Lignin developing microsphere as well as preparation method and application thereof

Abstract

The invention relates to lignin developing microspheres as well as a preparation method and application thereof, and belongs to the technical field of embolism agents. The preparation method comprises the following steps: grafting N-hydroxyalkyl acrylamide on lignin to obtain modified lignin; mixing the modified lignin solution, an ionic monomer and an initiator in an aqueous solution to obtain an aqueous phase solution; adding the water-phase solution into the oil-phase solution to form a water-in-oil reversed-phase suspension polymerization system, and reacting to obtain lignin hydrogel microspheres; performing iodination reaction on the lignin hydrogel microspheres and iodine simple substances and / or iodine-containing compounds to obtain the lignin developing microspheres. The lignin developing microsphere has good X-ray developing performance, high strength and elasticity and good catheter passing ability, and the clinical application range of the developing embolism microsphere is widened.

Description

Technical Field

[0001] This application relates to the field of embolic agents, and in particular to a lignin-developing microsphere, its preparation method, and its application. Background Technology

[0002] Interventional embolization therapy (such as transcatheter arterial embolization, TAE) has become an important treatment for tumors, hemorrhagic diseases, etc., but its core challenge lies in how to achieve precise embolization and postoperative monitoring. Although traditional embolization microspheres (such as polyvinyl alcohol and polyacrylic acid microspheres) can block blood flow, imaging depends on external contrast agents. During the procedure, contrast agents need to be mixed to locate the microspheres, which is cumbersome and may lead to the risk of misembolization due to contrast agent leakage or uneven distribution.

[0003] Existing research has included clinical reports on contrast-enhancing embolization microspheres (DC Bead LUMI), demonstrating their significant clinical value in precise surgical control, postoperative evaluation, and as an indicator for combined treatment. However, in achieving the contrast-enhancing function, the LUMI microsphere structure incorporates a large number of highly hydrophobic contrast agent molecules, 2,3,5-triiodobenzaldehyde, leading to a significant increase in microsphere hardness and a decrease in elasticity. This makes them prone to vascular damage and unable to adapt to complex vascular morphologies, severely limiting the clinical application of contrast-enhancing embolization microspheres. Summary of the Invention

[0004] To address the aforementioned technical problems, the objective of this application is to provide a lignin-based imaging microsphere, its preparation method, and its application. This allows the embolization microsphere to possess good imaging performance, as well as high strength and elasticity, and good catheter permeability, thereby broadening the clinical application scope of imaging embolization microspheres. In a first aspect, this application provides a method for preparing lignin-developable microspheres, comprising the following steps: S1: N-hydroxyalkylacrylamide is grafted onto lignin to obtain modified lignin; S2: The modified lignin, ionic monomer and initiator are mixed in an aqueous solution to obtain an aqueous phase solution; S3: Add the aqueous solution to the oil solution to form a water-in-oil reverse suspension polymerization system, and obtain lignin hydrogel microspheres after the reaction; S4: The lignin hydrogel microspheres are subjected to an iodination reaction with elemental iodine and / or iodine-containing compounds to obtain lignin-developable microspheres.

[0005] In the above technical solution, N-hydroxyalkylacrylamide is grafted onto lignin under the action of an epoxy crosslinking agent to achieve modification. Then, the modified lignin is copolymerized with ionic monomers to obtain lignin hydrogel microspheres. Finally, lignin imaging microspheres are obtained by iodine substitution modification. This method can easily achieve high iodine content, thereby enabling the lignin imaging microspheres to have excellent in vivo X-ray imaging ability. Furthermore, by copolymerizing modified lignin with ionic monomers containing double bonds, rigid lignin molecules and flexible ionic monomer segments covalently cross-link to form a three-dimensional network framework. After iodine atom substitution modification, the intermolecular binding force can be enhanced by forming halogen bonds. Moreover, due to the large size of iodine atoms, the substitution of hydrogen atoms on the benzene ring can produce a significant steric hindrance effect, further enhancing the hydrophilicity of lignin segments and improving their compatibility with ionic monomers. This optimizes the construction of a "rigid-flexible alternating" three-dimensional network structure, enabling lignin imaging microspheres to simultaneously possess high strength and elasticity, as well as good catheter permeability. This facilitates precise delivery, effective occlusion, long-term stability, and biocompatibility, thereby effectively broadening the clinical application range of imaging embolization microspheres.

[0006] In addition, because the lignin-developing microspheres have a porous three-dimensional network, they can physically encapsulate drug molecules; and lignin contains a large number of hydrophilic groups such as phenolic hydroxyl and alcohol hydroxyl groups, which can bind to drug molecules through hydrogen bonds; furthermore, they can bind to drug molecules with opposite charges through electrostatic interactions based on the ion types in the ionic monomers. In other words, the lignin-developing microspheres can effectively load a variety of drugs and have high drug loading capacity and loading stability.

