Metal-coordinated iohexol nanoparticles, preparation method and application thereof

Abstract

This invention discloses a metal-coordinated iohexol nanoparticle, its preparation method, and its applications. The metal-coordinated iohexol nanoparticles of this invention are prepared by reacting a metal salt with iohexol in an organic medium; the particle size range of the metal-coordinated iohexol nanoparticles is 50-100 nm. This invention synthesizes metal-coordinated iohexol nanoparticles via a one-pot method, which is simple and does not require multiple reaction steps. The metal-coordinated iohexol nanoparticles prepared by this invention mainly accumulate in the liver, with only a small amount accumulating in the kidneys. They can significantly reduce the nephrotoxicity of chronic renal failure model mice after CT imaging, and exhibit good biocompatibility and almost no cytotoxicity in vitro.

Description

Technical Field

[0001] This invention belongs to the field of medical contrast agent technology, specifically relating to a metal-coordinated iohexol nanoparticle, its preparation method, and its application. Background Technology

[0002] Computed tomography (CT) is one of the most frequently used and widely applied diagnostic techniques in clinical practice, particularly suitable for diagnosing lesions through three-dimensional visualization based on differences in X-ray absorption. CT contrast intensity is determined by the amount of X-ray-absorbing elements in human tissues, bone, or hard tissues. Therefore, high X-ray absorption levels of calcium appear bright in CT scans, while soft tissues or blood, which transmit most X-rays, appear dark in CT images. This makes it difficult to distinguish normal areas from abnormal lesions. For this reason, contrast agents were developed to provide brighter contrast for soft tissues and blood.

[0003] Currently, commonly used contrast agents in clinical practice mainly include barium sulfate suspension and water-soluble iodinated contrast agents, such as iohexol, a second-generation nonionic monomeric contrast agent. Due to iodine's ideal contrast agent properties, including high k-edge energy and stability in vivo, iohexol is currently the most widely used contrast agent in clinical practice, primarily for angiography, including cardiovascular angiography, myocardial perfusion, image-induced intravascular intervention, and cancer diagnosis.

[0004] Because the contrast intensity of iohexol, a small-molecule contrast agent, depends on concentration and dosage, and has a short metabolic half-life in vivo, high doses or multiple injections are required to achieve high-resolution contrast intensity. However, such high-dose injections lead to rapid excretion and high osmotic pressure, which is a major factor in inducing contrast-induced nephropathy (CIN). Elderly patients and those with chronic renal failure (often caused by diabetes, hypertension, or hyperlipidemia) have poor tolerance to CT contrast agents. After large injections of contrast agents, these patients often experience rapid deterioration of renal function, leading to renal failure and seriously endangering their lives. Currently, CIN is the third leading cause of hospital-acquired acute kidney injury. More specifically, up to 30% of patients receiving iodinated contrast agents develop CIN, resulting in nearly 150,000 cases worldwide each year. Therefore, many nanomaterials, such as polymeric contrast agents (Yuxun Ding et al. Polymerization-induced self-assembly of large-scale iohexol nanoparticles as contrast agents for X-ray computed tomography imaging, Polym. Chem., 2018, 9, 2926-2935.), nanocarrier-loaded small-molecule contrast agents, and dendritic macromolecules, have been developed to attempt to reduce the kidney side effects of contrast agents and improve CT imaging by increasing in vivo circulation time. However, these polymeric nanoparticle contrast agents are composed of iodine-containing small molecules and other organic compounds, resulting in reduced solubility in water and, due to their difficulty in degradation in vivo, can cause side effects in other organs, such as the liver.

[0005] Nanoscale coordination polymers (NCPs) are a class of hybrid materials composed of metal ions or clusters linked together by organic linkers. Currently, NCPs have attracted considerable attention from researchers due to their promising applications in biomedicine. In recent years, researchers have integrated various building blocks into NCPs to enable different therapeutic modalities, such as photothermal therapy, photodynamic therapy, and radiotherapy. Furthermore, NCPs with unique physicochemical properties have been shown to possess different imaging modalities, including optical imaging, magnetic resonance imaging, computed tomography imaging, and even radionuclide imaging. Notably, NCPs often exhibit pH-sensitive release characteristics, typically gradually degrading into small molecules and ions that can be rapidly excreted without long-term retention in the animal body. In particular, some NCPs can be directly used to coordinate drugs with metal ions to form a "carrier-free" nanomedicine. Its advantages include the elimination of the need for carrier materials, allowing for direct drug-carrier construction, resulting in high drug loading capacity and excellent thermal stability. It can also increase liver accumulation time and reduce renal metabolic harm, making it a promising therapeutic platform, especially for patients with chronic renal failure. Summary of the Invention

