Kidney excretable gold nanoparticle aggregates, methods of making and use as ct contrast agents

Abstract

The application relates to a kidney-excretable nano-gold aggregate, a preparation method and application as a CT contrast agent, and comprises the following steps: mixing chloroauric acid solution, lye and a mercapto hydrophilic compound to obtain mixed solution A; under the condition of ice water bath and stirring, a reducing agent is added into the mixed solution A to obtain mixed solution B containing nano-gold particles; the mixed solution B is mixed with a wrapping material-buffer solution to obtain mixed solution C containing nano-gold particles@wrapping material; a positively charged compound solution is added into the mixed solution C to obtain mixed solution D; the nano-gold is made into a stable aggregate by the positively charged compound; and the mixed solution D is centrifuged to obtain the kidney-excretable nano-gold aggregate. The synthesized super-small nano-gold is agglomerated into a nano-gold aggregate with stable structure, and the contrast agent can be obtained by simple centrifugal concentration, the contrast agent is stable in property, has good biocompatibility, and can be discharged out of the body along with urine within a period of time after entering the body.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of contrast agent, in particular to a kidney excretable gold nanoparticle aggregate, a preparation method and application as a CT contrast agent. BACKGROUND

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

[0003] Gold nanoparticles are a potential CT contrast agent, and the contrast principle is that gold elements have relatively large X-ray absorption capacity, which is 2.7 times that of iodine elements. Gold nanoparticles as a contrast agent have many advantages: simple preparation method, stable performance, long shelf life, good biocompatibility, easy surface modification, and long circulation time, etc. However, as an element with a large atomic number, although most cell experiments consider that gold nanoparticles are safe and non-toxic, when used as a CT contrast agent, a large dose of gold nanoparticles entering the body will accumulate in important organs such as the liver and spleen, and will not be excreted from the body in a short period of time, which will cause a certain degree of harm to animals and humans. And the final gold nanoparticle solution prepared by the traditional aqueous gold nanoparticle preparation method has a very low mass fraction (about 0.089 mg / mL), and it is extremely difficult to concentrate due to the small particle size and small mass, which seriously limits its industrial production, and causes great inconvenience for subsequent application (the dosage of CT animal and human contrast is extremely large). SUMMARY

[0004] The purpose of the present application is to overcome the above technical deficiencies, provide a kidney excretable gold nanoparticle aggregate, a preparation method and application as a CT contrast agent, and solve the technical problems of difficult concentration or difficult excretion from the body in a short period of time of gold nanoparticles used as a contrast agent in the prior art.

[0005] To achieve the above technical purpose, the technical solution provided by the present application is:

[0006] In a first aspect, the present application provides a kidney excretable gold nanoparticle aggregate formed by aggregation of gold nanoparticle@coating material, the average particle size of the gold nanoparticle aggregate is 100-200 nm; the gold nanoparticle@coating material is a core-shell nanoparticle with gold nanoparticles with an average particle size of less than 10 nm as the core and the coating material as the shell.

[0007] In a second aspect, the present application provides a preparation method of a kidney-removable gold nanoparticle aggregate, comprising the following steps: (1) mixing a chloroauric acid solution, a lye and a mercapto hydrophilic compound to obtain a mixed solution A; (2) adding a reducing agent to the mixed solution A under the condition of ice water bath and stirring to obtain a mixed solution B containing gold nanoparticles; (3) mixing the mixed solution B with a wrapping material-buffer solution to obtain a mixed solution C containing gold nanoparticle@wrapping material; (4) adding a positively charged compound solution to the mixed solution C to obtain a mixed solution D; the positively charged compound makes the gold nanoparticles into a stable aggregate; and (5) centrifuging the mixed solution D to obtain the kidney-removable gold nanoparticle aggregate.

[0008] In a third aspect, the present application provides an application of the gold nanoparticle aggregate as a CT contrast agent.

