Preparation method and application of magnetic resonance imaging nanoprobe capable of penetrating pancreatic cancer tumor interstitial substance

Abstract

The invention discloses a preparation method and application of a magnetic resonance imaging nanoprobe capable of penetrating pancreatic cancer tumor interstitial substance, and belongs to the technical field of self-driven magnetic resonance imaging nanoprobes. The magnetic resonance imaging nanoprobe Ag / Ag2S-GP capable of penetrating pancreatic cancer tumor interstitial substance can be subjected to oxidation-reduction reaction with H2O2 in a tumor microenvironment to continuously generate oxygen airflow, and the reverse thrust of the airflow autonomously drives the probe to move towards the deep part of the tumor interstitial substance; in addition, the Plectin-1 targeting peptide with the Ag / Ag2S-GP surface modified can also be specifically combined with Plectin-1 protein highly expressed by pancreatic cancer cells, and accurate spatial positioning and monitoring of pancreatic cancer are achieved under the guidance of MRI (Magnetic Resonance Imaging). Meanwhile, Ag / Ag2S-GP reduces Schottky barriers under the piezoelectric catalysis action of ultrasonic excitation, hydroxyl radicals are generated, tumor cell apoptosis is induced, and therefore the pancreatic cancer diagnosis and treatment effect is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of self-driven magnetic resonance imaging nanoprobes, and particularly to a preparation method and application of a magnetic resonance imaging nanoprobe capable of penetrating pancreatic cancer tumor stroma. Background Art

[0002] Pancreatic cancer is a digestive system malignant tumor with extremely poor prognosis, and the 5-year survival rate is only 13%, which is the third leading cause of cancer-related deaths globally. Due to its insidious onset and non-obvious early symptoms, approximately 80% of patients are diagnosed at an advanced stage and lose the opportunity for surgery. Currently, chemotherapy is still the main treatment method. Despite the continuous emergence of new anti-tumor drugs, the prognosis of pancreatic cancer patients has not been significantly improved, which is mainly attributed to the drug delivery barrier caused by the dense tumor stroma.

[0003] During the evolution of pancreatic cancer, tumor-associated fibroblasts and pancreatic stellate cells secrete a large amount of extracellular matrix components such as collagen, fibronectin, and hyaluronic acid through complex interactions, forming a highly dense fibrous connective tissue microenvironment. This unique structure not only increases the tumor stromal pressure but also hinders the effective penetration and distribution of drugs into the tumor parenchyma through the physical barrier effect, reducing the treatment effect. Therefore, developing a new drug delivery system that can overcome the physical barrier and enhance drug permeability has become a key research direction for improving the treatment effect and prognosis of pancreatic cancer.

[0004] The "self-propulsion" technology represented by nanomotors can convert external environmental energy into its own mechanical kinetic energy, and is expected to penetrate the dense stromal barrier of tumors to achieve more efficient drug delivery and imaging diagnosis and other functions. The Ag / Ag2S Schottky junction is an asymmetric heterostructure formed by the interfacial contact of metal Ag and semiconductor Ag2S. Its unique interfacial electron characteristics and energy band structure can catalyze the redox reaction of H2O2 to continuously generate oxygen (O2). As the reaction proceeds, O2 molecules gradually accumulate on the surface of Ag / Ag2S and form microbubbles. The periodic formation, growth, and detachment of microbubbles generate microscale thrust to drive the directional movement of Ag / Ag2S. This property of Ag / Ag2S provides a new exploration direction for breaking through the tumor stromal barrier and is expected to improve the tumor treatment effect by promoting the directional transport of drugs.

