Magnetic nanoprobe with small size and high magnetic particle imaging performance, preparation method and application thereof

Abstract

The application discloses a magnetic nanometer probe with small size and high magnetic particle imaging performance, and a preparation method and application thereof. In the application, iron chloride is dissolved in a glycol solution, and a uniform transparent solution is formed through magnetic stirring; manganese chloride with different concentrations is added into the above solution, and stirring and dissolution are carried out; sodium acetate is added, and uniform stirring is carried out to form a transparent solution; finally, sodium citrate is dissolved in the above solution, uniform stirring is carried out, and the mixed solution is reacted through a solvothermal method; after the reaction is completed, the reaction product is purified through centrifugation and dialysis; finally, the supernatant is collected and concentrated, and the magnetic nanometer probe is obtained. The magnetic nanometer probe prepared through the method has small size, high sensitive imaging performance and excellent hydrophilic performance, and is expected to be used for the diagnosis of micro lesions.

Description

Technical Field

[0001] This invention relates to the field of biomedical engineering, and in particular to a magnetic nanoprobe with small size and high magnetic particle imaging performance, its preparation method, and its application. Background Technology

[0002] Non-invasive imaging techniques have enabled the visualization of molecularly characterized biological processes, significantly advancing the role of medical imaging in disease diagnosis, monitoring, and treatment. In particular, targeted imaging strategies targeting endogenous molecules have demonstrated higher sensitivity and specificity in non-invasive imaging, promising to improve disease diagnosis and accurate assessment of treatment outcomes. This strategy leverages the functionality of prepared probes and has been effectively applied to various imaging modalities, including optical imaging, positron emission tomography (PET), and magnetic resonance imaging (MRI). Magnetic particle imaging (MPI), first introduced in 2005, is a novel non-invasive and tomographic medical imaging modality where the signal originates solely from the nonlinear dynamic magnetization response of superparamagnetic nanoparticles, aiming to provide real-time, functional, and quantitative non-invasive imaging. By directly detecting magnetic nanoparticles (MNPs), it offers high sensitivity, avoids ionizing radiation, and minimizes background interference from tissues, overcoming the limitations of current imaging modalities. However, as MPI is a new molecular imaging technology, its tracers are still under development, and developing MNPs with high MPI imaging performance is an urgent need for the development of MPI technology.

[0003] As the core tracer in MPI technology, the magnetic properties of microNPs directly determine imaging resolution and sensitivity. Studies have shown that when the size of MNPs is <30 nm, their superparamagnetic properties can significantly improve the magnetization reversal rate, thereby increasing the MPI signal intensity. However, existing synthesis techniques generally face a paradox of "size-performance-biocompatibility": traditional coprecipitation methods, while simple, produce products with wide particle size distributions (20-200 nm) and low crystallinity, resulting in poor magnetic response consistency; thermal decomposition methods, while capable of preparing highly uniform MNPs, rely on organometallic precursors and high-temperature conditions (>300 ℃), not only generating bioincompatible hydrophobic surfaces but also increasing preparation costs due to complex phase transfer processes; while hydrothermal methods, although able to improve crystallinity, pose safety risks due to their high-pressure closed environment and lack precision in particle size control. More importantly, existing methods generally exhibit a performance paradox: lowering the annealing temperature to pursue smaller sizes leads to increased crystal defects and reduced magnetic moments; while the high-temperature treatment required to improve crystallinity causes particle agglomeration and increases size. This contradiction directly leads to the difficulty in improving the sensitivity of MPI performance in current commercial MNPs (such as Resovist). In addition, the traditional process uses a large amount of organic solvents, high-energy-consuming reaction conditions and complex post-processing steps, which seriously violates the principles of green chemistry and restricts the clinical translation of MNPs.

[0004] Therefore, developing green preparation technologies for MNPs that combine small size (<10 nm), high crystallinity, good biocompatibility, and environmental friendliness has become a key issue in overcoming the bottleneck of MPI clinical applications. This will not only improve the sensitivity of lesion detection to the level of hundreds of cells, but will also promote the development of therapeutic probes. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a magnetic nanoprobe with small size and high magnetic particle imaging performance, along with its preparation method and applications. The magnetic nanoprobe prepared by the method of this invention is small in size, possesses highly sensitive imaging performance and excellent hydrophilic properties, and holds promise for the diagnosis of minute lesions.

[0006] In a first aspect, the present invention provides a method for preparing a magnetic nanoprobe with small size and high magnetic particle imaging performance, which is achieved by the following technical solution.

