheres prepared in Comparative Example 1 of the present invention.

[0038] Figure 8 This is a morphological diagram of the microspheres prepared in Comparative Example 2 of the present invention.

[0039] Figure 9 This is a morphological diagram of the microspheres prepared in Comparative Example 3 of the present invention.

[0040] Figure 10 This is a morphological diagram of the microspheres prepared in Comparative Example 4 of the present invention.

[0041] Figure 11 This is a morphological diagram of the microspheres prepared in Comparative Example 5 of the present invention.

[0042] Figure 12 The diagram shows the morphology and compression curve of the microspheres obtained in Example 3 of this invention.

[0043] Figure 13 This is a comparison diagram of the degradation of microspheres prepared in Example 1 of the present invention at different times. Detailed Implementation

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1

[0046] This embodiment provides a method for preparing rapidly degradable embolic microspheres for knee artery embolization, including the following steps:

[0047] (1) Preparation of 10% w / v starch solution: Take 10g of potato starch and stir to dissolve it in 100 mL of 1M sodium hydroxide solution.

[0048] (2) Oil phase preparation: Dissolve 2 mL of Span80 in 98 mL of isopropyl palmitate until homogeneous.

[0049] (3) Aqueous phase preparation: Take 20 mL of 10% w / v starch solution and 50 μL of polyethylene glycol diglycidyl ether and stir for 10 min to dissolve evenly.

[0050] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0051] (5) Crosslinking agent reaction: Add 200 μL of epichlorohydrin to the solution in step (4) and react at room temperature for 18 h.

[0052] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0053] Example 2

[0054] This embodiment provides a method for preparing rapidly degradable embolic microspheres for knee artery embolization, including the following steps:

[0055] (1) Preparation of 20% starch solution: Take 20g of soluble starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0056] (2) Preparation of oil phase: Dissolve 2 mL of Span80 in 98 mL of n-butyl acetate until homogeneous.

[0057] (3) Aqueous phase preparation: Take 20 mL of 20% w / v starch solution and 100 μL of polyethylene glycol diglycidyl ether and stir for 10 min to dissolve evenly.

[0058] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0059] (5) Crosslinking agent reaction: Add 400 μL of epichlorohydrin to the solution in step (4) and react at room temperature for 18 h.

[0060] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0061] Example 3

[0062] This embodiment provides a method for preparing rapidly degradable embolic microspheres for knee artery embolization, including the following steps:

[0063] (1) Preparation of 10% w / v starch solution: Take 10g of potato starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0064] (2) Preparation of oil phase: Dissolve 1 mL of Span 85 and 1 mL of Tween 80 in 98 mL of a mixed solution of cyclohexane and decane (1:1) until homogeneous.

[0065] (3) Aqueous phase preparation: Take 20 mL of 10% w / v starch solution and 200 μL of polyethylene glycol diglycidyl ether and stir for 10 min to dissolve evenly.

[0066] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0067] (5) Crosslinking agent reaction: Add 200 μL of epichlorohydrin to the solution in step (4) and react at room temperature for 18 h.

[0068] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0069] Example 4

[0070] This embodiment provides a method for preparing rapidly degradable embolic microspheres for knee artery embolization, including the following steps:

[0071] (1) Preparation of 20% w / v starch solution: Take 20g of soluble starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0072] (2) Oil phase preparation: Dissolve 2 mL of Span80 in 98 mL of n-heptane until homogeneous.

[0073] (3) Aqueous phase preparation: Take 20 mL of 20% w / v starch solution and 200 μL of polyethylene glycol diglycidyl ether and stir for 10 min to dissolve evenly.

[0074] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0075] (5) Crosslinking agent reaction: Add 400 μL of epichlorohydrin to the solution in step (4) and react at room temperature for 18 h.

[0076] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0077] Example 5

[0078] This embodiment provides a method for preparing rapidly degradable embolic microspheres for knee artery embolization, including the following steps:

[0079] (1) Preparation of 20% w / v starch solution: Take 20g of soluble starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0080] (2) Preparation of oil phase: Dissolve 2 mL of Span80 in 98 mL of petroleum ether until homogeneous.

[0081] (3) Aqueous phase preparation: Take 20 mL of 20% w / v starch solution and 100 μL of polyethylene glycol diglycidyl ether and stir for 10 min to dissolve evenly.