[0005] In addition, Ag / Ag2S has important application value in the field of piezocatalysis. Ag2S is a sulfide semiconductor, and its unique crystal structure can undergo changes in the relative positions of atoms under the action of ultrasonic vibration, leading to crystal deformation. Based on the piezoelectric effect, this crystal deformation can generate a piezoelectric potential, driving electrons to migrate directionally inside the material and forming a local electric field. With its excellent electrical conductivity, metallic Ag can serve as an efficient electron transport channel, accelerating the migration of electrons during the piezocatalysis process and enabling them to participate more efficiently in subsequent chemical reactions. The Schottky barrier can precisely regulate the direction of electron transfer, further enhancing the piezocatalytic efficiency. As described above, under ultrasonic-excited piezocatalysis, the Ag / Ag2S Schottky junction can efficiently generate cytotoxic hydroxyl radicals, providing a new strategy for the precise treatment of pancreatic cancer. Summary of the Invention

[0006] The object of the present invention is to provide a preparation method and application of a magnetic resonance imaging nanoprobe that can penetrate the pancreatic cancer tumor stroma to solve the problem of difficult drug delivery for pancreatic cancer.

[0007] To achieve the above object, the present invention provides a preparation method of a magnetic resonance imaging nanoprobe that can penetrate the pancreatic cancer tumor stroma, including the following steps: S1. Prepare an Ag / Ag2S solution using silver acetylacetonate and thioacetamide as raw materials; S2. Dissolve SH-PEG-NHS and Gd-DOTA in deionized water and stir for 6 hours under an ice bath to obtain a Gd-DOTA-PEG-SH solution; S3. Mix the pancreatic cancer targeting peptide KTLLPTP and SH-PEG-NHS and stir for 6 hours under an ice bath to obtain a PTP-(CO-NH)-PEG-SH solution; S4. Mix the Ag / A g2 S solution, the Gd-DOTA-PEG-SH solution, and the PTP-(CO-NH)-PEG-SH solution, stir under an ice bath, and wash with pure water to obtain the final product, the magnetic resonance imaging nanoprobe Ag / Ag2S-Gd-PTP.

[0008] Preferably, in S1, the preparation of the Ag / Ag2S solution includes: S11. Dissolve silver acetylacetonate and trisodium citrate in ethylene glycol, add polyethyleneimine, and stir and react for 2 hours to obtain solution A; S12. Sequentially add 0.05 M thioacetamide and 0.5 mL triethanolamine to solution A under stirring to obtain a mixture; the mixture is reacted at 200 °C for 1 hour using the solvothermal method to obtain the Ag / Ag2S solution.

[0009] Preferably, in S11, the volume-mass ratio of silver acetylacetonate: trisodium citrate: ethylene glycol: polyethyleneimine is 0.186 mg: 0.882 mg: 15 mL: 150 mg.

[0010] Preferably, in S12, the volume ratio of thioacetamide: triethanolamine: solution A is 1.5 mL: 0.5 mL: 15 mL.

[0011] Preferably, in S2, the mass-volume ratio of SH-PEG-NHS: Gd-DOTA: deionized water is 3 mg: 0.5 mg: 4 mL.

[0012] Preferably, in S3, the mass ratio of KTLLPTP: SH-PEG-NHS is 20 μg: 1 mg.

[0013] Preferably, in S4, the volume ratio of Ag / Ag2S solution: Gd-DOTA-PEG-SH solution: PTP-(CO-NH)-PEG-SH solution is 17 mL: 4 mL: 4 mL.

[0014] On the other hand, the present invention provides a magnetic resonance imaging nanoprobe Ag / Ag2S-Gd-PTP that can penetrate the pancreatic cancer tumor stroma prepared by the above preparation method.

[0015] On the other hand, the present invention provides an application of the above nanoprobe Ag / Ag2S-Gd-PTP in the preparation of drugs for active targeting, stroma penetration, piezoelectric catalysis and magnetic resonance imaging of pancreatic cancer.