[0007] In some embodiments, elemental iodine and / or iodine-containing compounds include radioactive iodine isotopes. Further, the radioactive iodine isotopes include... 123 I, 124 I, 125 I, 129 I, 131 At least one of I; further, the iodine-containing compound includes at least one of iodine chloride and sodium iodide.

[0008] In the aforementioned technical solutions, the currently available radioactive microspheres are all made of high-density glass and resin, which cannot be effectively suspended in saline and blood. Accurate delivery into the tumor target vessels via microcatheters is therefore challenging, requiring preoperative microsphere distribution simulation. Furthermore, most of these microspheres lack visualization capabilities under conventional detection methods (DSA, CT, and MRI), severely impacting delivery accuracy and postoperative traceability. Additionally, the existing radioactive microspheres contain low levels of radioactive iodine, limiting therapeutic efficacy and preventing them from achieving imaging capabilities. This application uses radioactive iodine isotopes to partially or completely replace elemental iodine and / or ordinary iodine elements in iodine-containing compounds (such as...). 125 I, 131(e.g., I) can easily achieve a high content of radioactive iodine isotopes in microspheres through iodination reactions, so that lignin-based imaging microspheres have radioactivity while also having imaging properties, which can be effectively used for radiotherapy, and further can be effectively used for real-time combined radiotherapy and TACE.

[0009] In some embodiments, step S1 includes: performing an etherification crosslinking reaction on lignin, N-hydroxyalkylacrylamide and an epoxy crosslinking agent in an alkaline aqueous solution to obtain modified lignin.

[0010] In the above technical solution, lignin contains phenolic hydroxyl groups and alcoholic hydroxyl groups, while N-hydroxyalkylacrylamide has alcoholic hydroxyl groups on hydroxyalkyl groups. Under alkaline conditions, the epoxy crosslinking agent can form ether bonds with these hydroxyl groups through the ring-opening reaction of the epoxy groups, thereby grafting N-hydroxyalkylacrylamide onto lignin.

[0011] In some embodiments, in step S1, the mass ratio of lignin, N-hydroxyalkylacrylamide and epoxy crosslinking agent is (5~8):(1~3):(0.5~2). In the above technical solution, by controlling the mass ratio of lignin, N-hydroxyalkylacrylamide and epoxy crosslinking agent within a suitable range during the etherification crosslinking reaction, it is beneficial to fully graft and modify lignin, thereby improving the degree of subsequent copolymerization reaction. In some embodiments, N-hydroxyalkyl acrylamide includes at least one of N-hydroxymethyl acrylamide, N-hydroxyethyl acrylamide, N-[tris(hydroxymethyl)methyl]acrylamide, N-(2-hydroxypropyl)acrylamide, N-(hydroxymethyl)methylacrylamide, N-(hydroxyethyl)methylacrylamide, N-[tris(hydroxymethyl)methyl]methylacrylamide or N-(2-hydroxypropyl)methylacrylamide. In the above technical solutions, all of these N-hydroxyalkyl acrylamides have acrylamide double bonds and hydroxyalkyl groups. The hydroxyalkyl groups can ring-open with epoxy groups, introducing acrylamide double bonds into the lignin molecule. In some embodiments, the epoxy crosslinking agent includes at least one of epichlorohydrin, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, or 1,6-hexanediol diglycidyl ether. In the above technical solution, epichlorohydrin has an epoxy group at one end, which can combine with hydroxyl groups through ring opening, and a chlorine atom at the other end, which can combine with hydroxyl groups by replacing hydrogen in the hydroxyl group with the chlorine atom; while ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, or 1,6-hexanediol diglycidyl ether have epoxy groups at both ends, which can combine with hydroxyl groups through ring opening, thereby effectively realizing the grafting modification of lignin. In some embodiments, in step S1, the temperature of the etherification crosslinking reaction is 20°C to 50°C, and the time is 0.5h to 4h. In the above technical solution, controlling the temperature and time of the etherification crosslinking reaction within a suitable range is beneficial to ensure that lignin is fully grafted and modified without excessive crosslinking, thereby obtaining a modified lignin solution with appropriate double bond content, controllable crosslinking degree, and good stability, laying the foundation for subsequent steps such as copolymerization with ionic monomers and iodination modification. In some embodiments, the alkaline aqueous solution includes at least one of sodium hydroxide aqueous solution or potassium hydroxide aqueous solution; further, the mass concentration of the alkaline aqueous solution is 5wt% to 30wt%. In the above technical solution, controlling the alkaline aqueous solution is beneficial to activating the hydroxyl groups of lignin, improving the reactivity, promoting the ring-opening of the epoxy crosslinking agent, increasing the solubility of lignin, stabilizing the reaction system, reducing side reactions, and thus further promoting the etherification crosslinking reaction. In some embodiments, in step S2, the mass ratio of lignin to ionic monomer is 1:(0.2~3). In the above technical solution, since the modified lignin and ionic monomers are copolymerized by reverse suspension polymerization, by controlling the mass ratio of the two within a suitable range, it is beneficial to reduce side reactions (such as homopolymerization of ionic monomers), further balance the rigidity and flexibility of the microspheres, and thus further improve the strength and elasticity of the microspheres. In some embodiments, the ionic monomer includes at least one of acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, acrylic anhydride, maleic acid, maleic anhydride, itaconic acid, β-(acryloyloxy)propionic acid, 2,4-hexadienoic acid, 2,4-pentadienoic acid, or p-styrenesulfonic acid. In the above technical solutions, the aforementioned ionic monomers can all copolymerize with modified lignin through double bonds, and introduce ionic groups (such as carboxyl groups, sulfonic acid groups, etc.) into the molecular chain.

