Embolism microsphere and preparation method thereof

Abstract

The invention discloses an embolism microsphere and a preparation method thereof.The embolism microsphere is prepared through the following steps that a polycarboxylate microsphere is prepared by combining a free radical polymerization method and an emulsion polymerization method, and the polycarboxylate microsphere is obtained; and saponifying and hydrolyzing the polycarboxylate microspheres to hydrolyze the polycarboxylate microspheres to obtain hydroxyl polymer microspheres, and introducing an acidic group onto the hydroxyl polymer microspheres to obtain the embolism microspheres containing both the hydroxyl group and the acidic group. The embolism microsphere disclosed by the invention realizes high loading capacity and controllable release of the anti-tumor drug, realizes accurate embolism in blood flow, and improves the treatment effect of the drug.

Description

Technical Field

[0001] This invention relates to the field of embolization microsphere technology, and particularly to an embolization microsphere and its preparation method. Background Technology

[0002] Transarterial chemoembolization (TACE) is currently one of the standard treatments for patients with intermediate-stage hepatocellular carcinoma (HCC). This technique delivers drug-loaded embolized microspheres to the tumor-feeding arteries, achieving precise embolization of tumor vessels and effective blockage of their blood supply. Simultaneously, the sustained local release of antitumor drugs loaded on the embolized microspheres achieves a synergistic antitumor effect. However, existing embolized microspheres still have significant limitations in terms of preparation processes and performance control, hindering their further development in clinical application. On the one hand, the microspheres obtained by current mainstream preparation methods (such as cross-linking or reverse suspension copolymerization) often have a wide particle size distribution and a high polydispersity index, making it difficult to precisely control the microspheres in the bloodstream. This inhomogeneity not only affects the consistency of embolization effects but also increases the uncertainty and risks in the treatment process, failing to meet the stringent clinical requirements for the predictability of treatment safety and efficacy. On the other hand, existing embolization microspheres rely heavily on intermolecular interactions (such as hydrogen bonds) for drug loading and release regulation. These forces are easily affected by the internal environment (such as pH, hemodynamics, etc.) and have poor stability, leading to difficulties in drug loading regulation and thus affecting the therapeutic effect of the drug. Summary of the Invention

[0003] The main objective of this invention is to provide a method for preparing embolization microspheres, enabling efficient loading and controlled release of antitumor drugs for precise embolization in the bloodstream, thereby improving the therapeutic effect of the drugs.

[0004] To achieve the above objectives, the present invention provides a method for preparing embolic microspheres, comprising the following steps:

[0005] Polycarboxylate microspheres were prepared by combining free radical polymerization and emulsion polymerization.

[0006] The polycarboxylate microspheres are saponified and hydrolyzed to obtain hydroxyl polymer microspheres, and acidic groups are introduced onto the hydroxyl polymer microspheres to obtain embolization microspheres containing both hydroxyl and acidic groups.

[0007] Optionally, the step of "preparing polycarboxylate microspheres by combining free radical polymerization and emulsion polymerization" includes:

[0008] Vinyl acetate was mixed with an acidic precursor monomer and an initiator was added to obtain an oil phase;

[0009] The dispersant is added to water to obtain an aqueous phase;

[0010] Under a nitrogen protective atmosphere, the oil phase and the aqueous phase are mixed and heated to induce the suspension copolymerization of the vinyl acetate and the acidic precursor monomer to generate polycarboxylate microspheres.

[0011] Optionally, in the step of "mixing vinyl acetate with an acidic precursor monomer", the acidic precursor monomer is selected from one or more of methacrylate, methyl methacrylate, hydroxyethyl methacrylate, dimethyl itaconic acid, and maleic anhydride, and the molar ratio of vinyl acetate to the acidic precursor monomer is not less than 19:1.

[0012] Optionally, the step of "saponifying and hydrolyzing the polycarboxylate microspheres" includes:

[0013] The polycarboxylate microspheres were placed in an alkaline alcohol / water system, and the reaction temperature and reaction time were adjusted to allow saponification and hydrolysis to generate hydroxyl polymer microspheres with carboxyl groups.

