Metal coordination iohexol nano particle as well as preparation method and application thereof

Abstract

The invention discloses a metal coordination iohexol nano particle as well as a preparation method and application thereof. The metal coordination iohexol nanoparticles are prepared by reacting metal salt with iohexol in an organic medium; the particle size range of the metal coordination iohexol nano particles is 50 to 100 nm. The metal iohexol nanoparticles are synthesized through a one-pot method, the preparation method is simple, and multi-step reaction is not needed. The prepared metal iohexol nanoparticles are mainly accumulated in the liver, only a small amount of metal iohexol nanoparticles are accumulated in the kidney, the toxicity of a chronic renal failure model mouse to the kidney after CT imaging can be greatly reduced, and the metal iohexol nanoparticles have good biocompatibility in vitro and almost have no cytotoxicity.

Description

Technical Field

[0001] The invention belongs to the technical field of medical contrast agents, and in particular relates to metal-coordinated iohexol nanoparticles and a preparation method and application thereof. Background Art

[0002] Computed tomography (CT) is one of the most frequently used and widely used diagnostic techniques in clinical practice, especially for 3D visualization of lesions based on differences in X-ray absorption. CT contrast intensity is determined by the sample content of X-ray absorbing elements in human tissue, bone tissue or hard tissue. Therefore, high X-ray absorbing calcium levels appear bright in CT scans, while soft tissue or blood, which transmits most of the X-rays, appears black in CT images. This makes it difficult to distinguish normal areas from abnormal lesions. For this reason, contrast agents have been developed to obtain brighter contrast in soft tissue and blood.

[0003] At present, the common contrast agents in clinical use mainly include: barium sulfate suspension and water-soluble iodinated contrast agents, such as iohexol, a second-generation non-ionic monomeric contrast agent. Due to the ideal contrast agent properties of iodine, including high k-edge energy and stability in the body, iohexol is currently the most widely used contrast agent in clinical practice, mainly used for angiography, including cardiovascular angiography, myocardial perfusion, image-induced intravascular intervention and cancer diagnosis.

[0004] Since the contrast intensity of iohexol small molecule contrast agents depends on concentration and dose, and has a short metabolic half-life in the body, high doses or multiple injections are required to obtain high-resolution contrast intensity, but this high-dose injection will cause rapid excretion and high osmotic pressure, which is the main factor inducing contrast-induced nephropathy (CIN). In particular, patients with renal insufficiency such as the elderly and chronic renal failure (usually caused by diabetes, hypertension or hyperlipidemia) have poor tolerance to CT contrast agents. After a large amount of contrast agent injection, these patients often experience rapid deterioration of renal function, which in turn leads to renal failure, seriously endangering the patient's life. Currently, CIN is the third leading cause of hospital-acquired acute kidney injury. More specifically, up to 30% of patients who receive iodinated contrast agents suffer from CIN, resulting in nearly 150,000 patients worldwide each year. Therefore, many nanomaterials such as polymer 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, dendrimers, etc. have been developed to try to reduce the side effects of contrast agents on the kidneys by increasing the circulation time in the body and increase the CT contrast effect. However, these polymer nanoparticle contrast agents are composed of iodine-containing small molecules and other organic compounds, resulting in a decrease in solubility in water, and due to the difficulty in degradation in the body, they 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 connected by organic linkers. Nowadays, NCPs have attracted much attention from researchers due to their promising applications in biomedicine. In recent years, various building blocks have been integrated into NCPs to enable them to have different treatment modes, such as photothermal therapy, photodynamic therapy, and radiotherapy. On the other hand, NCPs with unique physicochemical properties have also been shown to have different imaging modes, including optical imaging, magnetic resonance imaging, computed tomography imaging, and even radionuclide imaging. It is worth noting that NCPs usually also have the characteristics of pH-sensitive release, and usually gradually degrade into small molecules and ions, which can be quickly excreted without being retained in the animal body for a long time. In particular, some NCPs can directly use drugs and metal ions to coordinate to form a "carrier-free" nanodrug. Its advantage is that it does not require a carrier material and directly uses drugs to construct the carrier, so it has a high drug loading capacity and excellent thermal stability. It can also increase the liver accumulation time and reduce the harm of kidney metabolism. Especially for patients with chronic renal failure, it is considered to be a promising therapeutic platform. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a metal-coordinated iohexol nanoparticle and a preparation method thereof. The present invention provides a simple and direct strategy for preparing nano-metal-coordinated iohexol IO-NPs contrast agents with high iodine content. The IO-NPs contrast agents prepared in this way have high biocompatibility and high solubility, and 24 hours after intravenous injection of IO-NPs, they have almost no cytotoxicity as evaluated by organ tissue chemical analysis. At the same iodine concentration, its in vivo imaging time is longer than that of the iohexol small molecule contrast agent, and it can be excreted from the body after CT scanning.

