Application of nano-carbon-iodine calcium alginate microspheres in preparation of X-ray / MR bimodal imaging embolization material

Abstract

The application belongs to the technical field of medical materials, and provides application of nano-carbon-iodine calcium alginate microspheres in preparation of X-ray / MR bimodal imaging embolization materials. The microspheres have X-ray and MR imaging capabilities, can be clearly imaged under conventional imaging equipment (such as CT and DSA) of interventional surgery, and have MR imaging capability. Animal experiments prove that the microspheres have excellent X-ray and MR bimodal imaging performance and embolization effect, and can be monitored by imaging throughout the operation and postoperative period. The application effectively solves the technical limitation that the existing embolization materials cannot have X-ray and MR dual imaging functions. The material preparation method is simple, stable and biologically safe, can realize industrial production, and has high clinical application value.

Description

Technical Field

[0001] This invention belongs to the field of medical materials technology, and in particular relates to the application of nano-carbon-iodine calcium alginate microspheres in the preparation of X-ray / MR dual-modal imaging embolization materials. Background Technology

[0002] Embolizing microspheres are commonly used embolizing materials in interventional treatment of primary liver cancer. Although there are many types of embolizing microspheres available clinically, a common problem is that the materials themselves cannot be visualized under X-rays. During the procedure, an iodine-containing contrast agent is required for imaging. However, the surgeon sees the contrast agent, not the embolizing agent, while the clinician actually wants to observe the embolizing agent, not the contrast agent. This creates a disconnect between the actual contrast agent used during the procedure and the imaging requirements of the embolizing material. More importantly, existing embolizing materials cannot be visualized by magnetic resonance imaging (MR) in postoperative monitoring, resulting in a lack of intuitive and reliable imaging evidence for postoperative disease assessment and complication diagnosis, thus limiting visualization and precise management throughout the treatment process.

[0003] In existing studies, barium sulfate calcium alginate microspheres (Wang Q, Qian K, Liu S, et al. X-rayvisible and uniform alginate microspheres loaded with in situ synthesized BaSO4 nanoparticles for in vivo transcatheter arterial embolization[J]. Biomacromolecules. 2015 Apr 13;16(4):1240-6.) showed slightly better imaging performance than calcium, but barium has a low toxicity threshold, which may limit its widespread use by clinicians. Tantalum nanoparticles calcium alginate (Zeng J, Li L, Zhang H, et al. Radiopaque and uniform alginate microspheres loaded with tantalum nanoparticles for real-time imaging during transcatheter arterialembolization[J]. Theranostics. 2018 Aug 10;8(17):4591-4600.) are expensive, and their toxicity needs further clarification. Calcium alginate iodized oil microspheres (Yi Hongfu, Ren Dongwen, Bao Decai, et al. Preparation of autoradiographic calcium alginate embolization microspheres [J]. Functional Materials, 2006, 37(12):1988-1990.) have good imaging properties, but the degraded iodized oil is a liquid embolization material, which may migrate, has poor adaptability to some organs, and has limited storage time after preparation, which makes clinical application difficult. Therefore, existing materials lack a function that can synergistically achieve dual-modal imaging of X-ray and MR, making it difficult to support imaging evaluation throughout the entire interventional treatment cycle.

[0004] Nano carbon black is a novel carbon-based nanomaterial with high drug loading capacity, good biocompatibility, and tunable physical and chemical properties, leading to its widespread application in the medical field in recent years. Applications of nano carbon black in biomedical imaging include: Nano carbon black can achieve good dispersibility and biocompatibility through surface modification, and can be used as an imaging probe in imaging techniques. It can also serve as a raw material for MRI contrast agents; its high absorption and scattering rates can enhance the imaging effects of corresponding imaging techniques. Furthermore, nano carbon black can serve as an excellent drug carrier and is widely used in pharmaceuticals. It can be used to prepare nano carbon black-based biomaterials and tissue engineering materials to achieve the repair and regeneration of biomaterials. In addition, nano carbon black can be widely used in the manufacture of artificial joints. The broad application prospects of nanoparticles are not limited to drugs, imaging and materials, but can also be applied to multiple fields such as tumor treatment and artificial organ manufacturing (Klein AL, Nugent g, Cavendish J, geldenhuys WJ, Sriram K, Porter D, Fladeland R, Lockman PR, Sherman JH. Nanoparticles as a Tool in Neuro-Oncology Theranostics. Pharmaceutics. 2021 Jun 24;13(7):948.).

