Near-infrared light nano probe as well as preparation method and application thereof

Abstract

The invention discloses a near-infrared light nano probe as well as a preparation method and application thereof. The preparation method of the near-infrared nano probe comprises the following steps: dissolving polylactic acid-co-acetic acid in an acetonitrile solution, and adding lecithin and 1, 2-dipalmitoyl-sn-glycerol-3-phosphatidyl glycol to obtain a solution A; dissolving indocyanine green in an ethanol solution to obtain a solution B; and mixing the solution A and the solution B, and carrying out ultrasonic treatment to obtain the near-infrared nano probe. The near-infrared light nanoprobe can be used for imaging diagnosis of acute kidney injury, and effectively solves the problems of long diagnosis time, poor stability, high in-vivo clearance rate, low cell absorption rate and the like. Compared with existing ICG nano-particles, the ICG nano-particles are high in biological tissue penetrability, high in resolution ratio, low in phototoxicity and good in fluorescence imaging effect in an acute kidney injury model and have wide application prospects in AKI clinical diagnosis.

Description

Technical Field

[0001] The present invention relates to the field of biomedical technology, and in particular to a near-infrared light nanoprobe and a preparation method and application thereof. Background Art

[0002] Acute kidney injury (AKI) is a serious syndrome with a high incidence in critically ill patients, characterized by a sudden decline in renal function, resulting in the accumulation of metabolic waste and an imbalance of electrolytes and blood fluids. Currently, the clinical diagnosis of AKI relies on renal function markers, but such renal function markers lack sensitivity in early detection of renal injury. For example, creatinine (Crea) and urea nitrogen (BUN), traditional markers such as serum creatinine and changes in urine volume are usually detected only after renal function has been impaired for some time, so true early diagnosis cannot be achieved. The early symptoms of AKI may not be obvious, and patients may not have obvious pain or other discomfort, which makes early detection and diagnosis more difficult. Inconsistent diagnostic criteria: The diagnostic criteria for AKI may vary in different studies and medical institutions, which leads to problems with consistency and comparability of diagnosis. Complex detection methods: Some potential biomarkers may require special detection methods, such as proteomics, metabolomics, or gene expression analysis, which may be complex, expensive, and require expertise. At present, molecular optical probes have made progress in the diagnosis of AKI, but the diagnostic process is often too time-consuming and cannot effectively treat or alleviate the condition. In addition, some nanoparticles (NPs) only have therapeutic effects on AKI but cannot be used for diagnosis. Therefore, nanomedicine that can be used for diagnosis of AKI is urgently needed.

[0003] Clinical diagnosis of AKI also includes imaging techniques: Ultrasonography, a non-invasive, radiation-free imaging technique that can be used to assess the size, structure, and blood flow of the kidneys. It is very useful for detecting structural abnormalities such as renal masses, stones, and urinary tract obstruction; Computed tomography (CT), CT imaging provides high-resolution images of the kidney structure, is very sensitive for detecting renal bleeding, necrosis, stones, or other structural lesions, and can show detailed information about the kidneys, including the distinction between the cortex and medulla; Magnetic resonance imaging (MRI), provides detailed information about the structure and function of the kidneys, including the hemodynamics of the kidneys and microscopic changes in the tissues, and is used to detect certain types of renal lesions, such as certain glomerular diseases; Nuclear medicine imaging, such as single photon emission computed tomography (SPECT) and positron emission tomography (PET), uses radioactive tracers to assess renal blood flow and function; Optical imaging techniques, including fluorescence microscopy and confocal microscopy, are used in laboratory settings to study the microscopic structure and function of the kidneys.

[0004] Near-infrared fluorescence imaging is a technique that uses near-infrared light bands for imaging, usually involving wavelengths ranging from 700 to 900 nanometers. Near-infrared light is able to penetrate deeper biological tissues because biological tissues have low absorption and less scattering of near-infrared light. This makes near-infrared fluorescence imaging suitable for imaging deep tissues. In the near-infrared wavelength range, biological tissues have less autofluorescence and scattered light, which reduces background noise and improves the signal-to-noise ratio of imaging. Near-infrared fluorescence imaging can also monitor biological processes in real time because fluorescent markers can continuously emit signals and the system can quickly acquire images. This imaging technique is non-invasive and can be imaged without harming biological tissues, making it suitable for in vivo imaging of living animals. Near-infrared fluorescence imaging can be combined with other imaging techniques (such as MRI, PET, CT, etc.) to provide more comprehensive information for a variety of biomedical studies, including tumor detection, vascular imaging, molecular and cell biology research, etc. These advantages of near-infrared fluorescence imaging make it a very valuable tool in biomedical research and clinical diagnosis, especially in applications that require deep tissue penetration and high-sensitivity detection. With the continuous development of fluorescent probes and imaging technology, the application prospects of near-infrared fluorescence imaging are very broad.

