Polyvinyl alcohol embolic microspheres with developer and preparation method and application thereof

Abstract

The present invention discloses a polyvinyl alcohol embolic microsphere with a developer, a preparation method and an application thereof, and belongs to the field of medical device technology. The preparation method of the polyvinyl alcohol embolic microsphere with a developer comprises: (1) preparing a cross-linking agent with a developer element: firstly, diethyltriamine pentaacetic acid dianhydride and 2-aminoethyl methacrylate are mixed to undergo an amidation reaction to generate DTPA connected with two 2-aminoethyl methacrylates, and then a chelation reaction is performed with a gadolinium salt to generate gadopentetate meglumine connected with 2-aminoethyl methacrylate, which is a cross-linking agent; (2) preparing polyvinyl alcohol microspheres by emulsion polymerization or microfluidics. In the preparation method provided by the present invention, a cross-linking agent with a developer element is used to cross-link the polyvinyl alcohol microspheres, so as to produce polyvinyl alcohol embolic microspheres with a developer effect and drug loading capacity under MRI.

Description

Technical Field

[0001] The invention relates to the technical field of medical devices, and in particular to a method for preparing polyvinyl alcohol embolic microspheres capable of being simultaneously developed and loaded with drugs. Background Art

[0002] Embolic microspheres are a type of diagnostic and therapeutic device that is often used in the medical field. For example, they are often used in interventional embolization therapy for hemostasis or tumor treatment. In interventional embolization therapy for tumors, high-definition medical imaging instruments are often used to guide the microspheres into the tumor site through blood vessels using a catheter to block its blood supply, causing tumor cells to lack nutrition and shrink and die. At the same time, chemotherapy drugs are loaded to kill tumor cells, thereby achieving the effect of treating tumors.

[0003] During the operation, it is necessary to observe the introduction of microspheres to determine whether the treatment endpoint has been reached. The embolic microspheres currently used clinically cannot be visualized under X-rays, CT or MRI. The method of use is to mix the microspheres with the developer before surgery and then introduce them into the tumor site, using the liquid developer to indirectly display the embolism. Due to the separation of the developer and the embolic material, this method will cause inaccurate development and lead to misjudgment of the treatment results; in addition, after the operation, the distribution of the embolic microspheres cannot be seen, resulting in an inability to accurately judge the embolism and treatment effects. The inability to visualize embolic microspheres affects the accuracy of embolism and postoperative tracking and evaluation. Therefore, the research and development of visualized microspheres has become one of the current hot spots in the field of interventional therapy.

[0004] Patent document CN 103861157 A discloses a gadolinium-based MRI imaging embolic microsphere, which uses sodium alginate as a raw material and forms gel beads through an electrostatic droplet generator. Lanthanide metal ions such as Gd are introduced into the microsphere. 3+ As a developing group, it is used for MRI imaging. However, the embolic microspheres are limited by the properties of alginate gel, which degrades quickly and easily releases toxic gadolinium, making them difficult to be used for embolic therapy of tumors.

[0005] Polyvinyl alcohol embolic microspheres are microspheres with polyvinyl alcohol (PVA) as the main embolic material, and are generally used for long-term embolic therapy in clinical practice. Patent document CN 102139128 A discloses a developable polyvinyl alcohol microsphere embolic agent, and its preparation method is: under continuous stirring, a mixture of polyvinyl alcohol and developer is added to an appropriate swelling agent solution, fully dissolved, the solution is adjusted to be acidic, heated to 40°C, esterified for several hours, and the solution is added to a suitable medium, cross-linked and solidified with an aldehyde compound, the medium and cross-linking agent are washed off, and freeze-dried to form microspheres. However, this method uses aldehydes as cross-linking agents, which are highly toxic to the human body. At the same time, the physically embedded contrast agent is easily released, resulting in unstable contrast performance.