[0007] Technical solution: The purpose of the present invention is achieved through the following technical solution:

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

[0009] The coordination of metal ions with iohexol can increase the circulation time in the body, which is beneficial for its dissociation into metal ions and small molecule iohexol in the body and its metabolism out of 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] Further 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] Further preferably, the organic medium is selected from N'N-dimethylformamide and acetonitrile.

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

[0015] (1) dissolving the metal salt and iohexol in an organic medium, stirring and mixing thoroughly to obtain a mixed solution;

[0016] (2) heating the mixed solution obtained in step (1) to react, and after the reaction is completed, washing and drying to obtain the metal-coordinated iohexol nanoparticles.

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

[0018] Preferably, in step (1), 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° C., and the stirring time is 0.5-1 h.

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

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

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

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

[0024] A specific preferred embodiment of the present invention is that the preparation method of the metal-coordinated iohexol nanoparticles comprises the following steps: 0.1 mmol of Al(NO3)3·9H2O and 0.1 mmol of iohexol are dissolved in 2 mL of N'N-dimethylformamide (DMF) solution, and then 3 mL of acetonitrile is added, and stirred at room temperature for 0.5 h to fully mix. The above mixed solution is reacted at 110° C. for 24 h to generate a yellow solid. Finally, the product is washed 5 times with DMF and ethanol respectively to remove free iohexol and metal ions, and stored at 4° C. for use.

[0025] The present invention synthesizes metal iodine hexol nanoparticles through a "one-pot method".

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

[0027] To evaluate the safety of IO-NPs, the present invention verified its in vitro cytotoxicity in various cell lines. In addition, 24 hours after intravenous injection of IO-NPs, its in vivo toxicity was evaluated by organ tissue chemical analysis. Finally, CT angiography was performed using chronic renal failure rats as a model, confirming that it can significantly reduce the risk of contrast-induced nephropathy without increasing the risk of liver damage.

[0028] IO-NPs adsorb phosphate or protein through electrostatic action in PBS and 5% FBS solutions, which can reduce their premature leakage in the circulation process, help accumulate in the liver, and reduce toxicity to the kidneys. IO-NPs have good biocompatibility in vitro and have almost no 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 iodine hexol nanoparticles by a "one-pot method". The preparation method of the present invention is simple and does not require multi-step reactions.

[0032] (3) The metal iodine hexol nanoparticles prepared by the present invention mainly accumulate in the liver, with only a small amount accumulated in the kidney, which can greatly reduce the toxicity to the kidneys of chronic renal failure model mice after CT imaging. Therefore, the metal-coordinated iodine hexol nanoparticles of the present invention can be used as a medical contrast agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the synthesis of nano-metal-coordinated iohexol and its renal protective effect.

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

[0035] Figure 3 For the structural characterization of IO-NPs; Figure 3 a is the infrared spectra of iohexol and IO-NPs, Figure 3 b is the UV spectra of iohexol and IO-NPs. Figure 3 c is the thermogravimetric spectra of iohexol and IO-NPs, Figure 3 d is the powder XRD diffraction spectrum of IO-NPs.

[0036] Figure 4 is the X-ray photoelectron (XPS) spectrum of iohexol and IO-NPs; wherein, Figure 4 a is the high-resolution XPS spectrum, Figure 4 b is the C1s spectrum, Figure 4 c is the N1s spectrum, Figure 4 d is the O1s spectrum, Figure 4 e is the I 3d spectrum, Figure 4 f is the Al 2p spectrum of IO-NPs.

