CT imaging nano-probe capable of specifically recognizing MMP-2 and preparation method of CT imaging nano-probe
By designing a CT imaging nanoprobe that can specifically recognize MMP-2, the problem of high sensitivity and low invasiveness in the prior art is solved, and accurate CT imaging diagnosis of early IPF is achieved.
Patent Information
- Application Number
- CN202411840142.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-21
AI Technical Summary
The prior art is difficult to achieve high sensitivity and low invasiveness in the early diagnosis of idiopathic pulmonary fibrosis (IPF), especially in patients with early IPF with mild lung injury.
A CT imaging nanoprobe that specifically recognizes MMP-2 was developed, and a nanoprobe that can be visualized in CT imaging was formed by combining HAuCl4, NaBH4, α-lipoic acid and specific designed peptide chains during the preparation process.
High sensitivity and low invasive CT imaging diagnosis for early IPF are achieved, which can significantly enhance the signal strength of CT images in the MMP-2-enriched microenvironment, supporting the accurate diagnosis of early IPF.
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Figure CN119661642A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a CT imaging nano probe capable of specifically identifying MMP-2 and a preparation method thereof, and belongs to the technical field of medical diagnostic reagents. Background Art
[0002] Pulmonary fibrosis is a terminal change of a large class of lung diseases characterized by fibroblast proliferation and accumulation of a large amount of extracellular matrix accompanied by inflammatory damage and tissue structure destruction. That is, the normal alveolar tissue is damaged and then repaired abnormally, resulting in structural abnormalities (scar formation). The cause of most pulmonary fibrosis patients is unknown (idiopathic). This group of diseases is called idiopathic interstitial pneumonia (Idiopathic Interstitial Pneumonia), which is a large category of interstitial pneumonia. Among idiopathic interstitial pneumonia (IIP), the most common type of disease with pulmonary fibrosis as the main manifestation is idiopathic pulmonary fibrosis (IPF), which is a serious interstitial lung disease that can lead to progressive loss of lung function. Pulmonary fibrosis seriously affects the respiratory function of the human body, manifested as dry cough, progressive dyspnea (feeling that there is not enough air), and as the disease and lung damage worsen, the patient's respiratory function continues to deteriorate. The incidence and mortality of idiopathic pulmonary fibrosis increase year by year. The average survival period after diagnosis is only 2.8 years, and the mortality rate is higher than that of most tumors. It is called a "tumor-like disease."
[0003] At present, the commonly used IPF treatment drugs are pirfenidone and nintedanib, but their effectiveness is limited to delaying the disease progression in mild and moderate patients. For advanced patients, there is currently no effective treatment other than lung transplantation to reverse their fibrotic lungs and repair lung function. However, only IPF patients at risk of death within 2 years can enter the lung transplantation evaluation. According to statistics, the misdiagnosis or missed diagnosis rate of the disease is 30%-50%, and the average diagnostic lag time is 1.5 years. Usually, when patients have significant pulmonary fibrosis lesions and clinical symptoms, the course of the disease has developed to the middle and late stages. Therefore, delayed diagnosis is the main reason for the high mortality rate of IPF. At present, the main means of diagnosing IPF is high-resolution computed tomography (HRCT), which has the advantages of non-invasiveness, lesion visualization, and wide clinical popularity. However, when the HRCT images show typical IPF features such as honeycomb, reticular, and traction bronchiectasis, the patient is often in the middle and late stages of the disease, resulting in a low detection rate of this technology for early IPF patients with mild lung damage. Lung tissue biopsy is considered to be the most accurate method for diagnosing IPF, but it can cause great pain and injury to patients, and due to the limitations of local sampling, it is also a challenge to accurately assess the damage to the entire lung tissue. Therefore, the development of a non-invasive early pulmonary fibrosis diagnosis technology has important scientific significance and clinical therapeutic value for achieving breakthroughs in IPF early diagnosis technology and further clinical transformation.