[0007] A method for preparing a magnetic nanoprobe with small size and high magnetic particle imaging performance includes the following steps:

[0008] S1. Dissolve ferric chloride in ethylene glycol solution and stir until homogeneous;

[0009] S2. Add manganese chloride to an ethylene glycol solution containing ferric chloride and stir until homogeneous; wherein the molar ratio of ferric chloride to manganese chloride is 1:(0-0.6);

[0010] S3. Dissolve sodium acetate in the solution obtained in step S2 and stir until homogeneous; wherein the molar ratio of sodium acetate to ferric chloride is (1-7):1;

[0011] S4. Dissolve sodium citrate in the solution obtained in step S3 and stir until homogeneous; the molar ratio of sodium citrate to ferric chloride is (1-2):1;

[0012] S5. The mixed solution obtained in step S4 is reacted using a solvothermal method, and the product after reaction is cooled to room temperature;

[0013] S6. Wash and centrifuge the product obtained in step S5, and collect the supernatant; concentrate the collected supernatant, then dialyze it, and concentrate the dialyzed product again to obtain a magnetic nanoprobe with small size and high magnetic particle imaging performance.

[0014] Furthermore, in step S5, the reaction conditions for the solvothermal method are 160-200℃ for 6-12 h.

[0015] Furthermore, in step S6, the centrifugation washing conditions are as follows: wash with ethanol and water at 8000-11000 rpm for 10-20 min, and wash 3-5 times.

[0016] Furthermore, in step S6, the supernatant collected by centrifugation is concentrated at 40-60°C for 12-48 h.

[0017] Furthermore, in step S6, the molecular weight cutoff of the dialysis bag is 1000-3500 kDa, and the dialysis time is 1-2 days.

[0018] Furthermore, in step S6, the dialysis product is concentrated again by a concentration factor of 10-20 times.

[0019] Secondly, the present invention provides a magnetic nanoprobe with small size and high magnetic particle imaging performance, which is achieved by the following technical solution.

[0020] A magnetic nanoprobe with small size and high magnetic particle imaging performance prepared by the above preparation method.

[0021] Thirdly, the present invention provides the use of a magnetic nanoprobe with small size and high magnetic particle imaging performance, which is achieved by the following technical solution.

[0022] Application of the above-mentioned magnetic nanoprobe with small size and high magnetic particle imaging performance in the preparation of diagnostic products for small lesions.

[0023] This application has the following beneficial effects.

[0024] (1) The manganese-doped MNPs prepared by this invention have small size, high MPI performance and good hydrophilicity.

[0025] (2) The MNPs prepared by this invention are magnetic particles smaller than 10 nm through the selection and purification of raw materials;

[0026] (3) The present invention effectively improves the MPI performance by doping with manganese. The prepared MNPs have a stronger MPI signal than the commercial gold standard Vivotrax under the same concentration conditions.

[0027] (4) The preparation of manganese-doped MNPs by the present invention is simple, has high biosafety and strong hydrophilicity. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the preparation method of MNPs according to the present invention;

[0029] Figure 2 These are photographs of MNPs doped with different elements in water in Examples 1 and 2 of the present invention (in the figures, from left to right, they are MNPs doped with cobalt, MNPs doped with manganese, MNPs, MNPs doped with sulfur, and MNPs doped with nickel).

[0030] Figure 3 These are MPI images of MNPs doped with different elements in Examples 1 and 2 of this invention;

[0031] Figure 4 This is a graph showing the MPI signal values ​​of MNPs doped with different elements in Examples 1 and 2 of the present invention at the same concentration.

[0032] Figure 5 These are saturation magnetization curves of MNPs doped with different elements in Examples 1 and 2 of this invention;

[0033] Figure 6 Example 2 of the present invention: Cobalt-doped MNPs (Co) 0.4 Fe 2.6 The spectrum of O4 signal;

[0034] Figure 7 Manganese-doped MNPs (Mn) of Example 2 of this invention 0.4 Fe 2.6 The spectrum of O4 signal;

[0035] Figure 8 The spectrum signal diagram of MNPs (Fe3O4) in Example 1 of this invention;

[0036] Figure 9The spectrum signal of sulfur-doped MNPs (FeS) in Example 2 of this invention;

[0037] Figure 10 This is the nickel-doped MNPs (Ni) of Example 2 of the present invention. 0.4 Fe 2.6 The spectrum of O4 signal;

[0038] Figure 11 MNPs (Mn) prepared by manganese doping in different proportions in Example 3 of this invention x Fe 3-x Photographs of manganese chloride (O4) dispersed in water (in the image, the amounts of manganese chloride added from left to right are 1 mmol, 0.8 mmol, 0.6 mmol, 0.5 mmol, 0.4 mmol, and 0.2 mmol, respectively).

