CN114146190B

CN114146190B - High-suspension developing microsphere and preparation method thereof

Info

Publication number: CN114146190B
Application number: CN202111648579.9A
Authority: CN
Inventors: 肖劲鹏; 孙宏涛; 孙蓬; 车海波
Original assignee: Cardiolink Shenzhen Medical Technology Development Co ltd
Current assignee: Cardiolink Shenzhen Medical Technology Development Co ltd
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2024-01-26
Anticipated expiration: 2041-12-30
Also published as: CN114146190A

Abstract

The embodiment of the application provides a high-suspension developing microsphere and a preparation method thereof, and relates to the field of medical instruments. The high-suspension developing microsphere comprises a polyvinyl alcohol microsphere formed by crosslinking an iodine-containing developer with polyvinyl alcohol and a water-soluble polymer with sulfonic groups, wherein the developer is coupled with the polyvinyl alcohol microsphere through covalent bonds; the crosslinking functionality of the polyvinyl alcohol microsphere is 0.2-0.9 mmol/g, the sulfonate content of the polyvinyl alcohol microsphere is 1.5-3.0 mmol/g, and the iodine content in each 1mL developing microsphere is 100-200 mg;1mL of the developed microspheres were capable of being suspended in 10mL of iodixanol 320 for at least 10min without precipitation. The high-suspension developing microsphere has rich specification, can be kept in a suspension state in a contrast agent for a long time, and is suitable for clinical use.

Description

High-suspension developing microsphere and preparation method thereof

Technical Field

The application relates to the field of medical instruments, in particular to a high-suspension developing microsphere and a preparation method thereof.

Background

Currently, radiopaque polymer microspheres (e.g., WO 2015/033092) having iodinated groups covalently coupled to the polymer backbone can be developed under X-rays and used as embolic microspheres for injection into the human body where the embolic effect can be directly observed under X-rays. Iodinated groups allow these microsphere materials to be seen on the basis of X-ray techniques, but the introduction of iodine-containing groups increases microsphere density, reduces microsphere hydrophilicity, drug loading and compressibility, and results in reduced suspension time of the microspheres.

Although BTG corporation has developed the only developed microsphere (lumibead of BTG) currently commercialized, which has an apparent density of about 1.26g/ml, since the microsphere contains a large amount of water molecules, when the microsphere is in contrast medium, the water molecules therein are replaced by contrast medium, resulting in a rapid increase in microsphere density. Thus, even if the microspheres are mixed with a very dense contrast agent (e.g., iohexol 350, density 1.406g/ml; iopromide, density 1.409 g/ml), they precipitate rapidly. The microspheres, particularly the large-particle-size microspheres, can easily block an injection device in the operation process, are difficult to operate, and only radiopaque polymer microspheres with the particle sizes of 40-90 microns and 70-150 microns are marketed at present and can be clinically used. In addition, although literature (Theranostics 2016,Vol.6,Issue 1, 28-39) also reports developing microspheres of 100-300 μm and 300-500 μm in particle size, the suspension time of microspheres of 300-500 μm is less than one minute. The suspension time of the microspheres with the particle size of 100-300 μm is approximately 9min and approximately 70-150 μm, because a large amount of microspheres with the particle size of 100-150 μm are mixed in the microspheres with the particle size of 100-300 μm, and the suspension time is determined by the best suspension part. In the actual operation process, a large number of 200-300 microspheres can sink rapidly, which leads to difficult operation in the operation process.

Disclosure of Invention

The embodiment of the application aims to provide a high-suspension developing microsphere and a preparation method thereof, wherein the microsphere has rich specification, can be kept in a long-time suspension state in a contrast agent, and meets clinical use requirements.

In a first aspect, embodiments of the present application provide a highly-suspended developing microsphere composed of a developer containing iodine and a polyvinyl alcohol microsphere formed by crosslinking a polyvinyl alcohol and a water-soluble polymer having a sulfonic acid group, and the polyvinyl alcohol microsphere is coupled with the developer through a covalent bond; the crosslinking functionality of the polyvinyl alcohol microsphere is 0.2-0.9 mmol/g, the sulfonate content of the polyvinyl alcohol microsphere is 1.5-3.0 mmol/g, and the iodine content in each 1mL developing microsphere is 100-200 mg;1mL of the developed microspheres can be suspended in 10mL of iodixanol 320 for at least 10min.