[0014] Optionally, the step of "introducing acidic groups onto the hydroxyl polymer microspheres" includes:

[0015] The hydroxy polymer microspheres are subjected to sulfonation grafting to introduce sulfonic acid groups onto the hydroxy polymer microspheres. After washing and drying, hydroxy polymer microspheres with sulfonic acid groups are obtained.

[0016] Optionally, the step of "sulfonating and grafting the hydroxyl polymer microspheres" includes:

[0017] The hydroxyl polymer microspheres are dispersed in an acidic solution. In a redox initiation system, a sulfonated monomer is added to the acidic solution of the hydroxyl polymer microspheres to cause the sulfonated monomer to undergo a free radical grafting reaction on the molecular chain of the hydroxyl polymer microspheres.

[0018] Optionally, in the step of "adding a sulfonated monomer to the acidic solution of the hydroxyl polymer microspheres", the sulfonated monomer is 2-acrylamido-2-methylpropanesulfonic acid, and the mass of the sulfonated monomer is 5% to 50% of the mass of the polyvinyl alcohol microspheres.

[0019] Optionally, after the step of "introducing acidic groups on the hydroxy polymer microspheres", the method further includes: cross-linking the hydroxy polymer microspheres to cross-link the hydroxyl groups of the hydroxy polymer microspheres.

[0020] Optionally, the step of "crosslinking the hydroxyl polymer microspheres" includes:

[0021] The hydroxyl polymer microspheres are dispersed in an acidically activated aldehyde compound, and the reaction temperature and reaction time are controlled so that the hydroxyl groups of the hydroxyl polymer microspheres react with the aldehyde groups of the aldehyde compound to form an acetal crosslinked structure.

[0022] The present invention also proposes an embolization microsphere, which is prepared by the above-described method for preparing embolization microspheres.

[0023] The technical solution of this invention combines free radical polymerization and emulsion polymerization to prepare polycarboxylate microspheres, resulting in polycarboxylate microspheres with a narrow particle size distribution and an average particle size of 50–180 μm. These polycarboxylate microspheres are then saponified and hydrolyzed to generate hydroxyl polymer microspheres. By introducing acidic groups onto the hydroxyl polymer microspheres, embolic microspheres containing both hydroxyl and acidic groups are obtained. Thus, the embolic microspheres of this invention not only have a narrow and uniform particle size distribution and a polymer dispersibility index (PDI) < 1.1, which is beneficial for precise control in blood flow, but also contain hydroxyl and acidic groups. The hydroxyl groups improve the hydrophilicity and mechanical adaptability of the prepared embolic microspheres, while the acidic groups significantly enhance the charge-binding force for cationic antitumor drugs, thereby facilitating high loading and controlled release of antitumor drugs. The embolic microspheres of this invention achieve high loading and controlled release of antitumor drugs and precise embolization in blood flow, improving the therapeutic effect of the drugs. Attached Figure Description

[0024] Figure 1 This is an optical microscope image of sample 1 of the present invention;

[0025] Figure 2 This is a scanning electron microscope image of sample 1 of the present invention;

[0026] Figure 3 This is a particle size distribution diagram of sample 1 of the present invention;

[0027] Figure 4 These are drug release curves for samples 1, 2, and 3 of this invention;

[0028] Figure 5 The Young's modulus diagrams for samples 1, 2, and 3 of this invention are shown.

[0029] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] In one embodiment of the present invention, a method for preparing embolic microspheres includes the following steps: preparing polycarboxylate microspheres by combining free radical polymerization and emulsion polymerization to obtain polycarboxylate microspheres; saponifying and hydrolyzing the polycarboxylate microspheres to obtain hydroxyl polymer microspheres, and introducing acidic groups onto the hydroxyl polymer microspheres to obtain embolic microspheres containing both hydroxyl and acidic groups.

