A method for preparing an iodine-based nano-contrast agent

Abstract

This invention relates to a method for preparing iodine-based nanocontrast agents. Based on the specific and efficient esterification reaction between fluorinated phenylboronic acid groups and ortho-dihydroxy structures, an amphiphilic block polymer containing fluorinated phenylboronic acid groups is co-crosslinked with water-soluble nonionic polyhydroxy iodine-based contrast agents such as iohexol, iodofol, iodixanol, iopromide, iodomeprazole, iodiphenol, iodpentol, and iotram. No chemical modification of the iodine-based contrast agents is required. The water-soluble nonionic polyhydroxy iodine-based contrast agents can be easily and efficiently nano-sized through the phenylboronic acid esterification crosslinking reaction to obtain iodine-based nanocontrast agents. This invention has the advantages of a simple and controllable preparation process, mild reaction conditions, inexpensive and readily available raw materials, and no toxic byproducts. Furthermore, the prepared iodine-based nanocontrast agents exhibit good dispersion stability and excellent imaging contrast performance. When the concentration of the iodine-based nanocontrast agent reaches 120 mg / mL, the CT value reaches as high as 1150 HU.

Description

Technical Field

[0001] This invention relates to a method for preparing iodine-based nanocontrast agents, which can easily and efficiently nanoscale water-soluble nonionic polyhydroxy iodine-based contrast agents to produce iodine-based nanocontrast agents, belonging to the field of medical contrast agent technology. Background Technology

[0002] With the rapid development of imaging medicine, the development of high-performance imaging contrast agents has gradually become a research hotspot in related fields at home and abroad. Contrast agents not only play a great auxiliary role in enhancing imaging effects, accurately judging the extent of lesions, and inferring the nature of lesions, but also show great application potential in in vivo targeted therapy. At present, the most commonly used contrast agents in clinical practice are a class of polyhydroxy compounds containing multiple iodine atoms, usually referred to as non-ionic iodine-based contrast agents. They have the characteristics of high water solubility, low viscosity, low osmotic pressure, and relatively safe use. They mainly include iohexol, iodofol, iodixanol, iopromide, iodomeprazole, iodipoxetine, iodine pentoxifyll, and iodtriam, etc. [Chemical Reviews, 2013, 113(3): 1641-1666; ACS Biomaterials Science & Engineering, 2022, 8(1): 32-53]. Nevertheless, these non-ionic iodine-based contrast agents have short circulation times, poor targeting, and require high injection volumes. In particular, large doses of iodine-based contrast agents are primarily metabolized by the kidneys, easily leading to kidney damage and even acute renal failure (New England Journal of Medicine, 2019, 380:2146-2155). These problems have severely limited the clinical application of non-ionic iodine-based contrast agents.

[0003] The rapid development of nanoscience and its integration with biomedicine, materials science, pharmacology, and other fields have brought about a revolutionary change in disease diagnosis and treatment. Nanomaterials possess excellent drug loading and delivery properties, as well as unique systemic circulation and metabolic pathways, offering new opportunities for the development of high-performance therapeutic agents. Recently, the nanofiberization of small-molecule iodine-based contrast agents to create iodine-based nanocontrast agents has become a major approach to addressing their challenges and has achieved significant progress. Compared to traditional iodine-based contrast agents, iodine-based nanocontrast agents can significantly prolong the systemic circulation time of contrast agents, improve the targeting of tissue and organ imaging, and achieve selective, high-quality imaging of lesions. While ensuring imaging effects, nano-contrast agents can reduce drug dosage and alter metabolic pathways, thereby significantly reducing the toxic side effects of iodine-based contrast agents, especially reducing their damage to kidney function [Advanced Drug Delivery Reviews, 2002, 54(2): 235-252; Advanced Materials, 2017, 29(10): 1603997; Acta Biomaterialia, 2018, 66: 200-212; Biomaterials Science, 2020, 8(20): 5715-5728; ACS Applied Materials & Interfaces, 2019, 11(21): 18953-18959]. Currently, there are two main approaches to preparing iodine-based nano-contrast agents. One approach is to physically load oil-soluble iodine-based contrast agents into the hydrophobic core of nanoliposomes or polymer micelles. Nevertheless, iodine-based nanocontrast agents loaded with nanoliposomes or polymer micelles not only suffer from low drug loading and poor cyclic stability, but these self-assembled nanocarriers can only be used to encapsulate hydrophobic, oil-soluble iodine-based contrast agents, and cannot effectively load the aforementioned highly water-soluble nonionic iodine-based contrast agents commonly used in clinical practice [Accounts of Chemical Research, 2012, 45(10): 1817–1827; ACS Biomaterials Science & Engineering, 2022, 8(1): 32-53]. Another method for preparing iodine-based nanocontrast agents is to graft iodine-based contrast agents onto polymers using a covalent coupling reaction and induce their self-assembly to form nanoparticles. This method not only faces complex and cumbersome synthesis steps and product purification processes, but also requires chemical modification of the iodine-based contrast agents to introduce specific coupling groups, which severely limits its research and application.[Accounts of Chemical Research, 2012, 45(10): 1817–1827; ACS Biomaterials Science & Engineering, 2022, 8(1): 32-53; Contrast Media & Molecular Imaging, 2015, 10(2): 81-95; Advanced Materials, 2013, 25(19): 2641-2660]. Therefore, the research and development of low-toxicity and high-efficiency iodine-based nanocontrast agents, and the development of simple and efficient nanotechnology for iodine-based contrast agents, have become a research hotspot in related fields at home and abroad, and are also important problems that urgently need to be solved in the fields of imaging medicine and medical materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention develops a novel, simple, and efficient method for preparing iodine-based nanocontrast agents that are stable under physiological conditions.