[0005] Based on this, the present invention aims to overcome the technical limitations of existing embolization materials that cannot have both X-ray and MR imaging functions, and proposes the application of nano-carbon-iodine calcium alginate microspheres in the preparation of X-ray / MR dual-modal imaging embolization materials. Summary of the Invention

[0006] The purpose of this invention is to provide an application of nano-carbon-iodine calcium alginate microspheres in the preparation of X-ray / MR dual-modal imaging embolization materials, aiming to solve the technical problem that existing embolization materials have a single imaging mode, that is, they cannot integrate X-ray and MR dual-modal imaging functions on the same material.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] An application of nano-carbon-iodine calcium alginate microspheres in the preparation of X-ray / MR dual-modal imaging embolization materials. The nano-carbon-iodine calcium alginate microspheres have a calcium alginate cross-linked network framework, and iodine and nano-carbon powder are loaded in the calcium alginate cross-linked network framework, so that the X-ray / MR dual-modal imaging embolization material can achieve dual-modal imaging under X-ray and magnetic resonance imaging.

[0009] Further applications include the preparation of X-ray / MR dual-modal imaging embolization materials for transarterial embolization therapy of solid tumors.

[0010] Furthermore, dual-modal imaging includes: X-ray / MR dual-modal imaging where the embolic material exhibits a density no less than that of bone in X-ray imaging, and produces a signal contrast distinct from the surrounding background tissue in magnetic resonance T1-weighted and / or T2-weighted imaging.

[0011] Furthermore, the iodine loading rate of the nano-carbon-iodine calcium alginate microspheres is 5-50%, the carbon loading rate is 5-40%, and the particle size is 20-1400μm.

[0012] Furthermore, the particle size of the nano-carbon powder is 2-500 nm.

[0013] A method for preparing nano-carbon-iodine calcium alginate microspheres for the above applications includes the following steps:

[0014] Step 1: Prepare an aqueous solution of sodium alginate containing iodine;

[0015] Step 2: Prepare an aqueous solution containing a cross-linking agent; the mass concentration of the aqueous solution containing the cross-linking agent is 20-150 mg / mL;

[0016] Step 3: Add nano-carbon powder to the additives to form a first suspension; mix the first suspension with the iodine-containing sodium alginate aqueous solution prepared in Step 1 and stir to form a second suspension;

[0017] Step 4: The second suspension is loaded into a syringe and injected into the aqueous solution containing the crosslinking agent prepared in Step 2. The aqueous solution containing the crosslinking agent is stirred to obtain nano-carbon-iodine calcium alginate microspheres.

[0018] Step 5: Filter and dry the nano-carbon-iodine calcium alginate microspheres obtained in Step 4;

[0019] Step 6: The nano-carbon-iodine calcium alginate microspheres obtained in Step 5 are sieved and sterilized by irradiation under cobalt 60.

[0020] Furthermore, the iodine-containing sodium alginate aqueous solution is obtained by dissolving iodine, potassium iodide, and sodium alginate in water, wherein the mass ratio of iodine, potassium iodide, and sodium alginate is iodine:potassium iodide:sodium alginate = 5-10:10-30:0.1-2.0, and the mass concentration of the sodium alginate aqueous solution is 10-20 mg / mL. Preferably, the mass ratio of iodine to potassium iodide is 10:10-14.

[0021] Furthermore, the crosslinking agent is a divalent metal cationic compound selected from one or more of magnesium chloride, zinc chloride, copper chloride, barium chloride, ferrous sulfate, magnesium sulfate, zinc sulfate, calcium chloride, calcium hypochlorite, calcium bromide, and calcium iodide.

[0022] Furthermore, the additives are one or more of water, anhydrous ethanol, propanol, and Tween 80.

[0023] Furthermore, each milliliter of the first suspension contains 0.05-0.15 g of nano-carbon powder; the mass ratio of sodium alginate to nano-carbon powder in the second suspension is 2-3:1.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention provides an application of nano-carbon-iodine calcium alginate microspheres in the preparation of X-ray / MR dual-modal imaging embolization materials. These microspheres possess both X-ray and MR imaging capabilities, allowing for clear imaging under conventional interventional surgical imaging equipment (such as CT and DSA), and also exhibiting MR imaging ability. This overcomes the limitations of existing clinical particulate embolization materials, which lack X-ray imaging, MR imaging, and simultaneous X-ray and MR imaging capabilities. The material preparation method is simple, exhibits good stability and biosafety, and can be industrialized, demonstrating high clinical application value. The specific effects are reflected in: (1) It has direct visibility in imaging, which facilitates intuitive and positive evaluation of the clinical embolization effect; (2) It helps to diagnose the cause of the disease and can provide important imaging diagnostic basis for the diagnosis of suspected ectopic embolism after interventional surgery, playing a decisive role in the treatment of related diseases; (3) It realizes real-time precision in the clinical operation process and solves the problem that the embolization material cannot be directly visualized under X-ray in interventional treatment; (4) Animal experiments have confirmed that the microsphere has excellent X-ray and MR dual-modal imaging performance and embolization effect, and can be monitored by imaging throughout the operation and after surgery; (5) The addition of nano carbon components provides potential for further expansion of its drug loading and delivery functions. Attached Figure Description

[0026] Figure 1 The image shows the morphology of the nano-carbon-iodine calcium alginate microspheres prepared in Example 1 under an optical microscope. In the figure: a shows the naked-eye image of the nano-carbon-iodine calcium alginate microspheres placed in a syringe; b shows the microsphere image under 10x magnification under an optical microscope; c shows the microsphere image after it has been broken up and magnified up to 10x; d shows the microsphere image after it has been broken up and magnified up to 40x.