[0037] Figure 5 is the hydrated 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 of IO-NPs, iohexol and Al(NO3)3 after incubation of different cells for 24 h (mean±SD, n=3); Figure 7 a is the cytotoxicity result of HEK 293 cells incubation. Figure 7 b is the cytotoxicity result of L02 cell incubation. Figure 7 c is the cytotoxicity result of incubation on HUVEC cells.

[0040] Figure 8 This is the imaging comparison of iohexol and IO-NPs; Figure 8 a is the CT imaging of different concentrations of iohexol and IO-NPs. Figure 8 b is the corresponding x-ray attenuation value, Figure 8 c is the intravenous injection of IO-NPs (500 mg I kg -1 ) Transverse and coronal sections of the chronic renal failure model before and after. Figure 8 d is an intravenous 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] Fig. 9 The distribution and metabolism of iohexol and IO-NPs in SD renal failure model rats; Fig. 9 a is the in vivo distribution data of rats in the iohexol control group at different time points, Fig. 9 b is the in vivo distribution data of rats in the IO-NPs experimental group at different time points.

[0042] Fig.10 The metabolism of iohexol and IO-NPs in rats; Fig.10 a is the change of iodine ion content in rat urine over time, Fig.10 b shows the change of iodine ion content in rat feces over time.

[0043] Fig.11 Serum creatinine ( Fig.11 a) Total antioxidant capacity ( Fig.11 b) and interleukin-6 ( Fig.11 c) level. DETAILED DESCRIPTION

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

[0045] Example 1 Preparation of Metalloidoxime Nanoparticles

[0046] Al(NO3)3·9H2O (37.5 mg, 0.1 mmol) and iodine hexol (80 mg, 0.1 mmol) were dissolved in 2 mL of N'N-dimethylformamide (DMF) solution, and 3 mL of acetonitrile was added and stirred at room temperature for 0.5 h to fully mix. The above mixed solution was reacted at 110 ° C for 24 h to generate a yellow solid. Finally, the product was washed with DMF and ethanol for 5 times to remove free iodine hexol and metal ions, and metal iodine hexol nanoparticles IO-NPs were obtained, which were stored at 4 ° C for future use.

[0047] Figure 1 Schematic diagram of the synthesis of nano-metal-coordinated iohexol and its renal protective effect. Under certain experimental conditions, traditional iohexol contrast agents and metal ions were made into nano-scale drug particles. Compared with traditional iohexol contrast agents, nano-metal-coordinated iohexol is significantly less metabolized from the kidneys and is mainly metabolized from the liver and intestines, thereby reducing the risk of renal damage.

[0048] Figure 2 The SEM and TEM images and elemental mapping of IO-NPs nanoparticles are shown in Figure 1. The successful synthesis of IO-NPs was confirmed by SEM and TEM images. Figure 2 As shown in Figure 1, IO-NPs appear as uniform spherical nanoparticles with a diameter of about 80 nm. The corresponding EDS spectrum intuitively shows that the five elements C, N, O, Al and I are evenly distributed throughout the nanoparticles, and there is a lot of overlap among these five elements, further illustrating the successful construction of IO-NPs.

[0049] Figure 3 For the structural characterization of IO-NPs; Figure 3 a is the infrared spectra of iohexol and IO-NPs, Figure 3 b is the UV spectra of iohexol and IO-NPs. Figure 3 c is the thermogravimetric spectra of iohexol and IO-NPs, Figure 3 d is the powder XRD diffraction spectrum of IO-NPs.

[0050] As shown in the FT-IR spectrum ( Figure 3 a), observed in the infrared spectrum at 3400-3100 cm -1 A broad -OH peak appears in the range of 1630 cm-1, which belongs to the stretching vibration peak of the alcoholic hydroxyl group in iohexol. -1 There is a peak at 1546 and 1393 cm, which is the characteristic peak of the stretching vibration absorption of the unsaturated C=C bond in the benzene ring. Other obvious peaks are at 1546 and 1393 cm -1 , which are attributed to the characteristic absorption peaks of C=O stretching vibration and NH bending of the amide bond in iohexol. After aluminum ions and iohexol form IO-NPs through coordination self-assembly, the characteristic peaks in its FT-IR spectrum are almost consistent with the characteristic absorption peaks of iohexol, but the peak at 1544 cm -1 The stretching vibration of the amide bond C=O at the position is significantly reduced, which also indicates that the IO-NPs nanoparticles are formed by mutual coordination between iohexol and aluminum ions.