[0006] Objective of this invention: This invention aims to provide metal-coordinated iohexol nanoparticles and their preparation method. This invention provides a simple and direct strategy for preparing nano-metal-coordinated iohexol IO-NPs contrast agents with high iodine content. The prepared IO-NPs contrast agents exhibit high biocompatibility and high solubility. After intravenous injection of IO-NPs for 24 hours, organ histochemical analysis showed almost no cytotoxicity. At the same iodine concentration, its in vivo imaging time is longer than that of iohexol small molecule contrast agents, and it can be excreted from the body after CT scans.

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

[0008] The present invention provides metal-coordinated iohexol nanoparticles, which are prepared by reacting metal salts with iohexol in an organic medium; the particle size range of the metal-coordinated iohexol nanoparticles is 50-100 nm.

[0009] The coordination of metal ions with iohexol can increase its circulation time in the body, which is beneficial for its dissociation into metal ions and small molecule iohexol and its excretion from the body.

[0010] Preferably, the metal salt is selected from Al(NO3)3·9H2O, Mg(NO3)2·6H2O, Zn(NO3)2·6H2O or Ca(NO3)2·6H2O.

[0011] More preferably, the metal salt is selected from Al(NO3)3·9H2O.

[0012] Preferably, the organic medium is selected from one or two of N'N-dimethylformamide, acetonitrile, or ethanol.

[0013] More preferably, the organic medium is selected from N'N-dimethylformamide and acetonitrile.

[0014] This invention also provides a method for preparing the aforementioned metal-coordinated iohexol nanoparticles, comprising the following steps:

[0015] (1) Dissolve the metal salt and iodhexol in an organic medium and stir thoroughly to obtain a mixed solution;

[0016] (2) The mixed solution obtained in step (1) is heated to react. After the reaction is complete, it is washed and dried to obtain the metal-coordinated iodhexol nanoparticles.

[0017] Preferably, in step (1), the molar ratio of the metal salt to iohexol is 1:1.

[0018] Preferably, in step (1), each 0.1 mmol of iohexol is dissolved in 3 ml of acetonitrile and 2 ml of N'N-dimethylformamide.

[0019] Preferably, in step (1), the stirring temperature is 20-30℃ and the stirring time is 0.5-1h.

[0020] Furthermore, the stirring temperature is 25°C, and the stirring time is 0.5 h.

[0021] Preferably, in step (2), the temperature of the heating reaction is 110-130℃ and the heating reaction time is 24-48h.

[0022] Furthermore, the heating reaction temperature is 110°C, and the heating reaction time is 24 hours.

[0023] Preferably, in step (2), the solvent for washing is DMF and ethanol.

[0024] A preferred embodiment of the present invention is a method for preparing the metal-coordinated iohexol nanoparticles, comprising the following steps: dissolving 0.1 mmol of Al(NO3)3·9H2O and 0.1 mmol of iohexol in 2 mL of N,N-dimethylformamide (DMF) solution, then adding 3 mL of acetonitrile, and stirring at room temperature for 0.5 h to ensure thorough mixing. The mixture is then reacted at 110 °C for 24 h to produce a yellow solid. Finally, the product is washed five times with DMF and ethanol respectively to remove free iohexol and metal ions, and stored at 4 °C for later use.

[0025] This invention synthesizes metal iodide nanoparticles using a one-pot method.

[0026] The present invention also provides the use of the aforementioned metal-coordinated iohexol nanoparticles as a medical contrast agent.

[0027] To assess the safety of IO-NPs, the in vitro cytotoxicity of these IO-NPs was validated in various cell lines. Furthermore, in vivo toxicity was evaluated by organ histochemical analysis 24 hours after intravenous injection of IO-NPs. Finally, CT imaging using a rat model of chronic renal failure confirmed that IO-NPs significantly reduced the risk of contrast-induced nephropathy without increasing the risk of liver damage.

