Phase-change nanodroplets, preparation method therefor, and use thereof

Abstract

The present invention relates to the technical field of myocardial imaging and specifically provides phase-change nanodroplets, a preparation method therefor, and use thereof. The ultrasound-responsive phase-change nanodroplets comprise a lipid membrane, a phase-change agent encapsulated in the lipid membrane, and a nuclide loaded onto the lipid membrane, wherein components of the lipid membrane include a phospholipid and a coupling agent for coupling the nuclide; the coupling agent is selected from an imidazole derivative. The ultrasound-responsive phase-change nanodroplets, when used for myocardial perfusion imaging, have the significant advantages of a high first-pass rate, a high instantaneous concentration, and a good imaging effect.

Description

A phase change nanodroplet, its preparation method and application Technical Field

[0001] This application relates to the technical field of myocardial imaging, specifically to a phase change nanodroplet, its preparation method, and its application. Background Technology

[0002] Ultrasonic targeted microbubble destruction (UTMD) is a key principle of this patent. It utilizes the cavitation effect of ultrasound in liquids to destroy microbubbles. The outer shell of the microbubble ruptures, releasing the substances it carries inside. The shear force generated by the cavitation effect increases the permeability of the surrounding cell membrane and blood vessel wall, forming pores, i.e., the acoustic pore effect. The substances carried by the microbubble enter the cytoplasm or extravascular tissue space before the pores close, achieving local delivery of nanomedicines.

[0003] Myocardial perfusion imaging is used for non-invasive examination of heart disease and has become an important imaging method for the diagnosis, treatment evaluation, and prognosis of coronary heart disease. Its basic principle is that the imaging agent accumulates in the myocardium after intravenous injection, clearly imaging normal myocardium. The amount of accumulation in the myocardium is directly proportional to the local myocardial blood volume and closely related to the function or activity of local myocardial cells.

[0004] SPECT-MPI is the most commonly used imaging agent. 99m Taking Tc-MIBI as an example, after the imaging agent enters the intercellular space of cardiomyocytes, it is transported into the cells and binds to low-molecular-weight proteins. This process is concentration-dependent. However, due to the high blood flow velocity in myocardium, less than 60% of the imaging agent can enter cardiomyocytes during the first pass. Several cardiac cycles are required for the radioactive signal in the myocardial tissue to reach a steady state. Furthermore, the temporal resolution of SPECT is lower than that of myocardial blood flow velocity, making it difficult to capture the information in the rising limb of the time-radioactivity signal curve. To ensure safe radiation dose exposure, it is impossible to simply increase... 99m The Tc-MIBI injection method addresses this issue, while D-SPECT, although improving spatial resolution, uses the same principle of radioactive imaging agents to trace myocardial blood flow as SPECT, and requires a change in imaging system hardware configuration, significantly increasing healthcare resource investment.

[0005] Therefore, increasing the concentration of imaging agents in myocardial tissue and improving the efficiency of first-pass uptake, in order to extend the residence time of imaging agents in the extracellular space to form a transient high concentration, is a problem that needs to be solved or partially solved. Summary of the Invention

[0006] In view of the above problems, in order to increase the concentration of imaging agents in myocardial tissue and improve the "first-pass" uptake efficiency, this application prepared ultrasound-responsive phase change nanodroplets and acoustic-magnetic dual-responsive phase change nanodroplets, aiming to increase the residence time of imaging agents in the extracellular space to form instantaneous high concentrations.

[0007] The acoustic-magnetic dual-response phase-change nanodroplets proposed in this application for myocardial perfusion enhance first-pass uptake efficiency, achieving steady-state uptake by cardiomyocytes within a very short time window. This fully utilizes existing SPECT equipment, representing a highly cost-effective solution. On one hand, the acoustic-magnetic dual-response phase-change nanodroplets exhibit manipulability in an ultrasonic field, overcoming the influence of high-speed blood flow in large arteries and significantly increasing their binding rate to endothelial cells. Furthermore, the UTMD effect effectively promotes the entry of the generated microbubble loads into endothelial cells. On the other hand, the phase-change droplets not only enable ultrasound imaging, allowing for ultrasound-based localization and tracking of the carrier, but also break down nanobubbles to facilitate rapid intracellular loading. Additionally, the droplets possess magnetic responsiveness; a weak magnetic field can prolong the local residence time without interfering with the ultrasound signal, further enhancing the residence time of the imaging agent in the extracellular space to achieve a transient high concentration. Moreover, this application innovates the microbubble preparation method by incorporating imidazole derivatives as the load (e.g., 99m Tc) provides coupling sites.

[0008] This application involves the following:

[0009] 1. An ultrasound-responsive phase change nanodroplet, comprising a lipid membrane, a phase change agent encapsulated within the lipid membrane, and a nuclide loaded on the lipid membrane;

[0010] The lipid membrane comprises phospholipids and a coupling agent for coupling the nuclide.

[0011] The coupling agent is selected from imidazole derivatives, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid derivatives, 1,4,7-triazacyclononane-1,4,7-triacetic acid derivatives, and methoxyisocyanate derivatives.

[0012] 2. The ultrasonically responsive phase-change nanodroplet according to claim 1, wherein the imidazole derivative is selected from any one or more combinations of the following group: 1-hexadecyl-3-methyl imidazole chloride, 1-butyl-3-methyl imidazole chloride, 1-octyl-3-methyl imidazole chloride, 1-octyl-3-methyl imidazole bromide, 1-dodecyl-3-methyl imidazole chloride, 1-dodecyl-3-methyl imidazole bromide, 1-hexadecyl-3-methyl imidazole bromide, 1-hexadecyl-3-methyl tetrafluoroborate imidazole, 1-hexadecyl-3-methyl hexafluorophosphate imidazole, 1-hexadecyl-3-carboxymethyl imidazole chloride, and 1-hexadecyl-3-hydroxyethyl imidazole chloride.

[0013] 3. The ultrasonically responsive phase change nanodroplets according to item 1 or 2, wherein the phospholipid is selected from any one or more combinations of the following group: dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and distearylphosphatidylcholine (DSPC).

[0014] Preferably, the phospholipid comprises dipalmitoyl phosphatidylcholine (DPPC) and distearate phosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000).

[0015] 4. The ultrasonically responsive phase change nanodroplets according to any one of items 1-3, wherein the phospholipid is dipalmitoylphosphatidylcholine (DPPC) and distearate phosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and the coupling agent is 1-hexadecyl-3-methylimidazole chloride;

[0016] Preferably, the molar ratio of dipalmitoylphosphatidylcholine (DPPC), distearate phosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazole chloride is (2.5-15):(0.1-2):(0.1-2); more preferably, it is (5-10):(0.5-1.5):(0.5-1.5).

[0017] 5. The ultrasonically responsive phase change nanodroplet according to any one of items 1-4, wherein the phase change agent comprises perfluoroalkane, perfluoroether, perfluoropolyether and perfluorobromide;

[0018] Preferably, the phase change agent is selected from any one or more of the following group: perfluoropentane, perfluorohexane, perfluorooctane, perfluoropropyl ether, perfluoropolyether, and perfluorobromooctane;

[0019] Preferably, the phase change agent is perfluorohexane.

[0020] 6. The ultrasonically responsive phase-change nanodroplet according to any one of items 1-5, wherein the nuclide is a radioactive nuclide, preferably... 99m Tc.

[0021] 7. A method for preparing ultrasonically responsive phase change nanodroplets according to any one of claims 1-6, comprising the following steps:

[0022] The phase change agent is the first prepared solution;

[0023] After the phospholipid and coupling agent are mixed evenly in the first solvent, the first solvent is removed to form a film. Then, the second solvent is added and mixed evenly to obtain the second preparation solution.

[0024] The first and second prepared solutions were mixed and then subjected to a third dispersion treatment to obtain empty ultrasonic-responsive phase change nanodroplets.

[0025] The empty ultrasonic-responsive phase change nanodroplets are mixed uniformly with the nuclide to obtain the ultrasonic-responsive phase change nanodroplets.

[0026] Preferably, the first solvent is selected from any one or more of the following group: dichloromethane, trichloromethane, tetrachloromethane, methanol, ethanol, tetrahydrofuran, and diethyl ether; more preferably, it is trichloromethane;

[0027] Preferably, the second solvent is an aqueous solvent; more preferably, it is water.

[0028] Preferably, the total content of the phospholipid and coupling agent in the first solvent is 0.5-10 mg / mL; more preferably, it is 1-5 mg / mL.

[0029] Preferably, the total content of the phospholipids and coupling agent in the second preparation solution is 0.05-10 mg / mL; more preferably, it is 0.1-5 mg / mL.

[0030] Preferably, the volume ratio of the first preparation solution to the second preparation solution is 1:30-100;

[0031] Preferably, the conditions for the third dispersion treatment include: ultrasonic power of 100-200W and ultrasonic time of 0.5-10min.

[0032] 8. An acoustic-magnetic dual-response phase change nanodroplet, which is the acoustic-magnetic dual-response phase change nanodroplet described in any one of items 1-6, further comprising magnetic nanoparticles coated within the lipid membrane;

[0033] Preferably, the magnetic nanoparticles are selected from any one or more of the following groups: magnetite nanoparticles, γ-ferric oxide magnetic nanoparticles, metallic ferromagnetic nanoparticles, metallic cobalt magnetic nanoparticles, metallic nickel sub-nanoparticles, iron-platinum alloy magnetic nanoparticles, and iron-cobalt alloy magnetic nanoparticles.

[0034] More preferably, it is ferric oxide magnetic nanoparticles.

[0035] 9. The acoustic-magnetic dual-response phase change nanodroplet according to item 8, wherein the mass ratio of the lipid membrane to the magnetic nanoparticles is 2-4:5.