[0051] UV-visible spectroscopy further confirmed the synthesis of IO-NPs. Figure 3 As shown in b, iohexol has a sharp peak at 244 nm. In IO-NPs, the main peak of iohexol shifts to a longer wavelength (252 nm), red-shifts by about 8 nm, and the absorption wavelength becomes broader. 3+ After mixing, the colorless color of iohexol turned into light yellow. These phenomena indicate that there are Al2O3 bonds at the C=O, NH4+, and OH sites of iohexol. 3+ Coordination interactions with iohexol.

[0052] The Al content in IO-NPs was 7.36% and the I content was 41.3% by inductively coupled plasma mass spectrometry (ICP-MS). 3+ The molar ratio is ≈ 2 / 5. In this case, it can be inferred that the structure of IO-NPs is composed of one iohexol molecule coordinated with two aluminum ions, and the remaining aluminum ions are coordinated with sites in another iohexol molecule.

[0053] Thermogravimetric analysis (TGA) results show that ( Figure 3c) The mass loss of iohexol at 800 °C is about 80.42%, and that of IO-NPs is about 71.57%. Therefore, the mass proportion of aluminum in IO-NPs is calculated to be 8.85%, which is consistent with the Al content in the ICP data. 3+ The proportions are similar.

[0054] The X-ray diffraction (XRD) patterns of IO-NPs are shown in Figure 3 As shown in (d), the results show that no obvious diffraction peaks are observed in the XRD spectrum, indicating that IO-NPs have an amorphous structure.

[0055] Figure 4 is the X-ray photoelectron (XPS) spectrum of iohexol and IO-NPs; wherein, Figure 4 a is the high-resolution XPS spectrum, Figure 4 b is the C1s spectrum, Figure 4 c is the N1s spectrum, Figure 4 d is the O1s spectrum, Figure 4 e is the I 3d spectrum, Figure 4 f is the Al 2p spectrum of IO-NPs.

[0056] like Figure 4 As shown in a, the X-ray photoelectron (XPS) spectrum of IO-NPs has five peaks at 74.1, 281.1, 398.1, 528.3, and 619.2 eV, which originate from Al 2p, C 1s, N 1s, O 1s, and I 3d, respectively. Figure 4 b It can be seen that two different peak signals are 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 move 1.17 and 0.69 eV to the high field, respectively. Figure 4 The obvious peak at 400.0 eV in the N1s region of c 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, and these two peaks will move upfield by 1.3 and 0.59 eV respectively ( Figure 4 d). Figure 4 e shows that two different peak signals are observed at 632.2 and 620.7 eV, which are respectively assigned to the representative binding energies of iohexol, I 3d3 / 2 and I 3d5 / 2, and both peaks move 1.0 eV upfield. The energy of the elements in the above IO-NPs has moved upfield to a certain extent compared with iohexol, indicating that iohexol and aluminum ions are self-assembled through coordination rather than physical combination. The binding energy peak at 74.16 eV belongs to the main peak of Al2p, confirming the presence of aluminum elements ( Figure 4 f).

[0057] Example 2 Stability test of metal iodine hexol nanoparticles in different media

[0058] In order to study 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 media, respectively, and incubated for 0.5, 1, 6, 12, 24, 48, 72 and 96 h.

[0059] The hydrated particle size and surface potential of IO-NPs dispersed in different media at different time periods are shown in Figure 2. Figure 5 .

[0060] like Figure 5 As shown in a, IO-NPs can be stably dispersed in various media, and their hydrated particle size is about 80nm. In 5% FBS, the hydrated particle size increases due to the adsorption of FBS on the surface of IO-NPs, but it still maintains a relatively stable size over time. The surface potential of IO-NPs in the three media also remains stable over time. IO-NPs maintain a positive charge in water and 5% FBS, but show a negative potential in PBS, which may be due to the adsorption of some phosphates on the surface of IO-NPs, thereby reducing the surface potential. In summary, even IO-NPs can maintain a relatively stable dispersion in water or solutions that simulate the biological environment in vivo.