[0012] In some embodiments, the initiator includes at least one of sodium persulfate, potassium persulfate, ammonium persulfate, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobisisobutylammonium valerate, or azobisisopropylimidazoline.

[0013] In the above technical solution, the initiator can decompose to generate free radicals, which can then initiate free radical polymerization of modified lignin and ionic monomers.

[0014] In some embodiments, in step S3, the reaction temperature is 50°C to 90°C, and the reaction time is 2 hours to 8 hours.

[0015] In the above technical solution, controlling the temperature and time of the polymerization reaction within a suitable range is beneficial to regulating the decomposition of the initiator and further improving the degree of reaction and the uniformity of the product structure.

[0016] In some embodiments, step S3 further includes adding a catalyst to the reverse-phase suspension polymerization system before the reaction. Further, the catalyst includes at least one of tetramethylethylenediamine or triethylamine.

[0017] In the above technical solutions, when the initiator is a persulfate (sodium persulfate, potassium persulfate, ammonium persulfate), a catalyst needs to be added to the polymerization system to promote the decomposition of the initiator to generate free radicals.

[0018] In some embodiments, in step S3, the oil phase solution includes an oil-soluble dispersant and an oil-soluble solvent.

[0019] Preferably, the oil-soluble dispersant includes at least one of the following: Span series compounds, Tween series compounds, octylphenol polyoxyethylene ether, dodecylphenol polyoxyethylene ether, cellulose acetate, or cellulose acetate butyrate.

[0020] Preferably, the oil-soluble solvent includes at least one of butyl acetate, petroleum ether, n-hexane, cyclohexane, or paraffin oil.

[0021] Preferably, the mass concentration of the oil-soluble dispersant in the oil phase solution is 3wt%~5wt%.

[0022] In the above technical solution, the aqueous phase is used as the dispersed phase and is dispersed in the oil phase in the form of droplets to form an emulsion. Preparing an oil phase solution is beneficial to improving the stability of the emulsion, controlling the microsphere size within a suitable range, and maintaining the morphology of the microspheres.

[0023] In some embodiments, step S4 includes: washing and drying the lignin hydrogel microspheres to obtain dry spheres; heating the dry spheres in a solvent at 60°C to 90°C to swell them; adding elemental iodine and / or iodine-containing compounds; and reacting under stirring conditions for 12 to 24 hours.

[0024] In the above technical solution, by washing, drying and then swelling the lignin hydrogel, the interference of impurities can be eliminated and the efficiency of the iodination reaction can be improved; by controlling the reaction temperature and time within a suitable range, it is beneficial to allow iodine to replace the hydrogen atoms on the benzene ring at a higher temperature.

[0025] In some embodiments, the mass ratio of dry pellets to elemental iodine and / or iodine-containing compounds is 1:(0.5~2).

[0026] In the above technical solution, by controlling the mass ratio of the two, the iodine content in the product microspheres can be adjusted accordingly, thereby simply controlling the development performance.

[0027] Secondly, embodiments of this application provide lignin-developing microspheres, prepared by the above-described preparation method. These lignin-developing microspheres comprise a copolymer of modified lignin and ionic monomers; wherein one or more hydrogen atoms on the benzene ring of the modified lignin are replaced by iodine atoms.

[0028] Thirdly, embodiments of this application also provide the application of lignin-enhancing microspheres as an embolic agent for interventional embolization therapy. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A process flow diagram of a method for preparing lignin-developing microspheres provided in this application embodiment.

[0031] Figure 2 These are images showing the appearance of the microspheres in Examples 1-3 and Comparative Examples 1-2 of this application.