[0005] In recent years, functionalized polymers of phenylboronic acid, which have advantages such as low toxicity, low immunogenicity and low price, have shown great application potential in the biomedical field [Journal of Controlled Release, 2019, 305: 50-64; Biomaterials Science, 2021, 9: 6851-6864; Biomacromolecules 2019, 20: 871-881]. It is particularly noteworthy that, due to its low pKa value, the fluorinated phenylboronic acid group can selectively form physiologically stable (pH 7.4) borate ester complexes with polyhydroxy compounds containing ortho-dihydroxy structures under very mild reaction conditions, as shown in formula (I) below. This demonstrates great application potential in the construction of functionalized nanomedicines or intelligent drug delivery systems [Journal of Controlled Release, 2019, 305: 50-64; Journal of Chromatography A, 2013, 1305: 123-130; Reactive and Functional Polymers, 2020, 146: 104435].

[0006]

[0007] Given that commonly used clinical water-soluble nonionic iodine-based contrast agents such as iohexol, iodofol, iodixanol, and iopromide are typical polyhydroxy compounds containing multiple ortho- and tho-dihydroxy groups in their molecular structures, these water-soluble nonionic polyhydroxy iodine-based contrast agents can undergo esterification reactions with compounds containing fluorinated phenylboronic acid groups without any chemical modification. This forms a stable covalent phenylboronic acid ester cross-linked structure under physiological conditions, providing a new approach for developing simple and efficient nano-scale technologies for iodine-based contrast agents. To date, no research reports have been found on the use of compounds containing phenylboronic acid and fluorinated phenylboronic acid groups for the nano-scale fabrication of iodine-based contrast agents.

[0008] In summary, this invention aims to achieve the nano-sizing of water-soluble nonionic iodine-based contrast agents by utilizing the esterification and cross-linking reaction of fluorinated phenylboronic acid with ortho-dihydroxy groups. This provides a new technical solution for the development of novel and efficient iodine-based nano-contrast agents, and in particular, offers a new approach to solving the key problem of the difficulty in nano-sizing water-soluble nonionic iodine-based contrast agents. It has significant scientific value and broad application potential.

[0009] The technical solution of the present invention is as follows:

[0010] A method for preparing an iodine-based nanocontrast agent involves cross-linking an amphiphilic block polymer containing fluorinated phenylboronic acid groups with a water-soluble nonionic polyhydroxy iodine-based contrast agent, and then obtaining the iodine-based nanocontrast agent through a phenylboronic acid esterification reaction.

[0011] The method for preparing the iodine-based nanocontrast agent involves dissolving an amphiphilic block polymer containing fluorinated phenylboronic acid groups and a water-soluble nonionic polyhydroxy iodine-based contrast agent in an organic mixed solvent, mixing and stirring at 25–60°C for 4–24 h, and then lyophilizing after dialyzing in a pH 7.4 PBS buffer solution.

[0012] The reaction solution is prepared by mixing the amphiphilic block polymer containing fluorinated phenylboronic acid groups and the water-soluble nonionic polyhydroxy iodide contrast agent in a molar ratio of fluorinated phenylboronic acid groups to ortho-dihydroxy groups of 1:2 to 1:8.

[0013] The amphiphilic block polymer containing fluorinated phenylboronic acid groups is composed of hydrophilic polyethylene glycol segments with a number-average molecular weight of 2000-10000 and hydrophobic segments containing fluorinated phenylboronic acid groups with a number-average molecular weight of 10000-50000, and its structural formula is as follows:

[0014]

[0015] In the aforementioned structural formula, R is H or CH3; when R is H, it is prepared using acrylamide fluorinated phenylboronic acid as a monomer; when R is CH3, it is prepared using methacrylamide fluorinated phenylboronic acid as a monomer.

[0016] The water-soluble nonionic polyhydroxy iodine-based contrast agents contain 2 to 4 ortho-dihydroxy groups in their molecular structure, including iohexol, iodofol, iodixanol, iopromide, iodomeprazole, iodipoxetine, iodine pentoxifylline, or iodritol.

[0017] The organic mixed solvent is a mixture of methanol or ethanol with dimethyl sulfoxide or N,N-dimethylamide. Preferably, the organic mixed solvent is a mixture of methanol and dimethyl sulfoxide in a volume ratio of 1:1.