[0036] 10. The acoustic-magnetic dual-response phase change nanodroplet according to item 8 or 9, wherein the ratio of phase change agent to magnetic nanoparticles is 5-15 μL phase change agent: 0.1-1 mg magnetic nanoparticles.

[0037] 11. The acoustic-magnetic dual-response phase change nanodroplet according to any one of items 8-10, wherein the magnetic nanoparticles are fluorinated magnetic nanoparticles;

[0038] Preferably, the fluorinating agent is selected from any one or more combinations of the following group: perfluorosuccinic acid, perfluorooctanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, and perfluorotetradecanoic acid; more preferably, the fluorinating agent is perfluorosuccinic acid.

[0039] 12. The method for preparing the fluorinated magnetic nanoparticles according to the acoustic-magnetic dual-response phase change nanodroplet described in item 11 comprises the following steps:

[0040] The magnetic nanoparticles are dispersed in a first dispersion solvent and mixed with an alkaline organic solvent; after the first dispersion treatment, a first suspension is obtained.

[0041] The first suspension and the fluorinating agent were mixed, and after a second dispersion treatment, the magnetic nanoparticles modified with the fluorinating agent were collected.

[0042] Preferably, the alkaline organic solvent is selected from any one or more of the following group: tetramethylammonium hydroxide, tetraethylammonium hydroxide, potassium hydroxide, and sodium bicarbonate;

[0043] Preferably, the mass ratio of the fluorinating agent to the magnetic nanoparticles is 30-80:1;

[0044] Preferably, the content of the magnetic nanoparticles in the first dispersion is 0.1-5 mg / mL or 0.5-5 mg / mL;

[0045] Preferably, the conditions for the first dispersion treatment include: ultrasonic power of 50-150W and ultrasonic time of 5-20min;

[0046] Preferably, the conditions for the second dispersion treatment include: ultrasonic power of 50-150W and ultrasonic time of 20-60min.

[0047] 13. A method for preparing acoustic-magnetic dual-response phase change nanodroplets according to any one of items 8-12, comprising the following steps:

[0048] The magnetic nanoparticles and the phase change agent are mixed to obtain a first preparation solution;

[0049] After the phospholipid and coupling agent are mixed evenly in the first solvent, the first solvent is removed to form a film. Then, the second solvent is added and mixed evenly to obtain the second preparation solution.

[0050] After mixing the first and second prepared solutions, the mixture is subjected to a third dispersion treatment to obtain empty acoustic-magnetic dual-response phase change nanodroplets.

[0051] The empty acoustic-magnetic dual-response phase change nanodroplets were mixed uniformly with a nuclide to obtain the acoustic-magnetic dual-response phase change nanodroplets.

[0052] Preferably, in the first preparation solution, the content of the magnetic nanoparticles is 10-200 mg / mL phase change agent or 50-200 mg / mL phase change agent;

[0053] Preferably, the first solvent is selected from any one or more of the following group: dichloromethane, trichloromethane, tetrachloromethane, methanol, ethanol, tetrahydrofuran, and diethyl ether; more preferably, it is trichloromethane;

[0054] Preferably, the second solvent is an aqueous solvent; more preferably, it is water.

[0055] Preferably, the total content of the phospholipid and coupling agent in the first solvent is 0.5-10 mg / mL; more preferably, it is 1-5 mg / mL.

[0056] Preferably, the total content of the phospholipids and coupling agent in the second preparation solution is 0.05-10 mg / mL; more preferably, it is 0.1-5 mg / mL.

[0057] Preferably, the volume ratio of the first preparation solution to the second preparation solution is 1:30-100;

[0058] Preferably, the conditions for the third dispersion treatment include: ultrasonic power of 100-200W and ultrasonic time of 0.5-10min.

[0059] 14. A SPECT myocardial perfusion imaging method, comprising the steps of using ultrasound-responsive phase change nanodroplets as described in any one of items 1-6 and / or ultrasound-dual-responsive phase change nanodroplets obtained by the preparation method described in item 7.

[0060] 15. An acoustic-magnetic assisted SPECT myocardial perfusion imaging method, comprising the steps of using acoustic-magnetic dual-response phase change nanodroplets as described in any one of items 8-12 and / or obtaining acoustic-magnetic dual-response phase change nanodroplets using the preparation method described in item 13.

[0061] 16. The acoustic-magnetic assisted SPECT myocardial perfusion imaging method according to item 15 further includes the following steps:

[0062] The subject ingests the acoustic-magnetic dual-response phase-change nanodroplets, which are then visualized on an acoustic-magnetic assisted SPECT. The condition parameters of the acoustic-magnetic assisted SPECT include:

[0063] The center frequency is 0.5-1.5MHz.

[0064] And / or, the pulse repetition frequency is 0.5-5Hz.

[0065] And / or, the negative sound pressure peak is 0.1-1.5 MPa.

[0066] And / or, with a duty cycle of 5-15%.

[0067] Invention Effects

[0068] 1. In preparing acoustic-magnetic dual-response phase change nanodroplets or ultrasonic-response phase change nanodroplets, this application uses a special coupling agent, such as an imidazole derivative, to achieve effective connection between radionuclides and lipid membranes.

[0069] 2. The acoustic-magnetic dual-response phase change nanodroplets prepared in this application are the first to encapsulate magnetic nanoparticles in a lipid membrane to obtain acoustic-magnetic dual-response phase change nanodroplets that can be used in the field of radionuclide myocardial perfusion imaging.

[0070] 3. When this acoustic-magnetic dual-response phase-change nanodroplet is used in the field of myocardial perfusion imaging with radionuclides, it exhibits manipulability in the ultrasonic field, effectively overcoming the influence of high-speed blood flow in large arteries and significantly increasing the binding rate of the acoustic-magnetic dual-response phase-change nanobubbles to endothelial cells. Furthermore, by utilizing the UTMD effect, it can effectively promote the loading of radionuclides (especially radioactive nuclides, such as...) onto the acoustic-magnetic dual-response phase-change nanobubbles. 99m Tc) enters endothelial cells. Furthermore, the acoustic-magnetic dual-response phase-change nanodroplets can not only be imaged under ultrasound, thus utilizing ultrasound to locate and trace the carrier; they can also break down nanobubbles to promote rapid intracellular entry of radionuclides. In addition, the acoustic-magnetic dual-response phase-change nanodroplets possess magnetic responsiveness. Without interfering with the ultrasound signal, a weak magnetic field can be used to prolong the residence time of the acoustic-magnetic dual-response phase-change nanobubbles in local areas of the subject's body (e.g., at target organs or target cells), further enhancing the residence time of the imaging agent in the extracellular space of the target cells to form a transient high concentration.

[0071] 4. The acoustic-magnetic dual-response phase change nanodroplets of this application can increase the concentration of imaging agents in myocardial tissue and improve the "first pass" uptake efficiency, thereby improving imaging efficiency and effect. Attached Figure Description

[0072] Figure 1. Schematic diagram of a method for preparing acoustic-magnetic dual-response phase change nanodroplets.

[0073] Figure 2. Residence time of acoustic-magnetic dual-response phase change nanodroplets in magnetic and non-magnetic environments.

[0074] Figure 3. Schematic diagram of the acoustic-magnetic co-location transducer and a schematic diagram of the acoustic-magnetic assisted SPECT imaging device.

[0075] Figure 4. Schematic diagram of an acoustic-magnetic assisted SPECT imaging device including a robotic arm.

[0076] Figure 5. Photographs of suspensions of acoustic-magnetic dual-response phase change nanodroplets and ultrasonically responsive phase change nanodroplets.

[0077] Figure 6. Transmission electron microscope image of the acoustic-magnetic dual-response phase change nanodroplet of Example 4.

[0078] Figure 7. Particle size distribution and Zeta potential results of the acoustic-magnetic dual-response phase change nanodroplets in Example 4.

[0079] Figure 8. Radiometric thin-layer chromatography analysis of acoustic-magnetic dual-response phase change nanodroplets in Example 4.

[0080] Figure 9. CCK8 assay results of cardiomyocytes from acoustic-magnetic dual-response phase change nanodroplets in Example 4.

[0081] Figure 10. Biodistribution of acoustic-magnetic dual-response phase change nanodroplets in mice in Example 4.

[0082] Figure 11. Schematic diagram of a three-dimensional structure including a robotic arm on an acoustic-magnetic assisted SPECT imaging device.

[0083] Figure 12. Schematic diagram of the three-dimensional structure of the robotic arm.

[0084] Figure 13. A schematic diagram of a structure with an electromagnetic coil on an ultrasonic probe.

[0085] Figure 14. A schematic diagram of a structure with an electromagnetic coil on an ultrasonic probe.

[0086] Figure 15. A schematic diagram of a structure with an electromagnetic coil on an ultrasonic probe.

[0087] Figure 16. Myocardial imaging results of the nanodroplets of this application.

[0088] Figure reference numerals: 1. Acoustic-magnetic assisted SPECT imaging device; 11. Frame body; 2. Robotic arm module; 21. Robotic arm; 211. Arm rod; 22. Clamping component; 3. Ultrasonic probe; 31. Electromagnetic coil; 32. Electromagnetic coil support. Detailed Implementation

[0089] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in their functions.

[0090] As used throughout the specification and claims, the terms "comprising" or "including" are open-ended and should be interpreted as "comprising but not limited to". The subsequent descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0091] It should be understood that the embodiments of this application described herein include embodiments that are "composed of" and / or "substantially composed of". References to values ​​or parameters of "about" herein include (and describe) variations of that value or parameter itself. For example, a reference to "about X" includes a description of "X".