[0028] IO-NPs adsorb phosphates or proteins via electrostatic interactions in PBS and 5% FBS solutions, reducing premature leakage during circulation, facilitating liver accumulation, and minimizing nephrotoxicity. IO-NPs exhibit good biocompatibility in vitro and show minimal cytotoxicity.

[0029] Beneficial effects:

[0030] (1) The metal-coordinated iohexol nanoparticles of the present invention have good biocompatibility in vitro and almost no cytotoxicity.

[0031] (2) The present invention synthesizes metal iodide nanoparticles by a one-pot method. The preparation method of the present invention is simple and does not require multiple reaction steps.

[0032] (3) The metal-coordinated iohexol nanoparticles prepared in this invention mainly accumulate in the liver, with only a small amount accumulating in the kidneys, which can significantly reduce the nephrotoxicity of chronic renal failure model mice after CT imaging. Therefore, the metal-coordinated iohexol nanoparticles of this invention can be used as a medical contrast agent. Attached Figure Description

[0033] Figure 1 A schematic diagram illustrating the synthesis of nano-metal-coordinated iohexol and its nephroprotective effect.

[0034] Figure 2 SEM and TEM images and elemental mapping of IO-NPs nanoparticles.

[0035] Figure 3 Characterization of IO-NPs structures; where, Figure 3 a is the infrared spectrum of iohexol and IO-NPs. Figure 3 b is the UV spectrum of iohexol and IO-NPs. Figure 3 c is the thermogravimetric spectrum of iohexol and IO-NPs. Figure 3 d is the powder XRD diffraction pattern of IO-NPs.

[0036] Figure 4 The X-ray photoelectron (XPS) spectra of iohexol and IO-NPs are shown; among them, Figure 4 a represents the high-resolution XPS image. Figure 4 b is the C1s spectrum. Figure 4 c represents the N1s spectrum. Figure 4 d represents the O1s spectrum. Figure 4 e represents the I 3d map. Figure 4 f is the Al 2p spectrum of IO-NPs.

[0037] Figure 5 The hydration particle size of IO-NPs dispersed in different media at different time periods ( Figure 5 a) and surface potential ( Figure 5 b).

[0038] Figure 6 SEM images of IO-NPs dispersed in different media at different time periods.

[0039] Figure 7 The cytotoxicity results (mean ± SD, n = 3) of IO-NPs, iohexol, and Al(NO3)3 after 24 h of incubation in different cells are shown; among them, Figure 7 a represents the cytotoxicity results after incubation with HEK 293 cells. Figure 7 b represents the cytotoxicity results after incubation with L02 cells. Figure 7 c represents the cytotoxicity results after incubation with HUVEC cells.

[0040] Figure 8 Imaging comparison of iohexol and IO-NPs; among which, Figure 8 a represents CT images of different concentrations of iohexol and IO-NPs. Figure 8 b is the corresponding X-ray attenuation value. Figure 8 c is an intravenous injection of IO-NPs (500 mg / kg). -1 Transverse and coronal sections of the chronic renal failure model before and after treatment. Figure 8 d represents an intravenous injection dose of 500 mg / kg. -1 3D CT angiography images of rats before and after iohexol (5 min) and IO-NPs (15 min and 30 min).

[0041] Figure 9 The distribution and metabolism of iohexol and IO-NPs in SD renal failure rats; among which, Figure 9 a represents the in vivo distribution data of iohexol control group rats at different time points. Figure 9 b represents the in vivo distribution data of rats in the IO-NPs experimental group at different time points.

[0042] Figure 10 The metabolism of iohexol and IO-NPs in rats; among them, Figure 10 a represents the change in iodide ion concentration in rat urine over time. Figure 10 b represents the change in the content of iodine ions in rat feces over time.