[0016] Therefore, the preparation method and application of a magnetic resonance imaging nanoprobe that can penetrate the pancreatic cancer tumor stroma of the present invention have the following beneficial effects: (1) Ag / Ag2S-GP undergoes a redox reaction with high-concentration H2O2 in the tumor microenvironment to continuously generate O2, and uses the reverse thrust of the airflow to drive it to penetrate the tumor stroma; (2) Ag / Ag2S-GP specifically binds to the highly expressed Plectin-1 protein on pancreatic cancer cells through the surface-modified Plectin-1 targeting peptide, improving the targeting of the diagnostic and therapeutic probe; (3) Based on the T1-weighted relaxation performance of Gd-DOTA, the distribution and movement trajectory of Ag / Ag2S-GP in vivo are visualized in real time under MRI guidance, providing spatial positioning for subsequent piezoelectric catalysis excited by ultrasound; (4) Under the action of piezoelectric catalysis excited by ultrasound, Ag / Ag2S-GP oxidizes water to hydroxyl radicals, and uses these strongly oxidizing radicals to induce apoptosis of tumor cells; (5) The synthesis method of the magnetic resonance imaging nanoprobe capable of penetrating the pancreatic cancer tumor stroma in the present invention is simple and highly operable; the synthesized product is stable and has repeatability; (6) The magnetic resonance imaging nanoprobe capable of penetrating the pancreatic cancer tumor stroma synthesized in the present invention has good biocompatibility; (7) The magnetic resonance imaging nanoprobe capable of penetrating the pancreatic cancer tumor stroma synthesized in the present invention is conducive to clinical disease diagnosis and treatment.

[0017] The technical solution of the present invention will be further described in detail below through the accompanying drawings and embodiments. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 is the transmission electron microscope image of Ag / Ag2S-GP; Figure 2 is the high-resolution transmission electron microscope lattice analysis image of Ag / Ag2S-GP; Figure 3 is the X-ray diffraction pattern of Ag / Ag2S-GP; Figure 4 is the mapping spectrum of Ag / Ag2S-GP; Figure 5 is the hydrated particle size diagram of Ag / Ag2S-GP; Figure 6 is the Zeta potential diagram of Ag / Ag2S, Ag / Ag2S-G, and Ag / Ag2S-GP; Figure 7 is the statistical chart of the hydrated particle size of Ag / Ag2S-GP within 5 days; Figure 8 is the binding energy analysis of Ag / Ag2S, where A is the XPS spectrum of the Ag 3d signal of Ag and Ag / Ag2S, and B is the XPS spectrum of the S 2p signal of Ag2S and Ag / Ag2S; Figure 9 is the Nyquist diagram of Ag, Ag / Ag2S, and Ag2S; Figure 10 is the oxygen production capacity analysis of Ag / Ag2S-GP, where A is the dissolved oxygen content generation curve of Ag / Ag2S-GP treated with H2O2 for different times, and B is the picture of the dissolved oxygen generation process; Figure 11 Analysis of the "self-propelled" penetration ability of Ag / Ag2S-GP. Among them, part A is the Z-stack tomographic fluorescence photograph of Ag / Ag2S-GP with or without H2O2 co-incubated with micro-tumor spheres for 6 hours, and part B is the distribution of Ag / Ag2S-GP at 150 μm along the white dotted line; Figure 12 The generation of hydroxyl radicals by Ag / Ag2S-GP under ultrasonic stimulation. Among them, part A is the fluorescence image of PANC-1 cells stained with DCFH-DA after different treatments, and part B is the quantification of the fluorescence image in part A; Figure 13 Analysis of the contrast-enhanced magnetic resonance imaging performance of Ag / Ag2S-GP. Among them, part A is the MRI image of Ag / Ag2S-GP, and part B is the T1WI relaxation rate; Figure 14 H&E staining images of tissue sections of important organs (heart, liver, spleen, lung, and kidney) of healthy mice on the 7th day after tail vein injection of Ag / Ag2S-GP. Specific implementation manners

[0020] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and examples.

[0021] In order to make the purpose, technical solutions and advantages of the present application clearer, more thorough and complete, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. The following detailed descriptions are all descriptions of examples, aiming to provide further detailed descriptions of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs.