[0092] As used herein, references to “not” values ​​or parameters generally refer to and describe “except” values ​​or parameters. For example, “The method is not used to treat type X cancer” means that the method is used to treat cancers other than type X.

[0093] As used in this article, the term “approximately XY” has the same meaning as “approximately X to approximately Y”.

[0094] As used herein and in the appended claims, the singular forms “a / an” and “the” include the plural objects unless the context clearly indicates otherwise. It should also be noted that claims may be drafted to exclude any optional elements. Therefore, this statement is intended as a preliminary basis for the use of exclusive terms such as “only” or “merely” in conjunction with the description of the elements of the claim, or for the use of the limitation of “no”.

[0095] As used herein, the term "and / or" in words such as "A and / or B" is intended to include both A and B; A or B; A (alone); and B (alone). Similarly, as used herein, the term "and / or" in words such as "A, B and / or C" is intended to include each of the following embodiments: A, B and C; A, B or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

[0096] This application provides an ultrasonically responsive phase change nanodroplet, which comprises a lipid membrane, a phase change agent coated within the lipid membrane, and a nuclide loaded on the lipid membrane;

[0097] The lipid membrane comprises phospholipids and a coupling agent for coupling the nuclide.

[0098] One of the key technologies of this application lies in constructing a nanodroplet system compatible with nuclide coupling. Achieving this technical effect does not depend on a specific imidazole derivative, but primarily on the coordination environment it provides. It should be noted that the coupling agents selected in the technical solution of this application are not limited to imidazole derivatives. Any coupling agent that can exist stably in the nanodroplet film system and can provide a suitable coordination environment is acceptable. 99m Compounds that coordinate or bind functional groups to Tc can be used as coupling agents. Selection of coupling agents includes, but is not limited to: polyamine ligands; thiol-containing ligands (such as cysteine ​​and its derivatives); chelating agents (such as DTPA, NOA, or DOTA); and other functional molecules capable of coordinating atoms. In some embodiments, the coupling agent is a molecule that simultaneously possesses membrane compatibility and coordination ability.

[0099] In some embodiments, the coupling agent is selected from imidazole derivatives, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid derivatives, 1,4,7-triazacyclononane-1,4,7-triacetic acid derivatives, and methoxyisocyanate derivatives. 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid derivatives are compounds or complexes used to couple nuclides and phospholipids, and such compounds or complexes should be included within this scope. In some embodiments, the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) derivative is a DOTA-phospholipid conjugate; for example, DOTA-DSPE (i.e., DOTA coupled with distearylphosphatidylethanolamine), for example, DOTA-PE (i.e., DOTA coupled with phosphatidylethanolamine). 1,4,7-Triazacyclononane-1,4,7-triacetic acid derivatives are compounds or complexes used for coupling radionuclides and phospholipids, and such compounds or complexes are included within this scope. In some embodiments, the 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) derivative is a NOTA-phospholipid conjugate; for example, NOTA-DSPE (i.e., NOTA coupled with distearylphosphatidylethanolamine (DSPE)) or NOTA-PE (i.e., NOTA coupled with phosphatidylethanolamine (PE)). Methoxyisocyanate derivatives are compounds or complexes used for coupling radionuclides and phospholipids, and such compounds or complexes are included within this scope. In some embodiments, the methoxyisocyanate derivative is a methoxyisocyanate-phospholipid conjugate; for example, methoxyisocyanate-DSPE (i.e., methoxyisocyanate coupled with distearylphosphatidylethanolamine (DSPE)) or methoxyisocyanate-PE (i.e., methoxyisocyanate coupled with phosphatidylethanolamine (PE)).

[0100] In some embodiments, the imidazole derivative is selected from any one or more combinations of the following group: 1-hexadecyl-3-methyl imidazole chloride, 1-butyl-3-methyl imidazole chloride, 1-octyl-3-methyl imidazole chloride, 1-octyl-3-methyl imidazole bromide, 1-dodecyl-3-methyl imidazole chloride, 1-dodecyl-3-methyl imidazole bromide, 1-hexadecyl-3-methyl imidazole bromide, 1-hexadecyl-3-methyltetrafluoroborate imidazole, 1-hexadecyl-3-methylhexafluorophosphate imidazole, 1-hexadecyl-3-carboxymethyl imidazole chloride, and 1-hexadecyl-3-hydroxyethyl imidazole chloride. In some embodiments, the imidazole derivative is 1-hexadecyl-3-methylimidazolium chloride; in some embodiments, the imidazole derivative is 1-butyl-3-methylimidazolium chloride; in some embodiments, the imidazole derivative is 1-octyl-3-methylimidazolium chloride; in some embodiments, the imidazole derivative is 1-octyl-3-methylimidazolium bromide; in some embodiments, the imidazole derivative is 1-dodecyl-3-methylimidazolium chloride; in some embodiments, the imidazole derivative is 1-dodecyl-3-methylimidazolium bromide; in some embodiments, the imidazole derivative is 1-hexadecyl-3-methyltetrafluoroborate imidazole; in some embodiments, the imidazole derivative is 1-hexadecyl-3-methylhexafluorophosphate imidazole; in some embodiments, the imidazole derivative is 1-hexadecyl-3-carboxymethylimidazolium chloride; in some embodiments, the imidazole derivative is 1-hexadecyl-3-hydroxyethylimidazolium chloride. It is understood that in some embodiments, the imidazole derivative is any two or more of the above-mentioned components in any proportion. In some preferred embodiments, the imidazole derivative is 1-hexadecyl-3-methylimidazolium chloride. This application has found that acoustic-magnetic dual-response phase change nanodroplets prepared using 1-hexadecyl-3-methylimidazolium chloride as a coupling agent have good particle size distribution (e.g., average particle size of 150.3±3 nm, Zeta potential of 20.7±0.6 mV) and reduction... 99m The labeling rate of Tc-labeled nanodroplets reached as high as 98.53% (even as high as 98.7%, 99%, or 99.5%); and the acoustic-magnetic dual-response phase change nanodroplets at a concentration of 10 μg / mL showed significantly excellent biocompatibility in cell experiments; further in vivo imaging in mice revealed that the acoustic-magnetic dual-response phase change nanodroplets exhibited an ideal two-compartment characteristic of "fast distribution and slow elimination" in the blood.

[0101] In some embodiments, the phospholipid is selected from any one or more combinations of the following group: dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and distearylphosphatidylcholine (DSPC).

[0102] In some preferred embodiments, the phospholipid comprises dipalmitoyl phosphatidylcholine (DPPC) and distearate phosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000).

[0103] In some preferred embodiments, the phospholipid is dipalmitoylphosphatidylcholine (DPPC) and distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and the coupling agent is 1-hexadecyl-3-methylimidazole chloride. In some embodiments, the molar ratio of dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazole chloride is (2.5-15):(0.1-2):(0.1-2); more preferably, it is (5-10):(0.5-1.5):(0.5-1.5).For example, the molar ratios of dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazolium chloride are 2.5:(0.1-2):(0.1-2), 5:(0.1-2):(0.1-2), 6:(0.1-2):(0.1-2), 7:(0.1-2):(0.1-2), 8:(0.1-2):(0.1-2), 9:(0.1-2):(0.1-2), 10:(0.1-2):(0.1-2), 12.5:(0.1-2):(0.1-2), and 15:(0.1-2). 1-2):(0.1-2),(2.5-15):0.1:(0.1-2),(2.5-15):0.2:(0.1-2),(2.5-15):0.3:(0.1-2),(2.5-15):0.4:(0.1-2),(2.5-15):0.5:(0.1-2),(2.5-15):0.6:(0.1-2),(2.5-15):0.7:(0.1-2),(2.5-15):0.8:(0.1-2),(2.5-15):0.9:(0.1-2),(2.5-15):1:(0.1-2),(2.5-15):1 .1:(0.1-2),(2.5-15):1.2:(0.1-2),(2.5-15):1.3:(0.1-2),(2.5-15):1.5:(0.1-2),(2.5-15):1.8:(0.1-2),(2.5-15):2:(0.1-2),(2.5-15):(0.1-2):0.1,(2.5-15):(0.1-2):0.2,(2.5-15):(0.1-2):0.3,(2.5-15):(0.1-2):0.4,(2.5-15):(0.1-2):0.5,(2.5-15):(0. 1-2):0.6, (2.5-15):(0.1-2):0.7, (2.5-15):(0.1-2):0.8, (2.5-15):(0.1-2):0.9, (2.5-15):(0.1-2):1, (2.5-15):(0.1-2):1.2, (2.5-15):(0.1-2):1.4, (2.5-15):(0.1-2):1.5, (2.5-15):(0.1-2):1.8, (2.5-15):(0.1-2):2 or any ratio or ratio range within the range of (2.5-15):(0.1-2):(0.1-2).In some preferred embodiments, the molar ratio of dipalmitoylphosphatidylcholine (DPPC), distearate phosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazole chloride is 8:1:1.

[0104] In some embodiments, the phase change agent comprises perfluoroalkanes, perfluoroethers, perfluoropolyethers, and perfluorobromines. In some embodiments, the phase change agent is selected from any one or more of the group consisting of perfluoropentane, perfluorohexane, perfluorooctane, perfluoropropyl ether, perfluoropolyether, and perfluorobromooctane. For example, the phase change agent is perfluorohexane.

[0105] In some embodiments, the nuclide is a radioactive nuclide, for example... 99m Tc.

[0106] This application also provides a method for preparing the above-mentioned ultrasonically responsive phase change nanodroplets, comprising the following steps:

[0107] After the phospholipid and coupling agent are mixed evenly in the first solvent, the first solvent is removed to form a film. Then, the second solvent is added and mixed evenly to obtain the second preparation solution.