[0009] Compared with the prior art, the present application has the following beneficial effects:

[0010] The present application aggregates the synthesized ultra-small gold nanoparticles into a structure-stable gold nanoparticle aggregate, which can be used as a contrast agent for CT imaging in animals by simple high-speed centrifugal concentration. The contrast agent has stable properties and good biocompatibility, and can be excreted out of the body with urine within a period of time after entering the body. The contrast agent has greater imaging effect and is safe and non-toxic compared with the previous commercial iodine-containing contrast agent. At the same time, the contrast agent can be prepared rapidly and in large quantities under simple conditions, and has great potential to become the next generation of clinical contrast agent. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 A transmission electron microscope photo of dopamine gold nanoparticles prepared in Example 1;

[0012] Figure 2 A macroscopic photo of gold nanoparticles, dopamine gold nanoparticles and gold nanoparticle aggregate samples (from left to right) prepared in Example 1;

[0013] Figure 3 A CT imaging image of a mouse 4 hours after intravenous injection of the gold nanoparticle aggregate in Example 1;

[0014] Figure 4 A CT imaging image of a mouse 24 hours after intravenous injection of the gold nanoparticle aggregate in Example 2;

[0015] Figure 5 A gold element content curve graph of mouse urine collected within 5 days after injection of dopamine gold nanoparticles and gold nanoparticle aggregates in Example 1 and citric acid gold in Comparative Example 2 into the body, detected by an atomic emission spectrometer;

[0016] Figure 6 A CT value comparison graph of Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0018] When the nano-gold is used as a contrast agent, a large dose of nano-gold enters the body and is enriched in important organs such as liver and spleen, and is not discharged from the body in a short period of time, which can cause a certain degree of harm to the animal body and human. Moreover, the mass fraction of the nano-gold solution prepared by the traditional aqueous nano-gold preparation method is extremely low (about 0.089 mg / mL), and it is extremely difficult to concentrate the nano-gold due to its small particle size and small mass, which seriously limits its industrial production, and causes great inconvenience for subsequent application (the dosage of CT animal and human contrast agent is extremely large).

[0019] In view of the problem that the nano-gold used as a contrast agent is difficult to concentrate or is difficult to be discharged from the body in a short period of time, if the small particle size nano-gold particles are aggregated into irregular aggregates of several to dozens of nano-gold aggregated together, the concentration of the nano-gold becomes relatively simple, which has great advantages in subsequent use. Moreover, after the nano-gold aggregates enter the body, they will be dispersed into ultra-small nano-gold particles with good biocompatibility, which will be discharged from the body with urine within a certain period of time, and will not cause impact on the animal body and human. The nano-gold aggregates use the principle of electrostatic adsorption to aggregate the negatively charged nano-gold together by using positively charged small molecules, and the particle size of the aggregates is controlled by adjusting the ratio of the small molecules to the nano-gold. Generally, the nano-gold aggregates have larger mass and are very stable, and can be concentrated in large quantities by a simple method such as centrifugation, which has great advantages in industrial production.

[0020] In order to prepare a nano-gold aggregate with uniform particle size, stable properties and good biocompatibility, the present application provides a kidney-dischargeable nano-gold aggregate CT contrast agent and a preparation method thereof. Firstly, a small molecule compound containing a thiol group and a reducing agent with strong reducing property are used to prepare ultra-small nano-gold particles with good water solubility, then a nano-gold particle is wrapped with a biocompatible wrapping material to enhance its thermal stability, and finally a positively charged compound is used to aggregate the negatively charged nano-gold into stable nano-gold aggregates. On the one hand, the nano-gold aggregates have stable physicochemical properties, the particle size is stable within three months, and have good biocompatibility. Animal experiments show that most of the nano-gold aggregates will be discharged from the body with urine within 5 days, and will not cause toxic reactions and rejection reactions in the animal body. On the other hand, the relative density of the particles is increased, and the particles can be quickly concentrated by a simple method, which is suitable for industrial production, ensures the convenience of subsequent biological application, and has great potential for commercial application.