[0027] Figure 2 Fourier transform infrared spectroscopy (FTIR) image of the nano-carbon-iodine calcium alginate microspheres prepared in Example 1.

[0028] Figure 3 The X-ray diffraction pattern of the nano-carbon-iodine calcium alginate microspheres prepared in Example 1 is shown.

[0029] Figure 4This is a multimodal imaging observation of the nano-carbon-iodine calcium alginate microspheres prepared in Example 1.

[0030] Figure 5 The image shows the development of nano-carbon-iodine calcium alginate microspheres prepared in Example 1 in an isolated liver. In the image, squares indicate the development of microspheres after injection of 0.1g of microspheres and 1mL of 0.9% sodium chloride; circles indicate the development of microspheres after injection of 0.2g of microspheres and 1mL of 0.9% sodium chloride; and arrows indicate the development of the control group (BIOSPHERE microspheres (300-500μm)).

[0031] Figure 6 The image shows the CT imaging of the nano-carbon-iodine calcium alginate microspheres prepared in Example 1 within isolated porcine liver blood vessels; in the figure: a represents the horizontal plane image; b represents the cross-sectional image.

[0032] Figure 7 The images show the CT images of the nano-carbon-iodine calcium alginate microspheres prepared in Example 1 used for embolization experiments in rabbits. The control group consisted of BIOSPHERE microspheres (300-500 μm). In the figures: a represents a cross-sectional image; b represents a coronal image; c represents a sagittal image; and d represents a three-dimensional reconstructed image.

[0033] Figure 8 The image shows the MR imaging of the nano-carbon-iodine calcium alginate microspheres prepared in Example 1 during an embolization experiment in rabbits.

[0034] Figure 9 The images show the embolization effects of the experimental and control groups at different time points after hepatic artery embolization.

[0035] Figure 10 The results of the rabbit auricular median artery embolization experiment using nano-carbon-iodine calcium alginate microspheres prepared in Example 1 are shown in the figure. In the figure: a represents the preoperative period; b represents the immediate postoperative period; c represents the 24-hour postoperative period; d represents the 48-hour postoperative period; and e represents the 72-hour postoperative period. Detailed Implementation

[0036] To provide a clearer understanding of the technical features, objectives, and beneficial effects of this invention, the technical solution of this invention is described in detail below, but this should not be construed as limiting the scope of implementation of this invention. Unless otherwise specified, the methods used in this invention are conventional methods in this technical field. In this invention, materials, reagents, or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0037] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0038] The nano-carbon powder used in the following examples was purchased from Suzhou CarbonFeng Graphene Technology Co., Ltd., with a particle size of 2-500nm.

[0039] Example 1: Preparation of nano-carbon-iodine-calcium alginate microspheres;

[0040] Step 1: Prepare an iodine-containing sodium alginate aqueous solution. Weigh 10g of iodine, 10g of potassium iodide, and 1.5g of sodium alginate into container A, and add 100mL of double-distilled water to make the system ratio iodine:potassium iodide (g):sodium alginate (g):water (mL) = 10:10:1.5:100; place the solution in container A on a stirrer and stir overnight (100r / min) until the sodium alginate is completely dissolved.

[0041] Step 2: Using calcium chloride as a crosslinking agent, prepare a calcium chloride aqueous solution with a concentration of 75 mg / mL, and let it stand for 2 hours for later use;

[0042] Step 3: Take 5 mL of anhydrous ethanol and place it in container B. Add 0.5 g of nano-carbon powder to form the first suspension. Add the first suspension to container A and adjust the system ratio to iodine:potassium iodide (g):sodium alginate (g):water (mL):anhydrous ethanol (mL):nano-carbon powder (g) = 10:10:1.5:100:5:0.5. Stir for more than 5 minutes to form the second suspension.