[0108] The phase change agent and the second prepared liquid are mixed and then subjected to a third dispersion treatment to obtain empty ultrasonic-responsive phase change nanodroplets.

[0109] The unloaded ultrasonic-responsive phase-change nanodroplets are mixed uniformly with a nuclide to obtain the ultrasonic-responsive phase-change nanodroplets.

[0110] The first solvent is an organic solvent, more preferably an organic solvent that can be removed by rotary evaporation, natural evaporation, thermal evaporation, etc. In some embodiments, the first solvent is selected from any one or more of the following group: dichloromethane, trichloromethane, tetrachloromethane, methanol, ethanol, tetrahydrofuran, diethyl ether; for example, trichloromethane. In some embodiments, the method for removing the first solvent can be rotary evaporation, for example, rotary evaporation at a temperature of 40-70°C, or vacuum rotary evaporation at a temperature of 50°C. It is understood that the method for removing the first solvent is not unique, as long as it can achieve the removal of the first solvent and cause the remaining non-evaporated components to form a film.

[0111] In some embodiments, the second solvent is an aqueous solvent; for example, water.

[0112] In some embodiments, the total content of the phospholipid and coupling agent in the first solvent is 0.5-10 mg / mL; more preferably 1-5 mg / mL; for example, it can be any total content range or any total content within the range of 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL, 10 mg / mL or 0.5-10 mg / mL.

[0113] In some embodiments, the total content of the phospholipids and coupling agents in the second preparation solution is 0.05-10 mg / mL; more preferably 0.1-5 mg / mL; for example, it can be any total content range or any total content within the range of 0.05 mg / mL, 0.1 mg / mL, 0.2 mg / mL, 0.3 mg / mL, 0.4 mg / mL, 0.5 mg / mL, 0.6 mg / mL, 0.7 mg / mL, 0.8 mg / mL, 0.9 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL, 10 mg / mL or 0.05-10 mg / mL.

[0114] In some embodiments, the volume ratio of the phase change agent to the second formulation liquid is 1:30-100; for example, it can be any volume ratio range or any volume ratio within the range of 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100 or 1:30-100.

[0115] In some embodiments, the conditions for the third dispersion treatment include: ultrasonic power of 100-200W and ultrasonic time of 0.5-10min. For example, ultrasonic power of 100W, 110W, 120W, 130W, 140W, 150W, 160W, 170W, 180W, 190W, 200W, or any power range or any power within the 100-200W range; and ultrasonic time of 0.5min, 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min, or any time range or any time within the 0.5-10min range.

[0116] This application provides an acoustic-magnetic dual-response phase change nanodroplet, which is the aforementioned ultrasonic-response phase change nanodroplet, and further includes magnetic nanoparticles coated within the lipid membrane.

[0117] It is understood that magnetic nanoparticles known to those skilled in the art are all usable in this application. These magnetic nanoparticles can be affected by a magnetic field, and are therefore the magnetic nanoparticles usable in this application. Being affected by a magnetic field can include, for example, slowing down, accelerating, aggregating, or dispersing movement under the influence of a magnetic field. In some embodiments, the magnetic nanoparticles are selected from any one or more of the following groups: ferromagnetic nanoparticles of triferrooxide, γ-ferromagnetic nanoparticles of γ-triferrooxide, metallic ferromagnetic nanoparticles, metallic cobalt magnetic nanoparticles, metallic nickel sub-nanoparticles, iron-platinum alloy magnetic nanoparticles, and iron-cobalt alloy magnetic nanoparticles. Ferric oxide magnetic nanoparticles, as a common and readily available raw material, are the preferred choice for this application. Furthermore, when ferromagnetic nanoparticles are selected, the prepared acoustic-magnetic dual-response phase change nanodroplets have a better particle size distribution (e.g., an average particle size of 150.3±3 nm and a Zeta potential of 20.7±0.6 mV), and the reduction... 99m The labeling rate of Tc-labeled nanodroplets reached as high as 98.53% (even as high as 98.7%, 99%, or 99.5%); and the acoustic-magnetic dual-response phase change nanodroplets at a concentration of 10 μg / mL showed significantly excellent biocompatibility in cell experiments; further in vivo imaging in mice revealed that the acoustic-magnetic dual-response phase change nanodroplets exhibited an ideal two-compartment characteristic of "fast distribution and slow elimination" in the blood.

[0118] In some embodiments, the mass ratio of the lipid membrane to the magnetic nanoparticles is 2-4:5; for example, any ratio or range within the range of 2:5, 2.5:5, 3:5, 3.5:5, 4:5 or 2-4:5.

[0119] In some embodiments, the ratio of phase change agent to magnetic nanoparticles is 5-15 μL phase change agent: 0.1-1 mg magnetic nanoparticles; for example, 5-15 μL phase change agent: 0.1 mg magnetic nanoparticles, 5-15 μL phase change agent: 0.2 mg magnetic nanoparticles, 5-15 μL phase change agent: 0.4 mg magnetic nanoparticles, 5-15 μL phase change agent: 0.5 mg magnetic nanoparticles, 5-15 μL phase change agent: 0.6 mg magnetic nanoparticles, 5-15 μL phase change agent: 0.7 mg magnetic nanoparticles, 5-15 μL phase change agent: 0. Any proportion or ratio within the range of 8mg magnetic nanoparticles, 5-15μL phase change agent: 1mg magnetic nanoparticles, 5μL phase change agent: 0.1-1mg magnetic nanoparticles, 7μL phase change agent: 0.1-1mg magnetic nanoparticles, 9μL phase change agent: 0.1-1mg magnetic nanoparticles, 11μL phase change agent: 0.1-1mg magnetic nanoparticles, 13μL phase change agent: 0.1-1mg magnetic nanoparticles, 15μL phase change agent: 0.1-1mg magnetic nanoparticles, or 5-15μL phase change agent: 0.1-1mg magnetic nanoparticles.

[0120] In some embodiments, the magnetic nanoparticles are fluorinated and / or non-fluorinated magnetic nanoparticles. Fluorination modification makes the magnetic nanoparticles easier to disperse in the phase change liquid rather than the aqueous phase, and improves their stability in the phase change liquid.

[0121] In some embodiments, the fluorinating agent is selected from any one or more combinations of the following group: perfluorodecanoic acid, perfluorooctanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, and perfluorotetradecanoic acid; for example, the fluorinating agent is perfluorodecanoic acid.

[0122] The fluorinated magnetic nanoparticles modified with fluorinating agents in this application can be prepared using conventional methods.

[0123] This application provides an exemplary method for preparing fluorinated magnetic nanoparticles, which includes the following steps:

[0124] The magnetic nanoparticles are dispersed in a first dispersion solvent and mixed with an alkaline organic solvent; after the first dispersion treatment, a first suspension is obtained.

[0125] The first suspension and the fluorinating agent are mixed, and after a second dispersion treatment, the magnetic nanoparticles modified with the fluorinating agent are collected.

[0126] In some embodiments, the alkaline organic solvent is selected from any one or more of the group consisting of tetramethylammonium hydroxide, tetraethylammonium hydroxide, potassium hydroxide, and sodium bicarbonate; for example, tetramethylammonium hydroxide is preferred.

[0127] In some embodiments, the mass ratio of the fluorinating agent to the magnetic nanoparticles is 30-80:1; for example, any mass ratio range or any mass ratio within the range of 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1 or 30-80:1.

[0128] In some embodiments, the magnetic nanoparticles in the first dispersion are present in concentrations of 0.1-5 mg / mL, 0.2-5 mg / mL, 0.3-5 mg / mL, 0.4-5 mg / mL, or 0.5-5 mg / mL; for example, any concentration range or concentration within the range of 0.1 mg / mL, 0.2 mg / mL, 0.3 mg / mL, 0.4 mg / mL, 0.5 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL, or 0.5-5 mg / mL.

[0129] In some embodiments, the conditions for the first dispersion process include: ultrasonic power of 50-150W and ultrasonic time of 5-20min; for example, ultrasonic power of 50W, 60W, 70W, 80W, 90W, 100W, 110W, 120W, 130W, 140W, 150W or any power range or any power within the range of 50-150W; for example, ultrasonic time of 5min, 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min, 19min, 20min or any time range or any time within the range of 5-20min.

[0130] In some embodiments, the conditions for the second dispersion treatment include: an ultrasonic power of 50-150W and an ultrasonic time of 20-60min. For example, the ultrasonic power is 50W, 60W, 70W, 80W, 90W, 100W, 110W, 120W, 130W, 140W, 150W, or any power range or any power within the 50-150W range; the ultrasonic time is 20min, 25min, 30min, 40min, 45min, 50min, 55min, 60min, or any time range or any time within the 20-60min range.

[0131] This application also provides a method for preparing the above-mentioned acoustic-magnetic dual-response phase change nanodroplets, comprising the following steps:

[0132] The magnetic nanoparticles and the phase change agent are mixed to obtain a first preparation solution;

[0133] After the phospholipid and coupling agent are mixed evenly in the first solvent, the first solvent is removed to form a film. Then, the second solvent is added and mixed evenly to obtain the second preparation solution.

[0134] After mixing the first and second prepared solutions, the mixture is subjected to a third dispersion treatment to obtain empty acoustic-magnetic dual-response phase change nanodroplets.

[0135] The empty acoustic-magnetic dual-response phase change nanodroplets are mixed uniformly with nuclides to obtain the acoustic-magnetic dual-response phase change nanodroplets.

