A nanogel targeting cardiac radiation injury and a preparation method and application thereof

Abstract

The application belongs to the technical field of medicine carrier preparation, and discloses a nanogel for targeting cardiac radioactive injury, which comprises a composite delivery carrier and a circNCX1 plasmid coupled with the composite delivery carrier; wherein the composite delivery carrier is prepared from pegylated sodium oxidized alginate, a myocardial targeting peptide and a cell penetrating peptide; and the pegylated sodium oxidized alginate is obtained by the reaction of oxidized sodium alginate and polyethylene glycol monomethyl ether amino. The nanogel can accurately deliver the circNCX1 plasmid to the cardiac tissue, reduce myocardial cell apoptosis, and improve the stability, targeting property and cell uptake capacity of the circNCX1 plasmid in the in-vivo delivery process, so as to realize the cardiac protection effect and be used for preventing coronary artery diseases, myocardial ischemia, ischemia-reperfusion injury, arrhythmia and the like.

Description

Technical Field

[0001] This invention belongs to the field of drug carrier preparation technology, specifically relating to a nanogel that targets cardiac radiation damage, its preparation method, and its application. Background Technology

[0002] Radiation-induced heart disease (RIHD) is a common and serious complication following radiotherapy for cancer. While advancements in modern radiotherapy techniques, such as intensity-modulated radiotherapy (IMRT) and proton therapy (PT), have reduced the risk of radiation injury, patients undergoing treatment for thoracic malignancies inevitably experience cardiac exposure to radiation, leading to a range of cardiovascular diseases such as coronary artery disease, pericarditis, cardiomyopathy, and arrhythmias. Current research indicates that these radiation-induced heart injuries typically manifest several years after treatment, significantly impacting the quality of life for survivors.

[0003] Currently, clinical treatments for RIHD mainly include: (1) symptomatic drug therapy, such as ACE inhibitors, β-blockers, and antioxidants, to alleviate cardiac dysfunction; and (2) radiation dose optimization and distribution control, such as using three-dimensional conformal radiotherapy to reduce the radiation dose to the heart. However, these methods only alleviate symptoms or the risk of radiation damage to a certain extent, and cannot fundamentally prevent cardiac damage or reverse myocardial damage.

[0004] In drug delivery, the application of nanotechnology has provided new insights into the treatment of RIHD. Nanodelivery systems, through targeted design, can deliver drugs to damaged myocardial regions, avoiding systemic side effects. However, currently used nanodelivery systems (such as liposomes and polymer nanoparticles) still suffer from low targeting efficiency, uncontrollable drug release, and rapid in vivo metabolism. Furthermore, the complex pathological mechanisms of radiation-induced cardiac injury, including inflammatory responses, oxidative stress, and cardiomyocyte apoptosis, further increase the challenges of precision treatment. Summary of the Invention

[0005] The purpose of this invention is to provide a nanogel that can target radiation damage to the heart and achieve controlled release.

[0006] The first aspect of the present invention provides a nanogel for targeting cardiac radiation damage, the nanogel comprising a composite delivery carrier and a circNCX1 plasmid coupled to the composite delivery carrier;

[0007] The composite delivery carrier is prepared from polyethylene glycolated sodium alginate, myocardial targeting peptide, and cell-penetrating peptide; the polyethylene glycolated sodium alginate is obtained by reacting sodium alginate with polyethylene glycol monomethyl ether amino groups.

[0008] In some embodiments, the ratio of the composite delivery vector to the circNCX1 plasmid is 0.1 mg to 50 mg: 0.1 μg to 1000 μg, preferably 1 mg to 20 mg: 10 μg to 100 μg, more preferably 1 mg to 10 mg: 15 μg to 25 μg, and even more preferably 5 mg: 15 μg to 25 μg.