[0082] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0083] (5) Crosslinking agent reaction: Add 5 mL of sodium tripolyphosphate containing 1.2 g to the solution in step (4), react at 40 °C for 3 h, and then react at room temperature for 15 h.

[0084] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0085] Example 6

[0086] This embodiment provides a method for preparing rapidly degradable embolic microspheres for knee artery embolization, including the following steps:

[0087] (1) Preparation of 20% w / v starch solution: Take 20g of soluble starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0088] (2) Preparation of oil phase: Dissolve 2 mL of Span80 in 98 mL of cyclohexane until homogeneous.

[0089] (3) Aqueous phase preparation: Take 20 mL of 20% w / v starch solution and 200 μL of polyethylene glycol diglycidyl ether and stir for 10 min to dissolve evenly.

[0090] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0091] (5) Crosslinking agent reaction: Add 5 mL of sodium tripolyphosphate containing 1.2 g to the solution in step (4), react at 40 °C for 3 h, and then react at room temperature for 15 h.

[0092] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0093] Comparative Example 1

[0094] The preparation method includes the following steps:

[0095] (1) Preparation of 20% w / v starch solution: Take 20g of soluble starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0096] (2) Oil phase preparation: Dissolve 2 mL of Span80 in 98 mL of cyclohexane until homogeneous.

[0097] (3) Aqueous phase preparation: Take 20 mL of 20% w / v starch solution and 200 μL of polyethylene glycol diglycidyl ether and stir for 10 min to dissolve evenly.

[0098] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0099] (5) Crosslinking agent reaction: Add 800 μL of polyethylene glycol glycidyl ether to the solution in step (4) and react at room temperature for 18 h.

[0100] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0101] Comparative Example 2

[0102] The preparation method includes the following steps:

[0103] (1) Preparation of 20% w / v starch solution: Take 20g of soluble starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0104] (2) Oil phase preparation: Dissolve 2 mL of Span80 in 98 mL of cyclohexane until homogeneous.

[0105] (3) Aqueous phase preparation: Take 20 mL of 20% w / v starch solution and 100 mg of sodium tripolyphosphate and stir for 10 min to dissolve evenly.

[0106] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0107] (5) Crosslinking agent reaction: Add 2 mL of sodium tripolyphosphate containing 0.4 g to the solution in step (4), react at 40 °C for 3 h, and then react at room temperature for 15 h.

[0108] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0109] Comparative Example 3

[0110] The preparation method includes the following steps:

[0111] (1) Preparation of 20% w / v starch solution: Take 20g of soluble starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0112] (2) Oil phase preparation: Dissolve 2 mL of Span80 in 98 mL of cyclohexane until homogeneous.

[0113] (3) Aqueous phase preparation: Take 20 mL of 20% w / v starch solution and 300 mg of sodium tripolyphosphate and stir for 10 min to dissolve evenly.

[0114] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0115] (5) Crosslinking agent reaction: Add 5 mL of sodium tripolyphosphate containing 1.2 g to the solution in step (4), react at 40 °C for 3 h, and then react at room temperature for 15 h.

[0116] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0117] Comparative Example 4

[0118] The preparation method includes the following steps:

[0119] (1) Preparation of 20% w / v starch solution: Take 20g of soluble starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0120] (2) Oil phase preparation: Dissolve 2 mL of Span80 in 98 mL of cyclohexane until homogeneous.

[0121] (3) Aqueous phase preparation: Take 20 mL of 20% w / v starch solution and 100 μL of epichlorohydrin and stir for 10 min to dissolve evenly.

[0122] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0123] (5) Crosslinking agent reaction: Add 800 μL of polyethylene glycol glycidyl ether to the solution in step (4) and react at room temperature for 18 h.

[0124] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0125] Comparative Example 5

[0126] The preparation method includes the following steps:

[0127] (1) Preparation of 20% w / v starch solution: Take 20g of soluble starch and stir to dissolve it in 100mL of 1M sodium hydroxide solution.

[0128] (2) Oil phase preparation: Dissolve 2 mL of Span80 in 98 mL of cyclohexane until homogeneous.

[0129] (3) Aqueous phase preparation: Take 20 mL of 20% w / v starch solution and 300 mg of sodium tripolyphosphate and stir for 10 min to dissolve evenly.

[0130] (4) Emulsification: Take 10 mL of aqueous phase and stir emulsify in 50 mL of oil phase for 10 min.