[0006] In view of the above problems, it is a problem that those skilled in the art need to solve to develop a preparation method that avoids the use of traditional aldehyde cross-linking agents to synthesize polyvinyl alcohol embolic microspheres that can be simultaneously developed and loaded with cationic drugs. Summary of the invention

[0007] The object of the present invention is to provide a method for preparing polyvinyl alcohol embolic microspheres that can be simultaneously developed and loaded with cationic drugs. The preparation process is simple and avoids the problems of the prior art of first making microspheres and then adsorbing or modifying the developer, such as complicated procedures, easy release of the developer, and high toxicity of the aldehyde cross-linking agent.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for preparing polyvinyl alcohol embolic microspheres with a developer, comprising the following steps:

[0010] (1) preparing a cross-linking agent with a developing element: diethyltriamine pentaacetic acid dianhydride (DTPAA) and 2-aminoethyl methacrylate are mixed to undergo an amidation reaction to generate DTPA connected with two 2-aminoethyl methacrylates, which is then subjected to a chelation reaction with a gadolinium salt to generate gadopentetate meglumine connected with 2-aminoethyl methacrylate, which is the cross-linking agent;

[0011] (2) Preparing microspheres: dissolving the crosslinking agent prepared in step (1) with polyvinyl alcohol, an initiator, a water-soluble functional monomer, and an acrylamide crosslinking agent in water to prepare an aqueous phase; adding an emulsifier into the oil phase, dispersing the aqueous phase in the oil phase, and then performing a polymerization reaction to obtain the polyvinyl alcohol embolic microspheres with a developer.

[0012] The present invention prepares polyvinyl alcohol embolic microspheres that can be developed under MRI and loaded with cationic drugs through the above method. During the preparation process of the embolic microspheres, a cross-linking agent with a developing element is used to replace part of the acrylamide cross-linking agent to achieve the purpose of preparing drug-loaded embolic microspheres with developing function.

[0013] In step (1), the present invention prepares gadopentetate meglumine connected with 2-aminoethyl methacrylate as a crosslinking agent in the process of crosslinking polyvinyl alcohol to form microspheres, wherein gadolinium provides a developing function, and two 2-aminoethyl esters are connected to gadopentetate meglumine, and its double bonds are used for crosslinking with polyvinyl alcohol and acrylic acid molecules.

[0014] Specifically, the synthesis method of the cross-linking agent with a developing element is as follows: first, diethyltriaminepentaacetic acid (DTPA) is reacted with acetic anhydride to generate an intermediate product, diethyltriaminepentaacetic dianhydride (DTPAA), and after purification, the obtained DTPAA is mixed with 2-aminoethyl methacrylate, and an amidation reaction occurs under the catalysis of an organic base to generate DTPA connected with two 2-aminoethyl methacrylates, and after extraction, a gadolinium salt is added to the extract to generate a chelating reaction to generate gadopentetate meglumine connected with 2-aminoethyl methacrylate, and the desired product is obtained after purification.

[0015] Preferably, the molar ratio of 2-aminoethyl methacrylate to diethyltriaminepentaacetic dianhydride is ≥2:1, and the mixture is reacted under the catalytic condition of an organic base for 10 to 15 hours.

[0016] The organic base includes but is not limited to triethylamine, and the catalytic reaction is carried out at room temperature.

[0017] More preferably, the molar ratio of 2-aminoethyl methacrylate to diethyltriaminepentaacetic dianhydride is 2 to 3:1.

[0018] Preferably, after the amidation reaction is completed, a sodium bicarbonate aqueous solution is added to the reaction system for extraction, the aqueous phases are combined to obtain an extract, and then a gadolinium salt is added to the extract to react at room temperature for 10 to 15 hours, wherein the molar ratio of the gadolinium salt to the DTPA connected with two 2-aminoethyl methacrylates is ≥1:1.

[0019] The gadolinium salt includes but is not limited to GdCl3·6H2O. More preferably, the molar ratio of GdCl3·6H2O to DTPA connected with two 2-aminoethyl methacrylates is 1 to 2:1.

[0020] In step (2), the crosslinking agent with the developing element prepared in step (1) and the acrylamide crosslinking agent participate in the crosslinking reaction of polyvinyl alcohol, so that the developing element is chemically bonded to the formed polyvinyl alcohol microspheres. Specifically, the polyvinyl alcohol microspheres are prepared by emulsion polymerization or microfluidics.

[0021] The emulsion polymerization method comprises: adding a water phase containing polyvinyl alcohol, a water-soluble functional monomer, an initiator, a crosslinking agent with a developing element, and an acrylamide crosslinking agent to a heated oil phase containing an emulsifier to form an emulsion, and then adding a catalyst to carry out an emulsion polymerization reaction to obtain developing microspheres.