[0004] Molecular imaging technology, which combines highly sensitive and high-resolution imaging equipment with highly specific and high-affinity imaging probes, can achieve early diagnosis of the disease and personalized molecular treatment at the molecular level by specifically binding the imaging probe to the target and generating imaging signals. Some existing nanoprobes mainly target the signaling pathways (collagen deposition, fibroblast activation) in the middle and late stages of IPF, thus limiting their role in the early diagnosis of IPF. If nanoprobes can specifically identify early diagnostic markers of IPF, it is expected to achieve high-sensitivity and low-invasive diagnosis of early IPF. At present, there are no relevant prior art reports.
[0005] Matrix metalloproteinase 2 (MMP2) is a zinc-dependent endopeptidase that can degrade a variety of extracellular matrix (ECM) proteins. It mostly exists in an inactive or low-activity form, and pulmonary fibrosis leads to a significant increase in its activity. Studies have shown that the imbalance of MMP-2 expression begins in the early stages of IPF, and it can be used as a potential diagnostic indicator for the early onset of IPF. However, the relative integrity of the patient's lung structure at this stage makes it impossible to make an effective diagnosis with CT images. Summary of the invention
[0006] The purpose of the present invention is to solve the above-mentioned deficiencies of the prior art and provide a CT imaging nanoprobe that can specifically identify MMP-2 and a preparation method thereof. The CT imaging nanoprobe can achieve high-sensitivity and low-invasive CT imaging diagnosis of early IPF.
[0007] To achieve the above object, the present invention adopts the following technical solution:
[0008] A method for preparing a CT imaging nanoprobe capable of specifically recognizing MMP-2 comprises the following steps:
[0009] (1) adding NaBH4 aqueous solution dropwise to HAuCl4 solution, stirring for reaction and centrifuging to obtain AuNPs aqueous solution;
[0010] (2) adding a methanol solution of α-lipoic acid (LA) to the AuNPs aqueous solution, stirring the reaction, centrifuging, and washing to obtain LA@Au;
[0011] (3) LA@Au was dispersed in deionized water, and then the peptide chain 1 solution was added and stirred at room temperature to obtain peptide chain 1@Au;
[0012] (4) Peptide chain 1@Au was dissolved in deionized water, and then the peptide chain 2 solution was added dropwise. After stirring for reaction, CT imaging nanoprobes (MSNPs) were obtained.
[0013] In step (3), the amino acid sequence of peptide chain 1 is: (C) m PLGLAG(E) n K,
[0014] Wherein, m is an integer of 1-10, n is an integer of 1-30, cysteine (C) can be replaced by cystine, and / or glutamic acid (E) can be replaced by aspartic acid (D).
[0015] The structure of peptide chain 1 is shown in formula (1):
[0016]
[0017] In step (4), the amino acid sequence of peptide chain 2 is: (C) h (R) i K,
[0018] Wherein, h is an integer of 1-10, i is an integer of 1-30, and arginine (R) can be replaced by lysine (L) or histidine (H).
[0019] The structure of peptide chain 2 is shown in formula (2):
[0020]
[0021] Furthermore, in step (1), the molar ratio of HAuCl4 to NaBH4 is 1:(10-50).
[0022] Furthermore, in step (1), the centrifugation is performed using an ultrafiltration tube with a molecular weight cutoff of 10,000 Da, the centrifugation speed is 6,000-7,000 rpm, and the time is 10-15 min.
[0023] Furthermore, in step (2), the mass ratio of AuNPs to α-lipoic acid is 50:1.
[0024] Furthermore, in step (3), the mass ratio of the AuNPs to the peptide chain 2 is (1-10):1.
[0025] Furthermore, in step (4), the mass ratio of peptide chain 2 to peptide chain 1 is (1-10):(10-1).
[0026] In order to reduce the electrostatic interaction between peptide chain 1 and peptide chain 2, it is preferred to pre-adjust the pH value of peptide chain 2 to 9-11 with 2M NaOH, and then slowly add the peptide chain 2 solution dropwise into the peptide chain 1@Au solution at room temperature.
