Radioactive montmorillonite embolic microspheres and preparation method and application thereof

Abstract

The present invention discloses a radioactive montmorillonite embolic microsphere and a preparation method and application thereof, and belongs to the field of medical technology. The present invention specifically relates to the loading of therapeutic metal nuclides on montmorillonite microspheres and their application in the preparation of selective internal radiotherapy drugs for liver cancer. The preparation of radioactive montmorillonite microspheres is to use micron-sized montmorillonite to complex therapeutic metal nuclides ions, and then centrifuge after stabilization treatment with anion solution to obtain the obtained microspheres. The radioactive montmorillonite embolic microspheres of the present invention have a simple preparation process, a low nuclide dissolution rate, and a low price, and can achieve effective selective internal radiotherapy for in situ liver cancer via catheter artery.

Description

Technical Field

[0001] The invention belongs to the field of medical technology, and specifically relates to radioactive montmorillonite embolic microspheres and a preparation method and application thereof. Background Art

[0002] Hepatocellular carcinoma is the most common primary liver cancer. Its high morbidity and mortality, hidden nature and invasiveness have become a problem for its effective treatment, which seriously threatens people's life and health. Since liver cancer is a radiosensitive tumor, radiotherapy can effectively improve the prognosis and survival of liver cancer patients. Radiotherapy for liver cancer is divided into two methods: internal irradiation and external irradiation. The external irradiation dose often requires at least 120Gy to effectively kill tumor cells, but normal liver tissue will be damaged and increase the probability of complications such as radiation hepatitis if the radiation dose exceeds 30Gy. Transcatheter radioembolization therapy (TARE) is an internal radiotherapy technology, which mainly delivers radioactive microspheres directly to the small arteries of the tumor through the catheter artery, thereby achieving local high-dose radiotherapy, which has the advantages of minimally invasive, selective and precise treatment, and few side effects.

[0003] The TARE effect of liver cancer often depends on the quality of radioembolization microspheres. The design and preparation of radioembolization microspheres need to have the following two characteristics: on the one hand, they have a micron-level size (20-75 microns) for microvascular embolism, and on the other hand, the radionuclides used need to have the ability to effectively kill cancer cells, such as lutetium-177, yttrium-90, holmium-166, rhenium-188 and samarium-153 commonly used in brachytherapy. The radioembolization microspheres currently used in clinical practice are yttrium-90 glass microspheres developed by NORDION of Canada and yttrium-90 resin microspheres developed by Sirtex Medical of Australia. Both use the beta rays released by yttrium-90 to kill tumor cells, but yttrium-90 glass microspheres need to be produced through neutron activation in nuclear reactors, which is costly. Yttrium-90 resin microspheres have a high radionuclide dissolution rate, and the detached yttrium-90 ions can easily enter the blood circulation, causing serious adverse reactions such as bone marrow suppression and pulmonary fibrosis. This is mainly because yttrium-90 is exchanged into the cationic resin and there is no stable complexation with chemical forces.

[0004] Therefore, there is an urgent need to develop a radioactive embolization microsphere that is simple to prepare, low-cost, stably loaded with radionuclides, and meets medical standards to meet the major needs in the field of liver cancer treatment. Summary of the invention

[0005] The purpose of the present invention is to provide a radioactive montmorillonite embolic microsphere and its preparation method and application, which can effectively solve the above problems. Montmorillonite, as a naturally occurring layered silicate clay mineral, can have a micro-nano size distribution under different grinding and screening processes, and has the properties of tumor microvascular embolism. In addition, its surface is rich in hard Lewis bases (Si-O, Al-O) that can complex metal ions to a certain extent, but due to the complex microenvironment in the body, metal nuclides ions may desorb from montmorillonite, so the adsorption stability of metal nuclides is crucial. Based on these backgrounds, the present invention selects micron-sized montmorillonite as a carrier of therapeutic metal nuclides, coordinates and complexes metal nuclides through temperature-controlled stirring, and then further stabilizes the load of metal nuclides through precipitation of anionic solution, and finally uses catheter embolization technology to achieve selective internal radiotherapy of liver cancer.