[0022] The microfluidic method comprises: using an oil phase containing an emulsifier to shear an aqueous phase containing polyvinyl alcohol, a water-soluble functional monomer, an initiator, a cross-linking agent with a developing element, and an acrylamide cross-linking agent into microspheres in a microchannel, and then collecting them in an oil phase containing a catalyst and an emulsifier to carry out a polymerization reaction to obtain developing microspheres.

[0023] Preferably, when preparing the aqueous phase, 0.1% to 0.3% by mass of an initiator, 0.2% to 1% by mass of an acrylamide crosslinker, and 0.5% to 5% by mass of a crosslinker with a developing element are added to a 30% to 50% by mass aqueous solution of a water-soluble functional monomer, and dissolved to obtain a solution A; then a 5% to 10% by mass polyvinyl alcohol solution is added to the solution A to obtain the aqueous phase, wherein the volume ratio of the solution A to the polyvinyl alcohol aqueous solution is 1:0.4 to 0.8.

[0024] The present invention uses functional monomers in the cross-linking process of polyvinyl alcohol to give the embolic microspheres the ability to adsorb cationic drug molecules. Preferably, the water-soluble functional monomer is one or a mixture of any of acrylic acid or acrylic acid salts.

[0025] In the present invention, an acrylamide crosslinking agent is added to the aqueous phase to participate in the crosslinking reaction of polyvinyl alcohol, which is conducive to forming microspheres with a stable structure, better sphericity and elasticity. Preferably, the acrylamide compound is N,N'-methylenebisacrylamide.

[0026] Preferably, the initiator is one or a mixture of any two of the persulfates.

[0027] Preferably, the oil phase is n-heptane or butyl acetate.

[0028] Preferably, the emulsifier is a nonionic surfactant or cellulose, specifically Span80 or cellulose acetate butyrate. The emulsifier enables the water phase and the oil phase to form a good emulsion, and the generated microspheres are more uniform.

[0029] Preferably, the concentration of Span 80 in the oil phase is 0.1% to 1% or the concentration of cellulose acetate butyrate is 1% to 10%.

[0030] In the present invention, the polyvinyl alcohol microspheres prepared by emulsion polymerization have good sphericity, regular spheres and smooth surfaces. Preferably, the method of the two-phase mixed catalytic reaction is: adding water phase to oil phase, stirring to form an emulsion and then adding a catalyst for reaction, wherein the volume ratio of water phase to oil phase is 0.01 to 1:1, the temperature of the oil phase is 50 to 70°C, and the stirring speed is 10 to 30 rpm.

[0031] Preferably, the catalyst is tetramethylethylenediamine or dimethylethylenediamine. The catalytic reaction time is 30 to 240 minutes.

[0032] In the present invention, the microspheres prepared by the microfluidic method have good sphericity, regular spheres, smooth surfaces, and more uniform particle sizes. Preferably, the method of the two-phase mixed catalytic reaction is: using a syringe pump to inject the two phases into a microfluidic chip to form microspheres, and the microspheres enter a collection bottle containing a catalyst, an emulsifier and an oil phase after exiting the microfluidic outlet to react, wherein the flow rate ratio of the water phase to the oil phase is 0.001 to 0.1:1, and the temperature of the oil phase in the collection bottle is 50 to 70°C.

[0033] The structure of the microchannel can be coaxial, confocal, T-shaped or Y-shaped.

[0034] Preferably, the catalyst is tetramethylethylenediamine or dimethylethylenediamine. The catalytic reaction time is 30 to 240 minutes.

[0035] The present invention also provides polyvinyl alcohol embolic microspheres with developer prepared by the preparation method. The embolic microspheres are made of polyvinyl alcohol as a substrate, and are cross-linked with a cross-linking agent with developer elements to form microspheres, which can be developed under MRI. Therefore, the microspheres can be detected by high-definition medical imaging instruments during and after the embolic surgery, helping doctors to determine the treatment endpoint and treatment effect. The embolic microspheres also have drug loading capacity, so the embolic microspheres prepared by the present invention can be directly used for embolic therapy, or loaded with tumor drugs for embolic therapy, such as doxorubicin.