[0043] Step 4: The second suspension obtained in Step 3 is placed in a 10mL syringe (needle inner diameter 22G-223G) and injected into the calcium chloride aqueous solution prepared in Step 2 while it is being stirred, to obtain nano-carbon-iodine calcium alginate microspheres; wherein the stirring speed is about 500r / min, the injection speed is about 5mL / min, the distance between the syringe needle and the liquid level is controlled at 25-50cm, and the injection is carried out at a uniform speed;

[0044] Step 5: After the injection is completed, continue stirring for 30 minutes; filter out the calcium chloride-containing liquid after the spheres are formed, collect the nano-carbon-iodine calcium alginate microspheres, rinse the nano-carbon-iodine calcium alginate microspheres twice with double-distilled water, and then filter out the liquid; place the nano-carbon-iodine calcium alginate microspheres in a vacuum freeze dryer and dry (-55℃) for more than 14 hours.

[0045] Step 6: Place the dried nano-carbon-iodine calcium alginate microspheres into a sieve with a pore size of 20-1400μm for screening, and collect microspheres with a particle size of 20-1400μm; sterilize the qualified microspheres by irradiation under cobalt 60 for 30min.

[0046] Example 2: Preparation of nano-carbon-iodine-calcium alginate microspheres;

[0047] Step 1: Prepare an iodine-containing sodium alginate aqueous solution. Weigh 10g of iodine, 10g of potassium iodide, and 1.2g of sodium alginate into container A, and add 100mL of double-distilled water to make the system ratio reach iodine:potassium iodide (g):sodium alginate (g):water (mL) = 10:10:1.2:100; place the solution in container A on a stirrer and stir overnight (100r / min) until the sodium alginate is completely dissolved.

[0048] Step 2: Using calcium chloride as a crosslinking agent, prepare a calcium chloride aqueous solution with a concentration of 100 mg / mL, and let it stand for 2 hours for later use;

[0049] Step 3: Place 5 mL of propanol in container B, add 0.5 g of nano-carbon powder to form the first suspension; add the first suspension to container A above, and adjust the system ratio to iodine:potassium iodide (g):sodium alginate (g):water (mL):propanol (mL):nano-carbon powder (g) = 10:10:1.2:100:5:0.5, stir for more than 5 minutes to form the second suspension;

[0050] Step 4: The second suspension obtained in Step 3 is placed in a 10mL syringe (needle inner diameter 22G-223G) and injected into the calcium chloride aqueous solution prepared in Step 2 while it is being stirred, to obtain nano-carbon-iodine calcium alginate microspheres; wherein the stirring speed is about 500r / min, the injection speed is about 5mL / min, the distance between the syringe needle and the liquid level is controlled at 25-50cm, and the injection is carried out at a uniform speed;

[0051] Step 5: After the injection is completed, continue stirring for 30 minutes; filter out the calcium chloride-containing liquid after the spheres are formed, collect the nano-carbon-iodine calcium alginate microspheres, rinse the nano-carbon-iodine calcium alginate microspheres twice with double-distilled water, and then filter out the liquid; place the nano-carbon-iodine calcium alginate microspheres in a vacuum freeze dryer and dry (-55℃) for more than 14 hours.

[0052] Step 6: Place the dried nano-carbon-iodine calcium alginate microspheres into a sieve with a pore size of 20-1400μm for screening, and collect microspheres with a particle size of 20-1400μm; sterilize the qualified microspheres by irradiation under cobalt 60 for 30min.

[0053] Example 3: Preparation of nano-carbon-iodine-calcium alginate microspheres;

[0054] Step 1: Prepare an iodine-containing sodium alginate aqueous solution. Weigh 10g of iodine, 10g of potassium iodide, and 1.5g of sodium alginate into container A, and add 100mL of double-distilled water to make the system ratio iodine:potassium iodide (g):sodium alginate (g):water (mL) = 10:10:1.5:100; place the solution in container A on a stirrer and stir overnight (100r / min) until the sodium alginate is completely dissolved.

[0055] Step 2: Using calcium chloride as a crosslinking agent, prepare a calcium chloride aqueous solution with a concentration of 120 mg / mL, and let it stand for 2 hours for later use;

[0056] Step 3: Take 5 mL of Tween 80 and place it in container B. Add 0.75 g of nano-carbon powder to form the first suspension. Before preparing the microspheres, add it to the above container A to adjust the system ratio to iodine: potassium iodide (g): sodium alginate (g): water (mL): Tween 80 (mL): nano-carbon powder (g) = 10:10:1.5:100:5:0.75. Stir for more than 5 minutes to form the second suspension.

[0057] Step 4: The second suspension obtained in Step 3 is placed in a 10mL syringe (needle inner diameter 22G-223G) and injected into the calcium chloride aqueous solution prepared in Step 2 while it is being stirred, to obtain nano-carbon-iodine calcium alginate microspheres; wherein the stirring speed is about 500r / min, the injection speed is about 5mL / min, the distance between the syringe needle and the liquid level is controlled at 25-50cm, and the injection is carried out at a uniform speed;

[0058] Step 5: After the injection is completed, continue stirring for 30 minutes; filter out the calcium chloride-containing liquid after the spheres are formed, collect the nano-carbon-iodine calcium alginate microspheres, rinse the nano-carbon-iodine calcium alginate microspheres twice with double-distilled water, and then filter out the liquid; place the nano-carbon-iodine calcium alginate microspheres in a vacuum freeze dryer and dry (-55℃) for more than 14 hours.