[0039] Figure 12 MNPs (Mn) prepared by manganese doping in different proportions in Example 3 of this invention x Fe 3-x Hydrated particle size distribution diagram of O4;

[0040] Figure 13 MNPs (Mn) prepared by manganese doping in different proportions in Example 3 of this invention x Fe 3-x Statistical results of hydrated particle size, potential and PDI of O4;

[0041] Figure 14 MNPs (Mn) prepared by manganese doping in different proportions in Example 3 of this invention x Fe 3-x MPI image of O4 (in the figure, 1: Mn) 0.4 Fe 2.6 O4; 2: Mn 0.8 Fe 2.2 O4;3:MnFe2O4;4:Mn 1.2 Fe 1.8 O4; 5: Mn 1.6 Fe 1.4 O4; 6: Mn2FeO4);

[0042] Figure 15 MNPs (Mn) prepared by manganese doping in different proportions in Example 3 of this invention x Fe 3-x The MPI signal value results for O4);

[0043] Figure 16 MNPs (Mn) prepared by manganese doping in different proportions in Example 3 of this invention x Fe 3-xSaturation magnetization curve of O4);

[0044] Figure 17 This invention relates to MNPs (Mn) doped with manganese (0.4 mmol) as described in Example 3 of the present invention. 0.8 Fe 2.2 The spectrum of O4 signal;

[0045] Figure 18 The spectrum of MNPs (MnFe2O4) doped with manganese (0.5 mmol) in Example 3 of this invention is shown.

[0046] Figure 19 This is MNPs (Mn) doped with manganese (0.6 mmol) in Example 3 of the present invention. 1.2 Fe 1.8 The spectrum of O4 signal;

[0047] Figure 20 MNPs (Mn) doped with manganese (0.8 mmol) in Example 3 of this invention 1.6 Fe 1.4 The spectrum of O4 signal;

[0048] Figure 21 The spectrum of MNPs (Mn2FeO4) doped with manganese (1 mmol) in Example 3 of this invention is shown.

[0049] Figure 22 MNPs (Mn) prepared by optimal manganese doping in this invention 0.4 Fe 2.6 Transmission electron microscope image of O4;

[0050] Figure 23 MNPs (Mn) prepared by optimal manganese doping in this invention 0.4 Fe 2.6 TEM size statistics for O4). Detailed Implementation

[0051] This invention provides a method for preparing MNPs with small size, high MPI performance, and good hydrophilicity. The initial raw materials for preparing MNPs include ferric chloride, sodium acetate, and sodium citrate. The reaction solvent is ethylene glycol, and the raw materials contain different dopant elements: manganese chloride, reduced glutathione, cobalt chloride, and nickel chloride. This invention provides a simple and green preparation and purification route for preparing highly sensitive and biosafety-compliant MPI tracer MNPs.

[0052] The present patent application will be further described below with reference to the accompanying drawings and embodiments.

[0053] Example 1

[0054] A method for preparing a magnetic nanoprobe with small size and high magnetic particle imaging performance includes the following steps:

[0055] Step 1: Dissolve ferric chloride in ethylene glycol solution and stir magnetically to form a uniform yellow transparent solution; add 1 millimole of ferric chloride to every 10 mL of ethylene glycol solution.

[0056] Step 2: Dissolve sodium acetate in an ethylene glycol solution containing ferric chloride and stir magnetically to form a uniform, transparent, brownish-red solution; add 7 millimoles of sodium acetate to every 10 mL of ethylene glycol solution.

[0057] Step 3: Dissolve sodium citrate in the ethylene glycol solution containing ferric chloride and sodium acetate, and stir magnetically to form a homogeneous solution; add 2 millimoles of sodium citrate to every 10 mL of ethylene glycol solution.

[0058] Step 4: Transfer the mixed solution from Step 3 to a high-pressure reactor with a polytetrafluoroethylene liner, place it in an oil bath, and react at 180 °C for 12 h using a solvothermal method. Cool the product after reaction to room temperature.