[0032] Figure 3 This is an image of the lignin hydrogel microspheres in Comparative Example 1 of this application under an optical microscope.

[0033] Figure 4 This is a Micro-CT image of the lignin-developing microspheres in Example 3. Detailed Implementation

[0034] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the lignin-developing microspheres, their preparation methods, and applications as described in this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0035] The "scope" disclosed in this application is defined by a lower limit and an upper limit. A given scope is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific scope. This scope can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a scope. Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions. Unless otherwise specified, all steps of this application can be performed sequentially or randomly, preferably sequentially.

[0036] Figure 1 A process flow diagram illustrating the preparation method of the lignin-developing microspheres provided in this application embodiment. Please refer to... Figure 1 The method for preparing lignin-developing microspheres provided in this application includes the following steps: S1: N-hydroxyalkylacrylamide is grafted onto lignin to obtain modified lignin.

[0037] In this application, lignin is a complex organic polymer that forms an important structural material in the supporting tissues of vascular plants and some algae, and exhibits good biocompatibility with humans. Lignin is the second largest biomass resource in the plant kingdom after cellulose, and is also one of the few renewable resources among aromatic compounds. The chemical structural formula of lignin is shown below: .

[0038] In this application, the N-hydroxyalkyl acrylamide has a polymerizable carbon-carbon double bond, an amide bond, and a hydroxyalkyl group in its molecular structure, exhibiting both polymerization reactivity and functional group reactivity. Its general chemical structural formula is shown below: ; Where m can be an integer from 1 to 6. For example, when m is 1, it is N-hydroxymethylacrylamide; when m is 2, it is N-hydroxyethylacrylamide.

[0039] In some embodiments, step S1 includes: performing an etherification crosslinking reaction on lignin, N-hydroxyalkylacrylamide and an epoxy crosslinking agent in an alkaline aqueous solution to obtain modified lignin.

[0040] In this application, an epoxy crosslinking agent refers to a compound having at least one epoxy group, which, under alkaline conditions, can form covalent bonds between linear or branched polymer molecules through a ring-opening reaction of the epoxy group, ultimately forming a three-dimensional network structure. The epoxy crosslinking agent can have an epoxy group at one end and an epoxy group or a substituted halogen atom (such as a Cl atom) at the other end. For example, the epoxy crosslinking agent can be epichlorohydrin or a diglycidyl ether crosslinking agent.

[0041] In some embodiments, the mass ratio of lignin, N-hydroxyalkylacrylamide, and epoxy crosslinking agent is (5~8):(1~3):(0.5~2). As examples, the mass ratio of lignin, N-hydroxyalkylacrylamide, and epoxy crosslinking agent is 5:1:1, 6:2:1.5, 8:3:2, etc.

[0042] In some embodiments, N-hydroxyalkyl acrylamide includes at least one of N-hydroxymethyl acrylamide, N-hydroxyethyl acrylamide, N-[tris(hydroxymethyl)methyl]acrylamide, N-(2-hydroxypropyl)acrylamide, N-(hydroxymethyl)methylacrylamide, N-(hydroxyethyl)methylacrylamide, N-[tris(hydroxymethyl)methyl]methylacrylamide or N-(2-hydroxypropyl)methylacrylamide.

[0043] In some embodiments, the epoxy crosslinking agent includes at least one of epichlorohydrin, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, or 1,6-hexanediol diglycidyl ether.

[0044] Understandably, epoxy crosslinking agents can also be other compounds with alkyl or alkoxy groups linked to ethylene oxide structures at both ends. For example, epoxy crosslinking agents can also be compounds having the following general chemical formula: ; Wherein, X is a C3~C12 alkyl or alkoxy group substituted with monohydroxy or dihydroxyl groups.

[0045] In some embodiments, the temperature of the etherification crosslinking reaction is 20°C to 50°C, and the time is 0.5h to 4h. As an example, the temperature of the etherification crosslinking reaction is an intermediate value between any two of 20°C, 30°C, 40°C, 50°C, or above; and the reaction time is an intermediate value between any two of 0.5h, 1h, 2h, 3h, 4h, or above.

[0046] In some embodiments, the alkaline aqueous solution includes at least one of an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide.

[0047] Furthermore, the mass concentration of the alkaline aqueous solution is 5 wt% to 30 wt%. As an example, the mass concentration of the alkaline aqueous solution is an intermediate value between any two of the following: 5 wt%, 10 wt%, 15 wt%, 20 wt%, 30 wt%, or more.

[0048] Understandably, in step S1, after the etherification crosslinking reaction, the solution is adjusted to neutral using an acid (e.g., hydrochloric acid).

[0049] S2: The modified lignin, ionic monomer and initiator are mixed in an aqueous solution to obtain an aqueous solution.