[0043] Figure 11 Serum creatinine in each component ( Figure 11 a) Total antioxidant capacity ( Figure 11 b) and interleukin-6 ( Figure 11 c) level. Detailed Implementation

[0044] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0045] Example 1: Preparation of Metallic Iodohexol Nanoparticles

[0046] Al(NO3)3·9H2O (37.5 mg, 0.1 mmol) and iohexol (80 mg, 0.1 mmol) were dissolved in 2 mL of N,N-dimethylformamide (DMF) solution, and then 3 mL of acetonitrile was added. The mixture was stirred at room temperature for 0.5 h to ensure thorough mixing. The mixture was then reacted at 110 °C for 24 h to produce a yellow solid. Finally, the product was washed five times with DMF and ethanol, respectively, to remove free iohexol and metal ions, yielding iohexol metal nanoparticles (IO-NPs), which were stored at 4 °C for later use.

[0047] Figure 1 This diagram illustrates the synthesis of nano-metal-coordinated iohexol and its nephroprotective effect. Under specific experimental conditions, conventional iohexol contrast agents and metal ions were formulated into nano-sized drug particles. Compared to conventional iohexol contrast agents, nano-metal-coordinated iohexol is metabolized significantly less by the kidneys, primarily through the liver and intestines, thus reducing the risk of kidney damage.

[0048] Figure 2 SEM and TEM images and elemental mapping of IO-NPs nanoparticles are shown. The successful synthesis of IO-NPs is confirmed by SEM and TEM images. Figure 2 As shown, IO-NPs are uniform spherical nanoparticles with a diameter of approximately 80 nm. The corresponding EDS spectra clearly show that the five elements C, N, O, Al, and I are uniformly distributed throughout the nanoparticles, and these five elements overlap significantly, further demonstrating the successful construction of IO-NPs.

[0049] Figure 3 Characterization of IO-NPs structures; where, Figure 3 a is the infrared spectrum of iohexol and IO-NPs. Figure 3 b is the UV spectrum of iohexol and IO-NPs. Figure 3 c is the thermogravimetric spectrum of iohexol and IO-NPs. Figure 3 d is the powder XRD diffraction pattern of IO-NPs.

[0050] As shown in the FT-IR spectrum ( Figure 3 a) Observed in the infrared spectrum at 3400–3100 cm⁻¹ -1 A broad -OH peak appears within the range, which belongs to the stretching vibration peak of the alcohol hydroxyl group in iohexol. At 1630 cm⁻¹... -1 There is a peak at 1546 cm⁻¹, which is the characteristic absorption peak of the stretching vibration of the unsaturated C=C bond in the benzene ring. Other obvious peaks are at 1546 and 1393 cm⁻¹. -1 The characteristic absorption peaks are attributed to the C=O stretching vibration and NH bending of the amide bond in iohexol, respectively. After aluminum ions and iohexol form IO-NPs through coordination self-assembly, the characteristic peaks in their FT-IR spectra are almost identical to those of iohexol, but the 1544 cm⁻¹ peak is different. -1 The significant reduction in the tensile vibration of the C=O amide bond at the IO-NPs nanoparticles also indicates that the IO-NPs nanoparticles are formed by the coordination of iohexol and aluminum ions.

[0051] UV-Vis spectroscopy further confirmed the synthesis of IO-NPs. Figure 3 As shown in b, iohexol has a peak at 244 nm. In IO-NPs, the main peak of iohexol shifts to a longer wavelength (252 nm), approximately a redshift of 8 nm, and the absorption wavelength broadens. Therefore, compared with Al... 3+ After mixing, the colorless iohexol turned pale yellow. These phenomena indicate that Al exists at the C=O, NH, and OH sites of iohexol. 3+ Coordination interaction with iohexol.

[0052] The Al content in IO-NPs was quantitatively determined to be 7.36% and the I content to be 41.3% using inductively coupled plasma mass spectrometry (ICP-MS). This yielded the results regarding the relative amounts of iohexol and Al in IO-NPs. 3+ The molar ratio is approximately 2 / 5. In this case, it can be inferred that the structure of IO-NPs consists of an iohexol molecule coordinated with two aluminum ions, while the remaining aluminum ions are coordinated with sites in another iohexol molecule.

[0053] According to the results of thermogravimetric analysis (TGA), ( Figure 3c) Iohexol loses approximately 80.42% of its mass at 800℃, and IO-NPs lose approximately 71.57%. Therefore, the calculated mass percentage of aluminum in IO-NPs is 8.85%, which aligns with the ICP data for Al. 3+ The proportions are similar.