[0018] The iodine-based nanocontrast agent prepared by the method of this invention is used in the field of medical imaging.

[0019] The preparation technology of the iodine-based nanocontrast agent of the present invention has the following advantages:

[0020] (1) No chemical modification of the contrast agent is required. Iodine-based nano-contrast agents can be prepared simply and efficiently by utilizing the esterification reaction between the fluorinated phenylboronic acid group and the ortho-dihydroxy group of the water-soluble nonionic polyhydroxy iodine-based contrast agent. The reaction byproduct is non-toxic and harmless water, and the reaction conditions are very mild. The reaction preparation process is simple and easy to control, making it suitable for large-scale industrial production.

[0021] (2) The prepared iodine-based nanocontrast agent has a narrow particle size distribution, high dispersion stability, and good imaging performance; when the concentration of the iodine-based nanocontrast agent reaches 120 mg / mL, the CT value is as high as 1150 HU.

[0022] (3) Traditional methods cannot load water-soluble nonionic polyhydroxy iodine-based contrast agents into nanocarriers to form nano-formulations. This invention provides an efficient solution for the nano-preparation of water-soluble nonionic polyhydroxy iodine-based contrast agents. Attached Figure Description

[0023] Figure 1 This is a diagram of the reaction equation for the preparation of acrylamide-fluorinated phenylboronic acid.

[0024] Figure 2 It is acrylamide fluorinated phenylboronic acid 1 HNMR spectrum.

[0025] Figure 3 It is acrylamide fluorinated phenylboronic acid 13 CNMR spectrum.

[0026] Figure 4 It is a macromolecular chain transfer agent containing polyethylene glycol segments with a molecular weight of 5000. 1 HNMR spectrum.

[0027] Figure 5 It is an amphiphilic block polymer containing fluorinated phenylboronic acid groups.1 HNMR spectrum.

[0028] Figure 6 This describes the formation mechanism of iodine-based nanocontrast agents.

[0029] Figure 7 This is a particle size and particle size distribution diagram of iodine-based nanocontrast agents.

[0030] Figure 8 This is a transmission electron microscope image of an iodine-based nanocontrast agent.

[0031] Figure 9 It is the dispersion stability of iodine-based nanocontrast agents.

[0032] Figure 10 Comparative performance evaluation of iodine-based nanocontrast agents. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0034] This invention is based on the specific and efficient esterification reaction between fluorinated phenylboronic acid groups and ortho-dihydroxy structures. An amphiphilic block polymer containing fluorinated phenylboronic acid groups is crosslinked with water-soluble nonionic polyhydroxy iodinated contrast agents such as iohexol, iodofol, iodixanol, iopromide, iodomeprazole, iodiphenol, iodpentol, and iotram. No chemical modification of the aforementioned iodinated contrast agents is required; iodinated nano-contrast agents can be prepared through phenylboronic acid esterification. This method has advantages such as simple and controllable preparation process, mild reaction conditions, inexpensive and readily available raw materials, and no toxic byproducts.

[0035] An amphiphilic block polymer containing fluorinated phenylboronic acid groups, the polymer being composed of hydrophilic polyethylene glycol segments with a number average relative molecular mass of 2,000 to 10,000 and hydrophobic segments containing fluorinated phenylboronic acid groups with a number average relative molecular mass of 10,000 to 50,000.

[0036] Amphiphilic block polymers containing fluorinated phenylboronic acid groups: hydrophilic polyethylene glycol segments can increase the dispersion and cycling stability of nanoparticles; hydrophobic segments containing fluorinated phenylboronic acid groups can form physiologically stable covalent phenylboronic acid ester crosslinking structures with iodine-based contrast agents containing multiple hydroxyl groups.

[0037] An amphiphilic block polymer containing fluorinated phenylboronic acid groups can directly nano-size water-soluble nonionic polyhydroxy iodine-based contrast agents through a specific esterification reaction between the fluorinated phenylboronic acid groups and the ortho-dihydroxy structure, forming iodine-based nano-contrast agents stable under physiological conditions.

[0038] Preferably, the above-mentioned amphiphilic block polymer containing fluorinated phenylboronic acid groups has the structure shown in formula (II) below:

[0039]

[0040] In formula (II) above, R is H or CH3; when R is H, it is prepared using acrylamide fluorinated phenylboronic acid as a monomer; when R is CH3, it is prepared using methacrylamide fluorinated phenylboronic acid as a monomer.