[0021] In a first aspect, the present application provides a kidney excretable gold nanoparticle aggregate formed by gold nanoparticles and a coating material, wherein the average particle size of the gold nanoparticle aggregate is 100-200 nm; and the gold nanoparticle-coating material is a core-shell nanoparticle with gold nanoparticles with an average particle size of less than 10 nm as the core and the coating material as the shell.

[0022] In a second aspect, the present application provides a preparation method of the kidney excretable gold nanoparticle aggregate, comprising the following steps:

[0023] (1) mixing a chloroauric acid solution, a lye and a mercapto hydrophilic compound to obtain a mixed solution A, and reducing gold ions;

[0024] (2) adding a reducing agent solution to the mixed solution A under ice water bath and stirring to obtain a mixed solution B containing gold nanoparticles;

[0025] (3) mixing the mixed solution B with a coating material-buffer solution to obtain a mixed solution C containing gold nanoparticle-coating material; improving the stability and dispersibility of the gold nanoparticles in the solution, reducing the toxicity, increasing the biocompatibility of the gold nanoparticles, and making the surface of the gold nanoparticles have abundant functional groups for subsequent biological modification;

[0026] (4) adding a positively charged compound solution to the mixed solution C to obtain a mixed solution D; making the gold nanoparticles into stable aggregates by the positively charged compound; and increasing the dispersibility, imparting specific biocompatibility, and increasing the CT imaging capability;

[0027] (5) centrifuging the mixed solution D to obtain the kidney excretable gold nanoparticle aggregate.

[0028] 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 lye is 0.5-1.5 mmol / L, and the concentration of the mercapto hydrophilic compound is 0.4-50 mg / L.

[0029] Further preferably, the preparation step of the mixed solution A of step (1) comprises mixing 0.005-0.015 g / mL of HAuCl4·3H2O solution, 0.1 mol / L of lye and mercapto hydrophilic compound, and then diluting to the target concentration.

[0030] Preferably, in step (1), the lye includes sodium carbonate solution or sodium hydroxide solution.

[0031] Preferably, in step (1), the mercapto hydrophilic compound includes but is not limited to dimercaptosuccinic acid, thiomalic acid, 2,3-dithiomalic acid, cysteine, mercaptoacetic acid or mercaptopropyl sulfonic acid sodium, etc.

[0032] 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).

[0033] Further preferably, in step (2), the concentration of the reducing agent solution is 0.5 mg / mL; after the reducing agent solution is added to the mixed solution A, the mixed solution B containing the gold nanoparticles is obtained by stirring at a speed of 1300-1500 r / min for 10-20 min.

[0034] Preferably, in step (3), the coating material-buffer solution is obtained by mixing the coating material solution and the Tris solution, and the concentration of the coating material in the coating material-buffer solution is 0.01-0.1 mg / mL.

[0035] The mixed solution B and the coating material-buffer solution are mixed at a volume ratio of 1:1, and the mixed solution C containing the gold nanoparticle@coating material is obtained by stirring for 4-5 h.

[0036] Further preferably, the coating material comprises dopamine hydrochloride or polyethylene glycol.

[0037] Further preferably, the concentration of the Tris solution is 10 mmol / L; and the mixed volume ratio of the coating material solution to the Tris solution is (9.0-9.9):(0.1-1).

[0038] Preferably, in step (4), the positively charged compound comprises polyacetylene imine (PEI), polyallylamine hydrochloride (PAH) or poly-β-amino ester (PBAE).

[0039] Preferably, in step (4), the concentration of the positively charged compound solution is 0.07-0.8 mg / mL; and the volume ratio of the positively charged compound solution to the mixed solution C is (10-200) μL:5 mL, further preferably (10-140) μL:5 mL.

[0040] Preferably, in step (4), after the positively charged compound solution is added to the mixed solution C, the mixed solution D is obtained by stirring at a speed of 200-500 r / min for 1-1.5 h at room temperature.

[0041] Preferably, in step (5), the centrifugation condition is centrifugation at a speed of 10000-12000 rpm for 30-40 min.