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

[0062] SEM characterization Figure 6 ) reveals the changes in size and morphology of IO-NPs dispersed in various media at different time periods. From the results in the figure, it can be seen that the size of IO-NPs dispersed in water and PBS has hardly changed at different time periods, and they can still be dispersed relatively evenly on the silicon wafer after 96 hours, and the morphology and structure remain intact. Although the IO-NPs dispersed in 5% FBS can also maintain the integrity of the morphology and structure, the SEM image shows that after being dispersed in the 5% FBS solution for 1 hour, the IO-NPs show obvious agglomeration on the silicon wafer, and the surface gradually becomes rough with time. This may be due to the adsorption of FBS on the surface of IO-NPs, resulting in the sample being dropped on the silicon wafer for sample preparation. As the sample dries, the FBS on the surface gradually sticks together, resulting in agglomeration.

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

[0064] To evaluate the safety of IO-NPs, the present invention verified 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 which were obtained from ATCC.

[0066] The CCK-8 method was used to evaluate the concentration dependence of cytotoxicity on liver, kidney and normal cells. The three types of cells were incubated (37°C) for 24 hours with IO-NPs in the experimental group and iohexol and Al(NO3)3 in the control group, respectively, at concentrations ranging from 0 to 400 mg / mL. The experimental results are shown in Figure 7 , where the control group con was the PBS group.

[0067] like Figure 7 As shown, after incubation of the experimental group IO-NPs and the control group iohexol and Al(NO3)3 materials with three different cells for 24 hours, there was no obvious effect on the activity of the cells. Even when the material concentration was as high as 400 mg / mL, the cell survival rate was higher than 90%, which preliminarily indicated that the material IO-NPs had good biocompatibility in vitro and almost no cytotoxicity.

[0068] Example 4 Establishment of chronic renal failure model

[0069] Adenine was administered to SD rats to establish a chronic renal failure model.

[0070] Male SD rats weighing about 120 g were purchased from Spaif Biotechnology Co., Ltd. Adenine was dissolved in water and gavaged for 4 weeks at a rate of 250 mg / kg / d. The rats were given free food and water. The basal creatinine level of the rats was measured before modeling, and the creatinine value was measured after modeling to confirm the success of the modeling. The detection of creatinine levels higher than the normal value was considered as the basis for the success of the model.

[0071] Example 5 Analysis of the temporal stability of nano-metal-coordinated iohexol in different media

[0072] Compared with small molecules, nanoparticles can exist in the blood circulation for a longer time, effectively extending the imaging time. The liver is the main organ that metabolizes and clears most exogenous drugs. There is evidence that nanoparticles are preferentially deposited in the liver. Considering the safety and long-lasting nature of contrast agents, we hope that CT images can be obtained within a wider time window without the need for multiple administrations of contrast agents, thereby greatly reducing the frequency of injections, which will minimize chronic kidney damage caused by contrast agents and avoid further burdening the kidneys when performing CT angiography in patients with chronic renal failure. As nanocontrast agents, we expect IO-NPs to have a low renal metabolic rate to obtain sufficient circulation time for in vivo CT imaging.

[0073] To verify the above viewpoints, we established a chronic renal failure model by gavage of adenine to SD rats according to the method of Example 4 and injected adenine (mg kg -1 ) iohexol and IO-NPs contrast agents to prove that IO-NPs can not only perform long-term CT imaging, but also accumulate in the liver to reduce the burden on the kidney. High iodine concentration and high loading efficiency are necessary prerequisites for iodine-based nanoparticles to be used as contrast agents.

[0074] Small animal PET-CT (Mdeiso, Hungary) was used to detect different concentrations of IO-NPs. IO-NPs were exposed to iodine at concentrations ranging from 0 to 50 mg mL -1 CT imaging of the inside Figure 8 a, using color and black and white modes to reflect the CT imaging results. Figure 8 b It can be seen that IO-NPs have a high iodine content ranging from 0 to 50 mg mL -1 The standard curves in Figure 4 show 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 CT quantitative studies.