[0136] In some embodiments, the magnetic nanoparticles in the first preparation solution contain 10-200 mg / mL of phase change agent, 20-200 mg / mL of phase change agent, 30-200 mg / mL of phase change agent, 40-200 mg / mL of phase change agent, or 50-200 mg / mL of phase change agent; for example, 10 mg / mL of phase change agent, 20 mg / mL of phase change agent, 30 mg / mL of phase change agent, 40 mg / mL of phase change agent, 50 mg / mL of phase change agent, 60 mg / mL of phase change agent, or 70 mg / mL of phase change agent. The concentration of phase change agent is 80 mg / mL, 90 mg / mL, 100 mg / mL, 110 mg / mL, 120 mg / mL, 130 mg / mL, 140 mg / mL, 150 mg / mL, 160 mg / mL, 170 mg / mL, 180 mg / mL, 190 mg / mL, 200 mg / mL, or any concentration within the range of 50-200 mg / mL.

[0137] In some embodiments, the first solvent is as described above.

[0138] In some embodiments, the second solvent is as described above.

[0139] In some embodiments, the total content of the phospholipid and coupling agent in the first solvent is as described above.

[0140] In some embodiments, the total content of the phospholipids and coupling agents in the second formulation is as described above.

[0141] In some embodiments, the volume ratio of the first preparation solution to the second preparation solution is 1:30-100; for example, it can be any volume ratio range or any volume ratio within the range of 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100 or 1:30-100.

[0142] In some implementations, the conditions for the third dispersion process are as described above.

[0143] This application provides a SPECT myocardial perfusion imaging method, including the steps of using the above-described ultrasound-responsive phase change nanodroplets and / or ultrasound-responsive phase change nanodroplets obtained by the above-described preparation method.

[0144] This application provides an acoustic-magnetic assisted SPECT myocardial perfusion imaging method, including the steps of using the above-described acoustic-magnetic dual-response phase change nanodroplets and / or acoustic-magnetic dual-response phase change nanodroplets obtained by the above-described preparation method.

[0145] In some embodiments, the acoustic-magnetic assisted SPECT myocardial perfusion imaging method further includes the following steps: allowing the subject to ingest the acoustic-magnetic dual-response phase-change nanodroplets for imaging on an acoustic-magnetic assisted SPECT.

[0146] In some implementations, the conditional parameters of the acoustic-magnetic assisted SPECT include: a center frequency of 0.5-1.5MHz, such as 0.5MHz, 0.6MHz, 0.7MHz, 0.8MHz, 0.9MHz, 1MHz, 1.1MHz, 1.2MHz, 1.3MHz, 1.4MHz, 1.5MHz, or any center frequency within the range of 0.5-1.5MHz.

[0147] In some implementations, the conditional parameters of the acoustic-magnetic assisted SPECT include: a pulse repetition frequency of 0.5-5 Hz, such as any pulse repetition frequency range or any pulse repetition frequency within the range of 0.5 MHz, 0.6 MHz, 0.7 MHz, 0.8 MHz, 0.9 MHz, 1 MHz, 1.5 MHz, 2 MHz, 2.5 MHz, 3 MHz, 3.5 MHz, 4 MHz, 4.5 MHz, 5 MHz or 0.5-5 MHz.

[0148] In some implementations, the conditional parameters of the acoustic-magnetic assisted SPECT include a negative sound pressure peak value of 0.1-1.5 MPa, such as 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.7 MPa, 0.8 MPa, 1 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, and 1.5 MPa.

[0149] In some implementations, the conditional parameters of the acoustic-magnetic assisted SPECT include a duty cycle of 5-15%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%.

[0150] Example

[0151] Specific embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0152] Example 1.

[0153] An acoustic-magnetic dual-response phase change nanodroplet comprises a lipid membrane, magnetic nanoparticles coated within the lipid membrane, a phase change agent coated within the lipid membrane, and a nuclide loaded on the lipid membrane.

[0154] Referring to Figure 1, the preparation method of this acoustic-magnetic dual-response phase change nanodroplet is as follows:

[0155] Step 1: Prepare the first and second preparation solutions

[0156] Preparation of the first solution:

[0157] 111.5 μL of tetramethylammonium hydroxide was added to 5 mL of anhydrous ethanol containing 10 mg of magnetite nanoparticles, and the mixture was sonicated at 100 W for 10 min to obtain a first suspension. This first suspension was then mixed with 0.5615 g of perfluorodecanoic acid. The entire mixture was sonicated at 100 W for 40 min in an ice bath. The fluorinated magnetite nanoparticles were then collected and washed three times with 1 mL of methanol.

[0158] After natural drying, the fluorinated magnetite nanoparticles were dispersed in 100 μL of tetradecylfluorohexane to obtain the first solution (the content of magnetite nanoparticles was 100 mg / mL).

[0159] Preparation of the second solution:

[0160] The lipid membrane was composed of dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazole chloride. Dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazole chloride were dissolved in 5 mL of chloroform at a molar ratio of 8:1:1 to form a 2 mg / mL solution. This solution was then transferred to a round-bottom flask and evaporated under rotary vacuum at 50 °C to form a thin film. 10 mL of deionized water was added to hydrate the membrane, and the mixture was ultrasonically vibrated for 10 minutes to obtain the second prepared solution.

[0161] Step 2: Preparation of unloaded acoustic-magnetic dual-response phase change nanodroplets

[0162] 100 μL of the first preparation solution was mixed with 6 mL of the second preparation solution, and the mixture was sonicated at 150 W for 3 min using an ultrasonic processor to synthesize unloaded acoustic-magnetic dual-response phase change nanodroplets (acomND).

[0163] Step 3: Couple with radionuclides

[0164] Empty acoustic-magnetic dual-response phase change nanodroplets with Na99m The TcO4 solution was mixed and stirred at room temperature for 20 min to obtain acoustic-magnetic dual-response phase change nanodroplets. 99m Tc-acomND), see Figure 5 for details.

[0165] The obtained acoustic-magnetic dual-response phase change nanodroplets were placed in a weak magnetic field of 160 mT (constructed by the sheet magnet in Figure 2A) for 17 min. Observations show that in the yellow area within the white box in Figure 2A, the acoustic-magnetic dual-response phase change nanodroplets remained on the tube wall; however, in Figure 2B, the acoustic-magnetic dual-response phase change nanodroplets in a non-magnetic environment did not exhibit this phenomenon and flowed directly out of the tube. Figure 2C shows the length of the region of the acoustic-magnetic dual-response phase change nanodroplets remaining under conditions of no weak magnetic field within 0-17 min. It can be seen that the magnetic environment can significantly increase the residence time of the acoustic-magnetic dual-response phase change nanodroplets, thereby increasing the residence time of the imaging agent in the extracellular space to form a transient high concentration. This improves the low first-pass effect of the imaging agent in target organs (e.g., cardiomyocytes) and increases the uptake rate of the imaging agent by the target organ.

[0166] Example 2.

[0167] SPECT (Single Photon Emission Computed Tomography)

[0168] Acoustic-magnetic assisted SPECT imaging equipment

[0169] (1) Design of acoustic-magnetic co-location transducer.

[0170] Conventional SPECT equipment includes an ultrasound probe (which contains an ultrasound transducer). This application further designs a triangular array of electromagnetic coils centered on a cardiac imaging ultrasound probe (see Figure 3B). Specifically, referring to Figure 3B, three sets of electromagnetic coils are encapsulated around the ultrasound probe of the existing SPECT equipment. This encapsulation can be done using conventional materials and methods to reduce magnetic field interference with the ultrasound transducer and achieve co-localization of the ultrasound and magnetic fields. A shell is then added as the outermost layer, resulting in an ultrasound probe containing an acoustic-magnetic co-localized transducer. The optimal magnetic field strength is then adjusted and determined based on in vitro and in vivo experiments. It should be noted that because this ultrasound probe adds electromagnetic coils to the existing structure, the volume of the ultrasound probe in this application may be larger than that of a conventional ultrasound probe.

[0171] When using an electromagnetic coil, it is necessary to energize the coil to generate a weak magnetic field. For example, a signal generator can be connected to produce a waveform, and a constant current source can generate current based on the waveform. This current flows into the coil to produce a magnetic field. The strength of the magnetic field can be controlled by changing the current intensity and voltage.

[0172] (2) Robotic arm module design

[0173] On existing echocardiography equipment (such as the one developed by the project team in the early stages) An echocardiography device integrating an electromagnetic control module and a robotic arm module; the robotic arm end effector was designed and optimized to hold an ultrasound probe containing an acoustic-magnetic co-location transducer.

[0174] Specifically, referring to Figure 4, the robotic arm module mainly includes a robotic arm. One end of the robotic arm is connected to the upper surface of the echocardiography device, and the other end is a clamping component. The clamping component is used to clamp the ultrasound probe containing an acoustic-magnetic co-location transducer (wherein the magnet and probe in Figure 4 are separate, this is only a schematic diagram to show that the ultrasound probe has an added electromagnetic coil with the function of providing a magnetic field; however, in reality, the electromagnetic coil on the ultrasound probe of this application is set inside it and is integrated with the ultrasound part; it can also be fixed on the ultrasound probe). This clamping component can realize the clamping and lowering of the ultrasound probe of this application.

[0175] Referring to Figure 3A, a remote display, robotic arm control module, and cardiac ultrasound imaging control module are designed and placed in the SPECT imaging control room. This remote control and display terminal is connected to the echocardiography host through a local area network. When the imaging agent is observed to reach the target organ (e.g., the left ventricle), the electromagnetic coil and UTMD pulse are activated, and the robotic arm is retracted as needed to prepare for subsequent SPECT imaging.