[0050] In some embodiments, the mass ratio of lignin to ionic monomers is 1:(0.2~3). As examples, the mass ratio of lignin to ionic monomers is 1:0.2, 1:0.5, 1:1, 1:2, 1:3, etc.

[0051] In this application, ionic monomers refer to monomers with ionizable groups in their molecules, which can form polymeric compounds with ionic groups (such as polyelectrolytes) through polymerization reactions.

[0052] In some embodiments, the ionic monomer includes at least one of acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, acrylic anhydride, maleic acid, maleic anhydride, itaconic acid, β-(acryloyloxy)propionic acid, 2,4-hexadienoic acid, 2,4-pentadienoic acid, or p-styrenesulfonic acid.

[0053] In this application, the initiator is a compound that can generate free radicals under heating or with the addition of a catalyst.

[0054] In some embodiments, the initiator includes at least one of sodium persulfate, potassium persulfate, ammonium persulfate, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobisisobutylammonium valerate, or azobisisopropylimidazoline.

[0055] In some embodiments, the mixing method can be stirring at room temperature for 10 to 60 minutes. S3: Add the aqueous solution to the oil solution to form a water-in-oil reverse suspension polymerization system, and obtain lignin hydrogel microspheres after the reaction.

[0056] In some embodiments, the reaction temperature is 50°C to 90°C, and the reaction time is 2h to 8h. As an example, the reaction temperature can be any value between any two of 50°C, 60°C, 70°C, 80°C, 90°C, or above; and the reaction time can be any value between any two of 2h, 4h, 5h, 6h, 8h, or above.

[0057] In some embodiments, step S3 further includes adding a catalyst to the reverse-phase suspension polymerization system before the reaction.

[0058] Furthermore, the catalyst includes at least one of tetramethylethylenediamine or triethylamine.

[0059] In some embodiments, the oil phase solution includes an oil-soluble dispersant and an oil-soluble solvent.

[0060] Furthermore, the oil-soluble dispersant includes at least one of the following: Span series compounds, Tween series compounds, octylphenol polyoxyethylene ether, dodecylphenol polyoxyethylene ether, cellulose acetate, or cellulose acetate butyrate.

[0061] Furthermore, the oil-soluble solvent includes at least one of butyl acetate, petroleum ether, n-hexane, cyclohexane, or paraffin oil.

[0062] Furthermore, the mass concentration of the oil-soluble dispersant in the oil phase solution is 3wt% to 5wt%. As an example, the mass concentration of the oil-soluble dispersant in the oil phase solution is an intermediate value between any two of the following: 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, or more.

[0063] S4: The lignin hydrogel microspheres are subjected to an iodination reaction with elemental iodine and / or iodine-containing compounds to obtain lignin-developable microspheres.

[0064] In some embodiments, elemental iodine (I2) and / or iodine-containing compounds include radioactive iodine isotopes.

[0065] As examples, iodine-containing compounds can be iodine chloride (ICl) or sodium iodide (NaI). Radioactive iodine isotopes can be... 123 I, 124 I, 125 I, 129 I, 131 Furthermore, iodine-containing compounds can be Na... 125 I.

[0066] Understandably, radioactive iodine isotopes can partially replace elemental iodine in iodine and / or iodine-containing compounds. For example, elemental iodine (I₂) and sodium can be used simultaneously. 125 I.

[0067] In some embodiments, step S4 includes: washing and drying the lignin hydrogel microspheres to obtain dry spheres; heating and swelling the dry spheres in a solvent at 60°C to 90°C; adding elemental iodine and / or an iodine-containing compound; and reacting under stirring conditions for 12 to 24 hours.

[0068] As an example, the temperature for heating and swelling is the midpoint between any two values ​​of 60°C, 70°C, 80°C, 90°C or above; and the reaction time under stirring conditions is the midpoint between any two values ​​of 12h, 15h, 18h, 20h, 24h or above.

[0069] Furthermore, the washing solvent can be acetone.

[0070] Furthermore, the swelling solvent includes at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMF), acetonitrile, 1,4-dioxane, tetrahydrofuran, and dichloromethane.

[0071] In some embodiments, the mass ratio of dry pellets to elemental iodine and / or iodine-containing compounds is 1:(0.5~2). As examples, this mass ratio is 1:0.5, 1:1, 1:1.5, 1:2, etc.

[0072] In addition, this application also provides a lignin-developing microsphere prepared by the above-described preparation method. The lignin-developing microsphere comprises a copolymer of modified lignin and an ionic monomer; wherein one or more hydrogen atoms on the benzene ring of the modified lignin are replaced by iodine atoms, and its chemical structural formula is shown below: ; Among them, R ⊖ This corresponds to the ionic groups formed by ionic monomers.