[0036] The present invention also provides the use of the polyvinyl alcohol embolic microspheres with developer in the preparation of anti-tumor drugs, that is, the embolic microspheres are loaded with anti-tumor drugs.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) In the preparation method provided by the present invention, a cross-linking agent with a developing element is used to replace part of the acrylamide cross-linking agent to cross-link the polyvinyl alcohol embolic microspheres, thereby producing polyvinyl alcohol embolic microspheres with developing effect and drug loading capacity under MRI. The developing element gadolinium is chelated in the cross-linking agent and chemically bonded in the microspheres, which can avoid the release of gadolinium ions. At the same time, this method simplifies the complicated process of developing microspheres in existing reports, such as the need to adsorb the developer after the microspheres are made, and there is no need to use the low temperature and organic solvent required in the step of adsorbing the developer, thereby reducing energy consumption and avoiding pollution caused by organic solvents.

[0039] (2) The polyvinyl alcohol microspheres produced by the present invention can be visualized under MRI, and can more accurately show the embolization effect during and after surgery, avoiding the problem of inaccurate judgment of the treatment endpoint caused by relying on the developer injected together with the microspheres to judge the embolization effect during the current clinical surgery, and facilitating doctors to judge the treatment situation after surgery; at the same time, the embolization microspheres have drug loading capacity, and by loading anti-tumor drugs, chemotherapy drugs can be introduced into tumor interventional embolization treatment to achieve the effect of combined tumor treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is the structural formula of gadopentetate meglumine with 2-aminoethyl methacrylate.

[0041] Figure 2 This is an image of microspheres generated under a microscope after the microspheres prepared by emulsion polymerization in Example 1 were sieved.

[0042] Figure 3 The images of microspheres displayed under MRI (left: pure water, middle: microspheres without contrast agent, right: microspheres containing gadolinium contrast agent).

[0043] Figure 4 This is an image of the microspheres prepared by microfluidics in Example 5 generated under a microscope. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with specific embodiments. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of application of the present invention. Without departing from the spirit and essence of the present invention, modifications or replacements made to the inventive method, steps or conditions all belong to the scope of the present invention.

[0045] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0046] Specifically, the compounds used in the examples are as follows:

[0047] Polyvinyl alcohol (CAS No. 9002-89-5), acrylic acid (CAS No. 79-10-7), sodium hydroxide (CAS No. 1310-73-2), sodium acrylate (CAS No. 7446-81-3), potassium persulfate (CAS No. 7727-21-1), N, N'-methylenebisacrylamide (CAS No. 110-26-9), 2-aminoethyl methacrylate (CAS No. 2420-94-2), gadolinium chloride hexahydrate (CAS No. 13450-84-5), diethyltriamine pentaacetic acid DTPA (CAS No. 67-43-6), acetic anhydride (CAS No. 108-24-7), n-heptane (CAS No. 142-82-5), butyl acetate (CAS No. 123-86-4), span 80 (CAS No.: 1338-43-8), cellulose acetate butyrate (CAS No.: 9004-36-8), tetramethylethylenediamine (CAS No.: 110-18-9), dimethylethylenediamine (CAS No.: 110-70-3).

[0048] Example 1

[0049] 1. Synthesis of DTPAA:

[0050] Weigh 15.72g (0.04mol) of DTPA into a 100mL flask, then add 32mL (0.16mol) of acetic anhydride and 20mL (0.24mol) of pyridine distilled off water through a water separator. Stir at 65°C for 24h. After the reaction is completed, cool to room temperature and remove the solvent by rotary evaporation to obtain a crude product. Wash with acetic anhydride and anhydrous ether three times respectively, and then dry in a vacuum drying oven to obtain a white solid final product DTPAA.

[0051]

[0052] 2. DTPAA reacts with 2-aminoethyl methacrylate and chelates Gd 3+ :

[0053] Weigh 714 mg (2 mmol) of DTPAA and 825 mg (5 mmol) of diaminoethyl methacrylate into a 25 mL flask, then add 10 mL of DMSO and 1.4 mL (10 mmol) of triethylamine, and stir at room temperature overnight. After the reaction is completed, dilute the reaction mixture with 100 mL of dichloromethane, extract with an appropriate concentration of sodium bicarbonate aqueous solution, combine the aqueous phases, and obtain a salt-containing crude product aqueous solution. Add 1.484 g (4 mmol) of GdCl3·6H2O to the above solution, stir at room temperature overnight, and freeze-dry the salt-containing crude product. Finally, purify by silica gel column chromatography (CH2Cl2:CH3OH=10:1) to obtain a white solid final product, which is gadopentetate meglumine of 2-aminoethyl methacrylate, and its structural formula is as follows Figure 1 shown.