[0042] In a third aspect, the application provides a use of the gold nanoparticle aggregate as a CT contrast agent.

[0043] The present application can ensure the easy operation of concentration by agglomerating the nano gold particles into larger aggregates, and achieves the purpose of rapid and large-scale synthesis; the method has simple preparation steps, convenient detection, high reliability and low cost; the obtained nano gold aggregates are stable in property and easy to be removed by kidney, and can be used as CT contrast agent.

[0044] The present application is further described in detail below through specific examples.

[0045] Example 1

[0046] A preparation method of a kidney-removable nano gold aggregate, comprising the following steps:

[0047] Step one, 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 are mixed in a 50 mL volumetric flask, and then the mixture is transferred to a conical flask after being diluted with double distilled water to obtain a mixed solution A;

[0048] Step two, under the condition of ice water mixed bath, 2.5 mL of 0.5 mg / mL sodium borohydride solution is added to the mixed solution A under vigorous stirring, and the stirring is continued for 15 min; finally, a mixed solution B (containing nano gold, the particle size is about 5.9 nm, and the solution is watermelon red) is obtained;

[0049] Step three, 9.9 mL of 10 mM Tris solution (pH 8.0-9.0) and 0.1 mL of 1 mg / mL dopamine hydrochloride solution are uniformly mixed in a conical flask, 10 mL of the mixed solution B obtained in step two is mixed into the conical flask, and the system is continuously stirred at room temperature for 4 h to make the reaction complete, and a mixed solution C containing dopamine nano gold is obtained;

[0050] Step four, 70 μL of 0.078 mg / mL PEI (molecular weight 600) solution is added dropwise into 5 mL of the mixed solution C obtained in step three, and the stirring is continued at room temperature for 1 h to obtain a mixed solution D containing nano gold aggregates;

[0051] Step five, the obtained mixed solution D is concentrated by centrifugation under the condition of 10000 rpm for 30 min to obtain nano gold aggregates.

[0052] Reference Figure 1 The dopamine nano gold particles obtained in step three in the embodiment have good dispersity, and the particle size (the particle size in the embodiment and the following text is the average particle size) is about 6.4 nm.

[0053] Reference Figure 2 In the embodiment, the solution color of the nano gold obtained in step two is watermelon red, the color is deepened after being coated with dopamine, and the color is the deepest after forming the nano gold aggregates, which is dark red or purple.

[0054] Example 2

[0055] A preparation method of a kidney-removable gold nanoparticle aggregate, comprising the following steps:

[0056] Step one, take 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, and then transfer it to a conical flask after constant volume with double distilled water;

[0057] Step two, under the condition of ice water mixed bath, add 2.5 mL of 0.5 mg / mL sodium borohydride solution while stirring vigorously, and stir vigorously for 15 min; finally get watermelon red solution;

[0058] Step three, mix 9 mL of 10 mM Tris solution and 1 mL of 1 mg / mL dopamine hydrochloride solution in the conical flask, take 10 mL of the solution obtained in step two and mix it into the conical flask, and continue to stir at room temperature for 4-5 h to make the system reaction complete;

[0059] Step four, add 100 μL of 0.078 mg / mL PEI solution to 5 mL of the solution obtained in step three, and gently stir at room temperature for 1 h;

[0060] Step five, centrifuge and concentrate the obtained solution, the centrifugation condition is 10000 rpm for 30 min, and the gold nanoparticle aggregate is obtained. Finally, the final concentration is determined by ultraviolet spectrophotometry.

[0061] The dopamine-coated gold nanoparticle obtained in step three of this example has a particle size of about 7 nm.