[0041] In the above formula (II), the number-average molecular weight of the polyethylene glycol segments is 2,000 to 10,000, and n = 40 to 300; preferably, the number-average molecular weight of the polyethylene glycol segments is 5,000, and n = 113;

[0042] In the above formula (II), the number-average relative molecular mass of the fluorinated phenylboronic acid group segment is 10,000 to 50,000, and m = 50 to 250; preferably, the number-average relative molecular mass of the fluorinated phenylboronic acid group segment is 30,000, and m = 150;

[0043] The aforementioned amphiphilic block polymer containing fluorinated phenylboronic acid groups is obtained by using acrylamide fluorinated phenylboronic acid or methacrylamide fluorinated phenylboronic acid as monomers, in the presence of a macromolecular chain transfer agent containing polyethylene glycol segments, through living controlled free radical polymerization initiated by azobisisobutyronitrile (AIBN), and polymerizing in an organic solvent at 60-80°C for 8-48 hours, followed by precipitation with ethanol, acetone or diethyl ether or dialysis in water.

[0044] The aforementioned organic solvent refers to one or a mixture of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), or dioxane (DOX).

[0045] Preferably, the monomers acrylamide fluorinated phenylboronic acid and methacrylamide fluorinated phenylboronic acid are compounds containing fluorinated phenylboronic acid groups prepared by acryloyl chloride or methacryl chloride and 3-amino-4-fluorophenylboronic acid, and their structures are shown in formula (III) below:

[0046]

[0047] In formula (III) above, R is H or CH3; when R is H, it is acrylamide fluorinated phenylboronic acid; when R is CH3, it is methacrylamide fluorinated phenylboronic acid.

[0048] Preferably, the aforementioned macromolecular chain transfer agent containing polyethylene glycol segments is a compound obtained by esterification of methoxy polyethylene glycol and 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid, and its structure is shown in formula (IV) below:

[0049]

[0050] In the above formula (IV), the number-average molecular weight of the polyethylene glycol segments is 2,000 to 10,000, and n = 40 to 300, wherein, preferably, the number-average molecular weight of the polyethylene glycol segments is 5,000.

[0051] The above-mentioned water-soluble nonionic polyhydroxyiodinated contrast agents, including but not limited to iohexol, iodofol, iodixanol, iopromide, iodomeprazole, iodipoxetine, iodopentol, and iodritol, have the following structure (V):

[0052]

[0053] The water-soluble nonionic polyhydroxyiodine contrast agents in formula (V) above contain 2 to 4 ortho-dihydroxy groups in their molecular structure.

[0054] The above-mentioned method for preparing iodine-based nanocontrast agents by crosslinking an amphiphilic block polymer containing fluorinated phenylboronic acid groups with a water-soluble nonionic polyhydroxy iodine-based contrast agent involves dissolving the amphiphilic block polymer containing fluorinated phenylboronic acid groups and the water-soluble nonionic polyhydroxy iodine-based contrast agent in an organic mixed solvent, mixing and stirring at 25–60°C for 4–24 h, and then lyophilizing after dialyzing in a pH 7.4 PBS buffer solution.

[0055] The aforementioned organic mixed solvent is a mixed solvent of methanol or ethanol with dimethyl sulfoxide or N,N-dimethylamide, etc., preferably a mixed solvent of methanol and dimethyl sulfoxide in a volume ratio of 1:1.

[0056] The above-mentioned amphiphilic block polymer containing fluorinated phenylboronic acid groups and water-soluble nonionic polyhydroxy iodide contrast agent are prepared into a reaction solution with a molar ratio of fluorinated phenylboronic acid groups to ortho-dihydroxy groups of 1:2 to 1:8.

[0057] The following examples are helpful for understanding the present invention, but do not limit the scope of the invention.

[0058] Example 1: Preparation of monomeric acrylamide fluorinated phenylboronic acid

[0059] The monomeric acrylamide fluorinated phenylboronic acid is prepared by an amidation reaction of 3-amino-4-fluorophenylboronic acid and acryloyl chloride, as shown in the attached figure. Figure 1As shown. A typical procedure is as follows: 3-Amino-4-fluorophenylboronic acid (6.2 g, 40 mmol) and 2 mol / L NaOH solution (80 mL) are added to a 250 mL single-necked flask. After stirring and maintaining the temperature in an ice-water bath for 20 min, acryloyl chloride (6.50 mL, 80 mmol) is added dropwise using a constant-pressure dropping funnel. The reaction is then carried out in an ice-water bath for 30 min, followed by a reaction at room temperature for 3 h. After the reaction is complete, the pH of the solution is adjusted to acidic with concentrated hydrochloric acid, resulting in the precipitation of a large amount of white solid. After filtration, the filter cake is washed 2-3 times with 80 mL of ice water and freeze-dried to obtain a white powder of acrylamide fluorophenylboronic acid.

[0060] The reaction equation for the preparation of acrylamide-fluorinated phenylboronic acid is attached. Figure 1 As shown.

[0061] The prepared acrylamide fluorinated phenylboronic acid was used... 1 HNMR characterization, NMR spectrum as attached. Figure 2 As shown in the figure, the proton peaks of the double bond are observed at 5.70 ppm (1H), 6.22 ppm (1H), and 6.44 ppm (1H); the proton peak on the amide group is 10.04 ppm (1H); the proton peaks on the aromatic ring are 7.23-7.77 ppm (4H); and the characteristic proton peak of the boric acid group B-OH is 7.98 ppm (2H), confirming that acrylamide fluorinated phenylboronic acid was successfully prepared.