[0027] Application of the CT imaging nanoprobe prepared by the above method in the preparation of diagnostic reagents for idiopathic pulmonary fibrosis.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] 1) The conventional MMP2 cleavable and activatable polypeptide sequence is a whole peptide chain, including an MMP2 recognition region, a cationic fragment, and an anionic fragment, which has the disadvantages of being difficult to prepare, high cost, and difficult to flexibly adjust the surface potential of the constructed nanoparticles. The MMP2 recognition peptide chains provided by the present invention are two functional polypeptides, peptide chain 1 is a cationic polypeptide containing polybasic amino acids, and peptide chain 2 is an anionic polypeptide containing both acidic amino acids and an MMP2 cleavable fragment. Both peptide chains are designed with cysteine or cystine sequences that can be connected to AuNPs. This achieves the advantages of shortened peptide chain length and adjustable potential of functionalized gold nanoparticles.
[0030] 2) The present invention provides a method for preparing a CT imaging nanoprobe that can specifically recognize MMP-2. The method has a simple preparation process and can be prepared in large quantities. The prepared nanoparticles have excellent biocompatibility and low toxicity; and can be used for co-incubation of biological samples, cells and tissues in vivo and in vitro.
[0031] 3) The nano-CT imaging diagnostic probe prepared by the present invention can specifically recognize MMP2, which can achieve non-invasive, rapid and accurate positioning of early fibrotic diseases. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 The results of HPLC-MS analysis of peptide chain 2 prepared in Example 1;
[0033] Figure 2 The results of HPLC-MS analysis of peptide chain 1 prepared in Example 1;
[0034] Figure 3 This is the particle size distribution diagram of the CT imaging nanoprobe prepared in Example 1;
[0035] Figure 4 TEM image of the CT imaging nanoprobe prepared in Example 1;
[0036] Figure 5 The UV-visible spectrum of the CT imaging nanoprobe prepared in Example 1;
[0037] Figure 6 The fluorescence emission spectrum of the CT imaging nanoprobe prepared in Example 1;
[0038] Figure 7 The fluorescence emission spectra of the CT imaging nanoprobe prepared in Example 1 at different time points after being treated with MMP2;
[0039] Figure 8 The zeta potential of the CT imaging nanoprobe prepared in Example 1 at different time points after being treated with MMP-2;
[0040] Fig. 9 Laser confocal scanning microscopy images of A549 cells after incubation with MSNPs for 4 h and 12 h in the absence and presence of MMP2;
[0041] Fig.10 The intracellular gold content of A549 cells after co-incubation with different nanoparticles and treatment with MMP2;
[0042] Fig.11 H&E and Masson staining images of lung tissues of healthy mice and BLM at 5, 10, and 21 days after injection;
[0043] Fig.12 Lung CT images and signal intensity statistics of healthy mice before and after MSNPs injection;
[0044] Fig.13 Lung CT images and signal intensity statistics of IPF model mice before and after MSNPs injection 5 days after BLM injection;
[0045] Fig.14 Lung CT images and signal intensity statistics of IPF model mice before and after MSNPs injection 10 days after BLM injection;
[0046] Fig.15 Lung CT images and signal intensity statistics of IPF model mice before and after MSNPs injection 21 days after BLM injection. DETAILED DESCRIPTION
[0047] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings and specific embodiments.
[0048] Example 1
[0049] The amino acid sequence of peptide chain 2 (polycationic polypeptide) is: CCRRRRRRK (FITC), in which cysteine serves as the connection site with gold nanoparticles; polyarginine serves as a basic amino acid to provide positive charge, and the terminal is modified with the fluorescent molecule fluorescein isothiocyanate (FITC) through lysine.
[0050] Peptide chain 2 was prepared by solid phase synthesis, and its structural formula is shown in formula (3):
[0051] Peptide1:CCRRRRRRK(FITC)
[0052]
[0053] Figure 1 is the HPLC-MS / MS analysis result of peptide chain 2 in Example 1 (SHIMADZU LCMS-2020), 560.45 and 840.25 are the [M+3H] 3+ and [M+2H] 2+ The molecular ion peak of , proved the successful synthesis of peptide chain 2.