[0022] The instrument equipment and reagent materials used in the examples are all obtained through commercial channels.

[0023] Example 1 A preparation method of a magnetic resonance imaging nanoprobe capable of penetrating pancreatic cancer tumor stroma includes the following steps: S1. Preparation of Ag / Ag2S nanoprobe.

[0024] Dissolve 0.186 mg of silver acetylacetonate and 0.882 mg of trisodium citrate in 15 mL of ethylene glycol, then add 150 mg of polyethyleneimine and stir well for 2 hours. While stirring, sequentially add 1.5 mL of 0.05 M thioacetamide and 0.5 mL of triethanolamine. Transfer the obtained mixture to a microwave synthesizer and react at 200 °C for 1 hour to obtain an Ag / Ag2S solution. Disperse the product in water and store it at 4 °C for later use.

[0025] S2. Preparation of Gd-DOTA-PEG-SH solution.

[0026] Dissolve 3 mg of SH-PEG-NHS (thiolated polyethylene glycol active ester) and 0.5 mg of magnetic resonance contrast agent Gd-DOTA (gadolinium(III)-1,4,7-tris(tert-butoxycarbonylmethyl)-10-(acetic acid)-1,4,7,10-tetraazacyclododecane) in 4 mL of deionized water, and stir well at 4 °C for 6 hours to obtain Gd-DOTA-PEG-SH solution.

[0027] S3. Preparation of PTP-(CO-NH)-PEG-SH solution.

[0028] Mix 20 μg of targeting peptide PTP (KTLLPTP) and 1 mg of SH-PEG-NHS, and stir well at 4 °C for 6 hours to obtain PTP-(CO-NH)-PEG-SH solution.

[0029] S4. Preparation of Ag / Ag2S-GP.

[0030] Mix 17 mL of Ag / Ag2S, 4 mL of Gd-DOTA-PEG-SH and 4 mL of PTP-(CO-NH)-PEG-SH solution, stir in an ice bath, and wash with pure water to obtain the final product magnetic resonance imaging nanoprobe Ag / Ag2S-Gd-PTP (abbreviated as Ag / Ag2S-GP).

[0031] Test Example 1 (1) After diluting the Ag / Ag2S-GP solution, take 10 μL and drop it onto a 200-mesh copper grid covered with a carbon film, and let it stand and air dry. Subsequently, observe its morphological characteristics by transmission electron microscopy and record the image. The transmission electron microscopy image of Ag / Ag2S-GP is as shown in Figure 1 shown. Analyze the lattice composition of Ag / Ag2S-GP using a high-resolution transmission electron microscope, as shown in Figure 2 shown.

[0032] The transmission electron microscopy image of Ag / Ag2S-GP shows a uniform heterojunction morphology and good dispersion, with an average particle size of about 8 nm. The high-resolution transmission electron microscopy image clearly shows the independent lattice fringes of the two components. Among them, the lattice spacing of 0.24 nm corresponds to the (111) crystal plane of cubic-phase Ag, while the lattice spacing of 0.31 nm corresponds to the (111) crystal plane of monoclinic-phase Ag2S. It is worth noting that the high-resolution transmission electron microscopy image shows an atomically smooth interface and continuous lattice between Ag2S and Ag, confirming the formation of a Schottky junction rather than a simple physical mixture.

[0033] Test Example 2 The Ag / Ag2S-GP was dried and ground into powder. The XRD instrument was calibrated using standard samples to ensure accurate angles and intensities. The instrument was started, and the sample was scanned according to the set parameters to record the diffraction data. The software was used to process the data and identify the diffraction peaks. The phase was determined by comparing with the standard database. The X-ray diffraction pattern of Ag / Ag2S-GP is as Figure 3 shown. The X-ray diffraction pattern further verified the successful synthesis of Ag / Ag2S-GP. The positions and relative intensities of all diffraction peaks were in complete agreement with the standard cards of cubic Ag and monoclinic Ag2S.