[0075] In addition, IO-NPs and iohexol contrast agents were used to perform in vivo CT imaging studies using a chronic renal failure model SD rat and a SOMATOM Force dual-source CT scanner. -1 ), resulting in a significant enhancement of vascular imaging, with arterial borders visible after 15 minutes and lasting for more than 30 minutes, and no signal was observed in the bladder. The duration of kidney and bladder enhancement was five times that of the commonly used iohexol ( Figure 8 c). These results suggest a long blood circulation time and a certain renal clearance rate, which may be related to the large size of IO-NPs. In addition, the slow metabolism of IO-NPs may help prevent renal damage. In sharp 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 the iohexol small molecule contrast agent is rapidly metabolized to the bladder through tubular filtration. These results confirm that IO-NP can be slowly metabolized in vivo to prolong CT imaging time and a small amount of IO-NP is metabolized by the kidneys, further reducing the burden on the kidneys.

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

[0077] In order to further prove that IO-NPs are mainly metabolized by tolerant organs such as the liver after being injected into the body through the tail vein, further reducing the burden on the kidneys and reducing renal toxicity, we tested the iodine content in various tissues and organs of mice by ICP-MS to track the distribution and metabolism of iodine in iohexol and IO-NPs in the body.

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

[0079] like Fig. 9 a shows that at 500 mg I kg -1 One hour after injection, iohexol is mainly metabolized by the kidneys, and after 24 hours, the kidneys have almost completely metabolized it, and it hardly accumulates in the liver. However, one hour after the tail vein injection of IO-NPs, most of the nanoparticles are concentrated in the reticuloendothelial organs such as the liver and spleen. Since nanomaterials are recognized and phagocytosed by phagocytes after entering the body, and phagocytes are mostly present in organs such as the liver and spleen, the nanomaterials injected into the rats through the tail vein are first enriched in the liver. Fig. 9 As shown in b, with the accumulation of time, the accumulation of IO-NPs in the liver gradually increased, reaching the highest accumulation 24 hours after injection. As time went on, IO-NPs showed a certain metabolic rate. After 72 hours of injection, the content of IO-NPs in the liver and spleen did not decrease significantly, and more than 50% of the materials remained in the organs and could not be metabolized outside the body, indicating that IO-NPs have the ability to accumulate mainly in the liver, thereby reducing the burden of renal metabolism.

[0080] At the same time, we also used ICP-MS to detect the content of iodide ions in the urine and feces of rats at different time periods to explore the metabolic pathways of iohexol and IO-NPs. Obtain rat feces and urine, add 10ml of nitric acid and 2ml of periodic acid to digest at room temperature for 1 day, heat at 180℃ for 8 hours, heat at 200℃ to fully evaporate the solution, add 50ml of water, and determine the aluminum ions and iodide ions in the solution by ICP-MS.

[0081] Fig.10 The metabolism of iohexol and IO-NPs in rats; Fig.10 a is the change of iodine ion content in rat urine over time, Fig.10 b shows the change of iodine ion content in rat feces over time.

[0082] like Fig.10 As shown in a, 2 hours after the mice were injected with the iodine ion small molecule imaging agent, high concentrations of iodine ions were detected in their urine, and almost all of them were metabolized within 24 hours, indicating that iodine ion was eventually excreted from the body through the kidneys in the form of small molecules. However, the concentrations of iodine ions in the urine and feces of the rats injected with IO-NPs were very low. Fig.10 As shown in (b), iodide ions reached a peak in urine and feces 72 hours after injection and were slowly metabolized at a very low concentration, proving that IO-NPs have a slow metabolism and excretion rate in the body.

[0083] Example 7 IO-NPs' ability to protect kidneys in clinical angiography

[0084] We used a chronic renal failure model to explore the protective ability of IO-NPs on the kidneys in clinical angiography. Normal SD rats were gavaged with adenine in saline (250 mg / kg / d) to induce chronic renal injury in SD rats, simulating patients with chronic renal insufficiency. The detection of creatinine levels higher than normal was used as the basis for the success of the model.

