Self-developing polyvinyl alcohol embolism microsphere as well as preparation method and application thereof

Abstract

The invention provides a self-developing polyvinyl alcohol embolization microsphere as well as a preparation method and application thereof, and belongs to the technical field of medical materials. The preparation method comprises the following steps: carrying out a condensation reaction on N-(2, 2-dimethoxyethyl)-2-acrylamide and polyvinyl alcohol to obtain a functionalized polyvinyl alcohol solution, then adding a monomer 2-acrylamide-2-methylpropanesulfonic acid and an initiator, mixing with cellulose acetate butyrate and ethyl acetate, suspending a water-based macromonomer / monomer mixture in butyl acetate, and carrying out a polymerization reaction to obtain a water-based polymer; the preparation method comprises the following steps: firstly, preparing microspheres, stabilizing the microspheres through cellulose acetate butyrate to prevent condensation, adding tetramethylethylenediamine under the action of an initiator in a water phase, carrying out polymerization reaction to form a water-swelled cross-linked network to obtain the microspheres, and then carrying out programmed vacuum freeze-drying to obtain the vacuum freeze-dried microspheres with rough surfaces and abundant pores. And then carrying out substitution reaction with an iodobenzene compound to obtain the self-developing polyvinyl alcohol embolization microsphere with high iodine content.

Description

Technical Field

[0001] The invention relates to the technical field of medical materials, and in particular to self-developing polyvinyl alcohol embolization microspheres and a preparation method and application thereof. Background Art

[0002] Embolization, also known as embolotherapy, is a controlled injection of plugs into the blood vessels supplying the diseased organ through an arterial or intravenous catheter to block it and interrupt the blood supply, in order to achieve the purpose of controlling bleeding, treating tumors and vascular lesions, and eliminating the function of the diseased organ. Embolization is an important technology in interventional therapy, one of the three major technologies in interventional radiology, and has become a major part of daily work. For embolization, the selection of appropriate embolic materials is a key link in the development of this technology. Currently, the commonly used embolic materials for interventional embolization therapy include microspheres, microcatheters, coils, silk threads, etc. Microspheres are receiving more and more attention due to their high targeting to specific tissues and organs, good embolic effect, combination with chemotherapy drugs, and sustained release of drugs. They are currently one of the most common embolic carriers.

[0003] Conventional solid embolic agents currently used in clinical practice do not develop under X-rays. The embolic agents need to be mixed with contrast agents and injected under X-ray fluoroscopy to indirectly determine the position and embolism of the microspheres. When the flow rate of the mixed solution of contrast agents and microspheres stagnates or refluxes, the operator determines that the embolism has reached the end point. However, the disadvantage of this method is that the final actual position of the embolic agent cannot be accurately determined, and the operator cannot obtain real-time feedback during the operation, which brings inconvenience to the operator's operation, affects the accuracy of the judgment of the embolism end point, and also increases the risk of ectopic embolism in non-targeted areas. Therefore, in order to allow the operator to directly observe the injection of solid embolic agents under X-ray fluoroscopy, improve the convenience of operation, have more confidence in the grasp of embolism pairs, effectively avoid the risk of ectopic embolism during surgery, and provide vascular access for subsequent treatment, it is of far-reaching significance to develop novel self-imaging absorbable embolic microspheres. In addition, due to the strong absorption of X-rays by iodine atoms, iodine-containing compounds, especially iodine-containing organic compounds, can be developed in the human body under X-ray detection. Therefore, an iodine-containing organic compound can be attached to the embolic material, so that the embolic material has the function of X-ray development. For example, the X-ray development function of the embolic microsphere plays an important role in providing visual feedback to clinicians. In this way, clinicians can monitor the precise position of the embolic microsphere and ensure that it is applied and retained in the correct position in the blood vessel, reducing the risk of clinical ectopic embolism.

[0004] Chinese patent CN114805644A describes the reaction of epichlorohydrin with polyvinyl alcohol under alkaline catalyst conditions, introducing chlorine atoms into the polyvinyl alcohol to obtain activated polyvinyl alcohol; then the activated polyvinyl alcohol and iodobenzyl alcohol are reacted through etherification to introduce iodobenzyl groups into the polyvinyl alcohol, thereby obtaining an iodine-containing polyvinyl alcohol polymer. The polymer is soluble in non-physiological solutions and insoluble under physiological conditions, and can be used as a liquid embolic material in medical treatment, with stability and development effect. The chemical structure of the development base in this method is -OCH 2 CH(OH)CH 2 OR, R is iodobenzyl. This method generates a hydroxyl group while developing and modifying, which can better maintain the hydrophilicity of PVA. However, this method requires two steps of reaction to achieve development and modification, and the process is complicated. In addition, this method requires the introduction of active chloride ions, and the biological safety of chlorinated hydrocarbons needs to be verified. The safety risk of this process is relatively high.

[0005] Example 1 in Chinese patent CN114259599A discloses a method for preparing developing microspheres with X-ray developing function, wherein the method dissolves iodine and iodide in water to form an iodine solution, adds polyvinyl alcohol embolization microspheres to the iodine solution, stirs the solution for reaction, and then washes the solution with water to obtain iodine-complexed polyvinyl alcohol embolization microspheres for X-ray developing. The preparation method dissolves the microspheres in water to complex with iodine, and the microspheres need to have a small swelling in water, which affects the complexing ability of iodine. The uncomplexed iodine is difficult to clean in water and remains in the microspheres, which affects the determination of the iodine content of the developing microspheres, resulting in the iodine content not being consistent with the actual content.