[0054] The amino acid sequence of peptide chain 1 (polyanionic polypeptide) is: CCPLGLAGEEEEEEEEK (TMR), in which cysteine is used as the connection site with gold nanoparticles; polyglutamic acid is used as an acidic amino acid to provide negative charge, and the terminal is modified with a fluorescent molecule 5-carboxytetramethylrhodamine (TMR) through lysine. The fluorescence spectra of FITC and TMR overlap to form a fluorescent molecular pair that can realize surface fluorescence resonance energy transfer (FRET), which is convenient for detecting the peptide chain cleavage process.
[0055] Peptide chain 1 was prepared by solid phase synthesis, and its structural formula is shown in formula (4):
[0056] Peptide 2: CCPLGLAGEEEEEEEEK(TMR)
[0057]
[0058] Figure 2is the HPLC-MS / MS analysis result of peptide chain 1 in Example 1 (SHIMADZU LCMS-2020), 769.7 and 1154.0 are the [M+3H] 3+ and [M+2H] 2+ The molecular ion peak of , proved the successful synthesis of peptide chain 1.
[0059] A method for preparing a CT imaging nanoprobe capable of specifically recognizing MMP-2 comprises the following steps:
[0060] (1) 2 mL of 1% HAuCl4 aqueous solution was dispersed in 190 mL of deionized water, and then 8 mL of 0.1 mol / L NaBH4 aqueous solution was gradually added using a dropping funnel. The mixture was stirred for 5 h at room temperature. The deionized water was filtered out using an ultrafiltration tube with a molecular weight cutoff of 10,000 MW and centrifuged at 6500 rpm for 10 min to concentrate the nanoparticles to obtain an AuNPs solution, and the concentration was determined by ICP-MS.
[0061] (2) 20 mL of 0.5 mg / mL AuNPs solution was mixed with 100 μL of 10 mmol / L α-lipoic acid (LA) methanol solution and stirred at room temperature for 1 h. The mixture was centrifuged at 6500 rpm for 10 min using a 10,000 MW ultrafiltration tube and washed three times with deionized water to remove unbound LA to obtain LA-modified gold nanoparticles (denoted as LA@Au).
[0062] (3) 5 mg LA@Au was dispersed in 20 mL deionized water, and then 0.625 mg peptide chain 1 (prepared into a 5 mg / mL solution using DMSO as solvent) was slowly added, stirred at room temperature for 6 h, and centrifuged at 6500 rpm for 10 min using an ultrafiltration tube with a molecular weight cutoff of 10,000 MW. The mixture was washed three times with deionized water to remove unbound peptide chain 1 to obtain peptide chain 1@Au (denoted as pep1@Au).
[0063] (4) The pep1@Au prepared in step (3) was dissolved in 20 mL of deionized water, and then 0.625 mg of peptide chain 2 was added dropwise (peptide chain 2 was prepared into an aqueous solution of 1 mg / mL, and the pH value was adjusted to 9-11 with 2 M NaOH). After stirring at room temperature for 6 h, the mixture was centrifuged at 6500 rpm for 10 min using an ultrafiltration tube with a molecular weight cutoff of 10,000 MW, and washed three times with deionized water to obtain CT imaging nanoprobes (MSNPs) that can specifically recognize MMP-2.
[0064] The zeta potential and hydrodynamic diameter of the nanoparticles were measured using a particle size analyzer (ZEN3600-nanoZS, Malvern). In order to observe the morphology, the nanoprobe solution was deposited on a carbon support film (Beijing Keyi Technology Co., Ltd.) to prepare a transmission electron microscope (TEM) sample. After staining with 1% uranyl acetate for 2 min, a Hitachi HT7700 TEM instrument with an accelerating voltage of 100 kV was used to obtain TEM images of the nanoparticles. The UV-visible absorption spectrum was recorded by a UV-2500 spectrophotometer (Shimadzu), and the fluorescence spectrum was recorded by a fluorescence spectrometer (Hitachi, F-4600).