In the technical scheme, the iodine-containing developing microsphere with high ion density is obtained by properly increasing the crosslinking degree and the sulfonate ion strength of the microsphere and controlling the increase of the iodine content, and the high ion density can lock water molecules, so that the contrast agent, particularly iodixanol, with large molecular weight enters the developing microsphere, and the density of the developing microsphere in the using process is reduced, and the problem that the developing microsphere blocks an injection device and a catheter due to sedimentation is avoided.

The suspending ability of the developing microsphere is closely related to the degree of crosslinking, ion density and iodine content: in order to ensure that the developed microspheres can have sufficient ionic strength, the sulfonate content of the polyvinyl alcohol microspheres (blank microspheres) should be greater than 1.5mmol/g, if the ionic strength is too low, it is difficult to block the contrast agent from entering the interior of the microspheres, but if the sulfonate content is greater than 3.0mmol/g, the amount of polyvinyl alcohol in the corresponding blank microspheres will be too small, and it is difficult to bind enough developer (such as triiodobenzaldehyde). The crosslinking functionality of the blank microsphere is controlled between 0.2mmol/g and 0.9mmol/g, and if the crosslinking degree is too low, it is difficult to ensure that the microsphere has enough ions per unit volume; if the degree of crosslinking is too high, it is difficult for the developer to enter the interior of the microspheres to undergo condensation, thus making it difficult to ensure that the developed microspheres have a sufficiently high iodine content. The iodine content of the developing microsphere per unit volume (1 mL) is 100 mg-200 mg, and if the iodine content is lower than 100mg, the ability of the microsphere to absorb radiation is weak; if the iodine content is higher than 200mg, the microspheres themselves become denser than the contrast agent and are difficult to suspend in the contrast agent. By controlling the degree of crosslinking and ionic strength during microsphere synthesis and the iodine content during microsphere synthesis, it is necessary to obtain highly suspended microspheres, in particular 1mL of developed microspheres, which can be suspended in 10mL of iodixanol 320 for at least 10min, preferably for 30min, more preferably for more than 1 hour.

In one possible implementation, the iodine-containing developer is an aromatic compound containing two or more iodides directly linked to an aromatic ring and linked to the polyvinyl alcohol microsphere via an ester bond and/or an ether bond.

In the above technical scheme, in order to ensure the stability of the iodine-containing developer, the iodine atom is preferably directly connected with the aromatic ring. The aromatic ring is preferably a benzene ring. To ensure the development effect, the number of iodine atoms on a single developer molecule is preferably two or more. Since the surface of the microsphere has a large number of hydroxyl groups, and the developer can be linked to the microsphere by covalent bond such as ether bond or ester bond, the developer is required to have hydroxyl-reactive groups such as carboxyl group, acid halide, aldehyde group and acetal. Preferred are developers of acyl halides, aldehyde groups and acetal structures which react with hydroxyl groups with high efficiency. Another way to increase the efficiency of the developer reaction is to activate the hydroxyl groups in a certain way before reacting with the developer.

In one possible implementation, the polyvinyl alcohol microspheres are a three-dimensional network structure formed primarily by cross-linking polyvinyl alcohol with sodium polyacrylamide-2-methylpropanesulfonate and/or sodium polymethacrylamide-2-methylpropanesulfonate.

In the technical scheme, the polymer is selected to crosslink to form blank microspheres, and the crosslinking degree and the sulfonate ion content of the formed microspheres are conveniently controlled and regulated by adjusting the dosage of each component.

In one possible implementation, the sulfonate content in the polyvinyl alcohol microsphere is 1.9 mmol/g-2.9 mmol/g; and/or the crosslinking functionality of the polyvinyl alcohol microsphere is 0.3mmol to 0.8mmol.

In the technical scheme, the sulfonate content and the crosslinking functionality in the polyvinyl alcohol microsphere are controlled within specific ranges, so that the developing microsphere capable of being suspended in the contrast agent for a long time is more easily obtained.

In the technical scheme, the iodine content range of the prepared high-suspension developing microsphere is different for the polyvinyl alcohol microsphere with different crosslinking degrees and ionic strength. The iodine content of the developing microsphere prepared by low crosslinking degree and low ionic strength should be controlled in a lower range, but the iodine content is too low to achieve a real developing effect. As the degree of crosslinking and the ion concentration increase, the prepared microspheres with higher iodine content can also have enough suspension time in the contrast agent.