[0006] The polyvinyl alcohol developing polyembolic microsphere product prepared by the above-mentioned prior art has the following disadvantages: (1) Since the polyvinyl alcohol microsphere is a non-degradable polymer material, it is difficult to dissolve in the chemical reagent solution and can only be expanded in the solvent, which not only causes the chemical bonding between the iodobenzene compound and the microsphere to be reduced, but also reduces the iodine content. Although it has a certain developing effect, the developing substance embedded in the microsphere will continue to seep out of the microsphere, making it difficult to maintain the developing effect for a long time; (2) Its ordinary dry surface is smooth and has no obvious pores, which affects the extension of the microsphere immersion time and increases the production process cost; (3) Its ordinary dry surface is smooth and has no obvious pores, which affects the microsphere when condensing with the iodobenzene compound. The high temperature affects the bonding ability of the iodine element in the iodobenzene compound, and finally causes the iodine content of the microsphere to be reduced; (4) Its ordinary dry surface is smooth and has no obvious pore structure, and the developing molecules cannot enter the microsphere to react with the active hydroxyl groups, resulting in a reduced iodine content of the microsphere and uneven development effect of the microsphere. Summary of the invention

[0007] The purpose of the present invention is to provide a self-developing polyvinyl alcohol embolic microsphere and a preparation method and application thereof. The self-developing polyvinyl alcohol embolic microsphere provided by the present invention has high iodine content and low production cost.

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

[0009] The present invention provides a method for preparing self-photographic polyvinyl alcohol embolization microspheres, comprising the following steps:

[0010] (1) mixing an aqueous solution of polyvinyl alcohol and N-(2,2-dimethoxyethyl)-2-acrylamide, and then sequentially performing a condensation reaction and adjusting the pH with an alkali to obtain a functionalized polyvinyl alcohol solution;

[0011] (2) mixing the functionalized polyvinyl alcohol solution obtained in step (1) with 2-acrylamide-2-methylpropane sulfonic acid and an initiator, and stirring to obtain a cross-linked polymerization monomer solution;

[0012] After mixing butyl acetate and cellulose acetate butyrate, heat-treating the mixture, sequentially adding the cross-linking polymerization monomer solution and tetramethylethylenediamine, sequentially performing polymerization reaction and post-treatment to obtain microspheres;

[0013] (3) subjecting the microspheres obtained in step (2) to programmed vacuum freeze-drying to obtain vacuum freeze-dried microspheres;

[0014] The process of vacuum freeze drying includes: firstly, pre-freeze drying at -45 to -35°C for 1 to 8 hours, then main freeze drying at -25 to 0°C for 8 to 45 hours, then first desorption drying at 0 to 20°C for 3 to 18 hours, and finally second desorption drying at 16 to 45°C for 3 to 18 hours;

[0015] (4) in an inert atmosphere, immersing the vacuum freeze-dried microspheres obtained in step (3) in dimethyl sulfoxide to obtain swollen microspheres;

[0016] The swollen microspheres are mixed with an iodobenzene compound, a solvent and an acid compound, and then subjected to a substitution reaction to obtain self-developable polyvinyl alcohol embolization microspheres.

[0017] Preferably, in the step (1), the mass ratio of polyvinyl alcohol to N-(2,2-dimethoxyethyl)-2-acrylamide in the aqueous solution of polyvinyl alcohol is 1:(0.01-0.15).

[0018] Preferably, the pH value of the reaction system before the condensation reaction in step (1) is 1-5.

[0019] Preferably, the mass ratio of the polyvinyl alcohol in step (1) to the initiator in step (2) is 1:(0.05-0.5).

[0020] Preferably, in the step (2), the polymerization reaction temperature is 40-80° C., the polymerization reaction time is 1-10 h, and the polymerization reaction stirring speed is 50-500 r / min.

[0021] Preferably, the programmed vacuum freeze-drying in step (3) includes: firstly performing pre-freeze-drying at -40°C for 2 to 6 hours, then performing main freeze-drying at -20 to 0°C for 10 to 40 hours, then performing first desorption drying at 0 to 15°C for 5 to 15 hours, and finally performing second desorption drying at 20 to 40°C for 5 to 15 hours.

[0022] Preferably, in step (4), the mass ratio of the iodobenzene compound to the swollen microspheres is 1:(0.5-3).

[0023] Preferably, the temperature of the substitution reaction in step (4) is 30 to 80° C., and the time of the substitution reaction is 10 to 48 hours.

[0024] The present invention also provides self-photographic polyvinyl alcohol embolization microspheres prepared by the preparation method described in the above technical solution.

[0025] The present invention also provides the use of the self-photographic polyvinyl alcohol embolic microspheres described in the above technical solution in embolic materials.

[0026] The invention provides a method for preparing self-photographic polyvinyl alcohol embolization microspheres. The method comprises the following steps: N-(2,2-dimethoxyethyl)-2-acrylamide (NAAADA) and 1,3-diol units on a polyvinyl alcohol skeleton are subjected to a condensation reaction under acid catalysis to synthesize a stable cyclic acetal structure propylene (i.e., an acrylamide group is introduced into a side chain of polyvinyl alcohol). The pH value is adjusted by alkali to obtain a functionalized polyvinyl alcohol solution. Then, a monomer 2-acrylamide-2-methylpropanesulfonic acid and an initiator are added to obtain a cross-linked polymerization monomer solution. The solution is then mixed with cellulose acetate butyrate and butyl acetate. The aqueous macromolecular monomer / monomer mixture is dispersed and suspended in butyl acetate. The aqueous phase microparticles are stabilized by cellulose acetate butyrate to prevent coagulation. A free radical olefin polymerization reaction is initiated by tetramethylethylenediamine and potassium persulfate to realize a reverse reaction of a side chain reactive acrylamide group macromolecular monomer (i.e., functionalized polyvinyl alcohol) and 2-acrylamide-2-methylpropanesulfonate. Suspended free radical copolymerization is performed to form microspheres with a water-swollen cross-linked network structure. The microspheres are washed and then vacuum-dried to obtain vacuum-dried microspheres with a rough surface and abundant pores. The microspheres are then subjected to a substitution reaction with an iodobenzene compound to obtain self-developable polyvinyl alcohol embolization microspheres with a high iodine content. The surface of the vacuum-dried microspheres has a structure with abundant pores, which not only facilitates as many iodobenzene compounds as possible to bond to the microsphere surface, but also reduces the temperature of the substitution reaction. At the same time, the iodobenzene compound enters the interior of the microsphere through the pore structure, and undergoes a condensation reaction with the active hydroxyl group to bond to the interior of the microsphere, thereby improving the bonding ability of the iodine element in the iodobenzene compound, significantly improving the iodine content of the prepared self-developable polyvinyl alcohol embolization microspheres, achieving a long-term development effect, avoiding the problem that the development material embedded in the microspheres in the prior art will continuously seep out of the microspheres to shorten the development time, and greatly shortening the preparation time of the swollen microspheres, thereby reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A diagram showing the reaction process of preparing the self-photographic polyvinyl alcohol embolic microspheres provided by the present invention;