[0032] The technical solution of this invention combines free radical polymerization and emulsion polymerization to prepare polycarboxylate microspheres, resulting in polycarboxylate microspheres with a narrow particle size distribution and an average particle size of 50–180 μm. These polycarboxylate microspheres are then saponified and hydrolyzed to generate hydroxyl polymer microspheres. By introducing acidic groups onto the hydroxyl polymer microspheres, embolic microspheres containing both hydroxyl and acidic groups are obtained. Thus, the embolic microspheres of this invention not only have a narrow and uniform particle size distribution and a polymer dispersibility index (PDI) < 1.1, which is beneficial for precise control in blood flow, but also contain hydroxyl and acidic groups. The hydroxyl groups improve the hydrophilicity and mechanical adaptability of the prepared embolic microspheres, while the acidic groups significantly enhance the charge-binding force for cationic antitumor drugs, thereby facilitating high loading and controlled release of antitumor drugs. The embolic microspheres of this invention achieve high loading and controlled release of antitumor drugs and precise embolization in blood flow, improving the therapeutic effect of the drugs.

[0033] It should be noted that the acidic groups in this embodiment include carboxyl groups and sulfonic acid groups. Carboxyl groups, sulfonic acid groups, or both can be introduced onto the molecular chain of the hydroxyl polymer microspheres. Preferably, in this embodiment, carboxyl groups and sulfonic acid groups are introduced simultaneously onto the hydroxyl polymer microspheres. Thus, the embolization microspheres simultaneously possess hydroxyl, carboxyl, and sulfonic acid groups. The hydroxyl groups ensure the hydrophilicity and mechanical adaptability of the embolization microspheres; the carboxyl groups provide a weak binding force for cationic antitumor drugs, which is beneficial for sustained drug release; and the sulfonic acid groups provide a strong binding force for cationic antitumor drugs, which is beneficial for increasing drug loading. This embodiment achieves high loading capacity and controlled release of antitumor drugs, and precise embolization in the bloodstream, thereby improving the therapeutic effect of antitumor drugs. Of course, the polycarboxylate microspheres in this embodiment can be homopolymer microspheres or copolymer microspheres. Preferably, the copolymer microspheres are polycarboxylate microspheres containing acidic precursors. The polycarboxylate microspheres are saponified and hydrolyzed to generate hydroxyl polymer microspheres with carboxyl groups. This embodiment is not limited to this, and all of the above are within the protection scope of this invention.

[0034] In one embodiment of the present invention, the step of "preparing polycarboxylate microspheres by combining free radical polymerization and emulsion polymerization" includes: mixing vinyl acetate with an acidic precursor monomer and adding an initiator to obtain an oil phase; adding a dispersant to water to obtain an aqueous phase; and mixing the oil phase and the aqueous phase under a nitrogen protective atmosphere and heating at a temperature of 65-75°C to induce suspension copolymerization of the vinyl acetate and the acidic precursor monomer to generate polycarboxylate microspheres. It should be noted that the acidic precursor monomer is an ester or anhydride with double bonds. Thus, the copolymerization of vinyl acetate and the acidic precursor monomer generates polycarboxylate microspheres with an acidic precursor. After saponification and hydrolysis, the acidic precursor hydrolyzes into carboxyl groups, and the polycarboxylate hydrolyzes into hydroxyl polymer microspheres, thereby obtaining hydroxyl polymer microspheres with carboxyl groups. In this embodiment, the acidic precursor monomer can be one or more of acrylates, dimethyl itaconic acid, maleic anhydride, etc. Acrylates include methacrylates, methyl methacrylate, hydroxyethyl methacrylate, etc., but this embodiment is not limited to these; all are within the scope of protection of this invention. Thus, the suspension copolymerized polycarboxylate microspheres are saponified and hydrolyzed to obtain hydroxyl polymer microspheres with carboxyl groups. Of course, to adjust the drug release effect, the content of carboxyl groups can be adjusted in this embodiment. Preferably, the molar ratio of vinyl acetate to the acidic precursor monomer is not less than 19:1. This embodiment increases the hydroxyl content in the hydroxyl polymer microspheres, thereby ensuring the hydrophilicity and mechanical suitability of the embolization microspheres while also improving the sustained-release effect of the antitumor drug and enhancing the therapeutic effect of the antitumor drug.