[0006] The technical solution adopted by the present invention comprises the following steps:

[0007] The present invention first provides a method for preparing radioactive montmorillonite embolic microspheres, which comprises the following steps:

[0008] Montmorillonite is dispersed in water, and then therapeutic metal nuclide ions are added, and the pH is adjusted to 2.0-6.0 after thorough mixing, and then constant temperature oscillation is performed at 25-70°C for 10-120 minutes and high-speed centrifugation is performed to obtain a precipitate; the precipitate is then redispersed in an anion solution and oscillated and centrifuged at room temperature to obtain stable radioactive montmorillonite microspheres.

[0009] Furthermore, the present invention selects micron-sized montmorillonite as a carrier of therapeutic metal nuclides, and the particle size of the montmorillonite is preferably 20 to 75 microns.

[0010] Furthermore, the concentration of the montmorillonite in water is 0.5-10 mg / mL. In this concentration range, the montmorillonite can have a good dispersion, which is convenient for uniform labeling of nuclides.

[0011] Furthermore, the therapeutic metal nuclide is lutetium-177, yttrium-90, holmium-166, rhenium-188 or samarium-153, which mainly utilizes the beta rays emitted by them to kill tumor cells.

[0012] Furthermore, the radioactive dose of the metal nuclides added to the water containing montmorillonite and fully mixed is 0.5-20 mCurry / mL. The purpose of the added radioactive dose is to ensure an effective nuclide therapeutic dose while embolizing the tumor blood vessels.

[0013] Furthermore, the high-speed centrifugation speed is 5000-14000 rpm.

[0014] Furthermore, the anion solution contains any one or more of phosphate, carbonate, sulfide, and tannate, and these anions are mainly used to chemically react with the metal nuclide ions complexed on the surface of montmorillonite to form stable insoluble precipitates on the surface of montmorillonite.

[0015] Furthermore, the concentration of the anion solution is 0.01-0.5 mol / L.

[0016] Furthermore, the time for the precipitate to be redispersed in the anion solution is 10 to 60 minutes.

[0017] The present invention also provides the use of the radioactive montmorillonite embolic microspheres in the preparation of drugs for selective internal radiotherapy of liver cancer. The radioactive montmorillonite embolic microspheres of the present invention use montmorillonite as a carrier, and the hard Lewis base (Si-O, Al-O) on the surface of montmorillonite can stably coordinate the metal ions of the Lewis acid, and the stable loading of the radioactive metal nuclides can be achieved through the process of temperature control stirring and mixing of anion solutions.

[0018] The advantages and features of the present invention are:

[0019] 1) The montmorillonite microspheres used in the present invention are used as a low-cost carrier. The particle size thereof is selected so as to be able to be used for effective embolization of tumor blood vessels.

[0020] 2) The present invention develops a method for stably loading therapeutic metal nuclide ions based on the properties of montmorillonite to obtain radioactive montmorillonite embolic microspheres. On the one hand, montmorillonite is a naturally occurring layered silicate clay mineral with abundant hard Lewis bases (Si-O, Al-O) on its surface that can complex metal ions to a certain extent. On the other hand, the present invention further uses anionic solutions to chemically react with metal nuclide ions complexed on the surface of montmorillonite to generate stable insoluble precipitates on the surface of montmorillonite. The entire method is simple to operate and easy to label and promote in clinical automation modules.

[0021] 3) The radioactive montmorillonite microspheres prepared by the present invention can be used for selective internal radiotherapy of liver cancer via catheter embolization technology. Digital subtraction angiography can reveal its good embolization effect. 18 F-FDG monitoring showed that it showed a good liver cancer inhibitory effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] Figure 1 In Example 1 of the present invention, normal mice were intravenously injected with (1) 90PET images of YCl3, (2) montmorillonite mixed with Y-90 ions and (3) Y-90 montmorillonite after 24 hours.

[0024] Figure 2 This is a digital subtraction angiography image of a rabbit with liver cancer before and after embolization with Y-90-montmorillonite in Example 1 of the present invention.

[0025] Figure 3 The liver cancer rabbits in Example 1 of the present invention were treated without any treatment and before and after Y-90 montmorillonite embolization radiotherapy. 18 F-FDG PET imaging. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention are described below, but the embodiments of the present invention are not limited thereto.

[0027] Example 1 The purchased montmorillonite was ground and sieved to obtain particles of 20 to 75 micrometers in size, and then prepared into a 5 mg / mL aqueous solution and added 90 YCl3 solution, the radioactive dose of each mixed solution was 5 mCi / mL, the pH of each mixed solution was adjusted to 4.0, and the mixed solutions were placed in a constant temperature mixer and oscillated at 70°C for 10 minutes. After the mixture was oscillated, it was centrifuged at 5000 rpm to obtain precipitate A.