[0059] Step 6: Place the dried nano-carbon-iodine calcium alginate microspheres into a sieve with a pore size of 20-1400μm for screening, and collect microspheres with a particle size of 20-1400μm; sterilize the qualified microspheres by irradiation under cobalt 60 for 30min.

[0060] Characterization and testing;

[0061] 1. The particle size and shape of the microspheres were determined using a micrometer under an optical microscope. The results are shown in [Figure number missing]. Figure 1 In the figures, a) is a naked-eye image of the nano-carbon-iodine calcium alginate microspheres placed in a 5mL syringe. The microspheres are black, matching the color of the carbon powder, and no free carbon powder is visible in the syringe solution. b) is a 10x magnified image of the microspheres under an optical microscope, showing their spherical shape. The carbon powder morphology was observed after the microspheres were cut with a blade. c) is a 10x magnified image of the broken microspheres, and d is a 40x magnified image. Figures c and d show that the carbon powder and calcium alginate matrix are tightly bound. The broken microspheres reveal a carbon powder encapsulated within the calcium alginate matrix, indicating that iodine and nano-carbon powder are co-encapsulated within the microspheres. The intact encapsulation after cutting confirms that iodine and nano-carbon powder are effectively encapsulated within the microspheres.

[0062] 2. The nano-carbon-iodine calcium alginate microspheres were analyzed using a Fourier transform infrared spectrometer. The results are shown in the figure. Figure 2 The results showed a wavenumber of 3423.9 cm⁻¹. -1 1630.43cm -1 563.86cm -1 The appearance of specific absorption peaks indicates that no new material was formed during the experiment, which is consistent with the experimental design.

[0063] 3. The nano-carbon-iodine calcium alginate microspheres were examined using an X-ray diffractometer. The results are shown in the figure below. Figure 3 The results showed a mixed morphology, with the smooth curve below suggesting a nano-carbon crystal structure, which is consistent with the design expectations.

[0064] 4. Testing of iodine encapsulation efficiency, iodine loading, carbon encapsulation efficiency, carbon loading, and water absorption rate;

[0065] The testing method is as follows:

[0066] Iodine encapsulation rate determination method: Encapsulated I = Total I - Unencapsulated I, Iodine encapsulation rate % = Encapsulated I / Total I * 100%. Prepare 500 mL of 1.5% (concentration unit 1.5 g / 100 mL) starch indicator, sodium thiosulfate titrant (0.1 mol / L), and 7.5% (7.5 g / 100 mL) calcium chloride solution. Collect the calcium chloride-containing liquid after microsphere formation in step 5 of Example 1, and the liquid filtered after rinsing the microspheres with double-distilled water, as a mixture and weigh it. Titrate the above mixture with the prepared sodium thiosulfate titrant (0.1 mol / L) until the reaction is almost finished, then add 2 mL of starch indicator and continue titrating until the blue color disappears. Each 1 mL of sodium thiosulfate titrant (0.1 mol / L) is equivalent to 12.69 mg of I2. Calculate the amount of iodine not encapsulated in the calcium alginate microspheres. The average value of three measurements is taken.

[0067] Method for determining iodine loading: Weigh 0.3 g of lyophilized nano-carbon-iodine calcium alginate microspheres into three separate beakers, each containing 0.1 g of microspheres. Dissolve the microspheres in 3% sodium citrate solution to release iodine. Titrate with sodium thiosulfate solution, and finally titrate with 1.5% starch indicator for color development. Calculate the iodine content using sodium thiosulfate titrant. Iodine loading rate % = iodine / total nano-carbon-iodine calcium alginate microspheres * 100%. Take the average of three measurements.

[0068] Carbon encapsulation efficiency determination method: Weigh a 2.5 mL syringe, draw 2 mL of the prepared nano-carbon-iodine sodium alginate solution, weigh it, and subtract the syringe weight to obtain the weight of the nano-carbon-iodine sodium alginate solution. Prepare microspheres from the solution in the syringe, then rinse repeatedly with 0.9% sodium chloride, allow to stand, and centrifuge. Unencapsulated carbon powder floats on top of the liquid, appearing black; discard the supernatant. Collect the floating matter, dry it, freeze-dry it, and weigh it; this is the unencapsulated carbon powder. Encapsulated carbon = total carbon - unencapsulated carbon; carbon encapsulation efficiency % = encapsulated carbon / total carbon * 100%. Repeat the experiment 3 times and take the average value of the measurements.