[0035] In one embodiment of the present invention, the step of "saponifying and hydrolyzing the polycarboxylate microspheres" includes: placing the polycarboxylate microspheres in an alkaline alcohol / water system, adjusting the reaction temperature and reaction time to induce saponification and hydrolysis to generate hydroxyl polymer microspheres with carboxyl groups. It should be noted that the polycarboxylate microspheres containing the acidic precursor are placed in an alkaline alcohol / water system, the reaction temperature is adjusted to 35–50°C, and the reaction time is 16–72 hours to induce saponification and hydrolysis of the polycarboxylate microspheres containing the acidic precursor. During this reaction, the carboxylate groups in the polycarboxylate microspheres are converted to hydroxyl groups to form hydroxyl polymer microspheres, and the introduced acidic precursor is converted to carboxyl groups, thereby obtaining hydroxyl polymer microspheres with carboxyl groups. This embodiment generates hydroxyl polymer microspheres with carboxyl groups through a one-step saponification and hydrolysis process, with mild process conditions suitable for large-scale production. Furthermore, the carboxyl groups are uniformly distributed in the hydroxyl polymer microspheres, which is beneficial for precise embolization in the bloodstream, thereby ensuring the therapeutic effect of the drug.

[0036] In one embodiment of the present invention, the step of "introducing acidic groups onto the hydroxy polymer microspheres" includes: sulfonating the hydroxy polymer microspheres to introduce sulfonic acid groups onto the hydroxy polymer microspheres; washing and drying to obtain hydroxy polymer microspheres with sulfonic acid groups. It should be noted that in this embodiment, sulfonation grafting yields hydroxy polymer microspheres with sulfonic acid groups. The sulfonic acid groups provide strong binding force for cationic antitumor drugs, thereby increasing the drug loading capacity of the embolization microspheres and enhancing the therapeutic effect. Of course, the sulfonation grafting in this embodiment can be performed using direct sulfonation or indirect sulfonation. Preferably, this embodiment introduces a sulfonated monomer containing sulfonic acid groups, causing the sulfonated monomer to undergo a free radical grafting reaction on the molecular chain of the hydroxy polymer microspheres. Of course, the amount of sulfonated monomer can be adjusted to regulate the proportion of sulfonic acid groups introduced, thereby increasing the drug loading capacity of the embolization microspheres and enhancing the therapeutic effect of the antitumor drugs. Specifically, hydroxyl polymer microspheres are dispersed in an acidic solution, and a redox initiation system of cerium salt oxidant or persulfate / sodium bisulfite is introduced. At 20–40°C, a sulfonated monomer is added to induce a free radical grafting reaction of the sulfonated monomer onto the molecular chains of the hydroxyl polymer microspheres. In this embodiment, 0–1.0 mol% of N,N'-methylenebisacrylamide can be added as a crosslinking agent as needed. After washing and drying, hydroxyl polymer microspheres with sulfonic acid groups are obtained. Preferably, in this embodiment, the sulfonated monomer is 2-acrylamido-2-methylpropanesulfonic acid, and the mass of the sulfonated monomer is 5–50% of the mass of the hydroxyl polymer microspheres. This embodiment, by adjusting the mass of the sulfonated monomer and the hydroxyl polymer microspheres, ensures the hydrophilicity and mechanical suitability of the embolization microspheres while also increasing the drug loading of antitumor drugs, thereby improving the therapeutic effect of antitumor drugs.