In one possible implementation, the particle size of the developing microsphere is 300 μm to 1200 μm, and 1mL of developing microsphere can be suspended in 10mL of iodixanol 320 for at least 15min; alternatively, 1mL of the developing microsphere can be suspended in 10mL of iodixanol 320 for at least 30min; further alternatively, 1mL of the developed microsphere can be suspended in 10mL of iodixanol 320 for at least 1h.

In the technical scheme, the microspheres with various specifications can be obtained, and particularly, the large-specification microspheres can also be suspended in the contrast agent for a long time, so that the clinical operation is convenient.

In one possible implementation, the developer is attached to the polyvinyl alcohol microspheres by the following structure:

in the above technical scheme, the adopted iodine-containing developer has an aromatic ring structure, iodine is directly connected to the aromatic ring, and can be combined with the microsphere through chemical bonds such as ester bonds, ether bonds and the like. For example, the iodine-containing contrast agent is linked to the microspheres through ether linkages of a cyclic acetal structure, the structure is relatively easy to form, the formation condition is relatively mild, and the structure is stable under neutral or weak alkaline conditions.

In one possible implementation manner, the developer is obtained by acetalization modification of one or more of 2,3, 5-triiodobenzaldehyde, acetal and hemiacetal thereof; optionally, the developer is 1- (dimethoxymethyl) -2,3, 5-triiodobenzene, and the polyvinyl alcohol microsphere is connected with the developer through the following structure:

in the technical scheme, the acetalation transformation is adopted, so that the reaction activity of the 1- (dimethoxy methyl) -2,3, 5-triiodobenzene is better than that of the 2,3, 5-triiodobenzaldehyde, and meanwhile, the stability of an acetal structure in a chemical reaction is guaranteed and the reaction efficiency is improved because no water is generated in the reaction process.

In a second aspect, an embodiment of the present application provides a method for preparing the high suspension developing microsphere provided in the first aspect, wherein the developer is dissolved in DMSO, and then the polyvinyl alcohol microsphere is added for reaction.

In one possible implementation, the developer is 1- (dimethoxymethyl) -2,3, 5-triiodobenzene, and the 1- (dimethoxymethyl) -2,3, 5-triiodobenzene is prepared by reacting triiodobenzaldehyde serving as a raw material with trimethyl orthoformate under acid catalysis; alternatively, the acid catalyst is methanesulfonic acid and/or p-toluenesulfonic acid.

In one possible implementation, the developer is 2,3, 5-triiodobenzoyl halide; alternatively, the developer is 2,3, 5-triiodobenzoyl chloride. The polyvinyl alcohol microsphere is connected with the developer through the following structure:

in one possible implementation, the method for preparing the polyvinyl alcohol microsphere comprises the following steps:

carrying out acid catalytic reaction on polyvinyl alcohol and N- (2, 2-dimethoxy) -2-methacrylamide to graft N- (2, 2-dimethoxy) -2-methacrylamide on the polyvinyl alcohol, so as to obtain a macromolecular polyvinyl alcohol monomer;

preparing a macromolecular polyvinyl alcohol monomer, a water-soluble monomer with a sulfonic group, an initiator and water into a water phase and adding the water phase into an oil phase to form a water-in-oil reversed-phase suspension polymerization system;

heating the reversed-phase suspension polymerization system to a reaction temperature, and adding a catalyst to react under stirring;

separating microspheres from the reacted system, purifying and drying.

In the technical scheme, polyvinyl alcohol is taken as a framework material, a water-soluble cross-linking agent N- (2, 2-dimethoxy) -2-methacrylamide is grafted, then the cross-linking reaction is carried out with a water-soluble monomer with a sulfonic group in the polymerization reaction process, and blank microspheres with different cross-linking degrees and different sulfonate ion contents can be obtained by controlling the consumption of each raw material.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a Micro CT scan of the developed microspheres of example 5 and example 12;

FIG. 2 is a CT image of the developed microspheres of example 5 and a control sample.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

The following describes the high suspension developing microsphere and the preparation method thereof in the embodiment of the present application.

