Nanogold aggregate capable of being excreted by kidney, preparation method and application of nanogold aggregate as CT (computed tomography) contrast agent

Abstract

The invention relates to a nanogold aggregate capable of realizing kidney excretion, a preparation method and application of the nanogold aggregate as a CT contrast agent, and the preparation method comprises the following steps: mixing a chloroauric acid solution, an alkali solution and a sulfydryl hydrophilic compound to obtain a mixed solution A; under the ice-water bath and stirring conditions, a reducing agent is added into the mixed solution A, and a mixed solution B containing nano-gold particles is obtained; mixing the mixed solution B with a wrapping material-buffer solution to obtain a mixed solution C containing the gold nanoparticles and the wrapping material; adding a positively charged compound solution into the mixed solution C to obtain a mixed solution D; the nanogold becomes a stable aggregate through a positively charged compound; and centrifuging the mixed solution D to obtain the nanogold aggregate capable of realizing kidney excretion. The synthesized ultra-small nanogold is agglomerated into the nanogold aggregate with a stable structure, the contrast agent can be obtained through simple centrifugal concentration, the contrast agent is stable in property and good in biocompatibility, and the contrast agent can be discharged out of a body along with urine within a period of time after entering the body.

Description

Technical Field

[0001] The invention relates to the field of contrast agents, and in particular to a nano-gold aggregate that can be excreted by kidneys, a preparation method thereof, and an application thereof as a CT contrast agent. Background Art

[0002] Computerized tomography (CT) imaging technology has a high spatial resolution and is currently widely used in the early diagnosis of various diseases, especially cancer, in clinical practice. In order to enhance the CT imaging effect, it is usually necessary to inject contrast agents containing heavy atoms. At present, the contrast agents that are widely used in commercial applications are mainly iodine-containing contrast agents, such as iohexol, diatrizoate, etc. These small molecules containing iodine usually have fast metabolism, short circulation time, and certain nephrotoxicity at high doses, and there are many defects in clinical application. At present, new contrast agents containing gold have become a research hotspot.

[0003] Nanogold is a potential CT contrast agent. Its contrast principle is mainly that gold has a relatively large X-ray absorption capacity, which is 2.7 times that of iodine. Nanogold has many advantages as a contrast agent: simple preparation method, stable performance, long shelf life, good biocompatibility, easy surface modification and long circulation time. However, as an element with a large atomic number, although most cell experiments believe that nanogold is safe and non-toxic, when used as a CT contrast agent, a large dose of nanogold will enter the body and accumulate in important organs such as the liver or spleen, and will not be excreted from the body in a short period of time, causing a certain degree of harm to animals and humans. In addition, the mass fraction of the nanogold solution obtained by the traditional aqueous nanogold preparation method is extremely low (about 0.089 mg / mL), and due to the small particle size and mass of nanogold, it is extremely difficult to concentrate, which seriously limits its industrial production and causes great inconvenience for subsequent applications (the amount of CT animal and human contrast drugs is very large). Summary of the invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, provide a nano-gold aggregate that can be excreted by the kidneys, a preparation method and an application as a CT contrast agent, and solve the technical problem that the nano-gold used as a contrast agent in the prior art is difficult to concentrate or difficult to be excreted from the body in a short period of time.

[0005] In order to achieve the above technical purpose, the technical solution provided by the present invention is: In the first aspect, the present invention provides a nanogold aggregate that can be excreted by the kidneys, which is formed by the aggregation of nanogold particles @ encapsulating materials, and the average particle size of the nanogold aggregate is 100-200nm; the nanogold particles @ encapsulating materials are core-shell nanoparticles with nanogold particles with an average particle size of less than 10nm as the core and the encapsulating material as the shell.

[0006] In a second aspect, the present invention provides a method for preparing nanogold aggregates that can be excreted by the kidneys, comprising the following steps: (1) mixing a chloroauric acid solution, an alkali solution and a thiol hydrophilic compound to obtain a mixed solution A; (2) adding a reducing agent to the mixed solution A under ice-water bath and stirring conditions to obtain a mixed solution B containing nanogold particles; (3) mixing the mixed solution B with a coating material-buffer to obtain a mixed solution C containing nanogold particles@coating material; (4) adding a positively charged compound solution to the mixed solution C to obtain a mixed solution D; the positively charged compound is used to make the nanogold become a stable aggregate; and (5) centrifuging the mixed solution D to obtain nanogold aggregates that can be excreted by the kidneys.