[0069] Carbon drug loading rate determination method: 2 mL of the prepared nano-carbon-iodine sodium alginate solution was drawn for microsphere preparation. After preparation, the syringe was rinsed three times with calcium chloride to ensure that all sodium alginate was converted into calcium alginate. The prepared nano-carbon-iodine calcium alginate microspheres were centrifuged, the liquid was discarded, and the microspheres were freeze-dried. The reconstituted carbon-iodine calcium alginate microspheres were then weighed. Since the carbon encapsulation rate was close to 100%, the amount of carbon in the solution was the amount of carbon loaded into the microspheres. Carbon drug loading rate = carbon / total carbon-iodine calcium alginate microspheres * 100%. Three measurements were taken, and the average value was used.

[0070] Water absorption rate determination method: Weigh an empty vial, place the nano-carbon-iodine-calcium alginate microspheres from Example 1 into the vial, invert it onto filter paper, wait for the water to be absorbed, weigh the vial, and subtract the weight of the empty vial to obtain the wet weight (B). Freeze-dry the weighed vial, weigh it again after freeze-drying, and subtract the weight of the empty vial to obtain the dry weight (G). Compare the two to obtain the water swelling rate. The average value of the three measurements is taken.

[0071] The results are as follows:

[0072] The average iodine encapsulation efficiency of the nano-carbon-iodine sodium alginate microspheres prepared in Example 1 was 70.31 ± 1.08%; the iodine loading rate was 44.7%; the average nano-carbon encapsulation efficiency was 98.0%; the carbon loading rate was 30.99%; and the average water absorption rate was 1070%.

[0073] The average iodine encapsulation efficiency of the nano-carbon-iodine sodium alginate microspheres prepared in Example 2 was 60.59 ± 2.10%; the iodine loading rate was 38.5%; the average nano-carbon encapsulation efficiency was 98.5%; the carbon loading rate was 39.99%; and the average water absorption rate was 1120%.

[0074] The average iodine encapsulation efficiency of the nano-carbon-iodine sodium alginate microspheres prepared in Example 3 was 65.42 ± 3.10%; the iodine loading rate was 43.3%; the average nano-carbon encapsulation efficiency was 98.3%; the carbon loading rate was 33.01%; and the average water absorption rate was 1221%.

[0075] 5. Development performance testing;

[0076] Microsphere imaging performance test: 0.5g of nano-carbon-iodine calcium alginate microspheres were placed in 0.9% sodium chloride solution (physiological saline) to prepare a suspension. 5mL of the suspension was then loaded into a syringe. First, naked-eye observation was performed. Figure 4 The microspheres appeared as black granules and settled at the bottom of the syringe. The suspension was then observed using a digital gastrointestinal X-ray machine and a DSA machine. A syringe containing the suspension was placed on the patient's lateral thigh for CT examination. Clinical X-ray fluoroscopy (80kVp, 529mA, 65ms delay, 7 frames / second) and standard Allura Xper image processing were used, along with X-ray radiography (120kVp, 350mA, 0.5mm collimator, FOV 22x22cm). Figure 4 As shown, microspheres are clearly visible under digital gastrointestinal imaging, appear as granular structures with uniform density and clear imaging under DSA, and are clearly visible under CT, with a density close to that of bone and significantly higher than that of muscle.

[0077] 6. Ex vivo liver experiments;

[0078] One commercially available pig liver, one syringe, and an appropriate amount of heparinized saline solution were prepared. The pig liver was first repeatedly flushed with heparinized saline solution to remove thrombi from the portal vein and hepatic artery. Suspensions of 0.1g and 0.2g of 0.1g / mL nano-carbon-iodine-calcium alginate microspheres were prepared with 1mL of 0.9% sodium chloride solution and injected into the pig liver parenchyma as the experimental group. Simultaneously, an equal volume of commercially available BIOSPHERE microspheres (Merit Medical, USA) (300-500μm) was injected into another portion of the pig liver parenchyma as the control group. The pig liver was then placed under a DSA machine to observe the imaging effect. The results are as follows: Figure 5 As shown in the figure, the square markings correspond to the experimental group areas injected with 0.1g microspheres and 1mL of 0.9% sodium chloride, where faint development is visible; the circular markings correspond to the experimental group areas injected with 0.2g microspheres and 1mL of 0.9% sodium chloride, where clear development is visible, indicating that the clarity of development increases with the increase of microsphere dosage; the control group area (marked by arrows) shows no development.