[0034] Test Example III Element mapping spectra were collected by field emission electron microscopy to verify the elemental composition of Ag / Ag2S-GP, as Figure 4 shown. The element mapping spectra indicated that the elements Ag, S, Gd, C, N, and O were evenly distributed, confirming the successful construction of Ag / Ag2S-GP.

[0035] Test Example IV The hydrodynamic diameter of Ag / Ag2S-GP is as Figure 5 shown, showing that the hydrodynamic diameter of Ag / Ag2S-GP is approximately 21.9 nm.

[0036] The Zeta potentials of Ag / Ag2S, Ag / Ag2S-G, and Ag / Ag2S-GP are as Figure 6 shown. During the functionalization modification process, the Zeta potential gradually decreased from 19.43 mV (Ag / Ag2S) to 5.24 mV (Ag / Ag2S-G), and then to 2.46 mV (Ag / Ag2S-GP).

[0037] To evaluate the colloidal stability of Ag / Ag2S-GP, the hydrodynamic diameter size was continuously monitored for 5 days. The results are as Figure 7 shown, and the results show that its particle size did not change significantly, indicating that the probe has good colloidal stability.

[0038] Test Example V X-ray photoelectron spectroscopy was used to systematically characterize the electronic states of Ag / Ag2S and compare and analyze them with pure Ag and Ag2S. As Figure 8 shown, where A is the XPS spectrum of the Ag 3d signal of Ag and Ag / Ag2S, and B is the XPS spectrum of the S2p signal of Ag2S and Ag / Ag2S.

[0039] The Ag 3d of pure Ag 5 / 2 and Ag 3d 3 / 2Compared with the binding energies (BE) of the signals (368.2 eV and 374.2 eV), the binding energies (BE) of Ag / Ag2S (367.8 eV and 373.8 eV) showed a negative shift, indicating that the Ag part of Ag / Ag2S has a higher electron density. The S 2p of Ag / Ag2S 3 / 2 and S 2p 1 / 2 The BE of the signals (160.3 eV and 161.5 eV) showed a positive shift compared to Ag2S (160.0 eV and 161.2 eV), indicating a decrease in the electron density of the Ag2S part in Ag / Ag2S. These binding energy changes confirmed the phenomenon of electron transfer from Ag2S to Ag at the Ag / Ag2S interface, resulting in the enrichment of negative charges on the Ag surface.

[0040] Test Example Six Electrochemical impedance tests were carried out on a standard three-electrode electrochemical workstation (CHI 660D) at 25 °C. A platinum (Pt) wire and an Ag / AgCl electrode were used as the counter electrode and reference electrode, respectively. Before measurement, the glassy carbon electrode was carefully polished with 0.05 μM alumina powder, then successively cleaned by ultrasound through Milli-Q water and ethanol, and finally dried at room temperature to prepare for the next experimental operation. Subsequently, catalyst inks (including Ag, Ag2S, and Ag / Ag2S) were drop-coated onto the glassy carbon electrode to prepare the working electrode. In 0.5 M KOH solution, cyclic voltammograms and Nyquist curves of the catalysts (including Ag, Ag2S, and Ag / Ag2S) were recorded at a scanning rate of 20 mV s −1 . During the whole test, ultrasound was used as the excitation source and focused on the working electrode to improve the signal response sensitivity.

[0041] The results are as Figure 9 shown. Electrochemical impedance spectroscopy analysis showed that compared with Ag and Ag2S, Ag / Ag2S has the smallest Nyquist circle radius, indicating the lowest charge transfer resistance and being beneficial to the charge of piezoelectric catalysis.

[0042] Test Example Seven First, the dissolved oxygen meter was calibrated for zero oxygen and saturated oxygen, and then the probe was inserted into zero oxygen water for standby. After mixing Ag / Ag2S-GP with a 10 mM H2O2 solution (simulating the tumor microenvironment conditions), the amount of O2 generated was monitored and recorded in real time by the dissolved oxygen meter. In addition, photos of Ag / Ag2S-GP mixed with a 10 mM H2O2 solution at different times were taken.