[0054]

[0055] 3. Preparation of developing microspheres:

[0056] Add 2.5g of polyvinyl alcohol to 27.5mL of water, stir at 85°C until the polyvinyl alcohol is completely dissolved, and cool for use; mix 17.5g of acrylic acid with 30mL of 8mol / L sodium hydroxide solution, and cool to room temperature. Take 10mL of the mixed solution, dissolve 0.025g of potassium persulfate, 0.05g of N,N'-methylenebisacrylamide and 0.125g of gadopentetate meglumine with 2-aminoethyl methacrylate; mix the resulting solution with 6mL of polyvinyl alcohol aqueous solution and stir evenly to form an aqueous phase.

[0057] 0.15 g of Span 80 was added to 25 mL of n-heptane, and stirred at 70°C for 10 minutes at a stirring speed of 20 rpm; then the mixed aqueous solution was added to n-heptane, and stirring was continued for 20 minutes. After the emulsion was formed, 0.25 g of tetramethylethylenediamine was added dropwise. After continuous stirring for 30 minutes, the product was collected, washed, and sieved to obtain microspheres.

[0058] 4. Characterization of the developable embolic microspheres prepared above:

[0059] Figure 2 This is a picture of the microspheres under a microscope, indicating that the microspheres based on polyvinyl alcohol have good spherical properties.

[0060] Figure 3 This is an imaging picture of the microspheres under MRI, indicating that the microspheres are loaded with the contrast agent gadolinium and can be visualized under MRI.

[0061] The texture analyzer test showed that the polyvinyl alcohol microspheres could maintain a deformation of 30% for 30 seconds and could still return to their original shape after the pressure was removed.

[0062] Determination of drug loading of microspheres:

[0063] 1 mL of the developing microspheres was measured and added to 20 mL of a 2 mg / mL doxorubicin solution. After shaking at room temperature for 30 minutes, the absorbance of the solution at a wavelength of 483 nm was detected using an ultraviolet spectrophotometer to obtain the concentration of doxorubicin in the aqueous solution. The mass of doxorubicin that can be adsorbed by 1 mL of the developing microspheres was calculated to be 34.32 mg. This proves its drug loading capacity.

[0064] Example 2

[0065] 1. The preparation of gadopentetate meglumine with 2-aminoethyl methacrylate is the same as in Example 1.

[0066] 2. Preparation of developing microspheres:

[0067] Add 2.5g of polyvinyl alcohol to 27.5mL of water, stir at 85°C until the polyvinyl alcohol is completely dissolved, and cool for use; mix 17.5g of acrylic acid with 30mL of 8mol / L sodium hydroxide solution, and cool to room temperature. Take 10mL of the mixed solution, dissolve 0.02g of potassium persulfate, 0.1g of N,N'-methylenebisacrylamide and 0.6g of gadopentetate meglumine with 2-aminoethyl methacrylate; mix the mixed solution with 6mL of polyvinyl alcohol aqueous solution and stir evenly to form an aqueous phase.

[0068] Add 2 g of cellulose acetate butyrate to 50 mL of butyl acetate, stir at 70°C for 10 minutes at a stirring speed of 20 rpm; then add the mixed aqueous solution to butyl acetate, continue stirring for 20 minutes, and after an emulsion is formed, add 0.5 g of tetramethylethylenediamine dropwise. After continuous stirring for 60 minutes, collect the product, wash it, and sieve it to obtain microspheres.

[0069] 3. The above-prepared developable embolic microspheres were characterized, and the results showed that the polyvinyl alcohol microspheres had good sphericity and could be developed under MRI. After being compressed for 30 seconds at a deformation of 30%, they could still return to their original shape after the pressure was removed.

[0070] Example 3

[0071] 1. The preparation of gadopentetate meglumine with 2-aminoethyl methacrylate and the preparation of polyvinyl alcohol aqueous solution are the same as in Example 1.

[0072] 2. Preparation of developing microspheres:

[0073] 1.5 g of polyvinyl alcohol was added to 27.5 mL of water, stirred at 85°C until the polyvinyl alcohol was completely dissolved, and cooled for later use; 6 g of sodium acrylate was dissolved in 10 mL of water, followed by the addition of 0.015 g of potassium persulfate, 0.025 g of N,N'-methylenebisacrylamide and 0.25 g of gadopentetate meglumine with 2-aminoethyl methacrylate. The mixed solution was mixed with 8 mL of polyvinyl alcohol aqueous solution and stirred evenly to form an aqueous phase.