[0176] Specifically, referring to Figures 11 and 12, an exemplary solution is as follows:

[0177] A robotic arm module 2 is provided on the upper surface of the frame body 11 of the acoustic-magnetic assisted SPECT imaging device 1. The robotic arm module 2 includes a robotic arm 21 and a gripper 22. The robotic arm 21 includes one or more arm links 211, such as two, three, four, five or more arm links 211. Figure 11 shows four arm links 211 as an example. The multiple arm links 211 are connected end-to-end in sequence, for example, by hinges. The multiple arm links 211 are connected end-to-end in sequence, specifically, for example, by fixed connection and / or movable connection (e.g., hinge). One end of the multiple hinged arm links 211 is fixedly or movably connected (e.g., hinged) to the upper surface of the frame body 11, and the other end of the multiple hinged arm links 211 is connected to the gripper 22. The gripper 22 includes, for example, a jaw to grip the ultrasound probe 3.

[0178] An electromagnetic component, specifically an electromagnetic coil 31, is provided in the ultrasonic probe 3. Furthermore, an electromagnetic coil 31 is arranged around the outer periphery of the ultrasonic probe 3. The number of electromagnetic coils 31 can be one, two, three, four, or more. Each electromagnetic coil 31 is circumferentially uniformly distributed or centrally symmetrically arranged around the ultrasonic probe 3, thereby ensuring the uniformity and stability of the magnetic field distribution around the ultrasonic probe 3, laying the structural foundation for the co-occurrence and coordinated operation of the ultrasonic field and magnetic field.

[0179] The ultrasonic probe of this application is based on the original structure of a conventional ultrasonic probe with an additional electromagnetic coil assembly. Therefore, its overall volume may be larger than that of a conventional single-function ultrasonic probe. The specific number of electromagnetic coils is not strictly limited and can be flexibly adjusted according to the actual application scenario, probe size and magnetic field control requirements. There are also no special restrictions on the connection method between the electromagnetic coil and the ultrasonic probe. Stable connection can be achieved by conventional assembly methods such as bonding and fixing or embedding integration.

[0180] To reduce the interference of the magnetic field on the working performance of the ultrasonic transducer, the electromagnetic coil can be encapsulated using conventional materials and processes. After encapsulation, a shell is wrapped around the outermost layer to finally produce an ultrasonic probe with an integrated acoustic-magnetic co-domain transducer.

[0181] Specifically, several exemplary schemes for setting electromagnetic coils 31 on the ultrasonic probe 3 are given below. Referring to Figure 13, an electromagnetic coil support 32 is fixed on the outer periphery of the probe end of the ultrasonic probe 3, and electromagnetic coils 31 are mounted on the electromagnetic coil support 32. There are three electromagnetic coils 31, and the three electromagnetic coils 31 are evenly arranged in the circumferential direction on the outer periphery of the ultrasonic probe 3.

[0182] Specifically, referring to Figure 14, an electromagnetic coil support 32 is fixed to the outer periphery of the probe end of the ultrasonic probe 3. An electromagnetic coil 31 is installed on the electromagnetic coil support 32 at the end away from the ultrasonic probe 3, and there is one electromagnetic coil 31. In actual imaging, the area to be imaged is located between the ultrasonic probe 3 and the electromagnetic coil 31.

[0183] Specifically, referring to Figure 15, an electromagnetic coil support 32 is fixedly provided on the outer periphery of the probe end of the ultrasonic probe 3, and an electromagnetic coil 31 is sleeved on the outer periphery of the probe end of the ultrasonic probe 3 by being fixed on the electromagnetic coil support 32. The number of electromagnetic coils 31 is one.

[0184] In subsequent operations, the structure shown in Figure 13 was selected.

[0185] An acoustic-magnetic assisted SPECT myocardial perfusion imaging method includes the steps of using the aforementioned acoustic-magnetic dual-response phase-change nanodroplets and / or acoustic-magnetic dual-response phase-change nanodroplets prepared by the aforementioned method. This method can be implemented using the aforementioned equipment or other equipment that conventionally provides the aforementioned electromagnetic conditions.

[0186] The following describes the acoustic-magnetic-assisted SPECT myocardial perfusion imaging method in conjunction with the aforementioned acoustic-magnetic-assisted SPECT imaging equipment. It specifically includes the following steps:

[0187] Step 1: Plan the motion trajectory of the robotic arm

[0188] After anesthetizing the mice, they were fixed in a supine position on the treatment table. An infusion channel was established by puncturing the tail vein with a disposable sterile intravenous infusion needle. Coupling agent was evenly applied between the bottom of the probe and the mouse's heart. The position of the ultrasound probe containing the acoustic-magnetic co-domain transducer was adjusted to clearly display the left ventricular section. This position was set as the starting point, and the initial position of the robotic arm on the ultrasound device was set as the ending point. The trajectory of movement between the two was planned.

[0189] Step II: Set up the SPECT program and acquire anterior and posterior images. Set the ultrasonic transducer parameters: center frequency 0.970MHz, pulse repetition frequency 1Hz, negative sound pressure peak value 0.60MPa, and duty cycle 10%.

[0190] Step III: Inject 0.2 μL / g of the acoustic-magnetic dual-response phase change nanodroplets from Example 1 into the tail vein of mice, and simultaneously start the device for imaging.

[0191] Example 3.

[0192] An ultrasonically responsive phase change nanodroplet comprises a lipid membrane, a phase change agent encapsulated within the lipid membrane, and a nuclide loaded on the lipid membrane.

[0193] The preparation method of this ultrasonically responsive phase change nanodroplet is as follows:

[0194] Step 1: Preparation of the second preparation solution

[0195] The lipid membrane was composed of dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazole chloride. Dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazole chloride were dissolved in 5 mL of chloroform at a molar ratio of 8:1:1 to form a 2 mg / mL solution. This solution was then transferred to a round-bottom flask and evaporated under rotary vacuum at 50 °C to form a thin film. 10 mL of deionized water was added to hydrate the membrane, and the mixture was ultrasonically vibrated for 10 minutes to obtain the second prepared solution.

[0196] Step 2: Preparation of unloaded acoustic-magnetic dual-response phase change nanodroplets

[0197] 0.5615 g of perfluorodecanoic acid was mixed with 6 mL of the second preparation solution and sonicated at 150 W for 3 min using an ultrasonic processor to synthesize unloaded ultrasonic-responsive phase change nanodroplets (acomND).

[0198] Step 3: Couple with radionuclides

[0199] Ultrasonic-responsive phase change nanodroplets with Na 99m The TcO4 solution was mixed and stirred at room temperature for 20 min to obtain ultrasonically responsive phase change nanodroplets. 99m Tc-acomND), see Figure 3 for details.

[0200] Example 4.

[0201] An acoustic-magnetic dual-response phase change nanodroplet comprises a lipid membrane, magnetic nanoparticles coated within the lipid membrane, a phase change agent coated within the lipid membrane, and a nuclide loaded on the lipid membrane.

[0202] Referring to Figure 1, the preparation method of this acoustic-magnetic dual-response phase change nanodroplet is as follows:

[0203] Step 1: Prepare the first and second preparation solutions

[0204] Preparation of the first solution:

[0205] 111.5 μL of tetramethylammonium hydroxide was added to 5 mL of anhydrous ethanol containing 2 mg of magnetite nanoparticles, and the mixture was sonicated at 100 W for 10 min to obtain a first suspension. This first suspension was then mixed with 0.5615 g of perfluorodecanoic acid. The entire mixture was sonicated at 100 W for 40 min in an ice bath. The fluorinated magnetite nanoparticles were then collected and washed three times with 1 mL of methanol.

[0206] After natural drying, the fluorinated magnetite nanoparticles were dispersed in 100 μL of tetradecylfluorohexane to obtain the first solution (the content of magnetite nanoparticles was 20 mg / mL).

[0207] Preparation of the second solution:

[0208] The lipid membrane was composed of dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazole chloride. Dipalmitoylphosphatidylcholine (DPPC), distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), and 1-hexadecyl-3-methylimidazole chloride were dissolved in 5 mL of chloroform at a molar ratio of 8:1:1 to form a 2 mg / mL solution. This solution was then transferred to a round-bottom flask and evaporated under rotary vacuum at 50 °C to form a thin film. 10 mL of deionized water was added to hydrate the membrane, and the mixture was ultrasonically vibrated for 10 minutes to obtain the second prepared solution.

[0209] Step 2: Preparation of unloaded acoustic-magnetic dual-response phase change nanodroplets

[0210] 100 μL of the first preparation solution was mixed with 6 mL of the second preparation solution, and the mixture was sonicated at 150 W for 3 min using an ultrasonic processor to synthesize unloaded acoustic-magnetic dual-response phase change nanodroplets (acomND).

[0211] Step 3: Couple with radionuclides

[0212] Empty acoustic-magnetic dual-response phase change nanodroplets with Na 99m The TcO4 solution was mixed and stirred at room temperature for 20 min to obtain acoustic-magnetic dual-response phase change nanodroplets. 99m Tc-acomND), see Figure 5 for details.

[0213] The acoustic-magnetic dual-response phase change nanodroplets obtained in Example 4 were tested as follows.

[0214] 1. Transmission electron microscopy

[0215] The samples to be tested (phase change nanodroplets from Examples 4 and 3, respectively) were prepared using conventional methods and subjected to transmission electron microscopy (TEM) testing. The specific results are shown in Figure 6. It can be seen that magnetic materials were loaded onto the acoustic-magnetic dual-response phase change nanodroplets, and a clear phospholipid shell-perfluorocarbon core interface was observed.

[0216] 2. Particle size distribution and surface charge

[0217] The particle size distribution was detected by DLS (dynamic light scattering), and the zeta potential was measured. Three parallel samples were tested for each sample, as shown in Figure 7. The average particle size was 150.3 ± 3 nm, and the zeta potential was 20.7 ± 0.6 mV.