[0085] Then, IO-NPs were injected (500 mg / kg -1 ) The changes in serum creatinine, total antioxidant capacity, and interleukin-6 levels in the kidneys before and after ) show the antioxidant capacity and relief efficiency of the kidneys. The detection methods of serum creatinine, total antioxidant capacity, and interleukin-6 levels were conventional experimental methods. The experimental results are shown in Fig.11 . Clinically, testing serum creatinine is one of the main methods to understand renal function and is an important indicator of renal function. Among them, an increase in serum creatinine means damage to renal function. The total antioxidant capacity can reflect the body's total ability to remove reactive oxygen / nitric oxide synthase (ROS / NOS) to a certain extent. Interleukin is an important inflammatory mediator that causes the occurrence and development of renal insufficiency.

[0086] like Fig.11 As shown, the levels of the three indicators in chronic renal failure model rats were increased. After 24 hours of injection of iohexol and IO-NPs, the three indicators reached the maximum peak and then gradually decreased. Fig.11 As shown in a, after the injection of IO-NPs, the creatinine level in the serum was higher than that in the control group (PBS), but significantly lower than that in the iohexol group. Even after 48 hours, the creatinine level was half of that in the iohexol group, indicating that IO-NPs were mainly accumulated in the liver after injection in the body, with a small part being metabolized through the kidneys, and their toxicity to the kidneys was less than that of iohexol (mainly metabolized through the kidneys).

[0087] 24 hours after the injection of IO-NPs contrast agent, the total antioxidant capacity was lower than that of the iohexol group. As time went on, the total antioxidant capacity values ​​of both groups were finally equal to those of the control group ( Fig.11 b).

[0088] Interleukin-6 showed a level that first increased and then decreased before and after injection, and the iohexol group was always higher than the IO-NPs group, indicating that the toxicity of IO-NPs to the kidneys was lower than that of iohexol ( Fig.11 c).

[0089] The above results show that after the injection of iohexol and IO-NPs respectively, although both of them will produce certain toxicity to the kidneys of chronic renal failure model rats, the iohexol group is much higher than the IO-NPs group (even 48 days after injection), indicating that IO-NPs mainly accumulate in the liver, with only a small amount accumulated in the kidneys, which can greatly reduce the toxicity to the kidneys of chronic renal failure model rats after CT imaging.

[0090] IO-NPs have the ability to accumulate preferentially in the liver, which can reduce the burden of renal metabolism. Compared with the small molecule iohexol contrast agent, the production of ROS in the chronic renal failure rat model treated with IO-NPs was less, and the degree of renal damage was less than that of the iohexol group, which is consistent with the in vivo renal protection results mentioned above.

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

Claims

1. A metal-coordinated iohexol nanoparticle, characterized in that: The nanoparticles are prepared by reacting metal salts with iohexol in an organic medium; the particle size of the metal-coordinated iohexol nanoparticles is in the range of 50-100 nm.

2. The metal-coordinated iohexol nanoparticles according to claim 1, characterized in that: The metal salt is selected from Al(NO3)3·9H2O, Mg(NO3)2·6H2O, Zn(NO3)2·6H2O or Ca(NO3)2·6H2O.

3. The metal-coordinated iohexol nanoparticles according to claim 1, characterized in that: The organic medium is selected from one or two of N'N-dimethylformamide, acetonitrile or ethanol.

4. The method for preparing metal-coordinated iohexol nanoparticles according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) dissolving the metal salt and iohexol in an organic medium, stirring and mixing thoroughly to obtain a mixed solution; (2) heating the mixed solution obtained in step (1) to react, and after the reaction is completed, washing and drying to obtain the metal-coordinated iohexol nanoparticles.

5. The preparation method according to claim 4, characterized in that: In step (1), the molar ratio of the metal salt to iohexol is 1:

1.

6. The preparation method according to claim 4, characterized in that: In step (1), 0.1 mmol of iohexol was dissolved in 3 ml of acetonitrile and 2 ml of N'N-dimethylformamide.

7. The preparation method according to claim 4, characterized in that: In step (1), the stirring temperature is 20-30° C., and the stirring time is 0.5-1 h.

8. The preparation method according to claim 4, characterized in that: In step (2), the heating reaction temperature is 110-130° C., and the heating reaction time is 24-48 hours.

9. The preparation method according to claim 4, characterized in that: In step (2), the washing solvents are DMF and ethanol.

10. Use of the metal-coordinated iohexol nanoparticles according to any one of claims 1 to 3 as a medical contrast agent.

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