The embodiment of the application provides a high-suspension developing microsphere which mainly comprises an iodine-containing developer and a polyvinyl alcohol microsphere formed by crosslinking a polyvinyl alcohol and a water-soluble polymer with a sulfonic group, and the polyvinyl alcohol microsphere is coupled with the developer through a covalent bond. As one embodiment, the polyvinyl alcohol microsphere is mainly a three-dimensional network structure formed by crosslinking polyvinyl alcohol with polyacrylamide-2-methylpropanesulfonic acid sodium salt and/or polymethacrylamide-2-methylpropanesulfonic acid sodium salt.

In the embodiment of the application, the developer containing iodine is an aromatic compound containing two or more iodides directly connected with an aromatic ring, the iodine is directly connected with the aromatic ring and can be connected with the polyvinyl alcohol microsphere through an ester bond and/or an ether bond, for example, the aromatic ring of the developer is a benzene ring. To ensure the development effect, a single developer molecule has more than 2 iodides, such as 2,3 or 4 iodides on the benzene ring.

As one embodiment, the developer is attached to the backbone of the polyvinyl alcohol microsphere by the following structure:the developer is generally 2,3, 5-triiodobenzaldehyde and one or more of acetal and hemiacetal thereof; alternatively, the developer is 1- (dimethoxymethyl) -2,3, 5-triiodobenzene, and these kinds of developers can form the above structure and be connected with polyvinyl alcohol microspheres.

As another embodiment, the developer is attached to the backbone of the polyvinyl alcohol microsphere by the following structure:the developer is typically 2,3,5 triiodobenzoyl halide; alternatively, the developer is 2,3,5 triiodobenzoyl chloride.

In the examples herein, the particle size of the developing microspheres is generally 100 μm to 1200. Mu.m, such as 100 μm to 300. Mu.m, 300 μm to 500. Mu.m, 500 μm to 700. Mu.m, 700 μm to 900. Mu.m, and 900 μm to 1200. Mu.m. For example, the particle size of the developing microsphere is 300-500 mu m, 500-700 mu m, 700-900 mu m and 900-1200 mu m, which can fill the gap of the developing microsphere with large particle size in the market.

The polyvinyl alcohol microsphere and the developing microsphere are required to simultaneously meet the following conditions:

(a) The crosslinking functionality of the polyvinyl alcohol microsphere is 0.2 mmol/g-0.9 mmol/g; alternatively, the polyvinyl alcohol microspheres have a crosslinking functionality of 0.3mmol to 0.8mmol.

(b) The sulfonate content of the polyvinyl alcohol microsphere is 1.5 mmol/g-3.0 mmol/g (usually corresponding to 5% -9% of sulfur content); optionally, the sulfonate content in the polyvinyl alcohol microsphere is 1.9 mmol/g-2.9 mmol/g (usually corresponding to 6% -9% of sulfur content); alternatively, the sulfonate content in the polyvinyl alcohol microsphere is 2.5 mmol/g-2.9 mmol/g (usually corresponding to 7% -8% of sulfur content), which can greatly improve the suspension time.

(c) The iodine content in each 1mL of the developing microsphere is 100 mg-200 mg, and can be selected to be 100 mg-180 mg. The iodine content is too low (< 100 mg/mL), the developing microsphere has weak X-ray absorption and poor developing property.

In the embodiment of the application, the ionic strength calculating method is that firstly, the microsphere is prepared into a dry sphere, and the ionic strength and crosslinking degree testing method for the dry sphere is as follows: the samples were tested for N content and S content by elemental analysis (Tachykusub Ai Limeng, germany), and the ionic strength and the degree of crosslinking were calculated, specifically:

ionic strength = molar amount of sulfur per unit mass = sulfur content per unit mass/32; for example, sulfonate content (mmol/L) =s content (mmol/L) =sulfur content weight/32 g/mol;

crosslinking degree = crosslinking agent molar amount per unit mass = total nitrogen molar amount per unit mass-ionic monomer nitrogen molar amount per unit mass = nitrogen content x unit mass/14-sulfur content x unit mass/32; such as the crosslinking degree (mmol/L) =total meq-S meq of N (n=s in AMPS) =n content weight/14 g/mol-sulfonate content (mmol/L).