[0007] In a third aspect, the present invention provides a use of nanogold aggregates as a CT contrast agent.

[0008] Compared with the prior art, the beneficial effects of the present invention include: The present invention aggregates the synthesized ultra-small nano-gold into a nano-gold aggregate with a stable structure, and obtains a contrast agent that can be used as CT contrast in animals by simple high-speed centrifugal concentration; the contrast agent has stable properties and good biocompatibility, and can be excreted from the body with urine within a period of time after entering the body. The contrast agent has a greater contrast effect than the previous commercial iodine-containing contrast agent and is safe and non-toxic. At the same time, the contrast agent can be quickly prepared in large quantities under simple conditions, and has great potential to become the next generation of clinical contrast agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a transmission electron microscope photo of dopamine gold nanoparticles prepared in Example 1; Figure 2 Macroscopic photos of the gold nanoparticles, dopamine gold nanoparticles and gold nanoparticle aggregate samples (from left to right) prepared in Example 1; Figure 3 This is a CT angiography image of a mouse 4 hours after intravenous injection of gold nanoparticles in Example 1; Figure 4 This is a CT angiography image of a mouse 24 hours after intravenous injection of gold nanoparticles in Example 2; Figure 5 The dopamine nanogold and nanogold aggregates of Example 1 and the gold citrate of Comparative Example 2 were injected into the body, and the urine of mice was collected within 5 days, and the gold content was detected by atomic emission spectrometer; Figure 6 It is a comparison chart of CT values ​​of Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0011] When nanogold is used as a contrast agent, a large dose of nanogold entering the body will be concentrated in important organs such as the liver or spleen, and will not be excreted from the body in a short period of time, causing a certain degree of harm to animals and humans. In addition, the mass fraction of the nanogold solution obtained by the traditional aqueous nanogold preparation method is extremely low (about 0.089 mg / mL), and it is extremely difficult to concentrate the nanogold due to its small particle size and low mass, which seriously limits its industrial production and causes great inconvenience for subsequent applications (CT animal and human contrast agents require a large amount of drugs).

[0012] In view of the problem that the nanogold used as a contrast agent is difficult to concentrate or difficult to be excreted from the body in a short period of time, if the small-sized nanogold particles are aggregated into irregular aggregates with uniform particle size composed of several to dozens of nanogolds, the concentration of nanogold will become relatively simple, which will have great advantages in subsequent use. And after such nanogold aggregates enter the body, they will disperse into ultra-small nanogold particles with good biocompatibility, which will be excreted from the body with urine within a certain period of time, and will not affect animals and humans. Nanogold aggregates use the principle of electrostatic adsorption to use positively charged small molecules to aggregate negatively charged nanogold together, and the purpose of controlling the aggregate particle size is achieved by adjusting the ratio of small molecules to nanogold. Usually, nanogold aggregates have a larger mass and are very stable. They can be concentrated in large quantities by simple methods such as centrifugation, which has great advantages in industrial production.

[0013] In order to prepare a nanogold aggregate with uniform particle size, stable properties and good biocompatibility, the present invention provides a nanogold aggregate CT contrast agent that can be excreted by the kidney and a preparation method thereof. First, a hydrophilic small molecule compound containing thiol and a reducing agent with strong reducing property are used to prepare ultra-small nanogold particles with good water solubility, and then the nanogold particles are wrapped with a wrapping material with good biocompatibility to enhance its thermal stability; finally, a positively charged compound is used to aggregate the negatively charged nanogold into a stable nanogold aggregate. On the one hand, this nanogold aggregate has stable physicochemical properties, keeps the particle size stable within three months and has good biocompatibility. Animal experiments show that most of this nanogold aggregate will be excreted from the body with urine within 5 days, and will not cause toxic reactions and rejection reactions in animals; on the other hand, the relative density of the particles is increased, and they can be quickly concentrated by a simple method, which is suitable for industrial production, ensuring the simplicity of subsequent biological applications, and has great potential for commercial applications.