[0005] Indocyanine Green (ICG) is a near-infrared fluorescent dye that has a wide range of applications in the field of near-infrared imaging. The absorption peak of ICG is within the near-infrared spectrum, around 780nm, while its emission peak is in the near-infrared region II, around 830nm. This property enables ICG to penetrate deep tissues while producing relatively little background noise, so it is widely used in biomedical imaging, such as vascular imaging, tumor detection, and lymphatic imaging. Although indocyanine green (ICG) has a wide range of uses in clinical applications, it still faces some challenges and limitations in practical applications, such as poor biocompatibility and stability between ICG and nanoparticle carriers, and limited improvement in photostability; low targeting and tissue specificity for AKI diagnosis, clearance rate affected by individual differences, poor storage stability, and long-term storage has a significant impact on fluorescence intensity. Summary of the invention

[0006] In view of the defects in the prior art, the present invention discloses a near-infrared light nanoprobe and a preparation method and application thereof.

[0007] The present invention provides a method for preparing a near-infrared nanoprobe, comprising the following steps:

[0008] (1) poly(lactic acid-co-glycolic acid) (PLGA) is dissolved in acetonitrile solution, and lecithin and 1,2-dipalmitoyl-sn-glycero-3-phosphatidylethylene glycol (DPPE-PEG) are added to obtain solution A;

[0009] (2) dissolving indocyanine green in an ethanol solution to obtain solution B;

[0010] (3) mixing the solution A and the solution B, and performing ultrasonic treatment to obtain the near-infrared nanoprobe;

[0011] The amount of lecithin and 1,2-dipalmitoyl-sn-glycerol-3-phosphatidyl glycol added is 0.3-1 mg / mL; lecithin has good membrane fluidity and can help form a flexible and uniform nanoprobe structure. The PEG (polyethylene glycol) part in DPPE-PEG prevents the aggregation of nanoparticles by providing a steric hindrance effect, thereby helping to maintain the uniformity of the particles. At the same time, the PEG chain can also improve the stability of the nanoprobe in aqueous solution and prevent it from agglomerating due to adsorption. The present invention adjusts the surface tension of the nanoprobe by adding lecithin and 1,2-dipalmitoyl-sn-glycerol-3-phosphatidyl glycol in a reasonable amount to promote the formation of more uniform particles. Excessive addition of lecithin and DPPE-PEG will lead to the formation of nanoparticles that are not stable enough, and the particles are easy to aggregate or disintegrate, thereby affecting their retention and penetration in damaged renal tissue.

[0012] The mass ratio of lecithin and 1,2-dipalmitoyl-sn-glycero-3-phosphatidylethylene glycol is (1-2): (2-3). The size and surface characteristics of the nanoprobe are crucial to its distribution and targeting in the body. When lecithin and DPPE-PEG are compounded outside the ratio range, the size of the nanoprobe may be too large or too small, thereby affecting its penetration ability in the blood and tissues. In addition, the compounding ratio of lecithin and DPPE-PEG can affect the encapsulation efficiency of ICG in the probe. When compounded outside the ratio range, it may cause ICG to be released too quickly, thereby affecting the imaging effect of the nanoparticles in acute renal injury.

[0013] In some embodiments, the particle size of the near-infrared nanoprobe is 200nm to 600nm; when the particle size of the nanoprobe is too large, its penetration ability will be weakened when circulating in the body. When targeting tissues such as the kidneys, the probe cannot effectively pass through the cell gap, resulting in weak or blurred imaging signals; when the particle size of the nanoprobe is too small, it cannot effectively bind specifically to the target tissue, affecting its ability to target accumulation and resulting in a weak imaging signal.

[0014] In some embodiments, in the solution A, the concentration of the poly(lactic acid-co-glycolic acid) is 1-2 mg / mL.