[0054] X-ray diffraction (XRD) patterns of IO-NPs are shown below. Figure 3 As shown in d, the results indicate that no obvious diffraction peaks were observed in the XRD pattern, suggesting that IO-NPs are an amorphous structure.

[0055] Figure 4 The X-ray photoelectron (XPS) spectra of iohexol and IO-NPs are shown; among them, Figure 4 a represents the high-resolution XPS image. Figure 4 b is the C1s spectrum. Figure 4 c represents the N1s spectrum. Figure 4 d represents the O1s spectrum. Figure 4 e represents the I 3d map. Figure 4 f is the Al 2p spectrum of IO-NPs.

[0056] like Figure 4 As shown in figure a, the X-ray photoelectron (XPS) spectrum of IO-NPs has five peaks: 74.1, 281.1, 398.1, 528.3, and 619.2 eV, originating from Al 2p, C 1s, N 1s, O 1s, and I 3d, respectively. Furthermore, from... Figure 4 b shows that two different peak signals were observed at 285.6 and 288.1 eV, which are attributed to the CC / C=C and CO bonds of iohexol, respectively. Compared with pure iohexol, IO-NPs shifted to higher fields by 1.17 and 0.69 eV, respectively. Figure 4 The prominent peak in the N1s region of c at 400.0 eV can be attributed to the CN peak in the amide bond, and the peak at 531.8 eV can be attributed to the CC=O peak. Both peaks shift upwards by 1.3 and 0.59 eV, respectively. Figure 4 d). Figure 4 The image shows two distinct peaks at 632.2 and 620.7 eV, corresponding to the representative binding energies I3d3 / 2 and I3d5 / 2 of iohexol, respectively, and both peaks shift upwards by 1.0 eV. The elemental energies in the IO-NPs show a certain degree of upward shift compared to iohexol, indicating that iohexol and aluminum ions are formed through coordination self-assembly, rather than physical bonding. The binding energy peak at 74.16 eV belongs to the Al2p main peak, confirming the presence of aluminum within the IO-NPs. Figure 4 f).

[0057] Example 2: Stability experiment of metal iodide nanoparticles in different media

[0058] To investigate the dispersibility and colloidal stability of IO-NPs, 1 mg of IO-NPs prepared in Example 1 was ultrasonically dispersed in water, PBS, and 5% FBS, and incubated for 0.5, 1, 6, 12, 24, 48, 72, and 96 h, respectively.

[0059] The hydration particle size and surface potential of IO-NPs dispersed in different media at different time periods are shown in the figure. Figure 5 .

[0060] like Figure 5 As shown in Figure a, IO-NPs can be stably dispersed in various media, with a hydrated particle size of approximately 80 nm. In 5% FBS, the hydrated particle size increases slightly due to FBS adsorption on the IO-NP surface, but remains relatively stable over time. The surface potential of IO-NPs in all three media also remains stable over time. IO-NPs maintain a positive charge in water and 5% FBS, but exhibit a negative potential in PBS, possibly due to the adsorption of some phosphates on the IO-NP surface, thus reducing the surface potential. In summary, even in solutions simulating in vivo biological environments, IO-NPs can maintain relatively stable dispersion.

[0061] Figure 6 SEM images of IO-NPs dispersed in different media at different time periods.

[0062] SEM characterization ( Figure 6 This study revealed the size and morphological changes of IO-NPs dispersed in various media over different time periods. The results show that the size of IO-NPs dispersed in water and PBS remained almost unchanged over various time periods, and they remained relatively uniformly dispersed on the silicon wafer after 96 hours, maintaining their morphology and structure. While IO-NPs dispersed in 5% FBS also maintained their morphology and structure, SEM images showed that after 1 hour in the 5% FBS solution, IO-NPs exhibited significant aggregation on the silicon wafer, and the surface gradually became rougher over time. This may be because FBS adsorbs onto the surface of the IO-NPs, causing the surface FBS to gradually adhere together as the sample dries during sample preparation, leading to aggregation.

[0063] Example 3: In vitro cytotoxicity experiment of nano-metal-coordinated iohexol

[0064] To assess the safety of IO-NPs, this invention validated their in vitro cytotoxicity in various cell lines.