[0014] In the first aspect, the present invention provides a nanogold aggregate that can be excreted by the kidneys, which is formed by the aggregation of nanogold particles @ encapsulating materials, and the average particle size of the nanogold aggregate is 100-200nm; the nanogold particles @ encapsulating materials are core-shell nanoparticles with nanogold particles with an average particle size of less than 10nm as the core and the encapsulating material as the shell.

[0015] In a second aspect, the present invention provides a method for preparing nanogold aggregates that can be excreted by the kidney, comprising the following steps: (1) mixing chloroauric acid solution, alkali solution and thiol hydrophilic compound to obtain a mixed solution A to reduce gold ions; (2) Adding a reducing agent solution to the mixed solution A under ice water bath and stirring conditions to obtain a mixed solution B containing gold nanoparticles; (3) Mixing the mixed solution B with the encapsulating material-buffered solution to obtain a mixed solution C containing gold nanoparticles@encapsulating material; improving the stability and dispersibility of the gold nanoparticles in the solution, reducing toxicity, increasing the biocompatibility of the gold nanoparticles, and making the surface of the gold nanoparticles have abundant functional groups, which is easy for subsequent biological modification; (4) Adding a positively charged compound solution to the mixed solution C to obtain a mixed solution D; the positively charged compound is used to make the gold nanoparticles into stable aggregates; and the dispersibility is increased, the gold nanoparticles are endowed with specific biocompatibility, and the CT imaging capability is increased; (5) Centrifuge the mixed solution D to obtain gold nanoparticles that can be excreted by the kidneys.

[0016] Preferably, in the mixed solution A of step (1), the mass concentration of chloroauric acid is 0.05-0.15 mg / mL, the concentration of the base is 0.5-1.5 mmol / L, and the concentration of the thiol hydrophilic compound is 0.4-50 mg / L.

[0017] Further preferably, the preparation step of the mixed solution A in step (1) comprises: mixing 0.005-0.015 g / mL HAuCl4·3H2O solution, 0.1 mol / L alkali solution and a thiol hydrophilic compound, and then adjusting the volume to the target concentration.

[0018] Preferably, in step (1), the alkali solution includes sodium carbonate solution or sodium hydroxide solution.

[0019] Preferably, in step (1), the thiol hydrophilic compound includes but is not limited to dithiosuccinic acid, thiomalic acid, 2,3-dithiomalic acid, cysteine, thioglycolic acid or sodium mercaptopropanesulfonate.

[0020] Preferably, in step (2), the reducing agent comprises sodium borohydride; and the mass ratio of chloroauric acid to the reducing agent is (1-1.5): (2.5-12.5).

[0021] Further preferably, in step (2), the concentration of the reducing agent solution is 0.5 mg / mL; after adding the reducing agent solution to the mixed solution A, the mixture is vigorously stirred at a speed of 1300 to 1500 r / min for 10 to 20 min to obtain a mixed solution B containing nano-gold particles.

[0022] Preferably, in step (3), the encapsulating material-buffer is prepared by mixing an encapsulating material solution with a Tris solution, and the concentration of the encapsulating material in the encapsulating material-buffer is 0.01 to 0.1 mg / mL; The mixed solution B is mixed with the encapsulating material-buffer in a volume ratio of 1:1, and stirred for 4 to 5 hours to obtain a mixed solution C containing nano-gold particles@encapsulating material.

[0023] Further preferably, the encapsulating material comprises dopamine hydrochloride or polyethylene glycol.

[0024] More preferably, the concentration of the Tris solution is 10 mmol / L; and the mixing volume ratio of the encapsulating material solution to the Tris solution is (9.0-9.9): (0.1-1).

[0025] Preferably, in step (4), the positively charged compound comprises poly(ethyleneimine) (PEI), poly(allylamine hydrochloride) (PAH) or poly(β-amino ester) (PBAE).

[0026] Preferably, in step (4), the concentration of the positively charged compound solution is 0.07-0.8 mg / mL; the volume ratio of the positively charged compound solution to the mixed solution C is (10-200) μL:5 mL, and more preferably (10-140) μL:5 mL.

[0027] Preferably, in step (4), after adding the positively charged compound solution to the mixed solution C, the mixture is stirred at a speed of 200 to 500 r / min for 1 to 1.5 h at room temperature to obtain a mixed solution D.

[0028] Preferably, in step (5), the centrifugation condition is at a speed of 10000-12000 rpm for 30-40 min.