[0015] In some embodiments, in the solution B, the concentration of indocyanine green is 0.25-0.75 mg / mL.

[0016] In some embodiments, the conditions of ultrasonic treatment in step (3) are: 10-20 kHz, 100-150W.

[0017] In some embodiments, the ultrasonic treatment time in step (3) is 30 min to 60 min.

[0018] The present invention also provides a near-infrared nanoprobe obtained by the preparation method.

[0019] The present invention also provides a biological imaging system for diagnosing acute kidney injury, comprising the near-infrared nanoprobe.

[0020] Phosphatidylcholine is a phospholipid naturally present in cell membranes, with good biocompatibility and membrane fusion ability. However, when combined with DPPE at a specific addition ratio, it can further enhance the fusion of nanoprobes with cell membranes, thereby increasing the aggregation of probes in kidney cells or specific damaged areas.

[0021] The present invention also provides the use of the near-infrared nanoprobe in preparing reagents related to diagnosing acute kidney injury.

[0022] In summary, compared with the prior art, the present invention achieves the following technical effects:

[0023] (1) The near-infrared light nanoprobe of the present application has good light exposure stability and storage stability, can be taken up by cells, and avoid being quickly cleared or degraded, thereby extending its circulation time in the body and increasing its chance of reaching the kidneys. It has a short diagnosis time, high stability, and high cell absorption rate.

[0024] (2) The ICG nanoprobe of the present application has no cytotoxicity, stronger penetration, higher imaging resolution, and good fluorescence imaging effect. It can be effectively enriched in kidney tissue, especially in damaged kidney tissue, and has higher sensitivity and accuracy for early diagnosis of acute kidney injury, and has broad application prospects in clinical diagnosis of AKI. In addition, the raw materials used in the preparation process of the present invention have good biocompatibility, which can reduce the immune response of the nanoprobe in the body, reduce side effects, and ensure safe and effective diagnosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 The encapsulation process and absorption and fluorescence spectra of the ICG nanoprobe prepared in Example 1 of the present invention;

[0027] Figure 2 Nanoparticle size detection and TEM image of the ICG nanoprobe prepared in Example 1 of the present invention;

[0028] Figure 3 Nanoparticle size detection and TEM image of the ICG nanoprobe prepared in Comparative Example 1 of the present invention;

[0029] Figure 4 Nanoparticle size detection and TEM image of the ICG nanoprobe prepared in Comparative Example 2 of the present invention;

[0030] Figure 5 Nanoparticle size detection and TEM image of the ICG nanoprobe prepared in Comparative Example 3 of the present invention;

[0031] Figure 6 The photostability results of the nanoprobe prepared in Example 1 of the present invention;

[0032] Figure 7 The storage stability results of the nanoprobe prepared in Example 1 of the present invention;

[0033] Figure 8 The cytotoxicity test results of the nanoprobe prepared in Example 1 of the present invention;

[0034] Fig. 9 The in vivo imaging results of the ICG nanoprobes prepared in Example 1 and Comparative Example 1 in small animals in the proximal II zone of AKI mice;

[0035] Fig.10 The imaging results of the proximal II zone of the ICG nanoprobes prepared in Example 1 of the present invention and Comparative Example 1 were performed on the organs of AKI mice injected 24 hours later. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0037] Source of raw materials:

[0038] Poly(lactic-co-glycolic acid) (PLGA): HY-B2247, MedChemExpress, USA;

[0039] 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-polyethylene glycol (DSPE-PEG): HY-143209, MedChemExpress, USA;

[0040] Lecithin: HY-B2235, MedChemExpress, USA;

[0041] Indocyanine green (ICG): National Medicine Approval No. H20055881, China;

[0042] Acetonitrile: A801458, Macklin, China;

[0043] Ethanol: E809061, Macklin, China.

[0044] Example 1

[0045] Solution A: PLGA was dissolved in 100% acetonitrile solution at a concentration of 2 mg / mL. 0.12 mg / mL of lecithin and 0.18 mg / mL of DSPE-PEG (lecithin: DSPE-PEG = 2:3) were added to the PLGA polymer.

[0046] Solution B: Add 750 μg ICG to 3 mL of 4% ethanol in water.