[0028] Figure 2 This is a microscope image of the self-photographic polyvinyl alcohol embolic microspheres prepared in Example 1 of the present invention;

[0029] Figure 3 This is a microscope image of the polyvinyl alcohol embolic microspheres prepared in Comparative Example 1 of the present invention;

[0030] Figure 4 Micro-CT image of the self-photographic polyvinyl alcohol embolic microspheres prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing self-photographic polyvinyl alcohol embolization microspheres, comprising the following steps:

[0032] (1) mixing an aqueous solution of polyvinyl alcohol and N-(2,2-dimethoxyethyl)-2-acrylamide, and then performing a condensation reaction and adjusting the pH with an alkali to obtain a functionalized polyvinyl alcohol solution; (2) mixing the functionalized polyvinyl alcohol solution obtained in step (1) with 2-acrylamide-2-methylpropanesulfonic acid and an initiator, and stirring to obtain a cross-linked polymerization monomer solution;

[0033] After butyl acetate and cellulose acetate butyrate are mixed, heat treatment is performed, and then the cross-linking polymerization monomer solution and tetramethylethylenediamine are added in sequence, and polymerization reaction and post-treatment are performed in sequence to obtain microspheres.

[0034] (3) subjecting the microspheres obtained in step (2) to programmed vacuum freeze-drying to obtain vacuum freeze-dried microspheres;

[0035] The process of vacuum freeze drying includes: firstly, pre-freeze drying at -45 to -35°C for 1 to 8 hours, then main freeze drying at -25 to 0°C for 8 to 45 hours, then first desorption drying at 0 to 20°C for 3 to 18 hours, and finally second desorption drying at 16 to 45°C for 3 to 18 hours;

[0036] (4) in an inert atmosphere, immersing the vacuum freeze-dried microspheres in dimethyl sulfoxide to obtain swollen microspheres;

[0037] The swollen microspheres are mixed with an iodobenzene compound, a solvent and an acid compound, and then subjected to a substitution reaction to obtain self-developable polyvinyl alcohol embolization microspheres.

[0038] In the present invention, unless otherwise specified, the raw materials used are conventional commercial products in the art.

[0039] The invention mixes a polyvinyl alcohol aqueous solution and N-(2,2-dimethoxyethyl)-2-acrylamide, and then sequentially performs condensation reaction and adjusts pH with alkali to obtain a functionalized polyvinyl alcohol solution.

[0040] In the present invention, the concentration of polyvinyl alcohol in the aqueous solution of polyvinyl alcohol is preferably 2 to 15 wt %, more preferably 3 to 13 wt %.

[0041] In the present invention, the mass ratio of polyvinyl alcohol to N-(2,2-dimethoxyethyl)-2-acrylamide in the aqueous solution of polyvinyl alcohol is preferably 1:(0.01-0.15), more preferably 1:(0.05-0.10). In the present invention, the mass ratio of polyvinyl alcohol to N-(2,2-dimethoxyethyl)-2-acrylamide in the aqueous solution of polyvinyl alcohol is controlled within the above range to ensure that a sufficient amount of acrylamide groups are introduced into the side chains of polyvinyl alcohol.

[0042] In the present invention, the pH value of the reaction system before the condensation reaction is preferably 1 to 5, more preferably 1 to 2; the reagent used to adjust the pH value of the system is preferably hydrochloric acid.

[0043] In the present invention, the temperature of the condensation reaction is preferably 20-25°C; the time of the condensation reaction is preferably 3-4 hours; the condensation reaction is preferably carried out under stirring conditions with a rotation speed of 150-250rpm. The present invention controls the temperature, time and stirring conditions of the condensation reaction to promote the condensation reaction sequence to proceed fully, ensure that the polyvinyl alcohol is fully functionalized, and introduce more acrylamide groups.

[0044] In the present invention, the base is preferably used to adjust the pH value of the system to 6-7 using NaOH solution.

[0045] After obtaining the functionalized polyvinyl alcohol solution, the present invention mixes the functionalized polyvinyl alcohol solution with 2-acrylamide-2-methylpropane sulfonic acid and an initiator, and stirs the mixture to obtain a cross-linked polymerization monomer solution.

[0046] In the present invention, the initiator is preferably at least one of potassium persulfate, ammonium persulfate and sodium persulfate; the mass ratio of the polyvinyl alcohol to the initiator is preferably 1:(0.05-0.5), more preferably 1:(0.05-0.3).

[0047] In the present invention, the mass ratio of the polyvinyl alcohol to 2-acrylamide-2-methylpropane sulfonic acid is preferably 1:(0.1-1.0), and more preferably 1:(0.1-0.5).

[0048] In the present invention, the stirring time is preferably 0.5 to 2 hours.

[0049] After obtaining the cross-linked polymerization monomer solution, the present invention mixes butyl acetate and cellulose acetate butyrate, performs heat treatment, and then sequentially adds the cross-linked polymerization monomer solution and tetramethylethylenediamine, sequentially performs polymerization reaction and post-treatment to obtain microspheres.

[0050] In the present invention, the temperature of the heat treatment is preferably 50-70° C., and the time of the heat treatment is preferably 20-40 minutes. The present invention promotes the dissolution of cellulose acetate butyrate into ethyl acetate through heat treatment.

[0051] In the present invention, the method of sequentially adding the cross-linked polymerization monomer solution and tetramethylethylenediamine is preferably: slowly adding the cross-linked polymerization monomer solution at a stirring speed of 150 to 250 rpm, and after the addition, stirring at 50 to 70° C. for 5 minutes, then adjusting the stirring speed to 50 to 70 rpm, adding tetramethylethylenediamine, and stirring at 50 to 70° C. for 5 minutes.