[0065] To investigate the effects of IO-NPs on kidney and liver function, we performed cytotoxicity assays using normal human hepatocytes (L02 cells), human embryonic kidney cells (HEK 293 cells), and human umbilical vein endothelial cells (HUVEC cells). All of these cells were derived from ATCC.

[0066] The concentration-dependent effects of cytotoxicity on liver, kidney, and normal cells were evaluated using the CCK-8 assay. The experimental group (IO-NPs) and the control group (iohexol and Al(NO3)3) were incubated with these three cell types at 37°C for 24 hours at concentrations ranging from 0 to 400 mg / mL. The results are shown below. Figure 7 The control group (con) consisted of the PBS group.

[0067] like Figure 7 As shown, after 24 hours of incubation of the experimental group IO-NPs and the control group iohexol and Al(NO3)3 materials with three different cells, no significant effect was observed on cell viability. Even at material concentrations as high as 400 mg / mL, cell survival rates were above 90%, preliminarily indicating that the IO-NPs material has good biocompatibility in vitro and almost no cytotoxicity.

[0068] Example 4: Establishment of a chronic renal failure model

[0069] A chronic renal failure model was established by gavage administration of adenine to SD rats.

[0070] Male SD rats weighing approximately 120g were purchased from Spifor Biotechnology Co., Ltd. Adenine was dissolved in water and administered via gavage at a dose of 250mg / kg / day for 4 consecutive weeks to establish a model. Rats were given free access to food and water. Baseline creatinine levels were measured before modeling, and creatinine values ​​were measured after modeling to confirm successful model establishment. A creatinine level exceeding the normal range was considered a successful model.

[0071] Example 5: Time Stability Analysis of Nano-Metal Coordinated Iohexol in Different Media

[0072] Compared to small molecules, nanoparticles can remain in the bloodstream for a longer period, effectively extending imaging time. The liver is the primary organ for metabolizing and clearing most exogenous drugs. Evidence suggests that nanoparticles preferentially deposit in the liver. Considering the safety and long-lasting effects of contrast agents, we desire CT images to be obtained over a wider time window without the need for multiple contrast agent administrations, thus significantly reducing injection frequency. This will minimize contrast agent-induced chronic kidney damage and avoid further burdening the kidneys during CT imaging in patients with chronic renal failure. As nanocontrast agents, we expect IO-NPs to have a low renal metabolic rate to achieve sufficient circulation time for in vivo CT imaging.

[0073] To verify the above points, we constructed a chronic renal failure model by gavage of SD rats with adenine using the method described in Example 4, via tail vein injection (mg / kg). -1 Iohexol and IO-NPs contrast agents were used to demonstrate that IO-NPs not only enable long-duration CT imaging but also cumulatively reduce the burden on the kidneys in the liver. High iodine concentration and high loading efficiency are necessary prerequisites for iodine-based nanoparticles to serve as contrast agents.

[0074] Different concentrations of IO-NPs were detected using small animal PET-CT (Mdeiso, Hungary). IO-NPs were measured at iodine concentrations ranging from 0 to 50 mg / mL. -1 CT imaging inside Figure 8 a. It reflects the CT imaging results through both color and black-and-white display modes. (By...) Figure 8 b indicates that IO-NPs are present in iodine concentrations ranging from 0 to 50 mg / mL. -1 The standard curves within the range exhibit a good linear relationship. The CT values ​​of all these contrast agents are approximately similar, indicating that the contrast effect of IO-NPs is not affected by the introduction of other metal ions, providing good statistical characteristics for further quantitative CT studies.

[0075] In addition, in vivo CT imaging studies were conducted using SD rats with a chronic renal failure model and a SOMATOM Force dual-source CT scanner to compare IO-NPs contrast agents with the clinically commonly used iohexol contrast agent. Rats were injected via tail vein with IO-NPs (500 mg / kg). -1 This resulted in significantly enhanced vascular imaging, with arterial boundaries visible after 15 minutes and lasting for over 30 minutes. No signal was observed in the bladder. The duration of enhancement in the kidneys and bladder was five times that of commonly used iohexol. Figure 8 c). These results indicate prolonged blood circulation time and some renal clearance, which may be related to the large size of IO-NPs. Furthermore, the slow metabolism of IO-NPs may help prevent kidney injury. In stark contrast, the same dose of iohexol did not produce any vascular enhancement after 5 minutes, and the signal in the bladder was significantly enhanced. Figure 8 d). These results suggest that iohexol, a small molecule contrast agent, is rapidly metabolized into the bladder via renal tubular filtration. These results confirm that IO-NPs can be slowly metabolized in vivo, prolonging CT imaging time, and that a small amount of IO-NPs are metabolized by the kidneys, further reducing the burden on the kidneys.