[0065] Figure 3 This is the particle size distribution diagram of the CT imaging nanoprobe prepared in Example 1. It can be seen that the prepared nanoprobes (MSNPs) have good size uniformity.
[0066] Figure 4 This is the TEM image of the CT imaging nanoprobe prepared in Example 1. It can be seen that the MSNPs are relatively uniform spherical, and the gold core is surrounded by a clear protein layer.
[0067] Figure 5 This is the UV-visible spectrum of the CT imaging nanoprobe prepared in Example 1. It can be seen that the position and shape of the characteristic absorbance peak have changed significantly before and after peptide modification.
[0068] Figure 6 The fluorescence emission spectrum of the CT imaging nanoprobe prepared in Example 1 shows that when excited at a wavelength of 480 nm, the maximum emission wavelength of MSNPs is 580 nm, which indicates that the co-modification of the Au NP surface with FITC and TMR peptides produces a FRET effect, further confirming the successful construction of MSNPs.
[0069] 1. Testing the response performance of the MSNPs obtained in Example 1 to MMP2 under solution conditions, including changes in surface charge and FRET effect, the operation method includes:
[0070] MMP-2 (MMP-2 human, Sigma-Aldrich) was added to a 5% 4% 4% 2 ... -3 The buffer solution of mM ZnCl2 was diluted to 100 ng / mL and the pH value was adjusted to 7.4. 0.4 mL of the above solution was incubated with 20 μL of MSNPs (5 mg / mL) at 37 °C in a shaker. Samples were taken at 3, 6, 12 and 24 h of incubation to measure the fluorescence spectrum and zeta potential changes.
[0071] Figure 7The fluorescence emission spectra of the CT imaging nanoprobe prepared in Example 1 at different time points after being treated with MMP2 show that under 480nm excitation, the initial maximum emission wavelength of MSNPs appears at 580nm, and the fluorescence intensity at 518nm is relatively low (0h). As the incubation time in MMP-2 increases, the fluorescence intensity at 518nm gradually increases, while the fluorescence intensity at 582nm gradually decreases. This change indicates that as peptide chain 1 is cleaved, the increase in the donor-acceptor distance causes the FRET efficiency to gradually decrease.
[0072] Figure 8 The Zeta potential of the CT imaging nanoprobe prepared in Example 1 at different time points after being treated with MMP-2 shows that with the extension of the incubation time in MMP-2, the charge of the MSNPs system gradually moves toward the positive value, indicating that the negatively charged peptide chain 1 gradually breaks down and detaches, exposing the positive charge of the peptide chain 2 modified on the surface of the gold nanoparticles.
[0073] 2. Use MSNPs to label cells, and determine the labeling ability of cells under different conditions through exogenous MMP-2 induction. The operation method includes:
[0074] According to 1×10 5 A549 cells were seeded into 12-well plates at a cell density of 100 cells / well. After the cells adhered to the wall, DMEM / F-12 culture medium (containing 10% fetal bovine serum and 1% penicillin-streptomycin, purchased from Gibco) was added. TM ) was replaced with 100 ng / mL MMP-2 and 100 μg / mL MSNPs, and a group without MMP-2 was set as a control, and incubation was continued for 4 h and 12 h. After incubation, A549 cells were gently rinsed with PBS. Subsequently, the labeled A549 cells were fixed with 4% paraformaldehyde, stained with 4′,6-diamidino-2-phenylindole (DAPI) for 10 min, and imaged with a laser scanning confocal microscope.
[0075] According to 1×10 5 A549 cells were seeded into 12-well plates at a cell density of 100 cells / well. After the cells adhered, the culture medium was replaced with 100 ng / mL of MMP-2 and 100 μg / mL of MSNPs. At the same time, a group without MMP-2 was set as a control and incubated for another 12 hours. After incubation, the A549 cells were gently rinsed with PBS. Subsequently, the cell samples were collected and fully digested in aqua regia (3:1 v / v HCl / HNO3). Subsequently, the samples were diluted to an appropriate concentration with 4% hydrochloric acid, and the gold content was quantified using inductively coupled plasma mass spectrometry (ICP-MS).