[0009] In some embodiments, the mass ratio of PEGylated sodium alginate, myocardial targeting peptide, and cell-penetrating peptide is 0.1–50:0.01–10:0.01–10; preferably, the mass ratio of PEGylated sodium alginate, myocardial targeting peptide, and cell-penetrating peptide is 1–20:1–10:1–10; more preferably, the mass ratio of PEGylated sodium alginate, myocardial targeting peptide, and cell-penetrating peptide is 5–10:1–5:1–5; even more preferably, the mass ratio of PEGylated sodium alginate, myocardial targeting peptide, and cell-penetrating peptide is 5–6:1–2:1–2; and / or,

[0010] The molar ratio of sodium alginate oxide to polyethylene glycol monomethyl ether amino is 1:1 to 50, preferably 1:1 to 20, more preferably 1:1:10, and even more preferably 1:1 to 5.

[0011] In some embodiments, the method for preparing the composite delivery carrier includes the following steps:

[0012] (1) A mixed solution was obtained by reacting polyethylene glycol-modified sodium alginate with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide;

[0013] (2) The resulting mixed solution was reacted with myocardial targeting peptide and cell-penetrating peptide to obtain the reaction product;

[0014] (3) The obtained reaction product was freeze-dried to obtain the composite delivery carrier;

[0015] Preferably, in step (2), the pH value of the reaction system is 4-8, more preferably 5-6; and / or,

[0016] In step (2), the reaction temperature is 0℃~50℃, and the reaction time is 1h~48h; and / or,

[0017] In step (1), the mass ratio of the polyethylene glycol-modified sodium alginate to 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide is 1:1 to 5:1 to 5; and / or,

[0018] In step (1), the reaction time is 20 min to 30 min.

[0019] In some embodiments, the method for preparing the polyethylene glycol-modified sodium alginate includes the following steps:

[0020] (a) Oxidizing sodium alginate to obtain oxidized sodium alginate;

[0021] (b) Sodium oxidized alginate, polyethylene glycol monomethyl ether amino, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide were subjected to an amidation reaction to obtain polyethylene glycol-modified sodium oxidized alginate.

[0022] In some embodiments, in step (b), the pH of the reaction system is 3–9; and / or,

[0023] In step (b), the reaction temperature is 0℃~50℃ and the reaction time is 1h~48h.

[0024] In some embodiments, the method for preparing the oxidized sodium alginate includes the following steps:

[0025] Sodium alginate was reacted with sodium periodate solution to obtain the reaction product;

[0026] The sodium alginate oxide was obtained by precipitating the reaction product with ethanol.

[0027] Preferably, the mass ratio of sodium alginate to sodium periodate is 0.1–10:0.2–20, more preferably 1–10:1–10, and even more preferably 3:1–5; and / or,

[0028] The concentration of the sodium periodate solution is 0.01 g / mL to 1 g / mL, preferably 0.1 g / mL to 0.5 g / mL, more preferably 0.1 g / mL to 0.2 g / mL; and / or,

[0029] In the system where sodium alginate reacts with sodium periodate solution, the reaction temperature is 0–50°C and the reaction time is 1–72 h.

[0030] In the step of precipitating the reaction product with ethanol, the reaction temperature is -10℃ to 10℃.

[0031] In some embodiments, the amino acid sequence of the myocardial targeting peptide is as shown in SEQ ID NO: 1; and / or,

[0032] The amino acid sequence of the cell-penetrating peptide is shown in SEQ ID NO: 2; and / or,

[0033] The nucleotide sequence of the circNCX1 plasmid is shown in SEQ ID NO: 3.

[0034] A second aspect of the present invention provides the use of the nanogel targeting cardiac radiation injury as described above in the preparation of medicaments for the prevention and / or treatment of cardiac radiation injury.

[0035] A third aspect of the present invention provides a method for preparing a nanogel targeting cardiac radiation damage, the method comprising the following steps:

[0036] The composite delivery carrier and circNCX1 plasmid were dissolved in water and then added dropwise to CaCl2 solution to react and obtain the nanogel.

[0037] Preferably, the concentration of the CaCl2 solution is 0.1 mM to 100 mM, more preferably 1 mM to 10 mM, and even more preferably 4 mM to 5 mM; the ratio of the composite delivery vector, circNCX1 plasmid, water, and CaCl2 solution is 0.1 mg to 50 mg : 0.1 μg to 1000 μg : 1 mL to 5 mL : 1 mL to 5 mL, preferably 1 mg to 10 mg : 15 μg to 25 μg : 1 mL : 2 mL; and / or,

[0038] The pH value of the reaction is 4–9; and / or,

[0039] The reaction temperature is 0℃~50℃, and the reaction time is 1h~72h.