[0079] Take one commercially available pig liver, one syringe, and an appropriate amount of heparinized saline. First, repeatedly flush the pig liver with heparinized saline to remove thrombi from the portal vein and hepatic artery. Prepare a suspension by mixing 0.1g of 0.1g / mL nano-carbon-iodine calcium alginate microspheres with 1mL of 0.9% sodium chloride. Inject this suspension into the pig liver parenchyma as the experimental group. Simultaneously, inject an equal volume of commercially available BIOSPHERE microspheres (300-500μm) into another portion of the pig liver parenchyma as the control group. Then, observe the imaging effect under a CT scanner. The results are as follows: Figure 6As shown: Image a is a horizontal localization image of nano-carbon-iodine calcium alginate microspheres in an isolated pig liver, showing high-density granular imaging along the blood vessels, with granular imaging visible in the terminal blood vessels; Image b is a cross-sectional image, showing high-density imaging along the blood vessels, with granular and strip-shaped embolic particles visible around the periphery, clearly imaged.

[0080] 7. Application of nano-carbon-iodine-calcium alginate microspheres;

[0081] Adult female New Zealand albino rabbits (provided by the Animal Experiment Center of Nanjing Drum Tower Hospital), weighing 4.0-5.0 kg, were used in the experiment and were approved by the Animal Ethics Committee of Nanjing Drum Tower Hospital. The rabbits were allowed free access to food and water during the experiment.

[0082] 7.1 Rabbit in vivo imaging experiment;

[0083] First, an in vivo imaging experiment was conducted in rabbits, in which nano-carbon-iodine calcium alginate microspheres were injected into the liver, lungs, and heart of rabbits, respectively.

[0084] CT imaging: Whole-body CT scans were performed on rabbits under tube voltage of 120KV and tube current of 90mA. Three-dimensional reconstruction of the scanned images was performed, and the images were observed from multiple different angles. The results are as follows: Figure 7 As shown: Image a is a cross-sectional image, showing high-density contrast in the liver and heart regions; Image b is a coronal image, showing patchy high-density shadows within the pleural cavity; Image c is a sagittal image, showing clear high-density contrast in the mediastinum, pleural cavity, liver, and abdominal cavity; Image d is a three-dimensional reconstructed image, showing high-density contrast with near-bone density within the pleural and abdominal cavities. In vivo CT experiments in rabbits confirmed that these microspheres can achieve clear contrast in the liver, pleural cavity, heart, and gastrointestinal tract, demonstrating excellent CT imaging performance.

[0085] MR imaging: Specimens following hepatic artery embolization (injection of nano-carbon-iodine calcium alginate microspheres into rabbit liver) underwent CT examination followed by MR scanning (Philips Ingenia Elition X, Netherlands). Scanning conditions: magnetic field strength 3.0 Tesla, gradient field strength 45 mT / m, gradient switching rate 220 T / s. Commercially available BIOSPHERE microspheres (300-500 μm) served as a control group. Results are as follows... Figure 8 As shown: In both T2 and T1 sequences, the experimental group could clearly display tumor signals and high signal images of microspheres. Compared with the control group, typical imaging was visible, confirming that the microspheres can produce obvious signal images under MR and exhibit good MR imaging performance.

[0086] 7.2 Histological verification of hepatic artery embolism;

[0087] The embolization effects of the experimental group and the control group were compared at different time points after hepatic artery embolization. The results are as follows: Figure 9 As shown. 24 hours post-operation (10x magnification): In the experimental group (t24h), embolic microparticle deposition was observed in the blood vessels, localized aggregation of red blood cells was observed in the liver tissue, and perivascular edema of the liver tissue was observed, particularly in the perisinusoidal space; the control group (c24h) showed milder edema. 72 hours post-operation (10x magnification): In the experimental group (t72h), significant liver tissue edema was observed, with edema fluid mainly accumulating in the hepatic sinusoids and distributed along the perisinusoidal space; hepatocyte edema was milder; the control group (c72h) showed reduced edema. 7 days post-operation (10x magnification): In the experimental group (t7×24h), inflammatory cell infiltration and fibrous tissue hyperplasia were observed, the normal structure of hepatocytes disappeared, perisinusoidal space edema decreased, the normal structure of intrahepatic veins was destroyed, and occasional aggregation of embolic microparticles was observed; in the control group (c7×24h), some liver tissue structure recovered. The results showed that the experimental group had better arterial embolization effect and less inflammatory response compared with the control group. Post-embolization tissue necrosis was significant and irreversible; the control group showed tissue recovery after 7 days of observation. This confirms that the microspheres possess excellent embolization performance.