[0037] In one embodiment of the present invention, after the step of "introducing acidic groups onto the hydroxyl polymer microspheres", the method further includes: crosslinking the hydroxyl polymer microspheres to crosslink the hydroxyl groups of the hydroxyl polymer microspheres. It should be noted that this embodiment, by crosslinking the hydroxyl groups of the hydroxyl polymer microspheres with acidic groups, ensures the structural stability of the prepared embolization microspheres, significantly improves the mechanical strength of the embolization microspheres, and meets the drug loading requirements of the embolization microspheres. Of course, in this embodiment, the hydroxyl groups of the hydroxyl polymer microspheres can be crosslinked through condensation reactions, such as ester bonds formed between hydroxyl and carboxyl groups, or polyurethane crosslinks formed between isocyanates and hydroxyl groups. Crosslinking can also be achieved through crosslinking agents, including aldehydes such as glutaraldehyde. Any agent capable of achieving hydroxyl crosslinking of the hydroxyl polymer microspheres is acceptable, and this embodiment is not limited to these methods; all of the above are within the scope of protection of the present invention.

[0038] In one embodiment of the present invention, the step of "crosslinking the hydroxyl polymer microspheres" includes: dispersing the hydroxyl polymer microspheres in an acidically activated aldehyde compound, controlling the reaction temperature and reaction time, so that the hydroxyl groups of the hydroxyl polymer microspheres react with the aldehyde groups of the aldehyde compound to form an acetal crosslinked structure. Preferably, the aldehyde compound is glutaraldehyde, and the hydroxyl groups of the polyvinyl alcohol microspheres react with the aldehyde groups of glutaraldehyde to form an acetal crosslinked structure. After washing and drying, embolic microspheres with an acetal crosslinked structure are obtained. The embolic microspheres of this embodiment have an acetal crosslinked structure, thereby improving the structural stability and mechanical strength of the embolic microspheres in the aqueous phase, which is beneficial for achieving precise embolization in the bloodstream and ensuring the therapeutic effect of the drug. Furthermore, this embodiment effectively controls the drug diffusion channels and regulates the sustained-release performance of the drug through crosslinking. Of course, this embodiment can adjust the amount of aldehyde compound to control the degree of crosslinking of the embolic microspheres and regulate the sustained-release performance of the drug. This embodiment is not limited to this, and all of the above are within the protection scope of the present invention.

[0039] In one embodiment of the present invention, an embolization microsphere is prepared using the aforementioned method. The embolization microspheres of the present invention have an average particle size of 50–180 μm and a polymer dispersibility index (PDI) < 1.1. These microspheres not only have a narrow and uniform particle size distribution, facilitating precise control in blood flow, but also contain hydroxyl and acidic groups. The hydroxyl groups enhance the hydrophilicity and mechanical adaptability of the prepared microspheres, while the acidic groups significantly strengthen the charge-binding force on cationic antitumor drugs, thereby enabling high loading and controlled release of antitumor drugs. The embolization microspheres of the present invention achieve high loading and controlled release of antitumor drugs and precise embolization in blood flow, thus improving the therapeutic effect of the drugs.

[0040] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0041] Example 1

[0042] Preparation of polycarboxylate microspheres: Vinyl acetate and an acidic precursor monomer were mixed at a molar ratio of 19:1. The acidic precursor monomer was selected from one or more of methacrylate, methyl methacrylate, hydroxyethyl methacrylate, dimethyl itaconic acid, and maleic anhydride. An oil-soluble free radical initiator was added to obtain an oil phase. A dispersant (polyvinyl alcohol or polyvinylpyrrolidone) was added to water to obtain an aqueous phase. Under a nitrogen protective atmosphere, the oil phase and the aqueous phase were mixed and heated to 65-75°C to allow the vinyl acetate and the acidic precursor monomer to be suspended and copolymerized to form a copolymer, thus obtaining polycarboxylate microspheres with the acidic precursor.

[0043] Preparation of hydroxyl polymer microspheres: Polycarboxylate microspheres with acidic precursors were placed in an alkaline alcohol / water system for saponification. The alcohol / water system included a mixed solvent of methanol and water, sodium hydroxide, and anhydrous sodium sulfate. The reaction temperature was adjusted to 35–50 °C, and the reaction time was 16–72 h, so that the carboxylate groups in the polycarboxylate microspheres were converted into hydroxyl groups, and the acidic precursors were converted into carboxylate groups. After washing and drying, hydroxyl polymer microspheres with carboxyl groups were obtained, denoted as Sample 1.