[0040] In this invention, sodium alginate oxide and polyethylene glycol monomethyl ether amino groups are amidated to obtain polyethylene glycol-modified sodium alginate oxide. The polyethylene glycol-modified sodium alginate oxide is then combined with TAT and PCM to prepare a composite delivery carrier. This composite delivery carrier is then combined with the circNCX1 plasmid to prepare a novel nanogel. It was found that this nanogel can accurately deliver the circNCX1 plasmid to cardiac tissue, reducing cardiomyocyte apoptosis caused by cardiac radiation damage. Furthermore, it can improve the stability, targeting, and cellular uptake capacity of the circNCX1 plasmid during in vivo delivery, achieving a cardioprotective effect. This nanogel can be used for the prevention and treatment of cardiac radiation damage, as well as for the prevention and treatment of other complications such as coronary artery disease, myocardial ischemia, ischemia-reperfusion injury, and arrhythmias.

[0041] Furthermore, this invention also discovered that by optimizing the synthesis conditions of oxidized sodium alginate and polyethylene glycol-modified sodium alginate, combined with modified peptide molecules, the particle size of the nanogel can be precisely controlled to around 150 nm, avoiding the precipitation problem caused by excessively large particles. Attached Figure Description

[0042] Figure 1 This is a plasmid map of the expression plasmid circNCX1(has_circ_0005232).

[0043] Figure 2 A is a TEM image of circNCX1 nanogel, scale line: 100nm; Figure 2 B is the hydrodynamic diameter of the circNCX1 nanogel in aqueous solution; Figure 2 C- Figure 2 D is the flow cytometry result of AC16 cells absorbing circNCX1 nanogel; Figure 2 E represents the encapsulation efficiency of circNCX1 plasmid with different concentrations of mPEG-OSA-PCM-TAT nanogels.

[0044] Figure 3 This is a graph showing the absorption efficiency of AC16 cells for circNCX1 plasmid and circNCX1 nanogel.

[0045] Figure 4 This is a plasmid map of the expression plasmid circNCX1(has_circ_0005232).

[0046] Figure 5 A- Figure 5 B represents the cumulative amount of circNCX1 nanogel in different organs.

[0047] Figure 6 A shows the HE staining results of mice after different treatments and radiation. Figure 6 B is a Masson pathological section staining image of mice after different treatments and radiation. Figure 6 C is a graph showing the serum CK-MB levels in mice after different treatments and radiation exposure; Figure 6 D is a graph showing the serum cTn-I levels in mice after different treatments and irradiation. Figure 6 E is a diagram showing the results of Massen staining of mouse heart tissue after different treatments and irradiations. Detailed Implementation

[0048] To facilitate understanding of the present invention, a more complete description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0049] Unless otherwise specified, experimental methods in the following examples are generally performed under standard conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the examples are commercially available products.

[0050] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0051] The present invention will be described below with reference to specific embodiments.

[0052] In the following embodiments:

[0053] The sequence of PCM (SEQ ID NO: 1) is: WLSEAGPVVTVRALRGTGSW.

[0054] The sequence of TAT (SEQ ID NO: 2) is: YGRKKRRQRRR.

[0055] The sequence of has_circ_0005232 (SEQ ID NO: 3) is:

[0056]

[0057] mmu_circ_0000823(SEQ ID NO:4):

[0058]

[0059] Example 1

[0060] This embodiment provides a method for preparing a nanogel targeting radiation damage to the heart, comprising the following steps:

[0061] 1.1 Preparation of sodium alginate (OSA)

[0062] First, sodium alginate (3.00 g) was dissolved in 280 mL of deionized water at room temperature. Then, 20 mL of sodium periodate aqueous solution (0.13 g / mL) was added dropwise to the sodium alginate solution, and the mixture was stirred at room temperature for 12 hours to synthesize OSA. The product was separated by precipitation with 100% pure ethanol at 4 °C. The obtained OSA precipitate was centrifuged (10,000 rpm, 10 min) and then washed three times with ethanol to obtain purified OSA.