[0047] Solution A was dissolved in solution B, and the solution was filtered by an ultrafiltration tube after ultrasonic treatment at 20 kHz and 130 W for 5 min, and washed three times to obtain ICG nanoparticles (ICG-NPS).

[0048] After synthesis, the absorption and emission spectra of the nanoparticles prepared in Example 1 were tested. Figure 1 As shown in the figure, the absorption spectrum is located at about 750nm, and the emission spectrum is located at about 800nm. The fluorescent nanoprobe is located in the near-infrared luminescence region. TEM is used to detect the formation of nanoparticles, such as Figure 2 As shown, the nanoparticles prepared in Example 1 have good spherical properties. Dynamic light scattering was used to determine that the average particle size of the nanoparticles was 356 nm.

[0049] Example 2

[0050] Solution A: PLGA was dissolved in 100% acetonitrile solution at a concentration of 2 mg / mL. 0.1 mg / mL of lecithin and 0.2 mg / mL of DSPE-PEG were added to the PLGA polymer (lecithin: DSPE-PEG = 1:2).

[0051] Solution B: Add 750 μg ICG to 3 mL of 4% ethanol in water.

[0052] Solution A was dissolved in solution B, and the solution was filtered by an ultrafiltration tube after ultrasonic treatment at 20kHz and 130W for 5 minutes. The solution was washed three times to obtain ICG nanoparticles. The particle size of the nanoparticles was determined by dynamic light scattering. The average particle size of the ICG nanoparticles was 298nm.

[0053] Example 3

[0054] Solution A: PLGA was dissolved in 100% acetonitrile solution at a concentration of 2 mg / mL. 0.1 mg / mL of lecithin and 0.1 mg / mL of DSPE-PEG were added to the PLGA polymer (lecithin: DSPE-PEG = 1:1).

[0055] Solution B: Add 750 μg ICG to 3 mL of 4% ethanol in water.

[0056] Solution A was dissolved in solution B, and the solution was filtered through an ultrafiltration tube after ultrasonic treatment at 20kHz and 130W for 5 minutes, and washed three times to obtain ICG nanoparticles. The particle size of the nanoparticles was determined by dynamic light scattering, and the particle size of the ICG nanoparticles was 384nm.

[0057] Example 4

[0058] Solution A: PLGA was dissolved in 100% acetonitrile solution at a concentration of 1 mg / mL. 0.12 mg / mL of lecithin and 0.18 mg / mL of DSPE-PEG (lecithin: DSPE-PEG = 2:3) were added to the PLGA polymer.

[0059] Solution B: Add 750 μg ICG to 3 mL of 4% ethanol in water.

[0060] Solution A was dissolved in solution B, and the solution was filtered through an ultrafiltration tube after ultrasonic treatment at 20kHz and 130W for 5 minutes, and washed three times to obtain ICG nanoparticles. The particle size of the nanoparticles was determined by dynamic light scattering, and the particle size of the ICG nanoparticles was 287nm.

[0061] Comparative Example 1

[0062] Solution A: PLGA was dissolved in 100% acetonitrile solution at a concentration of 2 mg / mL.

[0063] Solution B: Add 750 μg ICG to 3 mL of 4% ethanol in water.

[0064] Solution A was dissolved in solution B, and then the solution was filtered by ultrafiltration tube after ultrasonic treatment at 20kHz and 130W for 5 minutes, and washed three times to obtain ICG nanoparticles (ICG-PLGA). Dynamic light scattering was used to determine the particle size of the nanoparticles, such as Figure 3 As shown on the left, the average particle size of ICG nanoparticles is 210 nm. TEM was used to analyze the sphering of nanoparticles. Figure 3 As shown in (right side), the synthesis method of Comparative Example 1 successfully formed nanoparticles with good uniformity.

[0065] Comparative Example 2

[0066] Solution A: Dissolve lecithin in 100% acetonitrile solution at a concentration of 0.12 mg / mL.

[0067] Solution B: Add 750 μg ICG to 3 mL of 4% ethanol in water.

[0068] Solution A was dissolved in solution B, and then the solution was filtered by ultrafiltration tube after ultrasonic treatment at 20kHz and 130W for 5 minutes, and washed three times to obtain ICG nanoparticles. Dynamic light scattering was used to determine the particle size of the nanoparticles, such as Figure 4 As shown on the left, the number of smaller nanoparticles is small. The particle size of ICG nanoparticles is 127nm. TEM was used to analyze the sphering of nanoparticles, as shown in Figure 2. Figure 4 As shown in (right side), no obvious nanoparticles were observed in the synthesis method of Comparative Example 2, and the film was more fragmented.