[0028] Then, the precipitate A was redispersed in a 0.05 mol / L sodium phosphate solution and shaken at room temperature for 60 minutes. The precipitate obtained by centrifugation at 5000 rpm was the stable yttrium-90 montmorillonite microspheres.

[0029] The loading rate of yttrium-90 was calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of radionuclides added, and it was found that its loading rate reached 100%; the dissolution rate was determined by incubating yttrium-90 montmorillonite in bovine serum albumin and then measuring the content of free yttrium-90 ions using a thin-layer scanner, and it was found that its dissolution rate was as low as 0.0062%.

[0030] When the stability of Y-90 ions was tested by intravenous injection in mice, it was found that the pure Y-90 ions ( 90 YCl3, 0.2 mCi) is diffusely distributed in vivo; the loading rate of the simple yttrium-90 ion-mixed montmorillonite (i.e., the precipitate A obtained by the first centrifugation, which was not re-dispersed into a 0.05 mol / L sodium phosphate solution for the second centrifugation) in vitro is almost 100%, and the dissolution rate is also very low, but after intravenous injection of 0.2 mCi, it is diffusely distributed in vivo, indicating that the simple montmorillonite complexed yttrium-90 is unstable in vivo. However, the radiation signals of the Y-90 montmorillonite microspheres synthesized in Example 1 are enriched in the lungs and liver after intravenous injection of 0.2 mCi ( Figure 1), which is the normal tissue distribution of micron-sized montmorillonite in the body, thus proving that the Y-90 montmorillonite microspheres developed by the present invention have good in vivo radioactive stability. We further delivered the Y-90 montmorillonite microspheres synthesized in Example 1 (5 mg montmorillonite labeled with 5 mCi yttrium-90) to the location of liver cancer lesions through rabbit interventional surgery, and found that it had a good embolization effect through digital subtraction angiography ( Figure 2 ); while the rabbits were given a seven-day 18 F-FDG monitoring, because tumors have a high uptake of FDG, can show the progression of tumors. We found that the tumors of liver cancer rabbits without treatment progressed rapidly, while the tumors of rabbits treated with yttrium-90 montmorillonite were completely eliminated, proving its good liver cancer inhibition effect ( Figure 3 ).

[0031] Example 2 The purchased montmorillonite was ground and sieved to obtain particles of 20 to 75 micrometers in size, and then prepared into a 3 mg / mL aqueous solution and added 90 YCl3 solution, the radioactive dose of each mixed solution is 5 mCi / mL, the pH of each mixed solution is adjusted to 5.0, and the mixed solution is placed in a constant temperature mixer and shaken at 50°C for 10 minutes. After the end, the precipitate is obtained by high-speed centrifugation at 5000rpm; then the precipitate is redispersed in 0.1mol / L sodium phosphate solution, shaken at room temperature for 10 minutes, and then centrifuged at 5000rpm to obtain yttrium-90 montmorillonite microspheres. The loading rate of yttrium-90 is calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of radionuclides added, and it is found that its loading rate reaches 100%; the dissolution rate is determined by incubating yttrium-90 montmorillonite in bovine serum albumin and then measuring the content of free yttrium 90 ions by a thin layer scanner, and it is found that its dissolution rate is as low as 0.0058%.

[0032] Example 3 The purchased montmorillonite was ground and sieved to obtain a size of 20 to 75 microns, and then prepared into a 3 mg / mL aqueous solution, to which was added 177 LuCl3 solution, the radioactive dose of the mixed solution is 6 millicuries / mL, the pH of each group of mixed solutions is adjusted to 5.5, and the mixed solutions are placed in a constant temperature mixer at 70°C for 60 minutes. After the end, the precipitate is obtained by high-speed centrifugation at 10,000 rpm; then the precipitate is redispersed in a 0.2 mol / L sodium phosphate solution, oscillated at room temperature for 30 minutes, and then centrifuged at 10,000 rpm to obtain lutetium-177 montmorillonite microspheres. The loading rate of lutetium-177 is calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of radionuclides added, and it is found that its loading rate reaches 100%; the dissolution rate is determined by incubating lutetium-177 montmorillonite in bovine serum albumin and then measuring the content of free lutetium-177 ions by a thin layer scanner, and it is found that its dissolution rate is as low as 0.0024%.