[0076] Fig. 9The laser confocal scanning microscopy images of A549 cells after incubation with MSNPs for 4h and 12h in the absence and presence of MMP2, where Fig. 9 (a) is a confocal laser scanning microscopy image of A549 cells after incubation with MSNPs for 4 h and 12 h in the absence of MMP2. Fig. 9 (b) is a confocal laser scanning microscopy image of A549 cells after incubation with MSNPs for 4h and 12h in the presence of MMP2. It can be seen that in the absence of MMP2, the A549 cells mainly showed TMR fluorescence, with very little FITC fluorescence, and there was no significant change in the fluorescence characteristics of the cells between 4h and 12h of co-incubation. In contrast, in the presence of MMP2, FITC fluorescence increased significantly at 4h, which may be due to the destruction of FRET after MMP2 cleavage of peptide chain 2. After exposure to MMP2 for 12h, the TMR fluorescence intensity decreased significantly, which may be due to the excretion of cells containing free TMR fragments.
[0077] Fig.10 The intracellular gold content of A549 cells after co-incubation with different nanoparticles and treatment with MMP2 was measured. It was found that under the condition of MMP2, the intracellular gold content of A549 cells increased significantly after MSNPs treatment, indicating that MSNPs can enhance cell labeling under the stimulation of MMP2. As a responsive nanoprobe, MSNPs can efficiently identify the microenvironment rich in MMP2 and promote the ability of cell nanoparticle transport.
[0078] 3. Application Test 1
[0079] The feasibility of MSNPs as an early diagnostic probe was evaluated by measuring lung CT images of healthy mice and IPF model mice at different stages of disease progression before and after intravenous injection of MSNPs. The specific methods include:
[0080] Step 1: Construction of Idiopathic Pulmonary Fibrosis (IPF) Mouse Model
[0081] The IPF mouse model induced by bleomycin (BLM) was constructed as follows: C57BL / 6 mice (5 weeks old, male, 18-22g, Suzhou Industrial Park Airmate Technology Co., Ltd.) were anesthetized by intraperitoneal injection of 1% sodium pentobarbital. Subsequently, 75 μL of bleomycin (2 mg / kg, Hubei Huizepu) was instilled into the trachea and the mouse chest was gently massaged to evenly disperse the drug. The healthy control group mice underwent similar operations by injecting 75 μL of normal saline. The model mice were sacrificed on days 0, 5, 10, and 21 of modeling, and their lung tissues were fixed in 4% neutral polyformaldehyde, and then the sections were analyzed by hematoxylin-eosin and Masson staining.
[0082] Step 2: CT imaging of the lungs of IPF model mice
[0083] MSNPs (100 mg / kg) were injected into the tail vein of healthy mice and IPF model mice on days 5, 10, and 21 after bleomycin injection, and in vivo lung CT imaging was performed using a Micro-CT scanner (Hiscan XM Micro CT).
[0084] Fig.11 These are H&E and Masson staining images of lung tissues of healthy mice and BLM at 5, 10, and 21 days after injection. The alveolar structural integrity and pulmonary collagen deposition in the model mice's lung tissues significantly deteriorated with prolonged modeling time, indicating the successful construction of IPF model mice at different stages of the disease.
[0085] Fig.12 The lung CT images and signal intensity statistics of healthy mice before and after MSNPs injection. The lung CT images of healthy mice are clear, with trachea and bronchi visible. There is no significant change in the images after MSNPs injection.
[0086] Fig.13 The lung CT images and signal intensity statistics of IPF model mice before and after MSNPs injection 5 days after BLM injection. The CT images showed obvious dense shadows near the trachea and bronchi, while the lung CT images of mice not injected with MSNPs were not significantly different from those of healthy mice, and only uniform ductal structures were observed. This result shows that MSNPs can be enriched in areas with mild lesions and can enhance the signal intensity under CT images.