[0131] (5) Crosslinking agent reaction: Add 800 μL of polyethylene glycol glycidyl ether to the solution in step (4) and react at room temperature for 18 h.

[0132] (6) Microsphere collection and washing: After the solution settles, the supernatant is discarded, and the solution is washed with ethyl acetate, ethanol, and purified water, and then replaced with physiological saline.

[0133] Performance testing

[0134] 1. Microsphere morphology

[0135] Methods: The microspheres were diluted with physiological saline and then observed and measured under an inverted microscope (40x magnification). The results are shown in [Table missing]. Figure 1-11 .

[0136] from Figures 1-6 It can be seen that when a small amount of polyethylene glycol diglycidyl ether is used as the internal crosslinking agent, both the external crosslinking agents, whether epichlorohydrin or sodium trimetaphosphate, have good sphericity, and the sphericity of the product is not affected when the ratio in the formulation is changed.

[0137] Comparative Examples 1-3 used the same crosslinking agent both internally and externally, but the sphericity was slightly worse than in the examples. In Comparative Examples 4-5, when a small amount of epichlorohydrin or sodium trimetaphosphate was used internally, and polyethylene glycol diglycidyl ether was used externally as the crosslinking agent, the microspheres exhibited less defined spherical edges.

[0138] 2. Compression performance and catheter permeability

[0139] Compression test method: The microspheres were compressed using a texture analyzer. The microspheres were removed from the preservation solution and the surface moisture was removed. The compression test was carried out within 2 minutes. The initial position was 2 mm away from the bottom of the microsphere, and the compression rate was 0.05 mm / s. The microspheres were kept in different deformations, paused for 10 seconds, and then restored. The microspheres were observed to see if they broke.

[0140] Catheter traversability method: Select 100-300 micrometer microspheres, prepare a 30% v / v saline suspension with normal saline, mix with contrast agent 1:1, and slowly inject using a 1.7F microcatheter. Observe whether the microspheres become blocked or break. Any blockage or breakage is considered a failure of catheter traversability.

[0141] The results are shown in Table 1.

[0142] Table 1 Microsphere compressibility and catheter permeability

[0143]

[0144] 3. Rapid degradation performance

[0145] Methods: A microsphere suspension was prepared to achieve a final α-amylase concentration of 140 U / L, and the microsphere morphology disappearance time was observed at 37℃ and 60 rpm.

[0146] The results are shown in Table 2.

[0147] Table 2

[0148]

[0149] 4. Cross-linked microsphere degradation test

[0150] Methods: A certain mass of α-amylase was dissolved in PBS to prepare a 140 U / L amylase solution. A certain amount of microspheres prepared in Example 1 was added, and the solution was degraded at 37℃. The morphology of the microspheres was observed under a microscope at different time points. Results are shown in […]. Figure 13 The microspheres maintained a largely spherical morphology for the first 60 minutes of degradation, although some exhibited indistinct edges. At 70 minutes, a large number of spherical microspheres suddenly disintegrated, gradually transforming into irregular spherical particles. By 90 minutes, the microsphere morphology had essentially disappeared. The initial maintenance of the microsphere morphology may be related to the higher degree of external cross-linking, while the rapid change in morphology in the later stages may be related to the lower degree of internal cross-linking compared to the external cross-linking.

[0151] The results above show that the microspheres prepared in Examples 1-6 of this invention have a particle size of 100μm-300μm. The microspheres are degraded at an α-amylase concentration of 100-200U / L and a temperature of 37℃, and their morphology completely disappears within 1-48 hours. The microspheres maintain a spherical shape for the first 60 minutes of degradation, undergo rapid morphological disintegration within 70-90 minutes, do not break at a 70% compression rate, and pass the injection test using a 1.7F microcatheter.

[0152] In Comparative Example 1, the microspheres did not break under 70% compression but broke under 90% compression. The use of polyethylene glycol diglycidyl ether inside and outside the microspheres can give them excellent compressibility. This is because the long-chain polyethylene glycol segments release or store energy through amorphous and crystalline transformations during compression and recovery, which improves the compressibility of the product. However, the 1.7F conduit experienced blockage. This may be because the use of polyethylene glycol diglycidyl ether as a crosslinking agent on the outside is insufficient to give the microspheres a high elastic modulus, resulting in blockage in the conduit and poor conduit passage.