[0062] The prepared acrylamide fluorinated phenylboronic acid was used... 13 CNMR characterization and NMR spectra are attached. Figure 3 As shown. The carbon peaks of the double bond, the carbon peak on the amide group, and the carbon peak on the aromatic ring are... Figure 3 Both observations confirm that acrylamide-fluorinated phenylboronic acid was successfully prepared.

[0063] Example 2: Preparation of monomeric methacrylamide fluorinated phenylboronic acid

[0064] The monomeric methacrylamide fluorinated phenylboronic acid is prepared by an amidation reaction of 3-amino-4-fluorophenylboronic acid and methacryloyl chloride. A typical procedure is as follows: 3-amino-4-fluorophenylboronic acid (6.2 g, 40 mmol) and 2 mol / L NaOH solution (80 mL) are added to a 250 mL single-necked flask. After stirring and maintaining the temperature in an ice-water bath for 20 min, methacryloyl chloride (7.0 mL, 80 mmol) is added dropwise using a constant-pressure dropping funnel. The reaction is then carried out in an ice-water bath for 30 min, followed by a reaction at room temperature for 3 h. After the reaction is complete, the pH of the solution is adjusted to acidic with concentrated hydrochloric acid, resulting in the precipitation of a large amount of white solid. The solid is filtered, and the filter cake is washed 2-3 times with 80 mL of ice water. After freeze-drying, a white powder of acrylamide fluorinated phenylboronic acid is obtained.

[0065] Example 3: Preparation of macromolecular chain transfer agents containing polyethylene glycol segments

[0066] The polyethylene glycol-containing macromolecular chain transfer agent is a compound prepared by esterification of methoxy polyethylene glycol and 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid. A typical preparation process is as follows: In a 250 mL single-necked flask, polyethylene glycol monomethyl ether (12.5 g, 2.5 mmol), 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid (1.83 g, 5 mmol), dicyclohexylcarbodiimide (5 g, 25 mmol), and DMAP (0.3 g, 2.5 mmol) with a molecular weight of 5000 are added, followed by dissolution in 150 mL of purified dichloromethane. The mixture is stirred at room temperature in the dark for 72 h. After the reaction is complete, filter the solution, collect the filtrate, concentrate the filtrate by rotary evaporation, and add it dropwise to ice-cold ether to precipitate the precipitate. Wash the precipitate continuously with ice-cold ether until the yellow color of the upper solvent disappears. Then filter the precipitate and collect the filter cake. Dry the cake under vacuum at room temperature to obtain a light yellow macromolecular chain transfer agent containing polyethylene glycol segments with a molecular weight of 5000.

[0067] By selecting polyethylene glycol monomethyl ether with a molecular weight of 2000 or 10000, macromolecular chain transfer agents containing polyethylene glycol segments with a molecular weight of 2000 or 10000 can be prepared under the same preparation conditions.

[0068] The prepared macromolecular chain transfer agent containing polyethylene glycol segments with a molecular weight of 5000 was utilized... 1 HNMR characterization, NMR spectrum as attached. Figure 4 As shown in the figure, the terminal methyl proton peak is 0.90 ppm (3H); the methylene and methyl proton peaks are 1.15-1.49 ppm (18H), 1.53-2.10 ppm (8H), and 3.28 ppm (2H); and the proton peak on the polyethylene glycol chain is 3.67 ppm (452H), confirming that a macromolecular chain transfer agent containing polyethylene glycol segments with a molecular weight of 5000 has been successfully prepared.

[0069] Example 4: Amphiphilic block polymers containing fluorinated phenylboronic acid groups

[0070] The amphiphilic block copolymer containing fluorinated phenylboronic acid groups is prepared by living controlled radical polymerization using acrylamide fluorinated phenylboronic acid as monomer in the presence of a macromolecular chain transfer agent containing polyethylene glycol segments. A typical preparation process is as follows: In a 50 mL reaction tube, a macromolecular chain transfer agent containing 5000 molecular weight polyethylene glycol segments (0.265 g, 0.05 mmol), acrylamide fluorinated phenylboronic acid (2.08 g, 10 mmol), AIBN (1.64 mg, 0.01 mmol), and 20 mL of N,N-dimethylformamide are added. After complete dissolution, the mixture undergoes three vacuum-argon purging cycles and is polymerized at 60 °C for 48 h. After the reaction, the product is dialyzed against deionized water for 48 h and then freeze-dried to obtain a pale yellow block copolymer. This polymer contains polyethylene glycol segments with a molecular weight of 5000 and fluorinated phenylboronic acid segments with a molecular weight of 30000.