[0043] The results are as Figure 10As shown in the figure, where A is the curve of the dissolved oxygen content of Ag / Ag2S-GP treated with H2O2 for different times, and B is the picture of the dissolved oxygen generation process. The results show that after Ag / Ag2S-GP is mixed with 10 mM H2O2 solution, a large number of bubbles are generated and the concentration of dissolved oxygen increases during the reaction process, confirming that Ag / Ag2S-GP can spontaneously catalyze the decomposition of H2O2 to produce O2 molecules.

[0044] Test Example VIII The micro-tumor cell spheres were prepared by the liquid covering method. 0.16 g of agarose was dissolved in 10 mL of DMEM medium, stirred and dissolved under the condition of a 100 °C water bath, and then subjected to high-temperature sterilization treatment. After sterilization, the dissolved agarose was quickly dropped into a 96-well plate and allowed to stand and cool until solidified. After the agarose solidified, pancreatic cancer cells PANC-1, pancreatic stellate cells HSPC and matrix gel suspension were inoculated into the 96-well plate pre-coated with agarose (8000 cells / well). After inoculation, the cells were cultured in a cell incubator until spheres with a diameter of about 300 μm were formed. The Ag / Ag2S-GP or Ag / Ag2S-GP + H2O2 (10 mM) composite solution was co-incubated with the micro-tumor cell spheres in a constant temperature incubator for 6 hours. After the incubation, the cell spheres were slowly washed with PBS and then transferred to a confocal dish. Z-stack tomography of the micro-tumor spheres was performed under a confocal laser microscope, and fluorescence images were taken every 15 μm. The obtained images were quantitatively analyzed by Image J software.

[0045] The results are as Figure 11 shown, where part A is the Z-stack tomography fluorescence photo of Ag / Ag2S-GP with or without H2O2 co-incubated with micro-tumor spheres for 6 hours, and B is the distribution of Ag / Ag2S-GP at 150 μm along the white dotted line.

[0046] The results show that in the depth range of 0 - 150 μm, within the same depth range, the micro-tumor spheres containing H2O2 show stronger fluorescence signals, which confirms that Ag / Ag2S-GP can enhance the tumor stroma penetration ability through "self-propelled" behavior in the tumor microenvironment.

[0047] Test Example IX The generation of free radicals was evaluated using a reactive oxygen species detection kit. Pancreatic cancer cells PANC-1 in the logarithmic growth phase were inoculated into confocal dishes. After the cells adhered to the wall, the intervention treatments were completed according to each experimental group. After the treatment, DCFH-DA probe was used to stain the cells in each group, and the nuclei were labeled with Hoechst staining at the same time. After the staining was completed, images were collected by a fluorescence microscope to observe the generation of hydroxyl radicals by Ag / Ag2S-GP under piezoelectric catalysis. Subsequently, the intensity differences of free radical generation in each experimental group were analyzed quantitatively by images to evaluate the piezoelectric catalytic efficiency of Ag / Ag2S-GP and its potential to induce oxidative stress in tumor cells.

[0048] The results are as Figure 12 shown. Among them, A is the fluorescence image of PANC-1 cells stained with DCFH-DA after different treatments, and B is the quantification of the fluorescence image in A. The results show that compared with other control groups, the level of hydroxyl radicals in the cells of the Ag / Ag2S-GP+US group increased significantly, confirming that Ag / Ag2S-GP can efficiently generate hydroxyl radicals under ultrasonic excitation.

[0049] Test Example Ten Ag / Ag2S-GP solutions with a series of concentration gradients were prepared and loaded into centrifuge tubes in turn. The frequency and pulse sequence for measuring the T1 relaxation time were set on a 9.4T magnetic resonance imaging (MRI) instrument. The system collected and analyzed the relaxation signal data to calculate the longitudinal relaxation rate (r1).