[0062] Example 3

[0063] A preparation method of a kidney-removable gold nanoparticle aggregate, comprising the following steps:

[0064] Step one, take 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, and then transfer it to a conical flask after constant volume with double distilled water;

[0065] Step two, under the condition of ice water mixed bath, add 2.5 mL of 0.5 mg / mL sodium borohydride solution while stirring vigorously, and stir vigorously for 15 min; finally get watermelon red solution;

[0066] Step three, 9.5 mL of 10mM Tris solution and 0.5 mL of 1 mg / mL dopamine hydrochloride solution were mixed in a conical flask, 10 mL of the solution obtained in step two was mixed into the conical flask, and the system was continuously stirred at room temperature for 4-5 h to make the reaction complete;

[0067] Step four, 140 μL of 0.078 mg / mL PEI solution was added dropwise into 5 mL of the solution obtained in step three, and stirred gently at room temperature for 1 h;

[0068] Step five, the obtained solution was concentrated by centrifugation at 10000 rpm for 30 min to obtain the gold nanoparticle aggregate. Finally, the final concentration was determined by UV spectrophotometry.

[0069] The dopamine-coated gold nanoparticle obtained in step three of the example has a particle size of about 6 nm.

[0070] Example 4

[0071] A preparation method of a kidney-excretable gold nanoparticle aggregate, comprising the following steps:

[0072] Step one, 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 were mixed in a 50 mL volumetric flask, and then transferred to a conical flask after being diluted to volume with double distilled water;

[0073] Step two, under the condition of ice water mixed bath, 2.5 mL of 0.5 mg / mL sodium borohydride solution was added with vigorous stirring, and stirred vigorously for 15 min; finally, a watermelon red solution was obtained;

[0074] Step three, 9.9 mL of 10mM Tris solution and 0.1 mL of 1 mg / mL dopamine hydrochloride solution were mixed in a conical flask, 10 mL of the solution obtained in step two was mixed into the conical flask, and the system was continuously stirred at room temperature for 4-5 h to make the reaction complete;

[0075] Step four, 100 μL of 0.078 mg / mL PEI solution was added dropwise into 5 mL of the solution obtained in step three, and stirred gently at room temperature for 1 h;

[0076] Step five, the obtained solution was concentrated by centrifugation at 10000 rpm for 30 min to obtain the gold nanoparticle aggregate. Finally, the final concentration was determined by UV spectrophotometry.

[0077] The gold nanoparticle obtained in step two of the example has a particle size of about 5 nm.

[0078] Example 5

[0079] A preparation method of a kidney excretable gold nanoparticle aggregate, comprising the following steps:

[0080] Step one, 0.5 mL of 1% HAuCl4·3H2O solution, 0.5 mL of 0.1 mol / L NaOH solution and 0.25 mg of cysteine are mixed in a 50 mL volumetric flask, and then transferred to a conical flask after constant volume with double distilled water;

[0081] Step two, under the condition of ice water mixed bath, 2.5 mL of 0.5 mg / mL sodium borohydride solution is added, and the mixture is stirred for 15 min; finally, a watermelon red solution is obtained;

[0082] Step three, 9.5 mL of 10 mM Tris solution and 0.5 mL of 1 mg / mL polyethylene glycol solution are uniformly mixed in the conical flask, 10 mL of the solution obtained in step two is mixed into the conical flask, and the system is continuously stirred at room temperature for 4-5 h to make the reaction complete;

[0083] Step four, 100 μL of 0.78 mg / mL PBAE solution is added dropwise into 5 mL of the solution obtained in step three, and the mixture is stirred at room temperature for 1 h;

[0084] Step five, the obtained solution is centrifuged and concentrated, the centrifugation condition is 10000 rpm for 30 min, and the gold nanoparticle aggregate is obtained. Finally, the final concentration is determined by ultraviolet spectrophotometry.

[0085] The particle size of the nanoparticles obtained in step two of the example is about 5 nm.

[0086] In the above examples, in step four, the gold nanoparticles will be aggregated into larger aggregates under the action of the positively charged compound, with a particle size of about 100 nm, which is beneficial to the centrifugal separation in step five, and finally the gold nanoparticle aggregate is obtained.

[0087] Comparative example 1

[0088] A commercial CT contrast agent, iohexol, is used.