[0074] 0.25 g of cellulose acetate butyrate was added to 25 mL of butyl acetate, and stirred at 50°C for 10 minutes at a stirring speed of 20 rpm; then the mixed aqueous solution was added to n-heptane and stirred for 20 minutes. After the emulsion was formed, 0.25 g of dimethylethylenediamine was added dropwise. After continuous stirring for 240 minutes, the product was collected, washed, and sieved to obtain microspheres.

[0075] 3. The above-prepared developable embolic microspheres were characterized, and the results showed that the polyvinyl alcohol microspheres had good sphericity and could be developed under MRI. After being compressed for 30 seconds at a deformation of 30%, they could still return to their original shape after the pressure was removed.

[0076] Example 4

[0077] 1. The preparation of gadopentetate meglumine with 2-aminoethyl methacrylate and the preparation of polyvinyl alcohol aqueous solution are the same as in Example 1.

[0078] 2. Preparation of developing microspheres:

[0079] 3 g of polyvinyl alcohol was added to 27.5 mL of water, stirred at 85°C until the polyvinyl alcohol was completely dissolved, and cooled for later use; 10 g of sodium acrylate was dissolved in 10 mL of water, followed by the addition of 0.05 g of ammonium persulfate, 0.1 g of N,N'-methylenebisacrylamide and 0.25 g of gadopentetate meglumine with 2-aminoethyl methacrylate. The mixed solution was mixed with 8 mL of polyvinyl alcohol aqueous solution and stirred evenly to form an aqueous phase.

[0080] Add 5 g of cellulose acetate butyrate to 50 mL of butyl acetate, stir at 70°C for 10 minutes at a stirring speed of 20 rpm; then add the mixed aqueous solution to butyl acetate, continue stirring for 20 minutes, and after an emulsion is formed, add 0.5 g of dimethylethylenediamine dropwise. After continuous stirring for 60 minutes, collect the product, wash it, and sieve it to obtain microspheres.

[0081] 3. The above-prepared developable embolic microspheres were characterized, and the results showed that the polyvinyl alcohol microspheres had good sphericity and could be developed under MRI. After being compressed for 30 seconds at a deformation of 30%, they could still return to their original shape after the pressure was removed.

[0082] Example 5

[0083] 1. The preparation of gadopentetate meglumine with 2-aminoethyl methacrylate is the same as in Example 1.

[0084] 2. Preparation of developing microspheres:

[0085] Add 2.5g of polyvinyl alcohol to 27.5mL of water, stir at 85°C until the polyvinyl alcohol is completely dissolved, and cool for use; mix 17.5g of acrylic acid with 30mL of 8mol / L sodium hydroxide solution, and cool to room temperature. Take 10mL of the mixed solution, dissolve 0.025g of potassium persulfate, 0.03g of N,N'-methylenebisacrylamide and 0.25g of gadopentetate meglumine with 2-aminoethyl methacrylate; mix the mixed solution with 6mL of polyvinyl alcohol aqueous solution and stir evenly to form an aqueous phase.

[0086] 1 g of cellulose acetate butyrate was dissolved in 20 mL of butyl acetate to form an oil phase.

[0087] 80 ml of butyl acetate in which 4 g of cellulose acetate butyrate and 0.8 g of tetramethylethylenediamine were dissolved was placed in a 100 ml beaker and stirred at 70° C. at a speed of 10 rpm to serve as a collection bottle.

[0088] The microfluidic channel used in this embodiment is a focusing glass tube chip, the outer tube of which is a 1.1*1.4 mm square glass tube, and the microsphere generating tube and the collecting tube are both 0.8*1.0 mm round tubes. The inner diameter of the microsphere generating tube orifice is 80 μm, and the inner diameter of the collecting tube orifice is 250 μm.

[0089] Connect the syringe containing the aqueous phase to the inner tube for generating microspheres, connect the syringe containing the oil phase to the external square tube, and pass the collection tube into the beaker containing the microsphere collection phase. Then use a syringe pump to inject the aqueous phase and the oil phase into the microfluidic chip, where the aqueous phase speed is 0.002ml / min and the oil phase speed is 0.2ml / min. In the chip, the aqueous phase forms stable droplets and enters the collection phase through the collection tube. After the droplets solidify in the collection phase for 30 minutes, they are washed and sieved to obtain polyvinyl alcohol embolic microspheres.