[0044] Example 2

[0045] Based on Example 1, sulfonation modification of hydroxy polymer microspheres was carried out: hydroxy polymer microspheres with carboxyl groups were dispersed in an acidic solution, and a redox initiation system of cerium salt oxidant or persulfate / sodium bisulfite was introduced. At 20-40°C, a sulfonating monomer was added to allow the sulfonating monomer to undergo a free radical grafting reaction on the molecular chain of the hydroxy polymer microspheres. The sulfonating monomer was 2-acrylamido-2-methylpropanesulfonic acid, and the mass of the sulfonating monomer was 50% of the mass of the hydroxy polymer microspheres. In this example, 1.0 mol% of N,N'-methylenebisacrylamide was added as a crosslinking agent. After washing and drying, hydroxy polymer microspheres with sulfonic acid groups and carboxyl groups were obtained, which was designated as Sample 2.

[0046] Example 3

[0047] Based on Example 2, hydroxyl polymer microspheres having sulfonic acid groups and carboxyl groups were subjected to crosslinking treatment. The crosslinking treatment steps included: dispersing the hydroxyl polymer microspheres having sulfonic acid groups and carboxyl groups into acidically activated glutaraldehyde, wherein the mass of glutaraldehyde was 5% of the mass of the hydroxyl polymer microspheres having sulfonic acid groups and carboxyl groups, so that the hydroxyl groups of the hydroxyl polymer microspheres reacted with the aldehyde groups of the aldehyde compound to form an acetal crosslinked structure, thereby obtaining crosslinked hydroxyl polymer microspheres having sulfonic acid groups and carboxyl groups, denoted as Sample 3.

[0048] Example 4

[0049] The morphology and particle size of sample 1 were characterized and analyzed. The specific procedure is as follows: A suitable amount of sample 1 before drying was placed on a glass slide and observed using an optical microscope. The results are as follows: Figure 1 As shown, the microspheres exhibit good dispersibility in a wet state, with each microsphere being relatively similar in size and having a relatively uniform particle size distribution.

[0050] A suitable amount of sample 1 microspheres, after being dehydrated and dried using gradient ethanol, was placed on a silicon wafer. The sample was then sputter-coated with gold, and the microstructure was observed using a cold field scanning electron microscope. The results are as follows: Figure 2 The microspheres are shown to be regular spherical in shape, with clear outlines, complete boundaries, and high sphericity.

[0051] The scanning electron microscope image of sample 1 was analyzed using the professional image analysis software ImageJ to measure the particle size distribution of the microspheres. At least 300 microspheres were counted. Origin 9.0 software was used to statistically analyze and calculate the microsphere particle size distribution range, average particle size, and monodispersity. The results are as follows: Figure 3 As shown, the particle size of sample 1 is mainly distributed between 130 and 150 μm. The number-average diameter D of sample 1 was calculated according to formulas (1) and (2). n =133.81μm and weight-average diameter D w =138.85μm; then, according to formula (3), the polydispersity index (PDI) of sample 1 is calculated to be 1.04.

[0052]

[0053] PDI=Dw / Dn formula (3)

[0054] In formulas (1) to (3), D n Representative number average diameter, D w Represents weight-average diameter, D i Represents the diameter of the i-th microsphere, n i The representative sample simultaneously has D i Number of microspheres with diameter.

[0055] Example 5

[0056] The carboxyl grafting rate of sample 1 and the sulfonic acid grafting rate of sample 2 were quantified as follows: 0.1 g of dry sample 1 was accurately weighed and 20.00 mL of 0.1 mol / L standard NaOH solution was added. The mixture was shaken until the microspheres were completely swollen and in equilibrium. The remaining NaOH was titrated with standard hydrochloric acid solution, and phenolphthalein was used as an indicator to titrate to the endpoint. The amount of hydrochloric acid solution used was recorded and the carboxyl grafting rate was calculated to be 1.15 mmol / g.