[0076] Example 6: Distribution and metabolism of iodine in vivo in nano-metal-coordinated iohexol IO-NPs

[0077] To further demonstrate that IO-NPs are primarily metabolized by tolerable organs such as the liver after intravenous injection via the tail vein, thereby reducing the burden on the kidneys and decreasing nephrotoxicity, we used ICP-MS to measure the iodine content in various tissues and organs of mice to track the distribution and metabolism of iohexol and IO-NPs in vivo.

[0078] The experimental results are shown in Figure 9 . Figure 9 The distribution and metabolism of iohexol and IO-NPs in SD renal failure rats; among which, Figure 9 a represents the in vivo distribution data of iohexol control group rats at different time points. Figure 9 b represents the in vivo distribution data of rats in the IO-NPs experimental group at different time points.

[0079] like Figure 9 a shows that at 500 mg / kg -1 One hour after injection, iohexol is primarily metabolized by the kidneys, and by 24 hours, it is almost completely metabolized, accumulating almost nothing in the liver. In contrast, one hour after tail vein injection, most IO-NPs are concentrated in reticuloendothelial organs such as the liver and spleen. Because nanomaterials are recognized and phagocytosed by phagocytes after entering the body, and phagocytes are mainly found in organs such as the liver and spleen, nanomaterials injected into rats via the tail vein initially accumulate in the liver. Figure 9 As shown in b, the accumulation of IO-NPs in the liver gradually increases over time, reaching its peak 24 hours after injection. With prolonged time, IO-NPs exhibit a certain metabolic rate; 72 hours after injection, the content of IO-NPs in the liver and spleen did not decrease significantly, with more than 50% of the material remaining in the organs and not being metabolized out of the body. This indicates that IO-NPs have the ability to accumulate primarily in the liver, thereby reducing the metabolic burden on the kidneys.

[0080] Meanwhile, we also used ICP-MS to detect the iodide ion content in the urine and feces of rats at different time points, thereby exploring the metabolic pathways of iohexol and IO-NPs. Rat feces and urine were obtained, and 10 ml of nitric acid and 2 ml of periodic acid were added for digestion at room temperature for 1 day. The solution was then heated at 180℃ for 8 hours, followed by heating at 200℃ to allow complete evaporation. 50 ml of water was added, and the aluminum and iodide ions in the solution were determined by ICP-MS.

[0081] Figure 10 The metabolism of iohexol and IO-NPs in rats; among them, Figure 10 a represents the change in iodide ion concentration in rat urine over time. Figure 10 b represents the change in the content of iodine ions in rat feces over time.

[0082] like Figure 10 As shown in Figure a, high concentrations of iodine ions were detected in the urine of rats injected with the small-molecule imaging agent iohexol two hours later. Almost all of the iodine ions were metabolized within 24 hours, indicating that iohexol is ultimately excreted from the body in small molecule form via the kidneys. In contrast, rats injected with IO-NPs showed very low concentrations of iodine ions in their urine and feces. Figure 10 As shown in b, iodide ions reached their peak in urine and feces 72 hours after injection and were slowly metabolized at very low concentrations, demonstrating that IO-NPs have a slow and low metabolic and excretion rate in vivo.

[0083] Example 7: The protective effect of IO-NPs on the kidneys in clinical angiography.

[0084] We used a chronic renal failure model to investigate the kidney-protective ability of IO-NPs in clinical angiography. Normal SD rats were gavaged with adenosine-containing saline solution (250 mg / kg / d) to induce chronic kidney injury, simulating patients with chronic renal insufficiency. A creatinine level higher than normal was used as the criterion for model success.