[0087] Fig.14 The lung CT images and signal intensity statistics of IPF model mice before and after MSNPs injection 10 days after BLM injection show that even without the use of contrast agent (ROI contrast of 378HU), CT imaging can also see high-density shadows formed by thickened alveolar walls in the right lung. After injection of MSNP, the abnormal imaging area expanded and the CT ROI contrast increased to 610HU, showing continuous and aggregated lesions throughout the lung interstitium. This enhancement shows that MSNP can enhance the display of lesions in the middle stage of IPF.
[0088] Fig.15 The lung CT images and signal intensity statistics of IPF model mice before and after MSNPs injection 21 days after BLM injection. The images show that the IPF model mice at this stage had extensive fibrotic lesions in the lungs, manifested as high-density shadows, with ROI contrast values between 575 and 623HU, and minimal contrast enhancement after MSNP injection.
[0089] These results support that MSNPs are an effective probe for early IPF detection and can enhance the CT imaging contrast of early IPF lesions.
Claims
1. A method for preparing a CT imaging nanoprobe capable of specifically recognizing MMP-2, characterized in that: The steps include: (1) adding NaBH4 aqueous solution dropwise to HAuCl4 solution, stirring for reaction and centrifuging to obtain AuNPs aqueous solution; (2) adding a methanol solution of α-lipoic acid to the AuNPs aqueous solution, stirring the reaction, centrifuging, and washing to obtain LA@Au; (3) LA@Au was dispersed in deionized water, and then the peptide chain 1 solution was added and stirred at room temperature to obtain peptide chain 1@Au; (4) dissolving peptide chain 1@Au in deionized water, then dropping peptide chain 2 solution, stirring and reacting, and obtaining a CT imaging nanoprobe; In step (3), the amino acid sequence of peptide chain 1 is: (C) m PLGLAG(E) n K, Wherein, m is an integer of 1-10, and n is an integer of 1-30; In step (4), the amino acid sequence of peptide chain 2 is: (C) h (R) i K, Wherein, h is an integer of 1-10, and i is an integer of 1-30.
2. The method for preparing the CT imaging nanoprobe capable of specifically recognizing MMP-2 according to claim 1, characterized in that: In step (1), the molar ratio of HAuCl4 to NaBH4 is 1:(10-50).
3. The method for preparing the CT imaging nanoprobe capable of specifically recognizing MMP-2 according to claim 1, characterized in that: In step (1), the centrifugation uses an ultrafiltration tube with a molecular weight cutoff of 10,000 Da, the centrifugal speed is 6,000-7,000 rpm, and the time is 10-15 min.
4. The method for preparing the CT imaging nanoprobe capable of specifically recognizing MMP-2 according to claim 1, characterized in that: In step (2), the mass ratio of AuNPs to α-lipoic acid is 50:
1.
5. The method for preparing the CT imaging nanoprobe capable of specifically recognizing MMP-2 according to claim 1, characterized in that: In step (3), the mass ratio of the AuNPs to the peptide chain 2 is (1-10):
1.
6. The method for preparing the CT imaging nanoprobe capable of specifically recognizing MMP-2 according to claim 1, characterized in that: In step (4), the mass ratio of peptide chain 2 to peptide chain 1 is (1-10):(10-1).
7. The method for preparing the CT imaging nanoprobe capable of specifically recognizing MMP-2 according to claim 1, characterized in that: The cysteine in the amino acid sequence of the peptide chain 1 is replaced by cystine, and / or the glutamic acid is replaced by aspartic acid.
8. The method for preparing the CT imaging nanoprobe capable of specifically recognizing MMP-2 according to claim 1, characterized in that: The arginine in the amino acid sequence of the peptide chain 2 is replaced by lysine or histidine.
9. Use of the CT imaging nanoprobe prepared by the method according to any one of claims 1 to 8 in the preparation of a diagnostic reagent for idiopathic pulmonary fibrosis.