[0071] The prepared amphiphilic block polymer containing fluorinated phenylboronic acid groups was utilized... 1 HNMR characterization, NMR spectrum as attached. Figure 5 As shown in the figure, the proton peaks on the macromolecular chain transfer agent and the polyphenylboronic acid backbone are 0.81-2.62 ppm and 6.60-8.02 ppm, respectively; while the proton peak on the polyethylene glycol chain is 3.40-3.71 ppm, confirming the successful preparation of the amphiphilic block polymer containing fluorinated phenylboronic acid groups.

[0072] Example 5: Amphiphilic block polymers containing fluorinated phenylboronic acid groups

[0073] The amphiphilic block polymer containing fluorinated phenylboronic acid groups is prepared by living controlled radical polymerization using methacrylamide fluorinated phenylboronic acid as monomer in the presence of a macromolecular chain transfer agent containing polyethylene glycol segments. A typical preparation process is as follows: 0.46 g (0.2 mmol) of a macromolecular chain transfer agent containing polyethylene glycol segments with a molecular weight of 2000, 2.22 g (10 mmol) of methacrylamide fluorinated phenylboronic acid, 8.2 mg (0.05 mmol) of AIBN, and 40 mL of dimethyl sulfoxide are added to a 50 mL reaction tube. After complete dissolution, the mixture undergoes three cycles of vacuum-argon purging, followed by polymerization at 80 °C for 8 h. After the reaction, the product is precipitated in ethanol and then vacuum-dried to obtain a pale yellow block copolymer. This polymer contains polyethylene glycol segments with a molecular weight of 2000 and fluorinated phenylboronic acid segments with a molecular weight of 10000.

[0074] Example 6: Amphiphilic block polymers containing fluorinated phenylboronic acid groups

[0075] The amphiphilic block copolymer containing fluorinated phenylboronic acid groups is prepared by living controlled radical polymerization using acrylamide fluorinated phenylboronic acid as monomer in the presence of a macromolecular chain transfer agent containing polyethylene glycol segments. A typical preparation process is as follows: 0.5 g (0.05 mmol) of a macromolecular chain transfer agent containing 10,000 molecular weight polyethylene glycol segments, 2.08 g (10 mmol) of acrylamide fluorinated phenylboronic acid, 1.64 mg (0.01 mmol) of AIBN, and 40 mL of tetrahydrofuran are added to a 50 mL reaction tube. After complete dissolution, the mixture is subjected to three cycles of vacuum-argon purging and then reacted at 70 °C for 24 h. After the reaction is complete, most of the tetrahydrofuran is removed by rotary evaporation, followed by precipitation in acetone and vacuum drying to obtain a pale yellow block copolymer. This polymer contains polyethylene glycol segments with a molecular weight of 10,000 and fluorinated phenylboronic acid segments with a molecular weight of 30,000.

[0076] Example 7: Amphiphilic block polymers containing fluorinated phenylboronic acid groups

[0077] The amphiphilic block polymer containing fluorinated phenylboronic acid groups is prepared by living controlled radical polymerization using acrylamide fluorinated phenylboronic acid as monomer in the presence of a macromolecular chain transfer agent containing polyethylene glycol segments. A typical preparation process is as follows: 0.265 g (0.05 mmol) of a macromolecular chain transfer agent containing 5000 molecular weight polyethylene glycol segments, 3.12 g (15 mmol) of acrylamide fluorinated phenylboronic acid, 1.64 mg (0.01 mmol) of AIBN, and 50 mL of dioxane are added to a 100 mL reaction tube. After complete dissolution, the mixture is subjected to three cycles of vacuum-argon purging and then reacted at 70 °C for 24 h. After the reaction, the product is dialyzed against deionized water for 48 h and then freeze-dried to obtain a pale yellow block copolymer. The polymer contains polyethylene glycol segments with a molecular weight of 5000 and fluorinated phenylboronic acid segments with a molecular weight of 50000.

[0078] Example 8: Amphiphilic block polymers containing fluorinated phenylboronic acid groups

[0079] The amphiphilic block polymer containing fluorinated phenylboronic acid groups is prepared by living controlled radical polymerization using acrylamide fluorinated phenylboronic acid as monomer in the presence of a macromolecular chain transfer agent containing polyethylene glycol segments. A typical preparation process is as follows: In a 100 mL reaction tube, a macromolecular chain transfer agent containing polyethylene glycol segments (0.265 g, 0.05 mmol), acrylamide fluorinated phenylboronic acid (1.25 g, 0.6 mmol), AIBN (1.64 mg, 0.01 mmol), and 30 mL of a 1:1 mixture of dioxane and dimethyl sulfoxide are added. After complete dissolution, the mixture is subjected to three vacuum-argon purging cycles and then reacted at 70 °C for 24 h. After the reaction, the product is precipitated in diethyl ether and vacuum dried to obtain a pale yellow block copolymer. This polymer contains polyethylene glycol segments with a molecular weight of 5000 and fluorinated phenylboronic acid segments with a molecular weight of 20000.