[0059] Step 5: Wash the product from Step 4 with ethanol and water (10,000 rpm, centrifuge for 10 min), wash five times, and collect the supernatant each time; concentrate the collected supernatant (60 g / L). o The sample was dialyzed for 1 day at 24 h in deionized water (dialysis bag molecular weight cutoff: 3500 kDa), and the dialyzed product was concentrated again to 5 mL. Finally, the concentrated MNPs sample was stored at 4 °C. o C's refrigerator.

[0060] Example 2

[0061] Preparation of MNPs doped with different elements

[0062] Step 1: Dissolve ferric chloride in ethylene glycol solution and stir magnetically to form a uniform yellow transparent solution; add 1 millimole of ferric chloride to every 10 mL of ethylene glycol solution.

[0063] Step 2: Add reagents containing different elements (cobalt chloride, nickel chloride, manganese chloride, and reduced glutathione) to ethylene glycol solution containing ferric chloride, and stir magnetically to form a uniform and transparent solution; add 0.2 mmol of reagents containing different elements to every 10 mL of ethylene glycol solution.

[0064] Step 3: Dissolve sodium acetate in the ethylene glycol solution obtained in step 2 and stir magnetically to form a uniform, transparent, brownish-red solution; add 7 millimoles of sodium acetate to every 10 mL of ethylene glycol solution.

[0065] Step 4: Dissolve sodium citrate in the ethylene glycol solution obtained in step 3 and stir magnetically to form a homogeneous solution; add 2 millimoles of sodium citrate to every 10 mL of ethylene glycol solution.

[0066] Step 5: Transfer the mixed solution from Step 4 to a high-pressure reactor with a polytetrafluoroethylene liner, place it in an oil bath, and react at 180 °C for 12 h using a solvothermal method. Cool the product after reaction to room temperature.

[0067] Step Six: Wash the product from Step Five with ethanol and water (10,000 rpm, centrifuge for 10 min), wash five times, and collect the supernatant each time; concentrate the collected supernatant (60 g / L). o The product was dialyzed in deionized water for 1 day (24 h at 4°C) (molecular weight cutoff of the dialysis bag: 3500 kDa), and the dialyzed product was concentrated again to 5 mL. Finally, the MNPs doped with different elements were stored at 4°C. o C's refrigerator.

[0068] The performance of the products prepared in Example 1 and Example 2 is tested below:

[0069] Reference Figure 2 , Figure 2 This is a white light photograph showing the dispersion of MNPs doped with different elements in water, prepared by the solvothermal method and purification described above. Observation shows that the MNPs prepared by this method exhibit strong hydrophilicity.

[0070] Reference Figure 3 Different MNPs (all with an iron concentration of 100 μL) were placed in enzyme-labeled strips and imaged using an MPI scanner, such as... Figure 3 As shown in the figure, MPI imaging signals reveal that highly sensitive MNPs can be obtained by doping with manganese during the preparation process. This result demonstrates that manganese doping can improve the sensitivity of MPI.

[0071] Reference Figure 4 , Figure 4 yes Figure 3 The MPI signal value after imaging, through Figure 3 The results more intuitively demonstrate that a manganese chloride feed ratio of 0.2 mmol / L can produce MNPs (Mn) with high MPI performance. 0.4 Fe 2.6 O4).

[0072] Reference Figure 5 , Figure 5 These are MNPs prepared by doping with different elements in Examples 1 and 2, namely Co. 0.4 Fe 2.6 O4, Mn0.4 Fe 2.6 O4, FeS, Fe3O4, Ni 0.4 Fe 2.6 Saturation magnetization curve of O4. Figure 5 This demonstrates that, under the same testing conditions, manganese doping can achieve a higher saturation magnetization (Mn). 0.4 Fe 2.6 O4).

[0073] Reference Figure 6-10 , Figure 6-10 They are Co 0.4 Fe 2.6 O4, Mn 0.4 Fe 2.6 O4, Fe3O4, FeS, Ni 0.4 Fe 2.6 The spectral signal spectrum of O4. The spectral signal of the material was measured using a magnetic particle spectrometer, such as... Figure 7 As shown, the 9th harmonic number appeared after manganese doping, proving that manganese doping can not only improve the MPI signal of MNPs, but also improve the resolution of magnetic particles.

[0074] The above data demonstrates that manganese doping can effectively improve the MPI imaging performance of MNPs. The next step is to explore the optimal manganese doping ratio by varying its concentration.