[0089] Comparative example 2

[0090] A synthesis method of citric acid gold:

[0091] Step one, 0.5 mL of 0.01 g / ml HAuCl4·3H2O solution and 0.5 mL of 0.1 mol / L Na2CO3 solution are mixed in a 50 mL volumetric flask, and then transferred to a conical flask after constant volume with double distilled water;

[0092] Step 2: Add 5 mL of 1 mg / mL sodium citrate solution under vigorous stirring, and stir vigorously for 15 min; finally, a watermelon red solution containing gold citrate is obtained; after multiple centrifugations, gold citrate is obtained.

[0093] The citrate gold nanoparticles obtained in this comparative example have a particle size of 15 nm.

[0094] Comparative Example 3

[0095] The only difference from Example 1 is that the volume of PEI added in step four is adjusted to 1 mL; the other steps and conditions are the same as in Example 1.

[0096] The results showed that the gold nanoparticles obtained in step five had a particle size of approximately 142 nm, but were not very stable and precipitated within a short time, which was not conducive to their application. This indicates that the ratio of PEI to gold nanoparticles affects the properties of the aggregates.

[0097] Comparative Example 4

[0098] The only difference from Example 1 is that the 2.5 mL, 0.5 mg / mL sodium borohydride solution in step two is replaced with 12.5 mL, 0.5 mg / mL sodium ascorbate solution. All other steps and conditions are the same as in Example 1.

[0099] The results showed that the particle size of the gold nanoparticles was approximately 180 nm. This indicates that the type and amount of reducing agent have a significant impact on the particle size of the generated gold nanoparticles.

[0100] Performance testing:

[0101] (1) Animal imaging experiment: The gold nanoparticles obtained in step five of the above examples were mixed with physiological saline to prepare an injection solution of 50 mg / mL, which was injected into mice (approximately 25 g) via the tail vein, at a dose of approximately 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 collected and processed at different time points to obtain images.

[0102] (2) In vivo metabolism experiment. The gold nanoparticles obtained in step five above were diluted with physiological saline to prepare an injection solution of 50 mg / mL, which was injected into mice (approximately 25 g) via the tail vein, at a dose of approximately 200 mg / kg. Subsequently, the mice were housed in metabolic cages for five days, and their urine was collected at regular intervals each day. After the urine was digested and decomposed, the gold content was measured using atomic emission spectroscopy to determine its metabolic curve.

[0103] like Figure 3 The image shown is a CT angiography image of a mouse 4 hours after intravenous injection of the gold nanoparticles obtained in Example 1. The image is clear.

[0104] like Figure 4 The image shown is a CT angiography image of a mouse 24 hours after intravenous injection of the gold nanoparticles obtained in Example 2. The image is clear.

[0105] Dopamine-containing gold nanoparticles (obtained by repeated centrifugation of mixture C followed by PEG dehydration) and gold nanoparticle aggregates prepared in Example 1, and gold citrate from Comparative Example 2, were respectively prepared into 50 mg / mL injection solutions with physiological saline. Mice were injected and their urine was collected within 5 days. The gold content was analyzed using atomic emission spectrometry. The results are shown in the figure. Figure 5 .

[0106] like Figure 5 As shown, the dopamine gold nanoparticles and gold nanoparticle aggregates of the present invention can remain in the body of mice for a period of time after being injected into the body via the tail vein, and can then be excreted in the urine, while gold citrate cannot be excreted in the urine.

[0107] The gold nanoparticles prepared in Example 1 of this invention were compared with the commercial CT contrast agent iohexol in Comparative Example 1. The gold nanoparticles and iohexol of the same concentration (50 mg / mL) were injected into mice via the tail vein and CT imaging was performed to compare the CT values ​​of the commercial contrast agent and the gold nanoparticles in this invention.

[0108] Depend on Figure 6 The results showed that, at the same concentration, the CT value of the gold nanoparticles in this invention was higher than that of commercial iohexol, indicating that the CT imaging effect was better.