The iodine content is determined by an oxygen bottle combustion method-ICPMS, a sample is processed by the oxygen bottle combustion method, and then the iodine ion content is tested by ICP-MS (Dyana ICS-1000), and the specific testing method is as follows: taking 5ml of radiopaque microspheres, namely developing microspheres, by using a measuring cylinder, and adding the microspheres into a penicillin bottle with a weighed weight; vacuum drying at 60deg.C overnight, and weighing the obtained solid; weighing 20mg of sample, taking hydrazine hydrate sodium hydroxide as an absorption liquid, and burning in an oxygen bottle; collecting absorption liquid and fixing the volume; iodine content was determined using ICP-MS (Inductively coupled plasma mass spectrometry ).

The iodine content per unit volume of the microsphere was calculated as =solid mass =iodine content per 5ml.

Under the premise of meeting the conditions, the obtained developing microsphere can meet the use requirements and has certain suspension property and developing property.

1mL of the developed microspheres were capable of being suspended in 10mL of iodixanol 320 for at least 10min (kept from settling for at least 10 min); alternatively, 1mL of the developing microsphere can be suspended in 10mL of iodixanol 320 for at least 15min;1mL of the developing microsphere was capable of being suspended in 10mL of iodixanol 320 for at least 30min; further alternatively, 1mL of the developed microsphere can be suspended in 10mL of iodixanol 320 for at least 1h.

As one embodiment, the particle size of the developing microsphere is 200 μm to 1200 μm, and 1mL of the developing microsphere can be suspended in 10mL of iodixanol 320 for at least 15min; alternatively, 1mL of the developing microsphere can be suspended in 10mL of iodixanol 320 for at least 30min; further alternatively, 1mL of the developed microsphere can be suspended in 10mL of iodixanol 320 for at least 1h.

As another embodiment, the particle size of the developing microsphere is 300 μm to 1200 μm, and 1mL of the developing microsphere can be suspended in 10mL of iodixanol 320 for at least 15min; alternatively, 1mL of the developing microsphere can be suspended in 10mL of iodixanol 320 for at least 30min; further alternatively, 1mL of the developed microsphere can be suspended in 10mL of iodixanol 320 for at least 1h.

In the application, the suspension time testing method comprises the following steps: 1mL of the developing microspheres stored in physiological saline was taken and placed in a 10mL penicillin bottle, 10mL of iodixanol 320 was added, and the mixture was slightly shaken to test the time until the total amount was 70%. This time is the time that 1mL of the developed microsphere can be suspended in 10mL of iodixanol 320 (the time to remain undeposited).

The present application considers the suspension performance of the developing microsphere by "the suspension time of 1mL of developing microsphere in 10mL of iodixanol 320", that is, the longer the suspension time, the better the suspension performance, and does not mean that the developing microsphere can be suspended only in a specific amount or in the iodixanol 320. The iodixanol 320 is selected because the dimer contrast agent with the highest concentration is the iodixanol 320, which is convenient to operate.

The embodiment of the application also provides a preparation method of the high-suspension developing microsphere provided by the first aspect, which comprises the following steps:

step S1: preparing polyvinyl alcohol microspheres:

separating microspheres from the reacted system, purifying and drying.

Step S2: introduction of iodinated groups:

reacting the polyvinyl alcohol microsphere with a developer to form a cyclic acetal structure in the polyvinyl alcohol microsphere structure, wherein the developer has aldehyde groups, acetals or hemi-acetals. As one embodiment, the developer is 1- (dimethoxy methyl) -2,3, 5-triiodobenzene, the 1- (dimethoxy methyl) -2,3, 5-triiodobenzene is obtained by taking triiodobenzaldehyde as a raw material and reacting with trimethyl orthoformate under the catalysis of acid, and the acid catalyst is methanesulfonic acid and/or p-toluenesulfonic acid. The corresponding developing microsphere may be prepared through dissolving 1- (dimethoxy methyl) -2,3, 5-triiodobenzene in DMSO, adding polyvinyl alcohol microsphere to swell, and reaction at 40-90 deg.c.

As another embodiment, the developer contains acyl halide groups, such as 2,3, 5-triiodobenzoyl chloride, and the acyl halide developer is combined with the microspheres under the action of an alkaline catalyst to obtain the developing microspheres. The corresponding preparation method comprises the steps of dissolving 2,3, 5-triiodobenzoyl chloride in DMSO, adding polyvinyl alcohol microspheres for swelling, adding a catalyst, and reacting at room temperature.