[0075] Example 3

[0076] The difference between this embodiment and Embodiment 2 is that the feed ratio of manganese element is changed (0.2-1 millimole) to prepare Mn. x Fe 3-x O4 (where x is the amount of manganese added). The specific feed ratios are: ferric chloride is fixed at 1 mmol, and different proportions of manganese chloride are added (0.2, 0.4, 0.5, 0.6, 0.8, and 1 mmol). The product prepared by the solvothermal method, and the white light photographs of the MNPs dispersed in water collected by centrifugation, dialysis, and concentration are shown below. Figure 11 As shown in the figure, the prepared MNPs exhibit good dispersibility in water.

[0077] Reference Figure 12 , Figure 12 These are MNPs (Mn) prepared with different proportions of manganese element doped with Mn. x Fe 3-x The hydrated particle size distribution of O4 is shown in the figure. As the proportion of manganese doping increases, the prepared Mn... x Fe 3-x The hydrated particle size of O4 gradually increases. This indicates that the doping of manganese gradually increases the number of magnetic particle nuclei.

[0078] Reference Figure 13 , Figure 13 Mn is prepared by using different feeding ratios of manganese element (0.2-1 mmol). x Fe 3-x Statistical analysis of the hydrated particle size, potential, and PDI of O4. Data shows that the hydrated particle size gradually increases with increasing manganese content. Simultaneously, the prepared MNPs exhibit negative potential and good dispersibility.

[0079] Reference Figure 14-15 , Figure 14 Mn prepared by doping 100 μL of different proportions of manganese x Fe 3-x MPI images of O4. Quantitative analysis of the imaging signals, such as... Figure 15 As shown, doping with 0.2 mmol of manganese chloride can significantly improve MPI imaging performance.

[0080] Reference Figure 16-21 Through the test of saturation magnetization curve ( Figure 16 ) and signal detection ( Figure 17-21 To verify the imaging performance of MNPs. Figure 17 The results show that as the doping concentration of manganese gradually increases, the saturation magnetization of the magnetic particles gradually decreases, and the harmonic order also gradually decreases. These data demonstrate that doping with 0.2 millimoles of manganese chloride can significantly improve saturation magnetization and imaging resolution.

[0081] Reference Figure 22-23 , Figure 22 Mn prepared for optimal manganese element doping 0.4 Fe 2.6 Transmission electron microscopy (TEM) images of O4 revealed that the prepared MNPs consisted of monodisperse, spherical nanoparticles. Statistical analysis of their size showed that the average size of the prepared magnetic nanoparticles was 6.29 ± 0.19 nm.

[0082] The data above demonstrates that the magnetic nanoparticles prepared by this invention possess small size and high MPI imaging performance. Furthermore, they exhibit a higher imaging signal than the commercially available Vivotrax. Therefore, this invention provides a simple and green method for preparing magnetic nanoparticles with high MPI performance.

[0083] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. The application of a magnetic nanoprobe with small size and high magnetic particle imaging performance in the preparation of diagnostic products for small lesions, characterized in that: The method for preparing the magnetic nanoprobe includes the following steps: Step 1: Dissolve ferric chloride in ethylene glycol solution and stir magnetically to form a uniform yellow transparent solution; add 1 millimole of ferric chloride to every 10 mL of ethylene glycol solution; Step 2: Add manganese chloride to the ethylene glycol solution containing ferric chloride and stir magnetically to form a uniform and transparent solution; add 0.2 mmol of manganese chloride to every 10 mL of ethylene glycol solution; Step 3: Dissolve sodium acetate in the ethylene glycol solution obtained in step 2, and stir magnetically to form a uniform, transparent, brownish-red solution; add 7 mmol of sodium acetate to every 10 mL of ethylene glycol solution. Step 4: Dissolve sodium citrate in the ethylene glycol solution obtained in step 3, and stir magnetically to form a homogeneous solution; add 2 mmol of sodium citrate to every 10 mL of ethylene glycol solution; Step 5: Transfer the mixed solution from Step 4 to a high-pressure reactor with a polytetrafluoroethylene liner, place it in an oil bath, and react at 180 °C for 12 h using a solvothermal method. Cool the product after reaction to room temperature. Step Six: Wash the product from Step Five with ethanol and water five times, centrifuge at 10,000 rpm for 10 min each time, and collect the supernatant after each wash; refrigerate the collected supernatant at 60°C. o The product was concentrated at C for 24 h, then dialyzed in deionized water for 1 day. The molecular weight cutoff of the dialysis bag was 3500 kDa. The dialyzed product was then concentrated again to 5 mL. Finally, the Mn-doped MNPs were stored at 4 °C. o C's refrigerator.

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