[0080] Example 9: Preparation of Iodine-Based Nanocontrast Agent

[0081] The preparation of iodine-based nanocontrast agents involves dissolving an amphiphilic block polymer containing fluorinated phenylboronic acid groups and a water-soluble nonionic polyhydroxy iodine-based contrast agent in an organic mixed solvent, stirring to induce an esterification reaction, followed by dialyzing in a pH 7.4 PBS buffer solution and then lyophilizing. A typical preparation process is as follows: an amphiphilic block polymer containing fluorinated phenylboronic acid groups is selected, wherein the molecular weight of the polyethylene glycol segment is 5000 and the molecular weight of the fluorinated phenylboronic acid segment is 30000. The polymer (0.35 g, 10 μmol, containing approximately 1.5 mmol of fluorinated phenylboronic acid groups) was dissolved in 20 mL of a mixed solvent of methanol and dimethyl sulfoxide in a volume ratio of 1:1. Then, iodixanol (1.55 g, 1 mmol, containing approximately 4 mmol of ortho-dihydroxy groups) containing four ortho-dihydroxy groups was added. After complete dissolution, the mixture was reacted at room temperature (25 °C) for 24 h. The aqueous solution of the iodine-based nanocontrast agent was dialyzed in PBS solution at pH 7.4, and then freeze-dried to obtain the iodine-based nanocontrast agent.

[0082] The formation mechanism of iodine-based nanocontrast agents is shown in the attached figure. Figure 6 As shown, the obtained iodine-based nanocontrast agent was prepared by esterification crosslinking of fluorinated phenylboronic acid groups and ortho-dihydroxy groups. The particle size, particle size distribution, and morphology of the iodine-based nanocontrast agent were tested using a laser particle size analyzer and transmission electron microscopy, as shown in the attached figure. Figure 7 and attached Figure 8 As shown in the figure, the iodine-based nanocontrast agent consists of nanoparticles with a particle size of approximately 200 nm and a very narrow particle size distribution. The dispersion stability of the prepared iodine-based nanocontrast agent was tested, as shown in the attached figure. Figure 9 As shown, the results indicate that the iodine-based nanocontrast agent possesses excellent dispersion stability. The contrast performance of the prepared iodine-based nanocontrast agent was tested, as shown in the attached figure. Figure 10 As shown in the figure, when the concentration of the iodine-based nanocontrast agent reaches 120 mg / mL, the CT value is as high as 1150 HU, indicating that the prepared iodine-based nanocontrast agent has good contrast performance. The results demonstrate that the iodine-based nanocontrast agent possesses excellent contrast performance.

[0083] The formation mechanism of iodine-based nanocontrast agents is as follows: Figure 6 As shown in the figure, phenylboronic acid groups in the polymer are covalently crosslinked with multiple ortho-dihydroxy groups in the iodine-based contrast agent to form phenylboronic acid ester bonds, thereby forming an iodine-based nanocontrast agent.

[0084] The particle size and particle size distribution of the prepared iodine-based nanocontrast agent were tested using a laser particle size analyzer, as shown in the attached figure. Figure 7 As shown in the figure, the obtained iodine-based nanocontrast agent has a particle size of approximately 160 nm and a very narrow particle size distribution.

[0085] The particle size and morphology of the prepared iodine-based nanocontrast agent were tested using transmission electron microscopy, as shown in the attached figure. Figure 8 As shown in the figure, the obtained iodine-based nanocontrast agent has a spherical structure with a particle size of approximately 150 nm.

[0086] The dispersion stability of the prepared iodine-based nanocontrast agent was tested, as shown in the attached figure. Figure 9 As shown in the figure, the obtained iodine-based nanocontrast agent can be stably dispersed for a long time.

[0087] The contrast performance of the prepared iodine-based nanocontrast agent was tested, as shown in the attached figure. Figure 10 As shown in the figure, the obtained iodine-based nanocontrast agent has good contrast performance.

[0088] Example 10: Preparation of iodine-based nanocontrast agents

[0089] The preparation of iodine-based nanocontrast agents involves dissolving an amphiphilic block polymer containing fluorinated phenylboronic acid groups and a water-soluble nonionic polyhydroxy iodine-based contrast agent in an organic mixed solvent, stirring to induce an esterification reaction, followed by dialyzing in a pH 7.4 PBS buffer solution and then lyophilizing. A typical preparation process is as follows: An amphiphilic block polymer containing fluorinated phenylboronic acid groups is selected. This polymer contains polyethylene glycol segments with a molecular weight of 10,000 and fluorinated phenylboronic acid segments with a molecular weight of 50,000. This polymer (0.6 g, 10 μmol) is dissolved in 30 mL of a mixed solvent of methanol and N,N-dimethylformamide in a 1:1 volume ratio. Then, iodixanol containing four ortho-dihydroxy groups (2.325 g, 1.5 mmol) is added. After complete dissolution, the reaction is carried out at 60 °C for 4 h. The aqueous solution of the iodine-based nanocontrast agent is dialyzed in a pH 7.4 PBS solution, and then lyophilized to obtain the iodine-based nanocontrast agent.