[0029] In a third aspect, the present invention provides a use of nanogold aggregates as a CT contrast agent.

[0030] The invention achieves the purpose of rapid and large-scale synthesis by agglomerating nano-gold particles into larger aggregates to ensure the easy operability of their concentration; the method has simple preparation steps, convenient detection, high reliability and low cost; the obtained nano-gold aggregates have stable properties and are easily eliminated by the kidneys, and can be used as CT contrast agents.

[0031] The present invention is further described in detail below through specific examples.

[0032] Example 1 A method for preparing nanogold aggregates that can be excreted by the kidneys comprises the following steps: Step 1: Mix 0.5 mL of 0.01 g / ml HAuCl4·3H2O solution, 0.5 mL of 0.1 mol / L Na2CO3 solution and 0.25 mg of thiomalic acid in a 50 mL volumetric flask, dilute to volume with double distilled water, and transfer to a conical flask to obtain a mixed solution A; Step 2: Add 2.5 mL of 0.5 mg / mL sodium borohydride solution to the mixed solution A under vigorous stirring in an ice-water mixed bath, and stir vigorously for 15 min; finally, a mixed solution B (containing nanogold, with a particle size of about 5.9 nm, and a watermelon red solution) is obtained; Step 3: Evenly mix 9.9 mL of 10 mM Tris solution (pH 8.0-9.0) and 0.1 mL of 1 mg / mL dopamine hydrochloride solution in a conical flask, take 10 mL of the mixed solution B obtained in step 2 and mix it into the conical flask, and continue stirring at room temperature for 4 hours to allow the system to react completely, to obtain a mixed solution C containing dopamine nanogold; Step 4: Add 70 μL of 0.078 mg / mL PEI (molecular weight 600) solution dropwise into 5 mL of the mixed solution C obtained in step 3, and stir at room temperature for 1 hour to obtain a mixed solution D containing nano-gold aggregates; Step 5: Concentrate the obtained mixed solution D by centrifugation at 10000 rpm for 30 min to obtain gold nanoparticles.

[0033] See also Figure 1 The dopamine gold nanoparticles obtained in step three of this embodiment have good dispersion and a particle size (the particle sizes mentioned in this embodiment and the following text are all average particle sizes) of about 6.4 nm.

[0034] See also Figure 2 In this embodiment, the color of the nano-gold solution obtained in step 2 is watermelon red, and the color deepens after being coated with dopamine. After the nano-gold aggregates are formed, the color is the darkest, dark red or purple.

[0035] Example 2 A method for preparing nanogold aggregates that can be excreted by the kidneys comprises the following steps: Step 1: Mix 0.5 mL of 0.01 g / ml HAuCl4·3H2O solution, 0.5 mL of 0.1 mol / L Na2CO3 solution and 0.025 mg of thiomalic acid in a 50 mL volumetric flask, dilute to volume with double distilled water, and transfer to a conical flask; Step 2: In an ice-water mixed bath, stir vigorously and add 2.5 mL of 0.5 mg / mL sodium borohydride solution, and stir vigorously for 15 minutes; finally, a watermelon red solution is obtained; Step 3: Evenly mix 9 mL of 10 mM Tris solution and 1 mL of 1 mg / mL dopamine hydrochloride solution in a conical flask, take 10 mL of the solution obtained in step 2 and mix it into the conical flask, and continue stirring at room temperature for 4-5 hours to allow the system to react completely; Step 4: Add 100 μL of 0.078 mg / mL PEI solution dropwise into 5 mL of the solution obtained in step 3, and stir gently at room temperature for 1 h; Step 5: The obtained solution was concentrated by centrifugation at 10,000 rpm for 30 min to obtain nano-gold aggregates. The final concentration was determined by ultraviolet spectrophotometry.

[0036] The particle size of the dopamine-coated gold nanoparticles obtained in step 3 of this embodiment is about 7 nm.