[0063] 1.2 Synthesis of Polyethylene Glycol Oxide Sodium Alginate (mPEG-OSA)

[0064] The prepared OSA (0.1 g, 0.505 mmol alginate units), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC, 20 mg), N-hydroxysuccinimide (NHS, 20 mg) and polyethylene glycol monomethyl ether amino (mPEG-NH2, molecular weight 2000, Ponsure Biological) (0.101 g, 0.0505 mmol, relative content of alginate units in OSA is 10 mol%) were added to deionized water (7 mL, pH = 5.5) and then reacted at room temperature for 24 hours to synthesize mPEG-OSA.

[0065] Then, unreacted OSA was removed by ethanol precipitation, and the resulting mPEG-OSA was dissolved in ethanol. Finally, the mPEG-OSA was dialyzed in deionized water for 48 hours using a dialysis membrane (molecular weight cutoff 3500 Da) to remove unreacted mPEG-NH2, and then lyophilized to obtain purified mPEG-OSA.

[0066] 1.3 Synthesis of Targeted Modified mPEG-OSA-PCM-TAT

[0067] The prepared mPEG-OSA (5 mg) was dissolved in 3 ml of phosphate buffer solution. EDC (5 mg) and NHS (5 mg) were added under magnetic stirring to activate the carboxyl groups. After 30 min, a polypeptide mixture of PCM (SEQ ID NO.1, 1 mg) and TAT (SEQ ID NO.2, 1 mg) was added, and the pH of the solution was adjusted to 5.5. The reaction was stirred at room temperature for 12 h. The reaction product was dialyzed through a dialysis bag (MWCO 10000 Da) for 48 h, and finally freeze-dried to obtain mPEG-OSA-PCM-TAT, which is the composite delivery carrier.

[0068] 1.4 Preparation of circNCX1@mPEG-OSA-PCM-TAT nanogels

[0069] 5 mg of the prepared mPEG-OSA-PCM-TAT and 20 μg of the circNCX1 expression plasmid (has_circ_0005232, SEQ ID NO.3) were used. The map of the circNCX1 expression plasmid is shown below. Figure 1 As shown, the solution was dissolved in 1 mL of ultrapure water, and the pH was adjusted to 8.0. Then, it was slowly added dropwise to 2 mL of CaCl2 solution (5 mM, pH = 6), and the reaction was stirred at room temperature for 12 h. The reaction product was separated by centrifugation, and the product was washed with ultrapure water and centrifuged three times. The final precipitate obtained was circNCX1@mPEG-OSA-PCM-TAT nanogel.

[0070] Example 2: Structural characteristics of circNCX1@mPEG-OSA-PCM-TAT nanogel

[0071] The circNCX1@mPEG-OSA-PCM-TAT nanogel (hereinafter referred to as circNCX1 nanogel) prepared in Example 1 was slowly added to ultrapure water (Milli-Q grade) to prepare an aqueous solution with a concentration of 1 mg / ml. After brief low-speed centrifugation (3000 rpm, 3 min) to remove air bubbles, the hydrodynamic diameter was measured three times at 25°C using a dynamic light scattering instrument. Figure 2 B), the measured circNCX1@

[0072] The particle size of mPEG-OSA-PCM-TAT nanogels ranges from 150nm to 500nm, with most concentrated around 150nm.

[0073] 10 μL of sample was dropped onto a carbon film copper grid, and after negative staining with 2% phosphotungstic acid for 1 minute, the morphology was observed and images were taken using a transmission electron microscope at 80 kV. The results are as follows. Figure 2 As shown in Figure A, nanogels with clear boundaries can be obtained.