[0153] The degradation experiment also showed that when polyethylene glycol diglycidyl ether was used as the external crosslinking agent, even when the amount added was increased to 800µL, the crosslinking efficiency of the product was lower (complete degradation in 3 hours) compared to the use of 400µL epichlorohydrin as the external crosslinking agent in Example 2 (complete degradation time of 5 hours).

[0154] In Comparative Examples 2 and 3, the microspheres did not break under 50% compression. Although the microspheres formed by crosslinking starch with sodium trimetaphosphate as the internal and external crosslinking agent had certain compressibility, they broke after the compression deformation was increased to 70%. This may be because the use of sodium trimetaphosphate as the internal crosslinking agent resulted in insufficient energy diffusion due to the short chain crosslinking points, leading to slightly poorer compressibility and breakage during the passage process.

[0155] In Comparative Examples 4 and 5, the microspheres used sodium trimetaphosphate or epichlorohydrin as internal crosslinking agents and polyethylene glycol diglycidyl ether as the external crosslinking agent. Although this also gave the microspheres a certain degree of compressibility, for the same reason as in Example 1, the microspheres blocked the tubes.

[0156] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapidly degradable embolic microsphere for knee artery embolization, characterized in that, The microspheres have a gradient cross-linking structure with decreasing cross-linking degree from the outside to the inside, and are formed by stepwise cross-linking of starch, internal cross-linking agent and external cross-linking agent through reverse emulsification; the starch is selected from at least one of acid-hydrolyzed starch, potato starch and soluble starch; the internal cross-linking agent is polyethylene glycol diglycidyl ether, and the external cross-linking agent is selected from at least one of sodium trimetaphosphate and epichlorohydrin; the microspheres are degraded at an α-amylase concentration of 100-200 U / L and 37°C, and their morphology completely disappears within 1-48 hours; the microspheres maintain a spherical morphology for the first 60 minutes of degradation, and undergo rapid morphological degradation within 70-90 minutes.

2. The rapidly degradable embolic microspheres for knee artery embolization according to claim 1, characterized in that, The microspheres did not break at 70% compression and passed the injection test using a 1.7F microcatheter.

3. A method for preparing rapidly degradable embolic microspheres for knee artery embolization as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Dissolve starch in sodium hydroxide solution to prepare starch solution; S2. Dissolve the surfactant in the oil phase solvent to prepare the oil phase; S3. Add the internal crosslinking agent to the starch solution obtained in step S1, stir until homogeneous, and obtain the aqueous phase; S4. Add the aqueous phase obtained in step S3 to the oil phase obtained in step S2, stir and emulsify to obtain a reverse emulsion; S5. Add an external crosslinking agent to the reverse emulsion obtained in step S4 to carry out a crosslinking reaction; S6. Allow the microspheres to stand and separate into layers, collect the microspheres, wash them with organic solvent and purified water, and then replace them with physiological saline to obtain rapidly degradable embolization microspheres for knee artery embolization.

4. The preparation method according to claim 3, characterized in that, In step (1), the concentration of the sodium hydroxide solution is 0.5M-2M, and the mass-volume concentration of the starch solution is 10%-20%.

5. The preparation method according to claim 3, characterized in that, In step (2), the surfactant is selected from at least one of Span 80, Span 85 and Tween 80; the oil phase solvent is selected from at least one of isopropyl palmitate, n-butyl acetate, cyclohexane, decane, n-heptane and petroleum ether.

6. The preparation method according to claim 3, characterized in that, In step (3), the amount of the internal crosslinking agent added to each 20 mL starch solution is 25 μL-200 μL.

7. The preparation method according to claim 3, characterized in that, In step (4), the volume ratio of the aqueous phase to the oil phase is 1:(3-5), and the emulsification time is 5min-30min.

8. The preparation method according to claim 3, characterized in that, In step (5), the external crosslinking agent sodium trimetaphosphate is added in the form of sodium trimetaphosphate aqueous solution, wherein the amount of sodium trimetaphosphate added is 0.4g-1.2g, and the reaction conditions are to react at 35℃-45℃ for 2h-4h first, and then at room temperature for 12h-18h.

9. The preparation method according to claim 3, characterized in that, In step (6), the organic solvent includes ethyl acetate and ethanol.

10. The use of the rapidly degradable embolic microspheres for knee artery embolization as described in claim 1 or 2 in the preparation of knee artery embolization therapeutic devices.

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