[0037] Example 3 A method for preparing nanogold aggregates that can be excreted by the kidneys comprises the following steps: Step 1: Mix 0.5 mL of 0.01 g / ml HAuCl4·3H2O solution, 0.5 mL of 0.1 mol / L NaOH solution and 2.5 mg of thiomalic acid in a 50 mL volumetric flask, dilute to volume with double distilled water, and transfer to a conical flask; Step 2: In an ice-water mixed bath, stir vigorously and add 2.5 mL of 0.5 mg / mL sodium borohydride solution, and stir vigorously for 15 minutes; finally, a watermelon red solution is obtained; Step 3: Evenly mix 9.5 mL of 10 mM Tris solution and 0.5 mL of 1 mg / mL dopamine hydrochloride solution in a conical flask, take 10 mL of the solution obtained in step 2 and mix it into the conical flask, and continue stirring at room temperature for 4-5 hours to allow the system to react completely; Step 4: Add 140 μL of 0.078 mg / mL PEI solution dropwise into 5 mL of the solution obtained in step 3, and stir gently at room temperature for 1 h; Step 5: The obtained solution was concentrated by centrifugation at 10,000 rpm for 30 min to obtain nano-gold aggregates. The final concentration was determined by ultraviolet spectrophotometry.

[0038] The particle size of the dopamine-coated gold nanoparticles obtained in step 3 of this embodiment is about 6 nm.

[0039] Example 4 A method for preparing nanogold aggregates that can be excreted by the kidneys comprises the following steps: Step 1: Mix 0.5 mL of 1% HAuCl4·3H2O solution, 0.5 mL of 0.1 mol / L NaOH solution and 2.5 mg of thiomalic acid in a 50 mL volumetric flask, dilute to volume with double distilled water, and transfer to a conical flask; Step 2: In an ice-water mixed bath, stir vigorously and add 2.5 mL of 0.5 mg / mL sodium borohydride solution, and stir vigorously for 15 minutes; finally, a watermelon red solution is obtained; Step 3: Evenly mix 9.9 mL of 10 mM Tris solution and 0.1 mL of 1 mg / mL dopamine hydrochloride solution in a conical flask, take 10 mL of the solution obtained in step 2 and mix it into the conical flask, and continue stirring at room temperature for 4-5 hours to allow the system to react completely; Step 4: Add 100 μL of 0.078 mg / mL PEI solution dropwise into 5 mL of the solution obtained in step 3, and stir gently at room temperature for 1 h; Step 5: The obtained solution was concentrated by centrifugation at 10,000 rpm for 30 min to obtain nano-gold aggregates. The final concentration was determined by ultraviolet spectrophotometry.

[0040] The nano-gold particles obtained in step 2 of this embodiment are about 5 nm.

[0041] Example 5 A method for preparing nanogold aggregates that can be excreted by the kidneys comprises the following steps: Step 1: Mix 0.5 mL of 1% HAuCl4·3H2O solution, 0.5 mL of 0.1 mol / L NaOH solution and 0.25 mg of cysteine ​​in a 50 mL volumetric flask, dilute to volume with double distilled water, and transfer to a conical flask; Step 2: In an ice-water mixed bath, stir vigorously and add 2.5 mL of 0.5 mg / mL sodium borohydride solution, and stir vigorously for 15 minutes; finally, a watermelon red solution is obtained; Step 3: Evenly mix 9.5 mL of 10 mM Tris solution and 0.5 mL of 1 mg / mL polyethylene glycol solution in a conical flask, take 10 mL of the solution obtained in step 2 and mix it into the conical flask, and continue stirring at room temperature for 4-5 hours to allow the system to react completely; Step 4: Add 100 μL of 0.78 mg / mL PBAE solution dropwise into 5 mL of the solution obtained in step 3, and stir gently at room temperature for 1 h; Step 5: The obtained solution was concentrated by centrifugation at 10,000 rpm for 30 min to obtain nano-gold aggregates. The final concentration was determined by ultraviolet spectrophotometry.

[0042] The particle size of the nanoparticles obtained in step 2 of this embodiment is about 5 nm.

[0043] In the above embodiments, in step 4, the gold nanoparticles will aggregate into larger aggregates under the action of the positively charged compounds, with a particle size of about 100 nm, which is beneficial for the centrifugal separation in step 5, and finally the gold nanoparticles aggregates are obtained.

[0044] Comparative Example 1 The commercial CT contrast agent iohexol was used.