[0073] In addition, this application also provides the application of the above-mentioned lignin imaging microspheres as an embolic agent for interventional embolization therapy.

[0074] Example To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0075] Example 1 This embodiment provides lignin-developing microspheres, the preparation process of which is shown below: , .

[0076] The specific preparation method of the lignin-developing microspheres in Example 1 includes the following steps: (1) Add 500 mg of lignin to 2 mL of 20 wt% NaOH solution, stir and dissolve thoroughly, then add 500 μL of 50 wt% N-hydroxyethyl acrylamide and 260 μL of epichlorohydrin, react at room temperature for 2 h, and adjust to neutral with 6 mol / L hydrochloric acid to obtain modified lignin solution.

[0077] (2) Add 1g of freshly prepared 50wt% acrylic acid aqueous solution and 7.5mg of ammonium persulfate (APS) to the modified lignin solution, and stir thoroughly to obtain an aqueous solution.

[0078] (3) Disperse and dissolve 3.0g of cellulose acetate butyrate in 100mL of butyl acetate at 60℃ and 300rpm to obtain an oil phase solution.

[0079] (4) While maintaining stirring, slowly add the aqueous phase solution to the oil phase solution, keep for 20 min, add 400 μL of tetramethylethylenediamine (TMEDA), raise the temperature to 80 °C, and continue the reaction for 4 h. After the reaction is complete, wash the obtained microspheres repeatedly with butyl acetate, water and sodium bicarbonate aqueous solution 3 to 5 times to obtain lignin hydrogel microspheres.

[0080] (5) The lignin hydrogel microspheres were drained of water, dehydrated with acetone, and dried in a vacuum oven at 60°C for 5 hours after removing the acetone to obtain granular dry spheres. 1 g of dry spheres were taken, 50 mL of anhydrous DMF was added, and the mixture was heated to 90°C to swell. Then 1.5 g of elemental iodine (I2) was added, and the mixture was reacted with mechanical stirring for 24 hours. After the reaction was completed, the microspheres were washed three times in sequence with DMF, a water-acetone (1:1) mixture, pure water, and 1% sodium bicarbonate solution to obtain lignin-developable microspheres with X-ray imaging capability.

[0081] Example 2 This embodiment provides lignin-developing microspheres, the preparation process of which is shown below: , .

[0082] The specific preparation method of the lignin-developing microspheres in Example 2 includes the following steps: (1) Add 500 mg of lignin to 2 mL of 25 wt% NaOH solution, stir well, then add 500 μL of 50 wt% N-hydroxyethyl acrylamide and 500 μL of ethylene glycol diglycidyl ether, and react at room temperature for 2 h. Adjust to neutral with 6 mol / L hydrochloric acid to obtain modified lignin solution.

[0083] (2) Add 1g of freshly prepared 50wt% 2-acrylamido-2-methylpropanesulfonic acid (AMPS) aqueous solution to the modified lignin solution, and then add 7.5mg of ammonium persulfate (APS) to obtain an aqueous solution.

[0084] (3) Disperse and dissolve 3.0g of cellulose acetate butyrate in butyl acetate at 60℃ and 300rpm to obtain an oil phase solution.

[0085] (4) While maintaining stirring, slowly add the aqueous phase solution to the oil phase solution and keep it for 20 min. Then add 400 μL of tetramethylethylenediamine (TMEDA), raise the temperature to 80 °C, and continue the reaction for 4 h. After the reaction is complete, wash the obtained microspheres repeatedly with butyl acetate, water, and sodium bicarbonate aqueous solution 3 to 5 times to obtain lignin hydrogel microspheres.

[0086] (5) The lignin hydrogel microspheres were drained of water, dehydrated with acetone, and dried in a vacuum oven at 60°C for 5 hours to obtain granular dry spheres. 1 g of dry spheres were added to 50 mL of anhydrous DMF, heated to 60°C to swell, and then 1 g of iodine chloride (ICl) was added. The mixture was stirred mechanically for 24 hours. After the reaction, the microspheres were washed three times in sequence with DMF, a water-acetone (1:1) mixture, pure water, and 1% sodium bicarbonate solution to obtain lignin-developable microspheres with X-ray imaging capability.

[0087] Example 3 This embodiment provides a lignin-developing microsphere, the preparation method of which differs from that of Example 1 in that: .

[0088] The corresponding step (5) includes: draining the water from the lignin hydrogel microspheres, adding acetone to dehydrate them, removing the acetone, and then drying them in a vacuum oven at 60°C for 5 hours to obtain granular dry spheres. Take 1g of dry spheres, add 50mL of anhydrous DMF, heat at 90°C to swell, add 0.5g of iodine (I2), and then immediately add 0.5mL of pre-mixed chloramine T-Na. 125 Solution I (volume ratio 1:1) was reacted under mechanical stirring for 24 hours. After the reaction, the microspheres were washed three times in sequence with DMF, a water-acetone mixture (volume ratio 1:1), pure water, and 1% sodium bicarbonate solution to obtain lignin-based microspheres with radiotherapy function and X-ray imaging capability.