[0069] Comparative Example 3

[0070] Solution A: DSPE-PEG was dissolved in 100% acetonitrile solution at a concentration of 0.18 mg / mL.

[0071] Solution B: Add 750 μg ICG to 3 mL of 4% ethanol in water.

[0072] Solution A was dissolved in solution B, and then the solution was filtered by ultrafiltration tube after ultrasonic treatment at 20kHz and 130W for 5 minutes, and washed three times to obtain ICG nanoparticles. Dynamic light scattering was used to determine the particle size of the nanoparticles, such as Figure 5 As shown on the left, the measured nanoparticle size is relatively large. The average nanoparticle size is 607nm. TEM was used to analyze the sphering of nanoparticles, as shown in Figure 2. Figure 5 As shown in (right side), the synthesis method of Comparative Example 3 does not produce obvious nanoparticles.

[0073] Comparative Example 4

[0074] Solution A: PLGA was dissolved in 100% acetonitrile solution at a concentration of 2 mg / mL. 2 mg / mL of lecithin and 3 mg / mL of DSPE-PEG (lecithin: DSPE-PEG = 2:3) were added to the PLGA polymer.

[0075] Solution B: Add 750 μg ICG to 3 mL of 4% ethanol in water.

[0076] Solution A was dissolved in solution B, and the solution was filtered by an ultrafiltration tube after ultrasonic treatment at 20kHz and 130W for 5 minutes, and washed three times to obtain ICG nanoparticles. Dynamic light scattering was used to determine the particle size of the nanoparticles, and the measured nanoparticle size was large and dispersed.

[0077] Comparative Example 5

[0078] Solution A: PLGA was dissolved in 100% acetonitrile solution at a concentration of 2 mg / mL. 0.18 mg / mL of lecithin and 0.1 mg / mL of DSPE-PEG (lecithin: DSPE-PEG = 3:1) were added to the PLGA polymer.

[0079] Solution B: Add 750 μg ICG to 3 mL of 4% ethanol in water.

[0080] Solution A was dissolved in solution B, and then the solution was filtered by an ultrafiltration tube after ultrasonic treatment at 20kHz and 130W for 5 minutes, and washed three times to obtain ICG nanoparticles. The particle size of the nanoparticles was determined by dynamic light scattering, and the particle size of the ICG nanoparticles was 114nm.

[0081] <Performance Test>

[0082] 1. Light exposure stability :

[0083] The ICG nanoparticles prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were irradiated with 808 laser for a long time. As the irradiation time increased, the fluorescence intensity of ICG not wrapped with nanoparticles gradually weakened, and the fluorescence intensity of ICG was almost undetectable after 2 hours of irradiation.

[0084] The ICG nanoparticles synthesized in Examples 1 to 4 of the present application still maintain good luminescence properties after continuous irradiation with 808 laser for 2 hours. The luminescence properties of Example 1 are as follows: Figure 6 As shown, the fluorescence intensity of the ICG nanoparticles prepared in Comparative Examples 1 to 5 gradually weakened after continuous laser irradiation, indicating that the ICG nanoparticles prepared in Examples 1 to 4 of this study have good light exposure stability.

[0085] 2. Storage stability:

[0086] The ICG nanoparticles prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were dissolved in water, phosphate buffer and DMEM / F12, respectively, and then stored at 4° C. for two weeks to detect their storage stability.

[0087] The results show that the images of the ICG nanoparticles of Examples 1 to 4 and Comparative Examples 1 and 5 stored in different solvents did not change significantly during the test period, while the color of the ICG nanoparticle solutions of Comparative Examples 2 to 4 gradually became lighter, and the color change of Example 1 was as follows: Figure 7 As shown, it is shown that the ICG nanoparticles prepared in Examples 1 to 4 can be stored for a long time and have good stability.

[0088] 3. Cellular uptake:

[0089] The ICG nanoparticles prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were co-incubated with HK-2 cells for 2 hours, and the uptake of the nanoparticles by HK-2 was detected by immunofluorescence microscopy. The results showed that only the nanoparticles prepared in Examples 1 to 4 and Comparative Examples 1 and 5 could be taken up by cells.