[0085] Subsequently, IO-NPs were injected (500 mg / kg). -1 The changes in serum creatinine, total antioxidant capacity, and interleukin-6 levels in the kidneys over time before and after treatment revealed the kidney's antioxidant capacity and remission efficiency. Serum creatinine, total antioxidant capacity, and interleukin-6 levels were measured using standard laboratory methods. The experimental results are shown below. Figure 11 Clinically, serum creatinine is one of the main methods for understanding kidney function and is an important indicator of kidney function. Elevated serum creatinine indicates impaired kidney function. Total antioxidant capacity can reflect, to some extent, the body's overall ability to scavenge reactive oxygen species / nitric oxide synthase (ROS / NOS). Interleukins are an important inflammatory mediator that contributes to the development and progression of renal insufficiency.

[0086] like Figure 11 As shown, the levels of the three indicators in the chronic renal failure model rats were elevated. The three indicators reached their maximum peak 24 hours after injection of iohexol and IO-NPs, and then gradually decreased thereafter. Figure 11 As shown in Figure a, after injection of IO-NPs, the serum creatinine level was higher than that of the control group (PBS), but significantly lower than that of the iohexol group. Even after 48 hours, the creatinine level was still half that of the iohexol group, indicating that IO-NPs mainly accumulate in the liver after injection, with a small portion metabolized by the kidneys, and are less toxic to the kidneys than iohexol (which is mainly metabolized by the kidneys).

[0087] 24 hours after injection of IO-NPs contrast agent, the total antioxidant capacity was lower in the group than in the iohexol group. Over time, the total antioxidant capacity values ​​of both groups eventually reached the same level as the control group. Figure 11 b).

[0088] Interleukin-6 levels initially increased and then decreased before and after injection, with the iohexol group consistently showing higher levels than IO-NPs, indicating that IO-NPs are less nephrotoxic than iohexol. Figure 11 c).

[0089] The results above show that, although both iohexol and IO-NPs have some toxicity to the kidneys of rats with chronic renal failure, the iohexol group is much more toxic than the IO-NPs group (even after 48 days of injection). This indicates that IO-NPs mainly accumulate in the liver and only a small amount accumulates in the kidneys, which can significantly reduce the toxicity to the kidneys of rats with chronic renal failure after CT imaging.

[0090] IO-NPs preferentially accumulate in the liver, thus reducing the metabolic burden on the kidneys. Compared with the small-molecule contrast agent iohexol, IO-NPs-treated rat models of chronic renal failure showed less ROS production and less kidney damage than the iohexol group, consistent with the in vivo renal protective effects reported earlier.

[0091] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for preparing metal-coordinated iohexol nanoparticles, characterized in that, Includes the following steps: (1) Dissolve the metal salt and iodhexol in an organic medium and stir thoroughly to obtain a mixed solution; (2) The mixed solution obtained in step (1) is heated to react. After the reaction is complete, it is washed and dried to obtain the metal-coordinated iodhexol nanoparticles. The metal salt is selected from Al(NO3)3·9H2O; The organic medium is selected from a combination of N'N-dimethylformamide and acetonitrile; In step (1), the molar ratio of the metal salt to iohexol is 1:

1.

2. The preparation method according to claim 1, characterized in that, In step (1), each 0.1 mmol of iohexol is dissolved in 3 ml of acetonitrile and 2 ml of N'N-dimethylformamide.

3. The preparation method according to claim 1, characterized in that, In step (1), the stirring temperature is 20-30℃ and the stirring time is 0.5-1h.

4. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the heating reaction is 110-130℃ and the heating reaction time is 24-48h.

5. The preparation method according to claim 1, characterized in that, In step (2), the solvents used for washing are DMF and ethanol.

6. A metal-coordinated iohexol nanoparticle prepared by the preparation method according to any one of claims 1-5, characterized in that, The nanoparticles are IO-NPs, which are three-dimensional coordination polymers formed by the coordination of iohexol and aluminum ions. Al is present at the C=O, NH, and OH groups at the iohexol sites. 3+ Coordination interaction with iohexol.

7. The metal-coordinated iohexol nanoparticles as described in claim 6, characterized in that, Iohexol and Al in IO-NPs 3+ The molar ratio is 2 / 5.

8. The use of the metal-coordinated iohexol nanoparticles according to claim 6 in the preparation of medical contrast agents.

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