[0089] Comparative Example 1 This comparative example provides a lignin hydrogel microsphere, the preparation method of which differs from that of Example 1 in that step (5) is not included.

[0090] Comparative Example 2 This comparative example provides a lignin hydrogel microsphere, the preparation method of which differs from that of Example 2 in that step (5) is not included.

[0091] Test case The microspheres from Examples 1-3 and Comparative Examples 1-2 were sieved, and microspheres with a particle size of 100μm-200μm were selected for performance testing.

[0092] Experimental Example 1 The appearance of the microspheres in Examples 1-3 and Comparative Examples 1-2 was observed. Figure 2 These are images showing the appearance of the microspheres in Examples 1-3 and Comparative Examples 1-2 of this application. Figure 3 This is an image of the lignin hydrogel microspheres in Comparative Example 1 of this application under an optical microscope. Figure 2 and Figure 3 As can be seen, the microspheres prepared in this application have a round and regular spherical morphology, and the color of the microspheres varies depending on the iodine substitution.

[0093] Experimental Example 2 Microspheres were spread evenly on a glass slide and placed under the probe of a texture analyzer (TA XT plus C). The Hold Compression mode was selected for testing. The test results are shown in Table 1.

[0094] Table 1. Test results of the mechanical properties of the microspheres in the examples and comparative examples.

[0095] As shown in Table 1, the lignin-developing microspheres prepared in Example 1 of this application can all be compressed by 30% without breaking, can all pass smoothly through 2.6F microvessels, and have high strength, resilience, and elasticity. Comparing Example 1 with Comparative Example 1, and Example 2 with Comparative Example 2, it can be seen that the strength and elasticity of the microspheres are significantly enhanced after iodination modification.

[0096] Experimental Example 3 Micro-CT tests were performed on the microspheres from Examples 1-3 and Comparative Examples 1-2 to evaluate their radiopaque linearity. The beads were suspended in 0.5% agarose gel in Nunc cryovials, and the radiopaque linearity of the microspheres was tested using a micro-CT imaging system scanner equipped with a tungsten anode and micro-computed tomography (micro-CT imaging system). The polymer was then segmented from the pore structure to report the polymer radiometric density. The radiometric density, expressed in HU, was then calculated using a water standard obtained on the same day. The measured HU values ​​for each sample are shown in Table 2.

[0097] Table 2. HU values ​​of microspheres in the examples and comparative examples.

[0098] As shown in Table 3, the lignin developing microspheres prepared in Examples 1-3 of this application all have excellent developing properties.

[0099] Test Example 4 The radioactivity of each microsphere was detected using a radioactive agent, and the test results are shown in Table 3.

[0100] Table 3. Radioactivity of microspheres in the examples and comparative examples

[0101] Figure 4 The image shows a Micro-CT image of the lignin-enhancing microspheres in Example 3, in conjunction with Table 3 and... Figure 4 As can be seen, in embodiment 3 of this application, by adopting 125 I replaces some of the ordinary iodine element, giving the lignin imaging microspheres strong radioactivity, which can still be retained after 14 days, making them suitable for radiotherapy.

[0102] Experimental Example 5 Prepare 20 mg / mL doxorubicin hydrochloride (DOx) aqueous solutions and 25 mg / mL irinotecan hydrochloride aqueous solutions, respectively. Measure 1 mL of wet-bulb solution into a 10 mL vial, then add 2 mL of the drug solution and shake rapidly to mix. At the sampling time point, take 20 µL of the supernatant drug solution, dilute it to 1 mL with 980 µL of purified water, and determine the concentration of the corresponding drug using liquid chromatography to calculate the drug loading on the microspheres. The drug loading test results are shown in Tables 4 and 5.

[0103] Table 4. Loading rate (%) of microspheres for doxorubicin hydrochloride in the examples and comparative examples.

[0104] Table 5. Loading rate (%) of microspheres for irinotecan hydrochloride in the examples and comparative examples.

[0105] As shown in Tables 4 and 5, the lignin-enhancing microspheres prepared in Examples 1-3 of this application can achieve more than 95% loading of doxorubicin (40 mg / mL microspheres) and irinotecan (50 mg / mL microspheres) at the conventional doses used in clinical TACE treatment within 10 minutes.