[0218] 3. 99m Thin-layer chromatography analysis of Tc-labeled nanodroplets

[0219] Prepare free sodium pertechnetate control group, unreduced sodium pertechnetate... 99m Tc-labeled nanodroplets and reduction 99m The specific method for creating Tc-labeled nanodroplets is as follows:

[0220] 3.1. Experimental Materials and Sample Preparation

[0221] 3.1.1 Free sodium pertechnetate control solution

[0222] The free sodium pertechnetate solution was a purchased radioactive drug and was used as a control group.

[0223] 3.1.2 Unrestored 99m Preparation of Tc-labeled nanodroplets

[0224] The sample was prepared according to the method described in Example 1.

[0225] 3.1.3 Restored 99m Preparation of Tc-labeled nanodroplets

[0226] Following steps 1 and 2 of Example 1, 1 mL of acoustic-magnetic dual-response phase change nanodroplets (concentration 2 mg / mL) were prepared and placed in an EP tube. 1 mL of Na₂O₃ was then added. 99m A mixture of TcO4 solution and a small amount of freshly prepared SnCl2 solution (concentration 2.5 mg / mL, solvent 0.5 M HCl) was inverted and left at room temperature for 15 min to obtain the reduced solution. 99m Tc-labeled nanodroplet samples.

[0227] 3.2. Thin-layer chromatography analysis procedure

[0228] 3.2.1 Preparation of Thin-Layer Chromatography Strips

[0229] Use Whatman No. 1 chromatography filter paper and cut it into strips of appropriate size. About 1.0 cm from the bottom of each strip of filter paper, lightly draw a straight line with a pencil as the starting line for spotting, and label the corresponding sample name.

[0230] 3.2.2 Spotting

[0231] Using three different capillary glass tubes, take the three samples prepared above (free sodium pertechnetate control solution, unreduced labeled solution, and reduced labeled solution) and gently spot them on the corresponding chromatographic filter paper strips. Allow them to air dry naturally, ensuring the spots are completely dry.

[0232] 3.2.3 Preparation of developing solvent

[0233] Measure an appropriate amount of acetone as the developing solvent and pour it into the chromatography tank. Cover the chromatography tank.

[0234] 3.2.4 Chromatographic Expansion

[0235] Place three spotted and dried chromatographic filter paper strips vertically into the chromatography tank with the spotted end facing down. Ensure that the bottom of the filter paper strip is immersed approximately 0.5-1.0 cm below the acetone surface, and that the spotted spot is above the surface. Seal the chromatography tank and wait for the acetone to rise due to capillary action and spread to a distance of 10 cm before removing the filter paper strips.

[0236] 3.2.5 Marking the leading edge

[0237] Immediately mark the solvent front with a pencil. Place the filter paper strip in a fume hood to air dry.

[0238] 3.3. Radioactivity Detection

[0239] The dried chromatographic filter paper strip was scanned using a radioactive thin-layer chromatography scanner to determine the radioactivity distribution along the entire chromatographic column in the development direction.

[0240] Thin-layer chromatography analysis was then performed, and the results are shown in Figure 8, indicating that the unreduced... 99m The labeling rate of Tc-labeled nanodroplets was 35.86% (the labeling rate measured by magnetic adsorption detection at the same concentration was 15%); reduced 99m The labeling rate of Tc-labeled nanodroplets was 98.53%.

[0241] 4. Biocompatibility of nanodroplets: CCK8 assay in cardiomyocytes

[0242] The testing method is as follows:

[0243] 4.1. Cell seeding

[0244] Mouse cardiomyocytes HL-1 were resuspended in MEM medium and seeded into 96-well plates at 100 μL per well. The plates were then incubated at 37°C in a 5% CO2 incubator for 24 h.

[0245] 4.2. Acousto-magnetic dual-response phase change nanodroplet treatment

[0246] Discard the supernatant. Take the acoustic-magnetic dual-response phase change nanodroplets prepared in Example 1 and dilute them with MEM medium to concentration gradients of 0 (control), 10, 25, 50, 80, 100, and 250 μg / mL. Add the above dilutions to a 96-well plate, 100 μL per well, with 6 replicates for each concentration. Continue culturing for 24 h.

[0247] 4.3. CCK-8 Detection

[0248] After the culture was completed, 10 μL of CCK-8 reagent was added to each well and incubated in the dark for 2 hours. The absorbance (OD value) at 450 nm was measured using a microplate reader.

[0249] The specific results are shown in Figure 9. At a concentration of 10 μg / mL, cell viability was almost identical to the control group (99.9%), indicating that the nanodroplets had no significant toxicity at this concentration. Cell viability gradually decreased with increasing concentration: 92.4% at 25 μg / mL, 91.7% at 50 μg / mL, 84.8% at 80 μg / mL, 73.9% at 100 μg / mL, and only 35.5% at 250 μg / mL.

[0250] 5. 99m Biodistribution of Tc-labeled nanodroplets in mice

[0251] The testing method is as follows:

[0252] 5.1. Grouping: SPF-grade male C57BL / 6 mice, 8 weeks old and weighing 20±2g, were selected. The mice were randomly divided into 5 groups of 3 mice each, corresponding to the following time points: 5min, 15min, 1h, 2h, and 4h.

[0253] 5.2. Sample Collection and Processing: Each mouse was injected intravenously with 100 μL of a radioactive compound with an activity of 0.1 mCi. 99m Tc-labeled acoustic-magnetic dual-response phase-change nanodroplets were used in Example 1. Blood samples were collected from the hearts of mice in the corresponding groups at 5 min, 15 min, 1 h, 2 h, and 4 h post-injection, followed by cervical dislocation and euthanasia. Major organs such as the heart, liver, spleen, and kidneys were rapidly dissected and removed. The removed organs were rinsed with physiological saline, surface moisture was blotted dry with filter paper, and the wet weight of each organ was recorded.

[0254] 5.3. Radioactivity Measurement and Calculation

[0255] Each organ and blood sample was placed in a gamma counter tube, and the radioactivity count per minute (cpm) was measured using a gamma counter. Simultaneously, the count of the pre-injection standard source (equivalent to the administered dose) was measured. All measurements were corrected for time decay and background subtracted. The percentage injection dose rate per gram of tissue for each organ (%ID / g) was calculated.

[0256] The specific results are shown in Figure 10. The results indicate that the nanodroplets exhibit the ideal two-compartment characteristic of "rapid distribution and slow elimination" in the blood.

[0257] Comparative Example 1.

[0258] The difference between this comparative example and Example 1 is that no coupling agent was added when preparing the acoustic-magnetic dual-response phase change nanodroplets; otherwise, it is the same as Example 1.

[0259] Specifically, in preparing the second solution, the lipid membrane components were: dipalmitoylphosphatidylcholine (DPPC) and distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000). Dipalmitoylphosphatidylcholine (DPPC) and distearylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000) were dissolved in 5 mL of chloroform at a molar ratio of 8:1 to form a 2 mg / mL solution. This solution was then transferred to a round-bottom flask and evaporated under rotary vacuum at 50°C to form a thin film. 10 mL of deionized water was then added to hydrate the membrane, and the mixture was ultrasonically vibrated for 10 minutes to obtain the second solution.

[0260] All other steps are the same as in Example 1. The acoustic-magnetic dual-response phase change nanodroplets prepared in this comparative example differ in particle size distribution from those in Example 4. 99m The Tc-labeled nanodroplets had poor labeling efficiency; their biosafety and in vivo imaging performance in mice were not as good as in Example 4.

[0261] Example 5. Effect of the amount of fluorinated magnetite nanoparticles added.

[0262] To investigate the effect of magnetic components on the performance of nanodroplet systems, this study set up comparative experiments with different amounts of magnetic iron oxide added, such as 1 mg, 2 mg, 3 mg, 5 mg and 10 mg (the amount added in Example 1 was 10 mg).

[0263] Acoustic-magnetic dual-response phase-change nanodroplets were prepared according to the method in Example 1 with different addition amounts. Subsequently, myocardial perfusion imaging was performed in mice according to the method in Example 2. Experimental results showed that when the addition amount of fluorinated magnetite nanoparticles was low (e.g., 1 mg), the magnetic response of the nanodroplet system was weak, which was not conducive to subsequent magnetic targeting applications. When the addition amount was high (e.g., ≥3 mg), the interaction between magnetic particles in the system was enhanced, and local aggregation was prone to occur, which adversely affected the structural stability of the nanodroplets, manifested as a wider particle size distribution and decreased storage stability. Under in vivo application conditions, the above-mentioned aggregated particles may have difficulty passing through microvessels due to increased particle size, thereby increasing the risk of microcirculatory blockage and affecting its biosafety and in vivo distribution characteristics.

[0264] Based on the above results, when the amount of magnetic iron oxide added is about 2 mg, the system achieves a good balance between magnetic response capability and structural stability. Therefore, this range is determined to be the preferred condition.

[0265] Example 6. Application of myocardial imaging

[0266] The acoustic-magnetic dual-response phase change nanodroplets prepared according to the method of Example 4 were used for myocardial imaging according to the method of Example 2, and were compared with conventional imaging agents. 99m Comparison of myocardial imaging effects of Tc-MIBI; see Figure 16 for specific results: provided in this application 99m Tc-labeled nanodroplets exhibit excellent myocardial enrichment capacity in vivo, with a significantly higher myocardial uptake rate than currently used clinical imaging agents. 99m Tc-MIBI (developer) 99m Tc-MIBI is commercially available; the myocardial uptake rate of this application is 16.42% ID / g; 99m The myocardial uptake rate of Tc-MIBI was 9.32% ID / g, indicating that this nanosystem has higher imaging contrast and detection sensitivity in myocardial perfusion imaging and has good potential for clinical translation.