[0074] AC16 cells (purchased from Guangzhou Peiyu Biotechnology Co., Ltd., male donor) were seeded into six-well plates at a density of 3 × 10⁶ cells per well. 5 Cells were cultured in 2 mL culture medium per well for 24 hours. Then, circNCX1 plasmid and circNCX1 nanogel (8 μg circNCX1 plasmid) were added to each well, and the cells were incubated at 37°C for 4 hours. After trypsinization, the cells were washed three times with cold PBS and resuspended in 500 μL PBS. circNCX1 signal was then detected by flow cytometry. Analysis was performed using FlowJo software version 10.0. Figure 2 C and Figure 2 As shown in D, the increased content of FITC markers inside AC16 cells indicates that circNCX1 nanogel was more effectively taken up by cells compared to the circNCX1 plasmid group (plasmid group) and the Control group (control group).

[0075] Following the preparation method of Example 1, different concentrations (10 μg, 20 μg, 40 μg, 80 μg, and 100 μg) of mPEG-OSA-PCM-TAT nanogel were added, and the encapsulation efficiency of the circNCX1 plasmid was tested. The results are as follows: Figure 2 As shown in E, good encapsulation efficiency can be maintained at different encapsulation concentrations.

[0076] Example 3: Detection of absorption efficiency of circNCX1 nanogel by AC16 cells

[0077] AC16 cells were seeded onto Lab-Tek slides for 48 hours, and then the circNCX1 plasmid and the circNCX1 nanogel prepared in Example 1 were added to the slides and incubated with AC16 cells at 37°C for 6 hours.

[0078] After rinsing with PBS, cells were fixed with 4% paraformaldehyde and stained with DAPI or GFP. DAPI and GFP expression was observed after 48 hours. The uptake efficiency of AC16 cells on circNCX1 plasmid and circNCX1 nanogel was observed using a confocal microscope (Zeiss LSM 710, Germany). Results are as follows. Figure 3 As shown, the circNCX1 nanogel exhibits more effective intracellular localization, and its distribution pattern is more uniform and widespread compared to the circNCX1 plasmid.

[0079] Example 4: Cardiac-targeting effect of circNCX1 nanogel in mice

[0080] circNCX1 nanogels were prepared according to the preparation method in Example 1. The nucleotide sequence of the circNCX1 plasmid (mmu_circ_0000823) is shown in SEQ ID NO.4, and the circNCX1 plasmid map is shown in [image missing]. Figure 4 As shown.

[0081] 10 mg of circNCX1 nanogel, 50 μg of Sulfo-Cy7 amino, 5 mg of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), and 5 mg of N-hydroxysuccinimide (NHS) were added to 1.5 mL of deionized water. After the reaction was complete, the mixture was dialyzed in deionized water for 48 hours using a dialysis membrane with a molecular weight cutoff (MWCO) of 3500 Da to remove unreacted Sulfo-Cy7 amino. The final product was then lyophilized.

[0082] C57 mice (n=21) were intravenously injected via tail vein with Cy7, mPEG-OSA-Cy7, and mPEG-OSA-PCM-TAT-Cy7 at a concentration of 0.05 mg / kg. Major organs (heart, liver, spleen, lung, and kidney) were harvested at different time points after injection (1, 2, 4, 8, 12, 24, and 48 hours). Cy7 fluorescence signals were observed using an IVIS imaging system to assess its distribution and compare relative accumulation. Results are as follows: Figure 5 A and Figure 5 As shown in Figure B, compared with the Cy7 and mPEG-OSA-Cy7 groups, the mPEG-OSA-PCM-TAT modified nanogel exhibited significantly higher cardiac accumulative activity 1 hour after administration.

[0083] Example 5: Protective effect of circNCX1 nanogel on mouse heart under radiation conditions.

[0084] The cardiac radiation injury model constructed in this embodiment used 8-week-old male C57BL / 6 mice. The mice were anesthetized with a specific amount of sodium pentobarbital based on their body weight, and the hair on their chests was removed before irradiation. After complete anesthesia, the mice were immediately laid flat on a specially designed lead block, which covered all other parts of the mouse except for the heart, allowing for targeted irradiation of the heart. The irradiation conditions were 20 Gy of X-rays at a dose rate of 1 Gy / min.