[0050] The results are as Figure 13 shown. Among them, A is the MRI image of Ag / Ag2S-GP, and B is the T1WI relaxation rate. The results show that as the concentration of Gd ions increases, the signal intensity of the MR image of Ag / Ag2S-GP increases significantly, and its longitudinal relaxation rate (r1) value is 3.9614 mM -1 S -1 , indicating that Ag / Ag2S-GP has good MRI enhancement performance.

[0051] Test Example Eleven Healthy mice were injected with Ag / Ag2S-GP (200 μg / mL) via the tail vein. The mice were sacrificed on the 7th day after administration, and the main organs such as the heart, liver, spleen, lung, and kidney were completely removed for H&E staining. The pathological changes of the tissues were observed, and the in vivo biosafety of Ag / Ag2S-GP was systematically evaluated.

[0052] The results are as shown in 14. On the 7th day after the tail vein injection of Ag / Ag2S-GP, the H&E staining of the tissue sections of the important organs of the mice (heart, liver, spleen, lung, and kidney) showed that there were no obvious pathological damages in each organ.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation method of a magnetic resonance imaging nanoprobe capable of penetrating the pancreatic cancer tumor stroma, characterized in that, It includes the following steps: S1. Prepare an Ag / Ag2S solution using silver acetylacetonate and thioacetamide as raw materials; S11. Dissolve silver acetylacetonate and trisodium citrate in ethylene glycol, add polyethyleneimine, and stir and react for 2 hours to obtain solution A; The volume-mass ratio of silver acetylacetonate:trisodium citrate:ethylene glycol:polyethyleneimine is 0.186 mg:0.882 mg:15 mL:150 mg; S12. Sequentially add 0.05 M thioacetamide and 0.5 mL triethanolamine to solution A under stirring to obtain a mixture; the mixture is reacted at 200 °C for 1 hour using the solvothermal method to obtain the Ag / Ag2S solution; The volume ratio of thioacetamide:triethanolamine:solution A is 1.5 mL:0.5 mL:15 mL; S2. Dissolve SH-PEG-NHS and Gd-DOTA in deionized water and stir for 6 hours under an ice bath to obtain the Gd-DOTA-PEG-SH solution; S3. Mix the pancreatic cancer targeting peptide KTLLPTP and SH-PEG-NHS and stir for 6 hours under an ice bath to obtain the PTP-(CO-NH)-PEG-SH solution; S4. Mix the Ag / A g2 S solution, Gd-DOTA-PEG-SH solution and PTP-(CO-NH)-PEG-SH solution, stir in an ice bath, and wash with pure water to obtain the final product, the magnetic resonance imaging nanoprobe Ag / Ag2S-Gd-PTP.

2. The preparation method of a magnetic resonance imaging nanoprobe capable of penetrating pancreatic cancer tumor stroma according to claim 1, characterized in that: In S2, the mass-volume ratio of SH-PEG-NHS:Gd-DOTA:deionized water is 3 mg:0.5 mg:4 mL.

3. The preparation method of a magnetic resonance imaging nanoprobe capable of penetrating pancreatic cancer tumor stroma according to claim 1, characterized in that: In S3, the mass ratio of KTLLPTP:SH-PEG-NHS is 20 μg:1 mg.

4. The preparation method of a magnetic resonance imaging nanoprobe capable of penetrating pancreatic cancer tumor stroma according to claim 1, characterized in that: In S4, the volume ratio of the Ag / Ag2S solution:Gd-DOTA-PEG-SH solution:PTP-(CO-NH)-PEG-SH solution is 17 mL:4 mL:4 mL.

5. A magnetic resonance imaging nanoprobe Ag / Ag2S-Gd-PTP that can penetrate the pancreatic cancer tumor stroma and is prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the nanoprobe Ag / Ag2S-Gd-PTP according to claim 5 in the preparation of drugs for active targeting, stromal penetration, piezoelectric catalysis, and magnetic resonance imaging of pancreatic cancer.

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