[0090] 4. Cytotoxicity:

[0091] The cytocompatibility and toxicity of the ICG nanoparticles prepared in Examples 1 to 4 and Comparative Examples 1 to 5 to HK-2 cells were evaluated by CCK8.

[0092] After the ICG nanoparticles of Examples 1 to 4 and Comparative Examples 1 to 5 with different concentrations (0, 0.01, 0.05, 0.1, 0.5, 1 μM) were applied to the cells, the cell viability was detected at 24 h and 48 h, respectively.

[0093] The results showed that the ICG nanoparticles of Examples 1 to 4 and the ICG nanoparticles of Comparative Examples 1 to 3 and 5 had no significant change in cell viability compared to the control group, while the ICG nanoparticles of Comparative Example 4 reduced cell viability after incubation for 48 hours. The cell viability of Example 1 changed as shown in FIG. Figure 8 shown.

[0094] 5. Animal experiments:

[0095] Eighteen male Balb / c mice weighing 20 g to 25 g were selected and randomly divided into three groups, with 6 mice in each group. The control group was intraperitoneally injected with normal saline, and the AKI mouse model was established by intraperitoneal injection of 20 mg / kg cisplatin. After 24 h and 48 h, the ICG nanoprobes prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were injected into the tail vein to record the imaging results.

[0096] First, a near-infrared II zone imaging diagnostic experiment was conducted on AKI mice. The results showed that the ICG nanoparticles synthesized using Examples 1 to 4 were enriched in the damaged kidney tissue 1 hour after tail vein injection, and the fluorescence signal could be detected for 24 hours, regardless of whether it was 24h AKI or 48h AKI mice. However, the ICG nanoparticles synthesized using Comparative Examples 1 to 5 had no obvious fluorescence signal in the damaged kidney tissue 1 hour after injection, and almost no obvious fluorescence signal was detected after 24 hours.

[0097] In addition, in order to further verify the in vivo experimental results, the fluorescence signal results of the dissected organs were detected 24 hours after the nanoparticle injection. The results were consistent with the in vivo experimental results. Only the ICG nanoparticles injected in Examples 1 to 4 could detect fluorescence signals in the kidneys, while the ICG nanoparticles in Comparative Examples 1 to 5 had no obvious fluorescence signals. The imaging results of the ICG nanoparticles in Example 1 are shown in Figure 2. Figures 9-10 The above results indicate that the ICG nanoparticles prepared in the example have good renal tissue aggregation, can be effectively enriched in damaged renal tissue, and can be used for early AKI diagnosis through near-infrared II zone imaging.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a near-infrared nanoprobe, characterized in that: The steps include: (1) polylactic acid-co-acetic acid is dissolved in acetonitrile solution, and lecithin and 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl glycol are added to obtain solution A; (2) dissolving indocyanine green in an ethanol solution to obtain solution B; (3) mixing the solution A and the solution B, and performing ultrasonic treatment to obtain the near-infrared nanoprobe; The amount of lecithin and 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl glycol added is 0.3-1 mg / mL; The mass ratio of the lecithin to 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl glycol is (1-2):(2-3).

2. The preparation method according to claim 1, characterized in that: The particle size of the near-infrared nanoprobe is 200nm-600nm.

3. The preparation method according to claim 1, characterized in that: In the solution A, the concentration of polylactic acid-glycolic acid copolymer is 1-2 mg / mL.

4. The preparation method according to claim 1, characterized in that: In the solution B, the concentration of indocyanine green is 0.5-0.75 mg / mL.

5. The preparation method according to claim 1, characterized in that: The conditions of ultrasonic treatment in step (3) are: 10-20kHz, 100-150W.

6. The preparation method according to claim 1, characterized in that: The ultrasonic treatment time in step (3) is 30 min to 60 min.

7. The near-infrared nanoprobe obtained by the preparation method according to any one of claims 1 to 6.

8. A biological imaging system for diagnosing acute kidney injury, characterized in that: Comprising the near-infrared nanoprobe as described in claim 7.

9. Use of the near-infrared nanoprobe according to claim 7 in the preparation of reagents related to the diagnosis of acute kidney injury.

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