In addition, the 1,1' -carbonyl diimidazole activated microsphere is adopted first and then reacts with ethylenediamine to obtain an amino-bearing microsphere, and the microsphere continuously reacts with 2,3, 5-triiodobenzoic acid to obtain a developing microsphere.

The features and capabilities of the present application are described in further detail below in connection with the examples.

Each of the examples and comparative examples provides a developing microsphere, which is prepared according to the following preparation process:

(1) Preparation of different samples of polyvinyl alcohol microspheres

100mL of purified water was added to a 250mL three-necked flask equipped with overhead mechanical stirring, about 15g of PVA (model 1888) was added, the temperature was raised to 95℃for dissolution, and the flask was cooled to room temperature; calculated amount of N- (2, 2-dimethoxyethyl) -2-acrylamide (NAAADA) was added, followed by 10mL of concentrated hydrochloric acid, and the reaction was performed at room temperature for 14 hours, and then neutralized to ph=7 using 2.5M sodium hydroxide solution, to obtain a macromolecular polyvinyl alcohol monomer solution.

600mL butyl acetate and 18g cellulose acetate butyrate are added into a three-necked flask with overhead mechanical stirring to obtain an oil phase;

the calculated amount of acrylamide-2-methylpropanesulfonic acid sodium salt (AMPS sodium) was dissolved in 60ml of water, and the calculated amount of the macromolecular polyvinyl alcohol monomer solution was added, and 1.5g of potassium persulfate was added to obtain a water phase.

The rotational speed was set at 400rpm, and the aqueous phase was added dropwise to the oil phase; after the completion of the dropwise addition, the temperature was raised to 55℃and 2.2ml of tetramethyl ethylenediamine was added for reaction for 8 hours. After cooling to 25 ℃, the product is transferred to a filtration reactor for purification, wherein butyl acetate is removed by filtration, and is washed with ethyl acetate 5 times and acetone 4 times; vacuum drying at 55deg.C for 2 hr to remove residual solvent to obtain polyvinyl alcohol microsphere dry spheres.

TABLE 1 raw materials amounts and polyvinyl alcohol microsphere parameters for different samples

(2) Preparation of different developing microspheres

(1) The experimental procedures for examples 1 to 5 and examples 11 to 17 were: 1- (dimethoxy methyl) -2,3, 5-triiodo benzene is selected as a developer: in a 250ml three-necked round bottom flask equipped with an overhead stirrer, thermometer, a specified amount of 1- (dimethoxymethyl) -2,3, 5-triiodobenzene was added and dissolved in 120ml of DMSO; adding 4.0g of polyvinyl alcohol microsphere dry spheres of different samples; after swelling for 1h, 1ml of methanesulfonic acid was added to react at 60℃for 48h to obtain developed microspheres.

The developed microspheres of examples 6-10 were screened from developed microspheres produced by one reaction, which was doubled in order to ensure that each particle size had sufficient sample for testing. Namely, 10.03g of 1- (dimethoxymethyl) -2,3, 5-triiodobenzene was charged into a 500ml three-necked round bottom flask equipped with an overhead stirrer and a thermometer, and dissolved in 240ml of DMSO; adding 8.0g of polyvinyl alcohol microsphere dry spheres; after swelling for 1h, 2ml of methanesulfonic acid was added to react at 60℃for 48h to obtain developed microspheres.

Wherein, the preparation method of the 1- (dimethoxy methyl) -2,3, 5-triiodobenzene comprises the following steps: 50g of 2,3, 5-triiodobenzaldehyde is dissolved in 500ml of methyl acetate under the protection of nitrogen, 2 equivalents of trimethyl orthoformate and 0.1 equivalent of p-toluenesulfonic acid are added and reacted for 12 hours at 40 ℃; recrystallisation from methanol-water gives a white solid. For the solid obtained ¹ H-NMR was identified as 1- (dimethoxymethyl) -2,3, 5-triiodobenzene.

Washing the microspheres with DMSO, 10% sodium bicarbonate and brine in sequence to remove residual developer and acid; finally, the microspheres are screened to obtain developing microspheres with different particle sizes.