[0267] The description in this disclosure is provided for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the disclosure to its forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of this disclosure and to enable those skilled in the art to understand this disclosure and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. An ultrasound-responsive phase change nanodroplet, comprising a lipid membrane, a phase change agent encapsulated within the lipid membrane, and a nuclide loaded on the lipid membrane; in, The lipid membrane comprises phospholipids and a coupling agent for coupling the nuclide; The coupling agent is selected from imidazole derivatives, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid derivatives, 1,4,7-triazacyclononane-1,4,7-triacetic acid derivatives, and methoxyisocyanate derivatives.

2. The ultrasonically responsive phase change nanodroplet according to claim 1, wherein the imidazole derivative is selected from any one or more combinations of the following group: 1-hexadecyl-3-methyl imidazole chloride, 1-butyl-3-methyl imidazole chloride, 1-octyl-3-methyl imidazole chloride, 1-octyl-3-methyl imidazole bromide, 1-dodecyl-3-methyl imidazole chloride, 1-dodecyl-3-methyl imidazole bromide, 1-hexadecyl-3-methyl imidazole bromide, 1-hexadecyl-3-methyltetrafluoroborate imidazole, 1-hexadecyl-3-methylhexafluorophosphate imidazole, 1-hexadecyl-3-carboxymethyl imidazole chloride, and 1-hexadecyl-3-hydroxyethyl imidazole chloride.

3. The ultrasonically responsive phase change nanodroplet according to claim 1 or 2, wherein the phospholipid is selected from any one or more combinations of the following: dipalmitoylphosphatidylcholine, distearylphosphatidylethanolamine-polyethylene glycol 2000, and distearylphosphatidylcholine; Preferably, the phospholipid comprises dipalmitoyl phosphatidylcholine and distearate phosphatidylethanolamine-polyethylene glycol 2000.

4. The ultrasonically responsive phase change nanodroplet according to any one of claims 1-3, wherein the phospholipid is dipalmitoylphosphatidylcholine and distearate phosphatidylethanolamine-polyethylene glycol 2000, and the coupling agent is 1-hexadecyl-3-methylimidazole chloride; Preferably, the molar ratio of dipalmitoyl phosphatidylcholine, distearate phosphatidylethanolamine-polyethylene glycol 2000 and 1-hexadecyl-3-methylimidazole chloride is (2.5-15):(0.1-2):(0.1-2); more preferably, it is (5-10):(0.5-1.5):(0.5-1.5).

5. The ultrasonically responsive phase change nanodroplet according to any one of claims 1-4, wherein the phase change agent comprises perfluoroalkane, perfluoroether, perfluoropolyether, and perfluorobromide; Preferably, the phase change agent is selected from any one or more of the following group: perfluoropentane, perfluorohexane, perfluorooctane, perfluoropropyl ether, perfluoropolyether, and perfluorobromooctane; Preferably, the phase change agent is perfluorohexane.

6. The ultrasonically responsive phase-change nanodroplet according to any one of claims 1-5, wherein the nuclide is a radioactive nuclide, preferably... 99m Tc.

7. A method for preparing ultrasonically responsive phase change nanodroplets according to any one of claims 1-6, comprising the following steps: After the phospholipid and coupling agent are mixed evenly in the first solvent, the first solvent is removed to form a film. Then, the second solvent is added and mixed evenly to obtain the second preparation solution. The phase change agent and the second prepared liquid were mixed and then subjected to a third dispersion treatment to obtain empty ultrasonic-responsive phase change nanodroplets. The empty ultrasonic-responsive phase change nanodroplets are mixed uniformly with the nuclide to obtain the ultrasonic-responsive phase change nanodroplets. Preferably, the first solvent is selected from any one or more of the following group: dichloromethane, trichloromethane, tetrachloromethane, methanol, ethanol, tetrahydrofuran, and diethyl ether; more preferably, it is trichloromethane; Preferably, the second solvent is an aqueous solvent; more preferably, it is water. Preferably, the total content of the phospholipid and coupling agent in the first solvent is 0.5-10 mg / mL; more preferably, it is 1-5 mg / mL. Preferably, the total content of the phospholipids and coupling agent in the second preparation solution is 0.05-10 mg / mL; more preferably, it is 0.1-5 mg / mL. Preferably, the volume ratio of the phase change agent to the second prepared liquid is 1:30-100; Preferably, the conditions for the third dispersion treatment include: ultrasonic power of 100-200W and ultrasonic time of 0.5-10min.

8. An acoustic-magnetic dual-response phase change nanodroplet, which is the ultrasonically responsive phase change nanodroplet according to any one of claims 1-6, further comprising magnetic nanoparticles coated within the lipid membrane; Preferably, the magnetic nanoparticles are selected from any one or more of the following groups: magnetite nanoparticles, γ-ferric oxide magnetic nanoparticles, metallic ferromagnetic nanoparticles, metallic cobalt magnetic nanoparticles, metallic nickel sub-nanoparticles, iron-platinum alloy magnetic nanoparticles, and iron-cobalt alloy magnetic nanoparticles. More preferably, it is ferric oxide magnetic nanoparticles.

9. The acoustic-magnetic dual-response phase change nanodroplet according to claim 8, wherein the mass ratio of the lipid membrane to the magnetic nanoparticles is 2-4:

5.

10. The acoustic-magnetic dual-response phase change nanodroplet according to claim 8 or 9, wherein the ratio of phase change agent to magnetic nanoparticles is 5-15 μL phase change agent: 0.1-1 mg magnetic nanoparticles.

11. The acoustic-magnetic dual-response phase change nanodroplet according to any one of claims 8-10, wherein the magnetic nanoparticles are fluorinated magnetic nanoparticles; Preferably, the fluorinating agent is selected from any one or more combinations of the following group: perfluorosuccinic acid, perfluorooctanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, and perfluorotetradecanoic acid; more preferably, the fluorinating agent is perfluorosuccinic acid.

12. The acoustic-magnetic dual-response phase change nanodroplet according to claim 11, wherein the method for preparing the fluorinated magnetic nanoparticles comprises the following steps: The magnetic nanoparticles are dispersed in a first dispersion solvent and mixed with an alkaline organic solvent; after the first dispersion treatment, a first suspension is obtained. The first suspension and the fluorinating agent were mixed, and after a second dispersion treatment, the magnetic nanoparticles modified with the fluorinating agent were collected. Preferably, among which, The alkaline organic solvent is selected from any one or more of the following group: tetramethylammonium hydroxide, tetraethylammonium hydroxide, potassium hydroxide, and sodium bicarbonate; Preferably, the mass ratio of the fluorinating agent to the magnetic nanoparticles is 30-80:1; Preferably, the content of the magnetic nanoparticles in the first dispersion is 0.1-5 mg / mL or 0.5-5 mg / mL; Preferably, the conditions for the first dispersion treatment include: ultrasonic power of 50-150W and ultrasonic time of 5-20min; Preferably, the conditions for the second dispersion treatment include: ultrasonic power of 50-150W and ultrasonic time of 20-60min.

13. A method for preparing acoustic-magnetic dual-response phase change nanodroplets according to any one of claims 8-12, comprising the following steps: The magnetic nanoparticles and the phase change agent are mixed to obtain a first preparation solution; After the phospholipid and coupling agent are mixed evenly in the first solvent, the first solvent is removed to form a film. Then, the second solvent is added and mixed evenly to obtain the second preparation solution. After mixing the first and second prepared solutions, the mixture is subjected to a third dispersion treatment to obtain empty acoustic-magnetic dual-response phase change nanodroplets. The empty acoustic-magnetic dual-response phase change nanodroplets were mixed uniformly with a nuclide to obtain the acoustic-magnetic dual-response phase change nanodroplets. Preferably, in the first preparation solution, the content of the magnetic nanoparticles is 10-200 mg / mL phase change agent or 50-200 mg / mL phase change agent; Preferably, the first solvent is selected from any one or more of the following group: dichloromethane, trichloromethane, tetrachloromethane, methanol, ethanol, tetrahydrofuran, and diethyl ether; more preferably, it is trichloromethane; Preferably, the second solvent is an aqueous solvent; more preferably, it is water. Preferably, the total content of the phospholipid and coupling agent in the first solvent is 0.5-10 mg / mL; more preferably, it is 1-5 mg / mL. Preferably, the total content of the phospholipids and coupling agent in the second preparation solution is 0.05-10 mg / mL; more preferably, it is 0.1-5 mg / mL. Preferably, the volume ratio of the first preparation solution to the second preparation solution is 1:30-100; Preferably, the conditions for the third dispersion treatment include: ultrasonic power of 100-200W and ultrasonic time of 0.5-10min.

14. A SPECT myocardial perfusion imaging method, comprising the steps of using ultrasound-responsive phase change nanodroplets as described in any one of claims 1-6 and / or ultrasound-dual-responsive phase change nanodroplets obtained by the preparation method described in claim 7.

15. An acoustic-magnetic assisted SPECT myocardial perfusion imaging method, comprising the steps of using acoustic-magnetic dual-response phase change nanodroplets as described in any one of claims 8-12 and / or acoustic-magnetic dual-response phase change nanodroplets obtained by the preparation method described in claim 13.

16. The acoustic-magnetic assisted SPECT myocardial perfusion imaging method according to claim 15 further includes the following steps: The subject ingests the acoustic-magnetic dual-response phase-change nanodroplets, which are then visualized on an acoustic-magnetic assisted SPECT. The condition parameters of the acoustic-magnetic assisted SPECT include: The center frequency is 0.5-1.5MHz. And / or, the pulse repetition frequency is 0.5-5Hz. And / or, the negative sound pressure peak is 0.1-1.5 MPa. And / or, with a duty cycle of 5-15%.

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