[0052] In the present invention, the polymerization temperature is preferably 40-80°C, more preferably 50-60°C; the polymerization time is preferably 1-10h, more preferably 3-5h; the polymerization stirring speed is preferably 50-500r / min, more preferably 50-150r / min. The present invention controls the polymerization temperature, time and stirring conditions to increase the degree of polymerization crosslinking, so as to improve the physical properties of the self-photographic polyvinyl alcohol embolic microspheres prepared subsequently.

[0053] After the polymerization reaction is completed, the product of the polymerization reaction is washed with butyl acetate and soaked in purified water to obtain microspheres.

[0054] The present invention removes cellulose acetate butyrate by washing with butyl acetate, and removes residual solvent by soaking in purified water.

[0055] After obtaining the microspheres, the present invention performs programmed vacuum freeze-drying on the microspheres to obtain vacuum freeze-dried microspheres.

[0056] In the present invention, the program vacuum freeze-drying preferably includes: first pre-freeze-drying at -45 to -35 ° C for 1 to 8 hours, then main freeze-drying at -25 to 0 ° C for 8 to 45 hours, then first analytical drying at 0 to 20 ° C for 3 to 18 hours, and finally second analytical drying at 16 to 45 ° C for 3 to 18 hours, more preferably: first pre-freeze-drying at -40 ° C for 2 to 6 hours, then main freeze-drying at -20 to 0 ° C for 10 to 40 hours, then first analytical drying at 0 to 15 ° C for 5 to 15 hours, and finally second analytical drying at 20 to 40 ° C for 5 to 15 hours. In the present invention, the temperature of the first analytical drying is further preferably 5 to 10 ° C, and the time is further preferably 5 to 10 hours; the temperature of the second analytical drying is further preferably 25 to 35 ° C, and the time is further preferably 5 to 10 hours. The present invention is vacuum-freeze-dried by the above-mentioned program, first freezing the microsphere hydrogel to form a solid, and then vacuum drying at different temperatures and times to form a rich pore structure on the surface of the microsphere.

[0057] After obtaining the vacuum freeze-dried microspheres, the present invention soaks the vacuum freeze-dried microspheres in dimethyl sulfoxide in an inert atmosphere to obtain swollen microspheres.

[0058] The swollen microspheres are mixed with an iodobenzene compound, a solvent and an acid compound, and then subjected to a substitution reaction to obtain self-developable polyvinyl alcohol embolization microspheres.

[0059] In the present invention, the soaking time is preferably 10 to 60 minutes, more preferably 30 to 60 minutes; the soaking is preferably carried out in a nitrogen atmosphere with stirring.

[0060] In the present invention, the iodinated benzene compound is preferably 2,3,5-triiodobenzaldehyde.

[0061] In the present invention, the mass ratio of the iodobenzene compound to the swollen microspheres is preferably 1:(0.5-3), more preferably 1:(0.8-2), and further preferably 1:1.

[0062] In the present invention, the solvent is preferably at least one of NN-dimethylformamide, dimethyl sulfoxide, xylene and toluene, and more preferably dimethyl sulfoxide.

[0063] In the present invention, the acid compound is preferably at least one of methanesulfonic acid, p-toluenesulfonic acid, hydrochloric acid, sulfuric acid, and acetic acid, and more preferably methanesulfonic acid.

[0064] In the present invention, the molar ratio of the acid compound to the iodobenzene compound is preferably (10-50):1, more preferably 20:1.

[0065] In the present invention, the temperature of the substitution reaction is preferably 30 to 80° C., more preferably 50 to 60° C.; the time of the substitution reaction is preferably 10 to 48 hours, more preferably 20 to 30 hours. The present invention controls the temperature, time and stirring conditions of the substitution reaction to ensure the chemical bonding effect of the iodobenzene compound and the active hydroxyl groups in the polyvinyl alcohol microspheres.

[0066] The method for preparing self-developing polyvinyl alcohol embolization microspheres provided by the present invention overcomes the following problems existing in the prior art: (1) in the process of preparing self-developing microspheres in the prior art, the surface of the microspheres is smooth and has no obvious pores, resulting in a decrease in the chemical bonding between the iodobenzene compound and the polyvinyl alcohol cross-linked microspheres, and a decrease in the iodine content. Although the method has a certain developing effect, the developing substance embedded in the microspheres will continuously seep out of the microspheres, making it difficult to maintain the developing effect for a long time; (2) in the prior art, the microspheres with smooth surfaces and no obvious pores require a longer time to immerse and swell, increasing the cost of the production process; (3) in the prior art, the microspheres with smooth surfaces and no obvious pores require a higher temperature when condensing with the iodobenzene compound, and the higher temperature affects the bonding ability of the iodine element in the iodobenzene compound, ultimately causing the problem of further reducing the iodine content of the microspheres; (4) the microspheres obtained in the prior art have a smooth surface and no obvious pore structure, and the developing molecules cannot enter the interior of the microspheres to perform condensation reaction with the active hydroxyl groups, resulting in a decrease in the iodine content of the microspheres and an uneven developing effect of the microspheres.

[0067] The present invention also provides self-photographic polyvinyl alcohol embolization microspheres prepared by the preparation method described in the above technical solution.

[0068] The present invention also provides the use of the self-photographic polyvinyl alcohol embolic microspheres described in the above technical solution in embolic materials.