[0090] 3. Characterization of the developable embolic microspheres prepared above:

[0091] Figure 4 This is a microscope picture of the microspheres, which shows that the microspheres based on polyvinyl alcohol have good sphericity and the prepared microspheres have a uniform particle size of 312±38 microns.

[0092] The texture analyzer test showed that the microspheres could return to their original shape after being compressed for 30 seconds at a deformation of 30%, and after the pressure was removed.

[0093] Polyvinyl alcohol embolization microspheres can be visualized under MRI. 1 mL of microspheres can absorb more than 30 mg of doxorubicin.

[0094] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing polyvinyl alcohol embolic microspheres with a developer, characterized in that: The following steps are involved: (1) Preparation of a cross-linking agent with a developing element: 0.04 mol DTPA was weighed and added to a 100 mL flask, and then 0.16 mol acetic anhydride and 0.24 mol pyridine was added after distillation through a water separator, and stirred at 65° C. for 24 h. After the reaction was completed, the mixture was cooled to room temperature, and the solvent was removed by rotary evaporation to obtain a crude product, which was then washed three times with acetic anhydride and anhydrous ether respectively, and then dried in a vacuum drying oven to obtain a white solid final product DTPAA; 2 mmol DTPAA and 5 mmol diaminoethyl methacrylate were weighed and added to a 25 mL flask, and then 10 mL DMSO and 10 mmol triethylamine were added, and stirred at room temperature overnight. After the reaction was completed, the reaction mixture was diluted with 100 mL dichloromethane, and then extracted with an aqueous solution of sodium bicarbonate. The aqueous phases were combined to obtain an aqueous solution of a salt-containing crude product, and 4 mmol GdCl3•6H2O, stirred overnight at room temperature, lyophilized to obtain a crude product containing salt, and finally purified by silica gel column chromatography, wherein the mobile phase is CH2Cl2 and CH3OH in a volume ratio of 10:1, to obtain a white solid final product, which is gadopentetate meglumine of 2-aminoethyl methacrylate; (2) Preparation of microspheres: 2.5 g of polyvinyl alcohol was added to 27.5 mL of water, stirred at 85° C. until the polyvinyl alcohol was completely dissolved, and cooled for use; 17.5 g of acrylic acid was mixed with 30 mL of 8 mol / L sodium hydroxide solution, and cooled to room temperature to form a mixed solution; 10 mL of the mixed solution was taken, and 0.025 g of potassium persulfate, 0.05 g of N,N'-methylenebisacrylamide and 0.125 g of gadopentetate meglumine with 2-aminoethyl methacrylate were dissolved; the resulting solution was mixed with 6 mL of polyvinyl alcohol aqueous solution and stirred evenly to form an aqueous phase; 0.15 g of Span 80 was added to 25 mL of n-heptane, and stirred at 70° C. for 10 minutes to form an oil phase at a stirring speed of 20 rpm; the aqueous phase was then added to the oil phase, and stirring was continued for 20 minutes. After an emulsion was formed, 0.25 g of tetramethylethylenediamine was added dropwise, and stirring was continued for 30 minutes. The product was collected and washed and sieved to obtain microspheres; Alternatively, 2.5 g of polyvinyl alcohol is added to 27.5 mL of water, stirred at 85° C. until the polyvinyl alcohol is completely dissolved, and cooled for use; 17.5 g of acrylic acid is mixed with 30 mL of 8 mol / L sodium hydroxide solution, cooled to room temperature to form a mixed solution, 10 mL of the mixed solution is taken, 0.02 g of potassium persulfate, 0.1 g of N,N'-methylenebisacrylamide and 0.6 g of gadopentetate meglumine with 2-aminoethyl methacrylate are dissolved; the resulting solution is mixed with 6 mL of polyvinyl alcohol aqueous solution and stirred evenly to form an aqueous phase; 2 g of cellulose acetate butyrate is added to 50 mL of butyl acetate, and stirred at 70° C. for 10 minutes to form an oil phase at a stirring speed of 20 rpm; the aqueous phase is then added to the oil phase, and stirring is continued for 20 minutes. After an emulsion is formed, 0.5 g of tetramethylethylenediamine is added dropwise, and after continuous stirring for 60 minutes, the product is collected and washed and sieved to obtain microspheres.

2. Polyvinyl alcohol embolic microspheres with developer prepared by the preparation method according to claim 1.

Images