(2) 2,3, 5-triiodobenzoyl chloride is selected as a developer: dissolving a specified amount of 2,3, 5-triiodobenzoyl chloride in 120mL of DMSO, adding 4g of polyvinyl alcohol microspheres of different samples for swelling, adding 2mL of triethylamine as a catalyst, and reacting for 48 hours at room temperature to obtain the microspheres.

Washing the microsphere with DMSO three times, methanol three times, and purified water three times, and sieving to obtain the developed microsphere with different particle diameters.

The developed microspheres of each example and comparative example were tested with only sample selection, developer selection, and amount of raw materials being different:

1. the suspension time testing method comprises the following steps: 1mL of the developing microspheres stored in physiological saline was taken and placed in a 10mL penicillin bottle, 10mL of iodixanol 320 was added, and the mixture was slightly shaken to test the time until the total amount was 70%. This time is the time that 1mL of the developed microsphere can be suspended in 10mL of iodixanol 320 (the time to remain undeposited).

The longer the suspension time, the better the suspension.

2. HU value test method: the developed microspheres obtained in each of the examples and comparative examples were subjected to a Micro CT test (bruckskyscan 1276).

Iodixanol is diluted into 100mg/mL, 150mg/mL and 200mg/mL of iodine content, and the iodine content is placed in a 1.8mL freezing tube to be used as a reference substance; the HU values measured are shown in Table 2:

TABLE 2 HU values for different controls

Reference substance	HU value
		100mg/mL	4955
150mg/mL	7676
		200mg/mL	9570

2.2mL of the different developed microspheres were placed in a 1.8mL freeze tube and their Hu values were determined.

The larger the HU value, the better the developing effect. As can be seen by comparison, the HU value of the developing microsphere is close to that of the control substance with the iodine content close to that of the control substance, which indicates that the developing microsphere has a similar developing effect as the developer.

The amounts of sample and raw material used in each example and comparative example are shown in Table 3 below, as well as the suspension properties and development effects of the resulting developed microspheres:

TABLE 3 suspension Properties and development Effect of different developed microspheres

As is clear from Table 1, by adjusting the amount of the crosslinking agent and the amount of the ionic monomer, it is possible to obtain polyvinyl alcohol microspheres having a specific degree of crosslinking and ionic strength.

As can be seen from tables 2 and 3, example 1 raw material microspheres: the polyvinyl alcohol microspheres (sample 1) had a degree of crosslinking of 0.6mmoL/g and the suspension time of the developed microspheres with an iodine content of about 102mg/mL exceeded ten minutes. Example 2 further increases the degree of crosslinking of the raw material microspheres, increasing the suspension time to 15 minutes when the iodine content of the developed microspheres was increased to about 130mg/mL, indicating that increasing the degree of crosslinking effectively increases the suspension time of the microspheres. The polyvinyl alcohol microsphere sulfonate ion concentration used in example 3 increased to 1.90mmoL/g, the degree of crosslinking was only 0.21mmoL/g, and the suspension time of the prepared developed microsphere was 11 minutes with an iodine content of about 102 mg/mL. Meanwhile, according to examples 4 and 5, it is understood that the effect of further increasing the suspension time is obtained on the premise of increasing the iodine content by further increasing the crosslinking degree of the raw material microspheres. From this, it is clear that the developed microspheres are capable of satisfying a suspension time of at least 10 minutes when satisfying the crosslinking functionality, sulfonate content and iodine content of the present invention.

Examples 6 to 10 are suspension times of developing microspheres of different particle sizes, and when the ionic strength and the crosslinking degree reach the medium content, the iodine ions are lower than 180mg/mL, and the suspension time of developing microspheres of different particle sizes in water can reach at least 10min.

Example 15 is a further increase in the amount of developer based on example 14 to increase the iodine content of the microspheres to about 200mg/mL, at which time the suspension time exceeds 10 minutes, indicating that an upper limit of 200mg/mL is suitable.