[0069] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0070] Example 1

[0071] A method for preparing self-photographic polyvinyl alcohol embolization microspheres, comprising the following steps:

[0072] (1) Add injection water (360 g) to a 1 L reaction bottle, add polyvinyl alcohol (50.0 g) while stirring, control the stirring speed to 200 rpm, stir evenly, raise the temperature to 90° C., keep stirring for 1 hour, and after the polyvinyl alcohol is completely dissolved, cool down to below 35° C. to obtain an aqueous solution of polyvinyl alcohol with a concentration of 12 wt %;

[0073] Add N-(2,2-dimethoxyethyl)-2-acrylamide (1.5 g) to the aqueous solution of polyvinyl alcohol, stir and disperse, add hydrochloric acid (6.0 ml), adjust the pH value of the system solution to 2, control the temperature to 25° C., and stir at 200 rpm to carry out condensation reaction for 3.5 hours. After the reaction is completed, adjust the pH of the reaction solution to pH=6 using 0.1 g / ml NaOH solution, stop stirring, and obtain a functionalized polyvinyl alcohol solution for standby use;

[0074] (2) Weigh 2-acrylamide-2-methylpropanesulfonic acid (6.0 g) and potassium persulfate (5.0 g), add them to the functionalized polyvinyl alcohol solution obtained in step (1), and stir for 1 hour to completely dissolve the solid. The cross-linked polymerization monomer solution is obtained and is set aside;

[0075] The mass ratio of the polyvinyl alcohol to the initiator potassium persulfate is preferably 1:0.1; the mass ratio of the polyvinyl alcohol to 2-acrylamide-2-methylpropane sulfonic acid is preferably 1:0.12;

[0076] Add butyl acetate (800 ml) to a 3L reactor, add cellulose acetate butyrate (20.0 g) while stirring, heat to 60°C, heat and stir for 30 minutes, and the solid is completely dissolved. Control the stirring speed to 200 rpm, slowly add the above cross-linked polymerization monomer solution, after adding, heat and stir for 5 minutes, adjust the stirring speed to 60 rpm, add tetramethylethylenediamine (7 ml), heat and stir for 5 minutes, cool to 50°C, heat and stir at 50°C for 3 hours, after the reaction, add butyl acetate to wash the cellulose acetate butyrate, soak in purified water, and obtain microspheres;

[0077] (3) subjecting the microspheres obtained in step (2) to programmed vacuum freeze-drying to obtain vacuum freeze-dried microspheres;

[0078] The process of vacuum freeze drying is shown in Table 1 below;

[0079] Table 1 Process of vacuum freeze drying in Example 1

[0080]

[0081] After freeze-drying, 42.5 g of vacuum freeze-dried microspheres were obtained, i.e., non-developing microspheres. The yield was 85% after weighing and calculation, wherein the yield = microsphere weight / (polyvinyl alcohol feed amount);

[0082] (4) Weigh the vacuum freeze-dried microspheres / non-developing microspheres (5.0 g) obtained in step (3), place them in dimethyl sulfoxide (200 mL), and stir them for 40 min under nitrogen protection to fully expand them to obtain swollen microspheres; accurately weigh 2,3,5-triiodobenzaldehyde (5.0 g) and methanesulfonic acid (0.35 g), add them to the reaction solution, and stir them at 55° C. for 24 h to carry out the substitution reaction. Take samples to detect the consumption of triiodobenzaldehyde. After the reaction is completed, cool to room temperature and filter. Wash the pellets with a large amount of dimethyl sulfoxide and water to obtain self-developing polyvinyl alcohol embolization microspheres.

[0083] The mass ratio of the 2,3,5-triiodobenzaldehyde to the swollen microspheres is 1:1; the molar ratio of the methanesulfonic acid to the 2,3,5-triiodobenzaldehyde is 0.07:1.

[0084] Example 2

[0085] A method for preparing self-photographic polyvinyl alcohol embolization microspheres, comprising the following steps:

[0086] (1) Add injection water (360 g) to a 1 L reaction bottle, add polyvinyl alcohol (50.0 g) while stirring, control the stirring speed to 200 rpm, stir evenly, raise the temperature to 95° C., keep stirring for 1 hour, and after the polyvinyl alcohol is completely dissolved, cool down to below 35° C. to obtain an aqueous solution of polyvinyl alcohol;

[0087] Add N-(2,2-dimethoxyethyl)-2-acrylamide (1.5 g) to the aqueous solution of polyvinyl alcohol, stir and disperse, add hydrochloric acid (6.0 ml), and adjust the pH value of the system solution to 1. Control the reaction temperature to 25° C., control the stirring speed to 200 rpm, and stir to carry out condensation reaction for 4 hours. After the reaction is completed, use 0.1 g / ml NaOH solution to adjust the pH of the reaction solution to pH=6, stop stirring, and obtain a functionalized polyvinyl alcohol solution for use;

[0088] (2) Weigh 2-acrylamide-2-methylpropanesulfonic acid (6.0 g) and potassium persulfate (5.0 g), add them to the functionalized polyvinyl alcohol solution obtained in step (1), and stir for 1 hour to completely dissolve the solid to obtain a cross-linked polymerization monomer solution for later use;

[0089] Add butyl acetate (800ml) to a 3L reactor, add cellulose acetate butyrate (20.0g) while stirring, heat to 60°C, keep stirring for 30 minutes, until the solid is completely dissolved, control the stirring speed to 200rpm, slowly add the above cross-linked polymerization monomer solution, and keep stirring for 5 minutes after the addition. Adjust the stirring speed to 60rpm, add tetramethylethylenediamine (7ml), and keep stirring for 5 minutes. Cool down to 50°C, keep stirring at 50°C for polymerization reaction for 3 hours. After the reaction is completed, add butyl acetate to wash the cellulose acetate butyrate, and soak it in purified water to obtain microspheres;

[0090] (3) performing programmed vacuum freeze drying on the microspheres obtained in step (2) to obtain vacuum freeze-dried microspheres; the process of the programmed vacuum freeze drying is shown in Table 2 below;

[0091] Table 2 Process of vacuum freeze drying in Example 2

[0092]

[0093] After freeze-drying, 39.2 g of microspheres were obtained, i.e., non-developing microspheres. The yield was 78.4% after weighing and calculation, where yield = microsphere weight / (polyvinyl alcohol feed amount);

[0094] (4) Weigh the vacuum freeze-dried microspheres / non-developing microspheres (5.2 g) obtained in step (3), place them in dimethyl sulfoxide (200 ml), and stir them for 40 min under nitrogen protection to fully expand them to obtain swollen microspheres; accurately weigh 2,3,5-triiodobenzaldehyde (5.2 g) and methanesulfonic acid (0.35 g), add them to the reaction solution, and stir and react at 55° C. for 24 h. Take samples to detect the consumption of triiodobenzaldehyde. After the reaction is completed, cool to room temperature and filter. Wash the pellets with a large amount of dimethyl sulfoxide and water to obtain self-developing polyvinyl alcohol embolization microspheres.