[0106] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for preparing lignin-developable microspheres, characterized in that, Includes the following steps: S1: N-hydroxyalkylacrylamide is grafted onto lignin to obtain modified lignin; S2: The modified lignin, ionic monomer and initiator are mixed in an aqueous solution to obtain an aqueous solution; S3: The aqueous solution is added to the oil solution to form a water-in-oil reverse suspension polymerization system, and lignin hydrogel microspheres are obtained after the reaction. S4: The lignin hydrogel microspheres are subjected to an iodination reaction with elemental iodine and / or iodine-containing compounds to obtain lignin-developing microspheres.

2. The preparation method according to claim 1, characterized in that, The iodine and / or iodine-containing compounds include radioactive iodine isotopes; Preferably, the radioactive iodine isotope includes 123 I, 124 I, 125 I, 129 I, 131 At least one of I; Preferably, the iodine-containing compound includes at least one of iodine chloride and sodium iodide.

3. The preparation method according to claim 1, characterized in that, Step S1 includes: performing an etherification crosslinking reaction on lignin, N-hydroxyalkylacrylamide and an epoxy crosslinking agent in an alkaline aqueous solution to obtain the modified lignin; Preferably, the mass ratio of lignin, N-hydroxyalkylacrylamide, and epoxy crosslinking agent is (5~8):(1~3):(0.5~2); Preferably, the N-hydroxyalkyl acrylamide includes at least one of N-hydroxymethyl acrylamide, N-hydroxyethyl acrylamide, N-[tris(hydroxymethyl)methyl]acrylamide, N-(2-hydroxypropyl)acrylamide, N-(hydroxymethyl)methylacrylamide, N-(hydroxyethyl)methylacrylamide, N-[tris(hydroxymethyl)methyl]methylacrylamide or N-(2-hydroxypropyl)methylacrylamide; Preferably, the epoxy crosslinking agent includes at least one of epichlorohydrin, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, or 1,6-hexanediol diglycidyl ether.

4. The preparation method according to claim 3, characterized in that, The etherification crosslinking reaction is carried out at a temperature of 20℃~50℃ for a time of 0.5h~4h. Preferably, the alkaline aqueous solution includes at least one of sodium hydroxide aqueous solution or potassium hydroxide aqueous solution; Preferably, the mass concentration of the alkaline aqueous solution is 5wt% to 30wt%.

5. The preparation method according to any one of claims 1 to 4, characterized in that, In step S2, the mass ratio of the lignin to the ionic monomer is 1:(0.2~3). Preferably, the ionic monomer includes at least one of acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, acrylic anhydride, maleic acid, maleic anhydride, itaconic acid, β-(acryloyloxy)propionic acid, 2,4-hexadienoic acid, 2,4-pentadienoic acid, or p-styrenesulfonic acid. Preferably, the initiator includes at least one of sodium persulfate, potassium persulfate, ammonium persulfate, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobisisobutylammonium valerate, or azobisisopropylimidazoline.

6. The preparation method according to any one of claims 1 to 4, characterized in that, In step S3, the reaction temperature is 50℃~90℃, and the reaction time is 2h~8h; Preferably, step S3 further includes: adding a catalyst to the reverse-phase suspension polymerization system before the reaction; Preferably, the catalyst comprises at least one of tetramethylethylenediamine or triethylamine.

7. The preparation method according to any one of claims 1 to 4, characterized in that, In step S3, the oil phase solution includes an oil-soluble dispersant and an oil-soluble solvent; Preferably, the oil-soluble dispersant includes at least one of Span series compounds, Tween series compounds, octylphenol polyoxyethylene ether, dodecylphenol polyoxyethylene ether, cellulose acetate or cellulose acetate butyrate; Preferably, the oil-soluble solvent includes at least one of butyl acetate, petroleum ether, n-hexane, cyclohexane, or paraffin oil; Preferably, the oil-soluble dispersant has a mass concentration of 3wt% to 5wt% in the oil phase solution.

8. The preparation method according to any one of claims 1 to 4, characterized in that, Step S4 includes: washing and drying the lignin hydrogel microspheres to obtain dry spheres; The dried pellets were heated and swollen in a solvent at 60°C to 90°C, and the elemental iodine and / or iodine-containing compounds were added. The mixture was then reacted for 12 to 24 hours under stirring. Preferably, the mass ratio of the dried pellets to the elemental iodine and / or iodine-containing compounds is 1:(0.5~2).

9. A lignin-developing microsphere, characterized in that, Prepared by the preparation method according to any one of claims 1 to 8; The lignin-developing microspheres comprise a copolymer of modified lignin and ionic monomers; wherein one or more hydrogen atoms on the benzene ring of the modified lignin are replaced by iodine atoms.

10. The use of the lignin-enhancing microspheres as described in claim 9 as an embolic agent for interventional embolization therapy.

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