From the above results, it can be seen that the suspension property of the developing microspheres can be improved by properly increasing the crosslinking functionality and sulfonate content of the raw material microspheres within the scope of the present invention, and when the sulfonate content of the raw material microspheres of examples 11 to 14 and examples 16 to 17 is more than 2.5, the suspension time of 30 minutes can be reached even if the iodide ion content reaches 187.7mg/mL, so that the preferable technical scheme of the present invention is that the sulfonate content is more than 2.5mmol/g; meanwhile, if the iodine content is lower than 180mg/mL, the suspension time is longer and can be more than 2 hours. The comparative examples 1 to 2 have a low iodine ion content, and although the suspension time of 2 hours or more was also achieved, the iodine content was too low and the development was poor.

As can be seen from examples 18 to 20, the microspheres prepared by using 2,3, 5-triiodobenzoyl chloride as a developer also exhibit high suspension properties.

Fig. 1 is a cross-sectional view of example 5 and example 12 after scanning with Micro CT, wherein the left image is a Micro CT scan of the developed microsphere of example 5 and the right image is a Micro CT scan of the developed microsphere of example 12. Fig. 1 may show that the developed microspheres prepared in the examples of the present application exhibit clear spheres.

In addition, by repeating examples 1 to 19, substantially the same polyvinyl alcohol microspheres and developing microspheres can be obtained, and the polyvinyl alcohol microspheres have close developing property and suspension property, which indicates that the preparation method determined in the example of the application has reproducibility and can be industrially popularized and applied.

3. The X-ray absorption effect of the developed microspheres of example 5 was compared to an iodixanol control sample having an iodine content of approximately by Micro CT (Brookyscan 1272).

Fig. 2 is a CT image, wherein the left image is a CT image of the developed microsphere of example 5, and the right image is a CT image of a control sample, and the results show that both have the same absorption effect on X-rays.

In summary, the high-suspension developing microsphere and the preparation method thereof in the embodiment of the application have rich specifications, can be kept in a suspension state in a contrast agent for a long time, and are suitable for clinical use.

The foregoing is merely exemplary embodiments of the present application and is not intended to limit the scope of the present application, and various modifications and variations may be suggested to one skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A highly suspended developing microsphere, characterized in that it comprises a developer containing iodine and a polyvinyl alcohol microsphere formed by crosslinking polyvinyl alcohol and a water-soluble polymer with sulfonic acid groups, and the polyvinyl alcohol microsphere is coupled with the developer through a covalent bond; the crosslinking functionality of the polyvinyl alcohol microsphere is 0.2-0.9 mmol/g, the sulfonate content of the polyvinyl alcohol microsphere is 2.5-3.0 mmol/g, the particle size of the developing microsphere is 300-500 mu m, and the iodine content in each 1mL of the developing microsphere is 100-180 mg;1mL of the developed microsphere was capable of being suspended in 10mL of iodixanol 320 for at least 30min;

the polyvinyl alcohol microsphere is a three-dimensional network structure formed by crosslinking polyvinyl alcohol with polyacrylamide-2-methylpropanesulfonic acid sodium and/or polymethyl acrylamide-2-methylpropanesulfonic acid sodium; the developer is connected with the polyvinyl alcohol microsphere through the following structure:

or->。

2. The highly suspended developing microsphere according to claim 1, wherein the cross-linking functionality of the polyvinyl alcohol microsphere is 0.3mmol/g to 0.8mmol/g.

3. A method of preparing the highly suspended developing microsphere according to claim 1 or 2, wherein the developing agent is dissolved in DMSO and then the polyvinyl alcohol microsphere is added to react.

4. A method of preparing highly suspended developing microspheres as claimed in claim 3, wherein the developer is 1- (dimethoxymethyl) -2,3, 5-triiodobenzene.

5. A method of preparing highly suspended developing microspheres as claimed in claim 3, wherein the developer is 2,3, 5-triiodobenzoyl halide.

6. The method for producing highly suspended developing microspheres according to claim 5, wherein the developer is 2,3, 5-triiodobenzoyl chloride.

7. The method for preparing high-suspension developing microspheres according to claim 3, wherein the method for preparing the polyvinyl alcohol microspheres comprises the following steps:

preparing the macromolecular polyvinyl alcohol monomer, a water-soluble monomer with a sulfonic group, an initiator and water into a water phase and adding the water phase into an oil phase to form a water-in-oil reversed-phase suspension polymerization system;

heating the reversed-phase suspension polymerization system to a reaction temperature, and adding a catalyst to react under the stirring condition;

separating microspheres from the reacted system, purifying and drying.