[0095] Example 3

[0096] A method for preparing self-photographic polyvinyl alcohol embolization microspheres, comprising the following steps:

[0097] (1) Add injection water (360 g) to a 1 L reaction bottle, add polyvinyl alcohol (50.0 g) while stirring, control the stirring speed to 200 rpm, stir evenly, raise the temperature to 95° C., keep stirring for 1 hour, and after the polyvinyl alcohol is completely dissolved, cool down to below 35° C. to obtain an aqueous solution of polyvinyl alcohol;

[0098] Add N-(2,2-dimethoxyethyl)-2-acrylamide (1.5 g) to the aqueous solution of polyvinyl alcohol, stir and disperse, add hydrochloric acid (6.0 ml), and adjust the pH value of the system solution to 1. Control the reaction temperature to 25° C., control the stirring speed to 200 rpm, and stir to carry out condensation reaction for 4 hours. After the reaction is completed, adjust the pH of the reaction solution to pH=7 with 0.1 g / ml NaOH solution, stop stirring, and obtain a functionalized polyvinyl alcohol solution for use;

[0099] (2) Weigh 2-acrylamide-2-methylpropanesulfonic acid (6.0 g) and potassium persulfate (5.0 g), add them to the functionalized polyvinyl alcohol solution obtained in step (1), and stir for 1 hour to completely dissolve the solid to obtain a cross-linked polymerization monomer solution for later use;

[0100] Add butyl acetate (800 ml) to a 3L reactor, add cellulose acetate butyrate (20.0 g) while stirring, heat to 60°C, keep warm and stir for 30 minutes, and the solid is completely dissolved. Control the stirring speed to 200 rpm, slowly add the above-mentioned cross-linked polymerization monomer solution, and keep warm and stir for 5 minutes. Adjust the stirring speed to 60 rpm, add tetramethylethylenediamine (7 ml), and keep warm and stir for 5 minutes. Cool down to 50°C, keep warm and stir at 50°C for 3 hours to carry out the polymerization reaction. After the reaction is completed, add butyl acetate to wash the cellulose acetate butyrate, and soak it in purified water to obtain microspheres;

[0101] (3) subjecting the microspheres obtained in step (2) to programmed vacuum freeze-drying to obtain vacuum freeze-dried microspheres;

[0102] The process of vacuum freeze drying is shown in Table 3 below;

[0103] Table 3 Process of programmed vacuum freeze drying in Example 3

[0104]

[0105] After freeze-drying, 39.2 g of microspheres were obtained, i.e., non-developing microspheres. The yield was 78.4% after weighing and calculation, where yield = microsphere weight / (polyvinyl alcohol feed amount);

[0106] (4) Weigh the microspheres / non-developing microspheres (5.0 g) obtained in step (3), place them in dimethyl sulfoxide (200 ml), and stir them for 40 min under nitrogen protection to fully expand them to obtain swollen microspheres; accurately weigh 2,3,5-triiodobenzaldehyde (5.0 g) and methanesulfonic acid (0.35 g), add them to the reaction solution, and stir and react at 55° C. for 30 h. Take samples to detect the consumption of triiodobenzaldehyde. After the reaction is completed, cool to room temperature and filter, and wash the pellets with a large amount of dimethyl sulfoxide and water to obtain self-developing polyvinyl alcohol embolization microspheres.

[0107] Comparative Example 1

[0108] A method for preparing polyvinyl alcohol developer microspheres, comprising the following steps:

[0109] (1) Preparation of polyvinyl alcohol functionalized solution: Add injection water (360g) to a 1L reaction bottle, add polyvinyl alcohol (50.0g) while stirring, control the stirring speed to 200rpm, and stir evenly. Raise the temperature to 95℃, keep stirring for 1 hour, and after the polyvinyl alcohol is completely dissolved, cool below 35℃, add N-(2,2-dimethoxyethyl)-2-acrylamide (1.5g), stir to disperse, add hydrochloric acid (6.0ml), the pH value of the reaction solution should be 1, control the reaction temperature to 25℃, control the stirring speed to 200rpm, keep stirring and react for 4 hours;

[0110] After the reaction is completed, the pH of the reaction solution is adjusted to pH=6 using 0.1 g / ml NaOH solution, and stirring is stopped to obtain a functionalized polyvinyl alcohol solution for standby use;

[0111] (2) Polymer cross-linking reaction: Weigh 2-acrylamide-2-methylpropanesulfonic acid (6.0 g) and potassium persulfate (5.0 g), add them to the functionalized polyvinyl alcohol solution, and stir for 1 hour to completely dissolve the solid to obtain a cross-linked polymerization monomer solution for later use;

[0112] Add butyl acetate (800 ml) to a 3L reactor, add cellulose acetate butyrate (20.0 g) while stirring, heat to 60° C., keep warm and stir for 30 minutes, until the solid is completely dissolved, control the stirring speed to 200 rpm, slowly add the above cross-linked polymerization monomer solution, after addition, keep warm and stir for 5 minutes, adjust the stirring speed to 60 rpm, add tetramethylethylenediamine (7 ml), keep warm and stir for 5 minutes, cool to 50° C., keep warm and stir at 50° C. for polymerization reaction for 3 hours, after the reaction is completed, add butyl acetate to wash the cellulose acetate butyrate, purify and wash with acetone, transfer to blast drying, and obtain 38.2 g of dried microspheres, i.e., microspheres without self-development, with a yield of 76.4%, yield = microsphere weight ÷ polyvinyl alcohol feed amount;

[0113] (4) Preparation of developing microspheres by condensation of 2,3,5-triiodobenzaldehyde and microspheres

[0114] Weigh the above-mentioned non-developing microspheres (5.0 g), place them in dimethyl sulfoxide (200 ml), and stir them for 40 minutes under nitrogen protection to fully expand them to obtain swollen microspheres; accurately weigh 2,3,5-triiodobenzaldehyde (5.0 g) and methanesulfonic acid (0.35 g), add them to the reaction solution, and stir and react at 55°C for 30 hours. Take samples to detect the consumption of triiodobenzaldehyde, cool to room temperature after the reaction is completed, filter, and wash the pellets with a large amount of dimethyl sulfoxide and water to obtain self-developing polyvinyl alcohol embolization microspheres.