[0090] Example 11: Preparation of iodine-based nanocontrast agents

[0091] The preparation of iodine-based nanocontrast agents involves dissolving an amphiphilic block polymer containing fluorinated phenylboronic acid groups and a water-soluble nonionic polyhydroxy iodine-based contrast agent in an organic mixed solvent, stirring to induce an esterification reaction, followed by dialyzing in a pH 7.4 PBS buffer solution and then lyophilizing. A typical preparation process is as follows: An amphiphilic block polymer containing fluorinated phenylboronic acid groups is selected. This polymer contains polyethylene glycol segments with a molecular weight of 2000 and fluorinated phenylboronic acid segments with a molecular weight of 10000. This polymer (0.12 g, 10 μmol) is dissolved in 30 mL of a 1:1 volume ratio of ethanol and dimethyl sulfoxide. Then, iodixanol containing four ortho-dihydroxy groups (4.65 g, 3 mmol) is added. After complete dissolution, the reaction is carried out at 40 °C for 10 h. The aqueous solution of the iodine-based nanocontrast agent is dialyzed in a pH 7.4 PBS solution, and then lyophilized to obtain the iodine-based nanocontrast agent.

[0092] Examples 12-18: Preparation of iodine-based nanocontrast agents

[0093] Following the method of Example 9, by changing the type and content of the water-soluble nonionic polyhydroxy iodine-based contrast agent, various iodine-based contrast agents can be obtained, with specific parameters shown in Table 1. In all these examples, 10 μmol of an amphiphilic block polymer containing fluorinated phenylboronic acid groups was selected. The polymer contained polyethylene glycol segments with a molecular weight of 5000 and fluorinated phenylboronic acid segments with a molecular weight of 30000. The solvent used was a mixture of methanol and dimethyl sulfoxide in a 1:1 volume ratio, and the reaction was carried out at 25°C for 24 h.

[0094] Table 1 Iodine-based nanocontrast agents

[0095]

[0096] As shown in Examples 12-18, by utilizing the esterification reaction between the fluorinated phenylboronic acid group and the ortho-dihydroxy group inherent in the water-soluble nonionic polyhydroxy iodine-based contrast agent, and by controlling the ratio of the fluorinated phenylboronic acid group to the ortho-dihydroxy group, iodine-based nano-contrast agents can be prepared simply and efficiently. Moreover, the prepared iodine-based nano-contrast agents have a narrow particle size distribution, high dispersion stability, and good imaging performance.

[0097] The technical solutions disclosed and proposed in this invention can be implemented by those skilled in the art by appropriately modifying the conditions and routes, etc. Although the methods and preparation techniques of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.

Claims

1. A method for preparing an iodine-based nanocontrast agent, characterized in that, An amphiphilic block polymer containing fluorinated phenylboronic acid groups was crosslinked with a water-soluble nonionic polyhydroxy iodine-based contrast agent, and then iodine-based nanocontrast agent was prepared by phenylboronic acid esterification reaction. The amphiphilic block polymer containing fluorinated phenylboronic acid groups is composed of hydrophilic polyethylene glycol segments with a number-average molecular weight of 2000-10000 and hydrophobic segments with a number-average molecular weight of 10000-50000 containing fluorinated phenylboronic acid groups. Its structural formula is as follows: ； In the structural formula, R is H or CH3; when R is H, it is prepared using acrylamide fluorinated phenylboronic acid as a monomer; when R is CH3, it is prepared using methacrylamide fluorinated phenylboronic acid as a monomer.

2. The method for preparing the iodine-based nanocontrast agent as described in claim 1, characterized in that, An amphiphilic block polymer containing fluorinated phenylboronic acid groups and a water-soluble nonionic polyhydroxy iodide contrast agent were dissolved in an organic mixed solvent, mixed and stirred at 25-60°C for 4-24 h, and then lyophilized after dialyzing in pH 7.4 PBS buffer solution.

3. The method for preparing the iodine-based nanocontrast agent as described in claim 2, characterized in that, A reaction solution was prepared by mixing an amphiphilic block polymer containing fluorinated phenylboronic acid groups and a water-soluble nonionic polyhydroxy iodide contrast agent in a molar ratio of fluorinated phenylboronic acid groups to ortho-dihydroxy groups of 1:2 to 1:

8.

4. The method for preparing the iodine-based nanocontrast agent as described in claim 1, characterized in that, Water-soluble nonionic polyhydroxy iodine-based contrast agents contain 2 to 4 ortho-dihydroxy groups in their molecular structure, including iohexol, iodofol, iodixanol, iopromide, iodomeprazole, iodipoxetine, iodipoxetine, or iodritol.

5. The method for preparing the iodine-based nanocontrast agent as described in claim 2, characterized in that, Organic mixed solvents are mixtures of methanol or ethanol with dimethyl sulfoxide or N,N-dimethylamide.

6. The method for preparing the iodine-based nanocontrast agent as described in claim 5, characterized in that, The organic mixed solvent is a mixture of methanol and dimethyl sulfoxide in a volume ratio of 1:1.

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