[0045] Comparative Example 2 A method for synthesizing gold citrate: Step 1: Take 0.5 mL of 0.01 g / ml HAuCl4·3H2O solution and 0.5 mL of 0.1 mol / L Na2CO3 solution and mix them in a 50 mL volumetric flask. After making up to volume with double distilled water, transfer it to a conical flask. Step 2: add 5 mL of 1 mg / mL sodium citrate solution under vigorous stirring and stir vigorously for 15 minutes; finally obtain a watermelon red solution containing citrate gold; obtain citrate gold after multiple centrifugation.

[0046] The particle size of the gold citrate nanoparticles obtained in this comparative example is 15 nm.

[0047] Comparative Example 3 The only difference with respect to Example 1 is that the added volume of PEI in step 4 is adjusted to 1 mL; the other steps and conditions are the same as those in Example 1.

[0048] The results showed that the nano-gold aggregates obtained in step 5 had a particle size of about 142 nm, but were not very stable and precipitated in a short time, which was not conducive to application. This showed that the ratio between PEI and gold nanoparticles had an effect on the properties of the aggregates.

[0049] Comparative Example 4 The only difference with respect to Example 1 is that 2.5 mL of 0.5 mg / mL sodium borohydride solution in step 2 is replaced by 12.5 mL of 0.5 mg / mL sodium ascorbate solution, and the other steps and conditions are the same as those in Example 1.

[0050] The results showed that the particle size of the gold nanoparticles was about 180nm, which showed that the type and amount of reducing agent had a great influence on the particle size of the generated gold nanoparticles.

[0051] Performance Test: (1) Animal imaging experiment: The nanogold aggregates obtained in step 5 of the above embodiment were added with physiological saline to prepare a 50 mg / mL injection solution, which was injected into mice (about 25 g) through the tail vein, with a dose of about 200 mg / kg. Subsequently, the mice were anesthetized by intraperitoneal injection of 100 μL of 2% phenobarbital PBS solution. CT data of the mice were scanned and collected at different time periods and processed to obtain images.

[0052] (2) In vivo metabolism experiment. The gold nanoparticles obtained in step 5 above were added with physiological saline to prepare a 50 mg / mL injection solution, which was then injected into mice (about 25 g) through the tail vein at a dose of about 200 mg / kg. Subsequently, the mice were kept in a metabolic cage for five days, and urine was collected from the mice at regular intervals every day. After the urine was digested and decomposed, the gold content was measured by atomic emission spectroscopy to determine its metabolic curve.

[0053] like Figure 3 The figure shows the CT angiography image of mice 4 hours after intravenous injection of the nanogold aggregates obtained in Example 1. The image is clear.

[0054] like Figure 4 The figure shows the CT angiography image of mice 24 hours after intravenous injection of the nanogold aggregates obtained in Example 2. The image is clear.

[0055] The dopamine nanogold prepared in Example 1 (mixed solution C was centrifuged repeatedly and then PEG was added to absorb water) and nanogold aggregates, and the citrate gold prepared in Comparative Example 2 were added with physiological saline to prepare a 50 mg / mL injection solution. The urine of mice was collected within 5 days after injection into the body of mice, and the gold content curve was detected by atomic emission spectrometer. The results are shown in FIG. Figure 5 .

[0056] like Figure 5 As shown, the dopamine gold nanoparticles and gold nanoparticle aggregates of the present invention can be injected into mice via the tail vein, remain in the animal body for a period of time, and then be excreted from the body with urine, while gold citrate cannot be excreted with urine.

[0057] The nanogold aggregates prepared in Example 1 of the present invention were compared with the commercial CT contrast agent iohexol of Comparative Example 1. The nanogold aggregates and iohexol of the same concentration (50 mg / mL) were injected into mice through the tail vein, and CT imaging was performed to compare the CT values ​​of the commercial contrast agent and the nanogold particles in the present invention.

[0058] Depend on Figure 6 The results showed that at the same concentration, the CT value of the nanogold aggregates in the present invention was higher than that of the commercial iohexol, indicating that the CT angiography effect was better.

[0059] The present invention provides a nano-gold aggregate that can be excreted by the kidney, a preparation method, and an application as a CT contrast agent. Ultra-small nano-gold is polymerized into nano-gold aggregates by electrostatic action using positively charged small molecules, and a CT contrast agent with stable properties, good biocompatibility, can be excreted from the body with urine, and is simple to prepare and suitable for industrial production is prepared. Due to the large mass fraction of gold, this contrast agent is easy to be quickly concentrated by a simple method, is suitable for industrial production, and has great potential to become the next generation of commercial contrast agents.