[0115] The self-developing polyvinyl alcohol embolization microspheres prepared in Example 1 of the present invention and the polyvinyl alcohol developing microspheres prepared in Comparative Example 1 were observed using an optical microscope. Figure 2 and Figure 3 As shown by Figure 2 and Figure 3 By comparison, it can be seen that the surface of the self-developable polyvinyl alcohol embolic microspheres prepared in Example 1 is relatively rough and has abundant pores, while the surface of the polyvinyl alcohol developing microspheres prepared in Comparative Example 1 is relatively smooth and has no pores.

[0116] The self-imaging polyvinyl alcohol embolic microspheres prepared in Example 1 of the present invention were detected by Micro-CT technology and implanted into mice and scanned in vitro. The Micro-CT images were as follows: Figure 4 As shown by Figure 4 It can be seen that the average CT value of the self-radioscopic microspheres is 1092, which is significantly different from the CT value of living soft tissue. It is clearly visible in the CT image after implantation in mice, and has good development and visibility. The in vitro Micro-CT scanning results can distinguish between self-radioscopic polyvinyl alcohol embolization microspheres, pure water, mouse femur and muscle, and iohexol.

[0117] Performance Testing

[0118] (1) Appearance of microspheres

[0119] The appearance of the self-developable polyvinyl alcohol embolization microspheres prepared in Examples 1 to 3 and the polyvinyl alcohol developing microspheres prepared in Comparative Example 1 was inspected using a microscope. The inspection results are shown in Table 4.

[0120] Table 4 Appearance properties of the self-developable polyvinyl alcohol embolization microspheres prepared in Examples 1 to 3 and the polyvinyl alcohol developing microspheres prepared in Comparative Example 1

[0121] sample Appearance Example 1 Yellow microspheres, spherical particles; good dispersibility Example 2 Yellow microspheres, spherical particles; good dispersibility Example 3 Yellow microspheres, spherical particles; good dispersibility Comparative Example 1 Light yellow microspheres, spherical particles; good dispersibility

[0122] It can be found from Table 4 that the polyvinyl alcohol developer microspheres obtained by freeze-drying in Examples 1 to 3 are darker in color than the developer microspheres obtained by air drying in Comparative Example 1. The color difference may be related to the bonding degree between triiodobenzaldehyde and the microspheres.

[0123] (2) Microsphere deformation

[0124] Microsphere deformation is an important mechanical characteristic of polyvinyl alcohol embolic microspheres, which characterizes the ability of microspheres to recover after being squeezed by external forces. It ensures that polyvinyl alcohol embolic microspheres can recover to their original shape in time after being squeezed and deformed into the microcatheter and delivered to the designated lesion vascular site.

[0125] The method for detecting the deformation of microspheres is as follows: 10 microspheres are randomly selected, the moisture on the surface of the microspheres is absorbed with filter paper, and they are placed on the outer measuring claws of the vernier caliper respectively. The micro-motion device is gently rotated so that both sides of the outer measuring claws just touch the microspheres, and the diameter of the ball is measured. Then, the micro-motion device is gently rotated to move the cursor so that the outer measuring claws press the microspheres to a deformation of 50%, and remain still for 10 seconds. Then, the outer measuring claws are slowly moved backwards to release the pressure and observe the rebound of the microspheres. The test results are detailed in Table 5.

[0126] Table 5 Microsphere deformation of self-developable polyvinyl alcohol embolization microspheres prepared in Examples 1 to 3 and polyvinyl alcohol developing microspheres prepared in Comparative Example 1

[0127]

[0128] It can be found from Table 5 above that the microsphere deformation rates of Examples 1 to 3 and Comparative Example 1 are all greater than 50%. After the pressure is released, the microspheres can quickly return to a spherical shape without being damaged, indicating that different drying methods have little effect on the elasticity of the polyvinyl alcohol microspheres.

[0129] (3) Determination of iodine content

[0130] Take 0.6 g of microspheres, weigh accurately, place in an evaporating dish, add 40 ml of potassium hydroxide ethanol solution (1→10), cover with a watch glass, evaporate on a water bath until it becomes a mass, wash the watch glass with a small amount of water, add the washing liquid into the evaporating dish, continue to evaporate until it is nearly dry, use 150-200 ml of hot water to quantitatively transfer the residue to a stoppered conical flask, cool, add 5 ml of glacial acetic acid and 5 drops of sodium eosin indicator solution, and titrate with silver nitrate titrant (0.1 mol / L) until it turns red. Each 1 ml of silver nitrate titrant (0.1 mol / L) is equivalent to 12.69 mg of I. The test results are shown in Table 6.

[0131] Table 6 Iodine content of self-developable polyvinyl alcohol embolization microspheres prepared in Examples 1 to 3 and polyvinyl alcohol developing microspheres prepared in Comparative Example 1

[0132] Sample source Example 1 Example 2 Example 3 Comparative Example 1 Iodine content 27.5％ 25.0％ 22.8％ 10.4％

[0133] It can be found from Table 6 above that the iodine content of Example 1 is significantly higher than that of Example 2 and Example 3, which indicates that different freeze-drying processes and drying methods have an impact on the iodine content of the microspheres. The iodine content of Comparative Example 1 is significantly lower than that of Examples 1 to 3. Since Comparative Example 1 adopts forced air drying, the surface of the dried microspheres prepared therein has no pores, which affects the adhesion ability of triiodobenzaldehyde, thereby affecting the bonding degree between triiodobenzaldehyde and the microspheres, thereby reducing the iodine content of the polyvinyl alcohol-developed microspheres prepared in Comparative Example 1.