[0057] Take 5mg of sample 2 dry sample, use an elemental analyzer to detect the mass percentage of sulfur in the sample, and calculate the grafting rate of sulfonic acid groups to be 0.79mmol / g.

[0058] Example 6

[0059] Drug loading performance and sustained-release effect tests were conducted on samples 1, 2, and 3. The specific procedures are as follows: 200 mg of DOX was weighed into a beaker, dissolved in physiological saline, and diluted to 100 mL to prepare a 2 mg / mL DOX solution. 50 mg of lyophilized sample was weighed into a 15 mL centrifuge tube, and 5 mL of prepared doxorubicin hydrochloride was added. The tubes were incubated in a constant temperature shaker (37℃) in the dark for 24 h. Three replicates were prepared for each sample group. An appropriate amount of physiological saline was added to the 15 mL centrifuge tube, the tubes were gently shaken for 2–3 seconds, and then centrifuged at 4000 rpm for 2 min. The supernatant was carefully aspirated. The above steps were repeated three times. The supernatant collected from each group was diluted to 100 mL in a volumetric flask. The test solutions were temporarily stored at 4℃, and the absorbance of each supernatant at 483 nm was measured using a microplate reader.

[0060] After washing the samples, they were dispersed in 20 mL of physiological saline (50 mL centrifuge tube) and shaken at 130 rpm. After centrifugation at 0 min, 0.5 h, 1 h, 2 h, 4 h, 6 h, 17 h, 19 h, 23 h, 29 h, 41 h, 2 d, 3 d, 4 d, 5 d, 6 d, and 7 d, 2.0 mL of the supernatant was collected and an equal volume of physiological saline was added. Five samples were taken at each time point, and the absorbance of each sample at 483 nm was measured using an ELISA reader.

[0061] The formulas for calculating sample drug loading and encapsulation efficiency are as follows:

[0062] Drug loading = (Mass of drug in sample / Mass of sample loaded with drug) × 100%

[0063] Encapsulation efficiency = (Material mass of drug in sample / Drug input) × 100%

[0064] The drug loading results are shown in Table 1. The introduction of sulfonic acid groups resulted in stronger binding of cationic drugs. Therefore, samples 2 and 3 could adsorb / bind more drug than sample 1 during the loading stage. However, the cross-linking of sample 3 increased the network density and inhibited diffusion during loading (leading to a decrease in drug loading relative to sample 2).

[0065] Table 1. Drug loading results of samples

[0066]

[0067] The drug release curve results are as follows Figure 4 The results showed that Sample 1 had the fastest release rate, Sample 2 had a moderate rate, and Sample 3 had the slowest rate. In Sample 1, DOX mainly binds to the carboxyl group through electrostatic adsorption, which has a weaker binding force and results in faster drug release. In Sample 2, the sulfonic acid group has a stronger binding force with DOX, and the release is controlled by both ion exchange and diffusion, resulting in a slower release. Sample 3, based on Sample 2, is cross-linked with glutaraldehyde, which significantly increases the cross-linking density and restricts the diffusion channels, thus exhibiting a more sustained-release characteristic.

[0068] Example 7

[0069] Mechanical property tests were performed on samples 1, 2, and 3. The specific procedure was as follows: 50 mg of each sample was placed in a 2 mL EP tube and fully swollen in 1 mL of pure water for 24 hours. An appropriate amount of the swollen sample was then pipetted onto the center of a clean glass slide, ensuring even distribution. An atomic force microscope (AFM) was adjusted, and after confirming the scanning probe was directly above the sample, a certain external force was applied to obtain the strain-stress curves. At least 10 different stress points were measured for each group of samples. The Young's modulus of each group of samples was calculated using the linear region of the strain-stress curve. The results are as follows: Figure 5 The results showed that sample 2 had a softer overall structure and a decreased modulus due to significant water absorption and swelling of the microsphere shell, while sample 3, after being cross-linked and fixed with glutaraldehyde, had an increased modulus and showed better mechanical stability.