[0033] Example 4 The purchased montmorillonite was ground and sieved to obtain a size of 20 to 75 microns, and then prepared into a 2 mg / mL aqueous solution, to which was added 177 LuCl3 solution, the radioactive dose of the mixed solution is 5 millicuries / mL, the pH of each group of mixed solutions is adjusted to 4, and the mixed solutions are placed in a constant temperature mixer at 60°C for 45 minutes. After the end, the precipitate is obtained by high-speed centrifugation at 5000rpm; then the precipitate is redispersed in a 0.1mol / L sodium phosphate solution, oscillated at room temperature for 30 minutes, and then centrifuged at 5000rpm to obtain lutetium-177 montmorillonite microspheres. The loading rate of lutetium-177 is calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of added radionuclides, and it is found that its loading rate reaches 100%; the dissolution rate is determined by incubating lutetium-177 montmorillonite in bovine serum albumin and then measuring the content of free lutetium-177 ions by a thin layer scanner, and it is found that its dissolution rate is as low as 0.0067%.

[0034] Example 5 The purchased montmorillonite was ground and sieved to obtain a size of 20 to 75 microns, and then prepared into a 4 mg / mL aqueous solution, to which was added 166 HoCl3 solution, the radioactive dose of the mixed solution is 8 millicuries / mL, the pH of each group of mixed solutions is adjusted to 5.5, and the mixed solutions are placed in a constant temperature mixer and shaken at 60°C for 60 minutes. After the end, the precipitate is obtained by high-speed centrifugation at 6000rpm; then the precipitate is redispersed in a 0.1mol / L sodium phosphate solution, shaken at room temperature for 60 minutes, and then centrifuged at 6000rpm to obtain holmium-166 montmorillonite microspheres. The loading rate of holmium-166 is calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of radionuclides added, and it is found that its loading rate reaches 100%; the dissolution rate is determined by incubating the holmium-166 montmorillonite in bovine serum albumin and then measuring the content of free holmium-166 ions by a thin layer scanner, and it is found that its dissolution rate is as low as 0.0047%.

[0035] Example 6 The purchased montmorillonite was ground and sieved to obtain a size of 20 to 75 microns, and then prepared into a 1 mg / mL aqueous solution, to which was added 166HoCl3 solution, the radioactive dose of the mixed solution is 2 millicuries / mL, the pH of each group of mixed solutions is adjusted to 6.0, and the mixed solutions are placed in a constant temperature mixer and shaken at 70°C for 15 minutes. After the end, the precipitate is obtained by high-speed centrifugation at 8000rpm; then the precipitate is redispersed in a 0.1mol / L sodium sulfide solution, shaken at room temperature for 15 minutes, and then centrifuged at 8000rpm to obtain holmium-166 montmorillonite microspheres. The loading rate of holmium-166 is calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of radionuclides added, and it is found that its loading rate reaches 100%; the dissolution rate is determined by incubating the holmium-166 montmorillonite in bovine serum albumin and then measuring the content of free holmium-166 ions through a thin layer scanner, and it is found that its dissolution rate is as low as 0.0073%.

[0036] Example 7 The purchased montmorillonite was ground and sieved to obtain a size of 20 to 75 microns, and then prepared into a 6 mg / mL aqueous solution, to which was added 188 ReCl3 solution, the radioactive dose of the mixed solution is 10 mCurry / mL, the pH of each group of mixed solutions is adjusted to 3.0, and the mixed solutions are placed in a constant temperature mixer and shaken at 40°C for 60 minutes. After the end, the precipitate is obtained by high-speed centrifugation at 7500rpm; then the precipitate is redispersed in a 0.1mol / L sodium carbonate solution, shaken at room temperature for 60 minutes, and then centrifuged at 7500rpm to obtain rhenium-188 montmorillonite microspheres. The loading rate of rhenium-188 is calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of radionuclides added, and it is found that its loading rate reaches 100%; the dissolution rate is determined by incubating rhenium-188 montmorillonite in bovine serum albumin and then measuring the content of free rhenium-188 ions by a thin layer scanner, and it is found that its dissolution rate is as low as 0.0036%.