[0134] (4) Catheter permeability

[0135] 1) Take this product for testing, shake it slightly to mix evenly, the microspheres should not aggregate, and should be fully suspended in a monodisperse state;

[0136] 2) Expel the air from the prefilled syringe, connect it directly to a catheter of the appropriate model that has been flushed with saline, and slowly and evenly push the microspheres suspended in the syringe into the microcatheter (the push speed is generally 10 mL / min. If the push is too fast, the liquid will pass through the microcatheter first, leaving the remaining microspheres). During the push process, shake the syringe in time to ensure that the microspheres are suspended. Observe whether the catheter is blocked. After the push is completed, flush the microcatheter with saline for 3 times. The test results are detailed in Table 7.

[0137] Table 7 Catheter passability of the self-developing polyvinyl alcohol embolic microspheres prepared in Examples 1 to 3 and the polyvinyl alcohol developing microspheres prepared in Comparative Example 1

[0138] Particle size Microcatheter Model Example 1 Example 2 Example 3 Comparative Example 1 150~300μm 2.7F pass pass pass pass

[0139] It can be found from Table 7 above that the corresponding microspheres prepared in Examples 1 to 3 and Comparative Example 1 can all pass through the catheter, and the microspheres all blocked the catheter in the catheter passability test, indicating that different drying methods have little effect on the hardness of the polyvinyl alcohol microspheres.

[0140] (5) Determination of the CT imaging ability of self-radiographic absorbable embolic microspheres.

[0141] The imaging property of the self-imaging polyvinyl alcohol embolic microspheres prepared in Example 1 was evaluated using electronic computed tomography technology:

[0142] Take 10 samples, take 25 mg of each sample and add it into an EP tube containing 1 ml of deionized water. Scan under a CT machine with a voltage of 120 kV, a current of 350 mAs, a layer thickness of 1 mm, and a pitch of 0.6. Measure the CT value at the same position at the bottom of the test tube where the microspheres are evenly distributed. The average value of ten line scans of the self-radiographic absorbable embolic microspheres prepared in Example 1 is 4908 HU.

[0143] In summary, the surface of the self-developable polyvinyl alcohol embolic microspheres prepared in Example 1 of the present invention is rough and has abundant pores, while the surface of the polyvinyl alcohol developing microspheres prepared in Comparative Example 1 is smooth and has no pores; the iodine content of the polyvinyl alcohol developing microspheres prepared in Comparative Example 1 is significantly lower than that of Examples 1 to 3, and the corresponding microspheres prepared in Examples 1 to 3 and Comparative Example 1 can pass through the catheter, have similar hardness, and the microsphere deformation rate is greater than 50%.

[0144] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing self-photographic polyvinyl alcohol embolic microspheres, characterized in that: The following steps are involved: (1) mixing an aqueous solution of polyvinyl alcohol and N-(2,2-dimethoxyethyl)-2-acrylamide, and then performing a condensation reaction and adjusting the pH with an alkali to obtain a functionalized polyvinyl alcohol solution; (2) mixing the functionalized polyvinyl alcohol solution obtained in step (1) with 2-acrylamide-2-methylpropanesulfonic acid and an initiator, and stirring to obtain a cross-linked polymerization monomer solution; After mixing butyl acetate and cellulose acetate butyrate, heat-treating the mixture, sequentially adding the cross-linking polymerization monomer solution and tetramethylethylenediamine, sequentially performing polymerization reaction and post-treatment to obtain microspheres; (3) subjecting the microspheres obtained in step (2) to programmed vacuum freeze-drying to obtain vacuum freeze-dried microspheres; The process of vacuum freeze drying includes: firstly, pre-freeze drying at -45 to -35°C for 1 to 8 hours, then main freeze drying at -25 to 0°C for 8 to 45 hours, then first desorption drying at 0 to 20°C for 3 to 18 hours, and finally second desorption drying at 16 to 45°C for 3 to 18 hours; (4) in an inert atmosphere, immersing the vacuum freeze-dried microspheres obtained in step (3) in dimethyl sulfoxide to obtain swollen microspheres; The swollen microspheres are mixed with an iodobenzene compound, a solvent and an acid compound, and then subjected to a substitution reaction to obtain self-developable polyvinyl alcohol embolization microspheres.

2. The preparation method according to claim 1, characterized in that: The mass ratio of polyvinyl alcohol to N-(2,2-dimethoxyethyl)-2-acrylamide in the aqueous solution of polyvinyl alcohol in step (1) is 1:(0.01-0.15).

3. The preparation method according to claim 1, characterized in that: The pH value of the reaction system before the condensation reaction in step (1) is 1-5.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the polyvinyl alcohol in the step (1) to the initiator in the step (2) is 1:(0.05-0.5).

5. The preparation method according to claim 1, characterized in that: The polymerization reaction temperature in step (2) is 40-80° C., the polymerization reaction time is 1-10 h, and the polymerization reaction stirring speed is 50-500 r / min.

6. The preparation method according to claim 1, characterized in that: The programmed vacuum freeze-drying in step (3) includes: firstly, pre-freeze-drying at -40°C for 2 to 6 hours, then main freeze-drying at -20 to 0°C for 10 to 40 hours, then first desorption drying at 0 to 15°C for 5 to 15 hours, and finally second desorption drying at 20 to 40°C for 5 to 15 hours.

7. The preparation method according to claim 1, characterized in that: In the step (4), the mass ratio of the iodobenzene compound to the swollen microspheres is 1:(0.5-3).

8. The preparation method according to claim 1, characterized in that: The temperature of the substitution reaction in step (4) is 30 to 80° C., and the time of the substitution reaction is 10 to 48 hours.

9. Self-imaging polyvinyl alcohol embolic microspheres prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the self-radioactive polyvinyl alcohol embolic microspheres according to claim 9 in embolic materials.

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