[0070] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing embolizing microspheres, characterized by, The method comprises the following steps: The polycarboxylate microspheres are prepared by combining the free radical polymerization method and the emulsion polymerization method, to obtain the polycarboxylate microspheres; The polycarboxylate microspheres are saponified and hydrolyzed, so that the polycarboxylate microspheres are hydrolyzed to obtain the hydroxyl polymer microspheres, and acid groups are introduced onto the hydroxyl polymer microspheres, to obtain the embolism microspheres containing both hydroxyl groups and acid groups.

2. The method of claim 1, wherein the embolic microspheres are prepared by the steps of: The step of "preparing the polycarboxylate microspheres by combining the free radical polymerization method and the emulsion polymerization method" comprises: The vinyl acetate and the acid precursor monomer are mixed, and an initiator is added, to obtain an oil phase; A dispersing agent is added to water to obtain an aqueous phase; Under a nitrogen protective atmosphere, the oil phase and the aqueous phase are mixed and heated, so that the vinyl acetate and the acid precursor monomer are suspended and copolymerized to generate the polycarboxylate microspheres.

3. The method for preparing embolic microspheres as described in claim 2, characterized in that, In the step of "mixing the vinyl acetate and the acid precursor monomer", the acid precursor monomer is selected from one or more of methacrylate, methyl methacrylate, hydroxyethyl methacrylate, dimethyl itaconic acid, and maleic anhydride, and the molar ratio of the vinyl acetate to the acid precursor monomer is not less than 19:

1.

4. The method of claim 2, wherein the embolic microspheres are prepared by the steps of: The step of "saponifying and hydrolyzing the polycarboxylate microspheres" comprises: The polycarboxylate microspheres are placed in an alkaline alcohol / water system, and the reaction temperature and the reaction time are adjusted, so that saponification and hydrolysis are generated to obtain the hydroxyl polymer microspheres with carboxyl groups.

5. The method of claim 1 to 4, wherein The step of "introducing acid groups onto the hydroxyl polymer microspheres" comprises: The hydroxyl polymer microspheres are subjected to sulfonation grafting, so that sulfonic acid groups are introduced onto the hydroxyl polymer microspheres, and after washing and drying, the hydroxyl polymer microspheres with sulfonic acid groups are obtained.

6. The method of claim 5, wherein the embolic microspheres are prepared by the process of: The step of "sulfonating and grafting the hydroxyl polymer microspheres" comprises: The hydroxyl polymer microspheres are dispersed in an acid solution, and in a redox initiation system, a sulfonated monomer is added to the acid solution of the hydroxyl polymer microspheres, so that the sulfonated monomer is subjected to a free radical grafting reaction on the molecular chains of the hydroxyl polymer microspheres.

7. The method for preparing embolic microspheres as described in claim 6, characterized in that, In the step of "adding the sulfonated monomer to the acid solution of the hydroxyl polymer microspheres", the sulfonated monomer is 2-acrylamido-2-methylpropanesulfonic acid, and the mass of the sulfonated monomer is 5% to 50% of the mass of the polyvinyl alcohol microspheres.

8. The method of claim 1 to 4, wherein The step of "introducing acid groups onto the hydroxyl polymer microspheres" further comprises: crosslinking treatment is performed on the hydroxyl polymer microspheres, so that the hydroxyl groups of the hydroxyl polymer microspheres are crosslinked.

9. The method for preparing embolic microspheres as described in claim 8, characterized in that, The step of "performing crosslinking treatment on the hydroxyl polymer microspheres" comprises: The hydroxyl polymer microspheres are dispersed into an acid-activated aldehyde compound, and the reaction temperature and the reaction time are controlled, so that the hydroxyl groups of the hydroxyl polymer microspheres react with the aldehyde groups of the aldehyde compound to form acetal crosslinking structures.

10. An embolizing microsphere, characterized by, The embolism microspheres are prepared by the method for preparing the embolism microspheres according to any one of claims 1 to 9.

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