[0109] This invention provides a renally excretable gold nanoparticle aggregate, its preparation method, and its application as a CT contrast agent. Ultra-small gold nanoparticles are polymerized into gold nanoparticle aggregates through electrostatic interactions using positively charged small molecules. This produces a stable, biocompatible CT contrast agent that can be excreted in urine and is simple to prepare, suitable for industrial production. Due to its high gold content, this contrast agent can be quickly concentrated using simple methods, making it suitable for industrial production and showing great potential as a next-generation commercial contrast agent.

[0110] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a kidney excretable nano-gold aggregate, characterized in that, The method comprises the following steps: a chloroauric acid solution, a lye and a mercapto-hydrophilic compound are mixed to obtain a mixed solution A; a reducing agent solution is added to the mixed solution A under the condition of ice water bath and stirring to obtain a mixed solution B containing nano-gold particles; the mixed solution B is mixed with a wrapping material-buffer solution to obtain a mixed solution C containing nano-gold particles and wrapping material; a positively charged compound solution is added to the mixed solution C to obtain a mixed solution D; the nano-gold is made into stable aggregates by the positively charged compound; the mixed solution D is centrifuged to obtain the nano-gold aggregates which can be excreted by kidney; the positively charged compound comprises polyacetylimine, polyallylamine hydrochloride or poly-beta-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 the positively charged compound solution is added to the mixed solution C, the mixed solution D is obtained by stirring at a speed of 200-500 r / min at room temperature for 1-1.5 h; in the mixed solution A, the mass concentration of chloroauric acid is 0.05-0.15 mg / mL, the concentration of the lye is 0.5-1.5 mmol / L, and the concentration of the mercapto-hydrophilic compound is 0.4-50 mg / L; the reducing agent comprises sodium borohydride; the mass ratio of chloroauric acid to reducing agent is (1-1.5):(2.5-12.5); and the concentration of the reducing agent solution is 0.5 mg / mL.

2. The method of claim 1, wherein the kidney-removable gold nanoparticle aggregates are prepared by the following steps of: the lye comprises sodium carbonate solution or sodium hydroxide solution; the mercapto-hydrophilic compound comprises dimercaptosuccinic acid, thiomalic acid, 2,3-dithiomalic acid, cysteine, mercaptoacetic acid or mercaptopropyl sulfonic acid sodium.

3. The method for preparing renal-excretable gold nanoparticles according to claim 1, characterized in that, after the reducing agent solution is added to the mixed solution A, the mixed solution B containing nano-gold particles is obtained by stirring at a speed of 1300-1500 r / min for 10-20 min.

4. The method of claim 1, wherein the kidney-removable gold nanoparticle aggregate is prepared by the process comprising: the wrapping material-buffer solution is obtained by mixing a wrapping material solution and a Tris solution; and the concentration of the wrapping material in the wrapping material-buffer solution is 0.01-0.1 mg / mL; the mixed solution B is mixed with the wrapping material-buffer solution at a volume ratio of 1:1, and the mixed solution C containing nano-gold particles and wrapping material is obtained by stirring for 4-5 h.

5. The method for preparing renally excretable gold nanoparticles according to claim 4, characterized in that, the wrapping material comprises dopamine hydrochloride or polyethylene glycol; the concentration of the Tris solution is 10 mmol / L; and the mixed volume ratio of the wrapping material solution to the Tris solution is (9.0-9.9):(0.1-1).

6. The method for preparing renally excretable gold nanoparticles according to claim 1, characterized in that, the centrifugation condition is centrifugation at a speed of 10000-12000 rpm for 30-40 min.

7. A kidney excretable gold nanoparticle aggregate, characterized in that, The nano-gold aggregates are obtained by the preparation method according to any one of claims 1-6; the nano-gold aggregates are formed by aggregation of nano-gold particles and wrapping material; the average particle size of the nano-gold aggregates is 100-200 nm; and the nano-gold particles and wrapping material are core-shell nanoparticles with the nano-gold particles with an average particle size of less than 10 nm as the core and the wrapping material as the shell.

8. Use of the nano-gold aggregates according to claim 7 or obtained by the preparation method according to any one of claims 1-6 in preparation of CT contrast agents.

Images