[0088] 7.3 Rabbit median auricular artery embolization experiment;

[0089] Preoperatively, the rabbit ears were prepared and anesthetized, then placed on the operating table. The median auricular artery was chosen as the puncture observation point. After disinfection, a coaxial needle was inserted into the median auricular artery. Commercially available BIOSPHERE microspheres (300-500μm, control group) were injected into one ear, while nano-carbon-iodine calcium alginate microspheres were injected into the other ear (experimental group). The injection volume was 0.1mL of a suspension of microspheres and 0.9mL of 0.9% sodium chloride (total 1mL). The embolization effect was observed at different time points postoperatively, and the results are as follows: Figure 10As shown in the images. Preoperatively (Image a): The rabbit ear median artery is clearly visualized, with fine peripheral vessels and a natural course. Immediately postoperatively (Image b): The rabbit ear median artery is clearly visualized, dilated, with internal black embolic microspheres; peripheral vessels are dilated and congested; black embolic particles are visible at the distal end, and the course is somewhat unnatural. 24 hours postoperatively (Image c): The rabbit ear median artery is clearly visualized, with increased dilation; internal black embolic microspheres; peripheral vessel dilation and congestion have improved; the course of the black embolic particles' fine vessels is clearer and more natural. 48 hours postoperatively (Image d): The rabbit ear median artery is clearly visualized, with reduced dilation; the number of internal black embolic microspheres has decreased compared to before; peripheral vessel dilation and congestion have disappeared; the course of the black embolic particles' fine vessels is clearer and more natural, and the color has faded. 72 hours postoperatively (Image e): The rabbit ear median artery is clearly visualized, with reduced dilation; the internal black embolic microspheres remain unchanged; peripheral vessel dilation has decreased and congestion has disappeared; the course of the black embolic particles' fine vessels is clearer and more natural, and the color has faded. Experimental results showed that the nano-carbon-iodine calcium alginate microspheres exhibited the same consistency with liver tissue results in the rabbit ear median artery embolization experiment, effectively achieving arterial embolization. The embolization effect on arterial blood flow was significant, and no inflammatory response was observed after embolization, indicating good tolerability.

[0090] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention.

Claims

1. The application of nano-carbon-iodine calcium alginate microspheres in the preparation of X-ray / MR dual-modal imaging embolic materials, characterized in that, The nano-carbon-iodine calcium alginate microspheres have a calcium alginate cross-linked network framework, which contains iodine and nano-carbon powder, enabling the X-ray / MR dual-modal imaging embolization material to achieve dual-modal imaging under X-ray and magnetic resonance imaging.

2. The application according to claim 1, characterized in that, The application is to prepare X-ray / MR dual-modal imaging embolization material for transarterial embolization therapy of solid tumors.

3. The application according to claim 1, characterized in that, The dual-modal imaging includes: the X-ray / MR dual-modal imaging embolic material exhibits imaging density no less than that of bone in X-ray imaging, and produces a signal contrast that is distinct from the surrounding background tissue in magnetic resonance T1-weighted and / or T2-weighted imaging.

4. The application according to claim 1, characterized in that, The nano-carbon-iodine calcium alginate microspheres have an iodine loading rate of 5-50%, a carbon loading rate of 5-40%, and a particle size of 20-1400 μm.

5. The application according to claim 1, characterized in that, The particle size of the nano-carbon powder is 2-500 nm.

6. A method for preparing nano-carbon-iodine calcium alginate microspheres for use in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Prepare an aqueous solution of sodium alginate containing iodine; Step 2: Prepare an aqueous solution containing a cross-linking agent; Step 3: Add nano-carbon powder to the additives to form a first suspension; mix the first suspension with the iodine-containing sodium alginate aqueous solution prepared in Step 1 and stir to form a second suspension; Step 4: The first suspension is placed in a syringe and injected into the aqueous solution containing the crosslinking agent prepared in Step 2. The aqueous solution containing the crosslinking agent is stirred to obtain nano-carbon-iodine calcium alginate microspheres. Step 5: Filter and dry the nano-carbon-iodine calcium alginate microspheres obtained in Step 4; Step 6: The nano-carbon-iodine calcium alginate microspheres obtained in Step 5 are sieved and sterilized by irradiation under cobalt 60.

7. The preparation method according to claim 6, characterized in that, The iodine-containing sodium alginate aqueous solution is a solution obtained by dissolving iodine, potassium iodide and sodium alginate in water, wherein the mass ratio of iodine, potassium iodide and sodium alginate is iodine:potassium iodide:sodium alginate = 5-10:10-30:0.1-2.0, and the mass concentration of the sodium alginate aqueous solution is 10-20 mg / mL.

8. The preparation method according to claim 6, characterized in that, The crosslinking agent is a divalent metal cation compound selected from one or more of magnesium chloride, zinc chloride, copper chloride, barium chloride, ferrous sulfate, magnesium sulfate, zinc sulfate, calcium chloride, calcium hypochlorite, calcium bromide, and calcium iodide.

9. The preparation method according to claim 6, characterized in that, The auxiliary agent is one or more of water, anhydrous ethanol, propanol, and Tween 80.

10. The preparation method according to claim 6, characterized in that, The first suspension contains 0.05-0.15g of nano-carbon powder per milliliter of solution; the mass ratio of sodium alginate to nano-carbon powder in the second suspension is 2-3:1.

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