[0037] Example 8 The purchased montmorillonite was ground and sieved to obtain a size of 20 to 75 microns, and then prepared into a 2 mg / mL aqueous solution, to which was added 188 ReCl3 solution, the radioactive dose of the mixed solution is 4 millicuries / mL, the pH of each group of mixed solutions is adjusted to 6.0, and the mixed solutions are placed in a constant temperature mixer and shaken at 70°C for 10 minutes. After the end, the precipitate is obtained by high-speed centrifugation at 5000rpm; then the precipitate is redispersed in a 0.1mol / L sodium phosphate solution, shaken at room temperature for 60 minutes, and then centrifuged at 5000rpm to obtain rhenium-188 montmorillonite microspheres. The loading rate of rhenium-188 is calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of radionuclides added, and it is found that its loading rate reaches 100%; the dissolution rate is determined by incubating rhenium-188 montmorillonite in bovine serum albumin and then measuring the content of free rhenium-188 ions by a thin layer scanner, and it is found that its dissolution rate is as low as 0.0058%.

[0038] Example 9 The purchased montmorillonite was ground and sieved to obtain a size of 20 to 75 microns, and then prepared into a 3 mg / mL aqueous solution, to which was added 153 SmCl3 solution, the radioactive dose of the mixed solution is 15 millicuries / mL, the pH of each group of mixed solutions is adjusted to 4.0, and the mixed solutions are placed in a constant temperature mixer and shaken at 50°C for 60 minutes. After the end, the precipitate is obtained by high-speed centrifugation at 10,000 rpm; then the precipitate is redispersed in a 0.05 mol / L sodium tannate solution, shaken at room temperature for 60 minutes, and then centrifuged at 10,000 rpm to obtain samarium-153 montmorillonite microspheres. The loading rate of samarium-153 is calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of radionuclides added, and it is found that its loading rate reaches 100%; the dissolution rate is determined by incubating samarium-153 montmorillonite in bovine serum albumin and then measuring the content of free samarium-153 ions through a thin layer scanner, and it is found that its dissolution rate is as low as 0.0061%.

[0039] Example 10 The purchased montmorillonite was ground and sieved to obtain a size of 20 to 75 microns, and then prepared into a 1 mg / mL aqueous solution, to which was added 153 SmCl3 solution, the radioactive dose of the mixed solution is 6 millicuries / mL, the pH of each group of mixed solutions is adjusted to 5.5, and the mixed solutions are placed in a constant temperature mixer and shaken at 70°C for 15 minutes. After the end, the precipitate is obtained by high-speed centrifugation at 6000rpm; then the precipitate is redispersed in a 0.2mol / L sodium phosphate solution, shaken at room temperature for 15 minutes, and then centrifuged at 6000rpm to obtain samarium-153 montmorillonite microspheres. The loading rate of samarium-153 is calculated by measuring the ratio of the radioactivity of the precipitate to the total amount of radionuclides added, and it is found that its loading rate reaches 100%; the dissolution rate is determined by incubating samarium-153 montmorillonite in bovine serum albumin and then measuring the content of free samarium-153 ions through a thin layer scanner, and it is found that its dissolution rate is as low as 0.0025%.

[0040] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing radioactive montmorillonite embolic microspheres, characterized in that: The steps include: Disperse montmorillonite in water, then add therapeutic metal nuclide ions, fully mix and adjust the pH to 2.0-6.0, then oscillate at a constant temperature of 25-70°C for 10-120 minutes and centrifuge at high speed to obtain a precipitate; then redisperse the precipitate in an anion solution and oscillate and centrifuge at room temperature to obtain stable radioactive montmorillonite microspheres; The particle size of the montmorillonite is 20-75 microns, and the concentration of the montmorillonite in water is 0.5-10 mg / mL; the therapeutic metal nuclide is lutetium-177, yttrium-90, holmium-166, rhenium-188 or samarium-153; the radioactive dose of the therapeutic metal nuclide ions after adding them to the water containing montmorillonite and fully mixing is 0.5-20 mCurry / mL; the anions in the anion solution are one or more of phosphate, carbonate, sulfide or tannate, and the concentration of the anion solution is 0.01-0.5 mol / L; the time for the precipitate to be redispersed in the anion solution is 10-60 minutes.

2. The method for preparing radioactive montmorillonite embolic microspheres according to claim 1, characterized in that: The speed of high-speed centrifugation is 5000~14000 rpm.

3. A radioactive montmorillonite embolic microsphere, characterized in that: Prepared by the method of claim 1 or 2.

4. Use of the radioactive montmorillonite embolic microspheres according to claim 3 in the preparation of drugs for selective internal radiotherapy of liver cancer.

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