[0060] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A nanogold aggregate that can be excreted by the kidney, characterized in that: The nano-gold aggregates are formed by the aggregation of nano-gold particles@wrapping materials, and the average particle size of the nano-gold aggregates is 100-200nm; the nano-gold particles@wrapping materials are core-shell nanoparticles with nano-gold particles with an average particle size of less than 10nm as cores and the wrapping materials as shells.

2. The method for preparing the nano-gold aggregates that can be excreted by the kidney as claimed in claim 1, characterized in that: The following steps are involved: Mixing chloroauric acid solution, alkali solution and thiol hydrophilic compound to obtain mixed solution A; Under ice-water bath and stirring conditions, adding a reducing agent solution to the mixed solution A to obtain a mixed solution B containing nano-gold particles; Mixing the mixed solution B with the encapsulating material-buffer to obtain a mixed solution C containing the nano-gold particles@encapsulating material; A positively charged compound solution is added to the mixed solution C to obtain a mixed solution D; the positively charged compound is used to make the gold nanoparticles become stable aggregates; The mixed solution D is centrifuged to obtain nanogold aggregates that can be excreted by the kidney.

3. The method for preparing the nano-gold aggregates that can be excreted by the kidney according to claim 2, characterized in that: In the mixed solution A, the mass concentration of chloroauric acid is 0.05-0.15 mg / mL, the concentration of the base is 0.5-1.5 mmol / L, and the concentration of the thiol hydrophilic compound is 0.4-50 mg / L.

4. The method for preparing the nano-gold aggregates that can be excreted by the kidney according to claim 2, characterized in that: Alkali solutions include sodium carbonate solution or sodium hydroxide solution; The mercapto hydrophilic compounds include dimercaptosuccinic acid, thiomalic acid, 2,3-dithiomalic acid, cysteine, thioglycolic acid or sodium mercaptopropanesulfonate.

5. The method for preparing the nano-gold aggregates that can be excreted by the kidney according to claim 2, characterized in that: The reducing agent includes sodium borohydride; the mass ratio of chloroauric acid to the reducing agent is (1-1.5): (2.5-12.5); The concentration of the reducing agent solution was 0.5 mg / mL; After adding the reducing agent solution to the mixed solution A, the mixture was vigorously stirred at a rotation speed of 1300 to 1500 r / min for 10 to 20 minutes to obtain a mixed solution B containing nano-gold particles.

6. The method for preparing the nano-gold aggregates that can be excreted by the kidney according to claim 2, characterized in that: The encapsulating material-buffer is formed by mixing an encapsulating material solution with a Tris solution, and the concentration of the encapsulating material in the encapsulating material-buffer is 0.01 to 0.1 mg / mL; The mixed solution B is mixed with the encapsulating material-buffer in a volume ratio of 1:1, and stirred for 4 to 5 hours to obtain a mixed solution C containing nano-gold particles@encapsulating material.

7. The method for preparing the nano-gold aggregates that can be excreted by the kidney according to claim 2, characterized in that: Encapsulating materials include dopamine hydrochloride or polyethylene glycol; The concentration of the Tris solution is 10 mmol / L; the mixing volume ratio of the encapsulating material solution and the Tris solution is (9.0-9.9): (0.1-1).

8. The method for preparing the nano-gold aggregates that can be excreted by the kidney according to claim 2, characterized in that: Positively charged compounds include polyacetimide, polyallylamine hydrochloride, or poly-β-amino ester; The concentration of the positively charged compound solution is 0.07-0.8 mg / mL; the volume ratio of the positively charged compound solution to the mixed solution C is (10-200) μL:5 mL; After adding the positively charged compound solution to the mixed solution C, the mixture is stirred at a speed of 200 to 500 r / min for 1 to 1.5 hours at room temperature to obtain a mixed solution D.

9. The method for preparing the nano-gold aggregates that can be excreted by the kidney according to claim 2, characterized in that: The centrifugation condition is to centrifuge at a speed of 10000-12000 rpm for 30-40 minutes.

10. Use of the nanogold aggregates as claimed in claim 1 or the nanogold aggregates prepared by the preparation methods as claimed in claims 2 to 9 as CT contrast agents.

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