[0085] Thirty-six 8-week-old male C57BL / 6 mice were randomly divided into 6 groups of 6 mice each, and injected via tail vein. Group 1 received only a certain amount of saline solution; Group 2 received saline solution followed by irradiation; Group 3 received mPEG-OSA-PCM-TAT (20 μg / cell) followed by irradiation; Group 4 received circNCX1 plasmid (20 μg / cell) followed by irradiation; Group 5 received circNCX1@mPEG-OSA-PCM-TAT nanogel (20 μg / cell) followed by irradiation; and Group 6 received circNCX1@mPEG-OSA-PCM-TAT nanogel followed by irradiation.

[0086] mPEG-OSA-PCM-TAT nanogel (20 micrograms / cell). Mice treated as described above were housed in groups in an animal facility, and their condition was observed daily. Fresh drinking water, food, and bedding were provided to the mice weekly, and their cages were cleaned to maintain cleanliness.

[0087] After 12 weeks of treatment, the mice underwent cervical spine dissection, followed by cardiac perfusion. After perfusion, the hearts were separated, washed with PBS, and stained with hematoxylin and eosin (HE). Masson's staining was then performed on the heart tissues. Serum CK-MB and cTn-I levels were measured using a mouse CK-MB and cTn-I enzyme-linked immunosorbent assay (ELISA) kit (FineTest, EM0929, EM1466). Masson's staining was performed on the heart tissues of all six groups of mice.

[0088] like Figure 6 A- Figure 6 As shown in Figure B, hematoxylin and eosin (H&E) staining revealed that in the IR-saline group pretreated with physiological saline before irradiation, the myocardial bundle boundaries were significantly dissolved, and the cardiac chamber volume increased, indicating severe myocardial disorder and dilation. Conversely, the IR-nanogel group pretreated with circNCX1@mPEG-OSA-PCM-TAT nanogels before irradiation showed minimal myocardial dilation and boundary dissolution, indicating strong resistance to radiation-induced damage. The circNCX1@mPEG-OSA-PCM-TAT nanogel group exhibited moderate protective effects after irradiation, while the pre-IR carrier and pre-IR plasmid groups showed varying degrees of cardioprotective effects. No significant pathological differences were found between the pre-IR plasmid group and the pre-IR saline group.

[0089] Two cardiac injury biomarkers, CK-MB and cTn-l, were used to assess myocardial injury at different sensitivity thresholds. For example... Figure 6 As shown in Figure C, compared with the control group and the nanogel group, both biomarkers were significantly elevated in mice in the pre-IR saline group at 12 and 16 weeks. In contrast, both biomarkers were significantly decreased in mice in the pre-IR nanogel group.

[0090] like Figure 6 As shown in Figure E, Masson's trichrome staining further revealed that fibrosis was most pronounced in the pre-IR saline group, characterized by extensive collagen deposition, while the pre-IR nanogel group exhibited minimal fibrosis. The post-IR nanogel group showed moderate fibrosis, the pre-IR carrier group showed some fibrotic changes, and the pre-IR plasmid group showed negligible fibrosis.

[0091] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A nanogel targeting cardiac radiation damage, characterized in that, The nanogel is made of a composite delivery carrier and circNCX1 plasmid; The composite delivery carrier is prepared from polyethylene glycol-modified sodium alginate, myocardial targeting peptide, and cell-penetrating peptide; the polyethylene glycol-modified sodium alginate is obtained by reacting sodium alginate with polyethylene glycol monomethyl ether amino groups. The mass ratio of the PEGylated sodium alginate, myocardial targeting peptide and cell-penetrating peptide is 5~10:1~5:1~5; The method for preparing the composite delivery carrier includes the following steps: (1) A mixed solution was obtained by reacting polyethylene glycolated sodium alginate with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide; (2) The resulting mixed solution was reacted with myocardial targeting peptide and cell-penetrating peptide to obtain the reaction product; (3) The obtained reaction product was freeze-dried to obtain the composite delivery carrier; The amino acid sequence of the myocardial targeting peptide is shown in SEQ ID NO: 1; The amino acid sequence of the cell-penetrating peptide is shown in SEQ ID NO: 2; The nucleotide sequence of circNCX1 is shown in SEQ ID NO: 3; The preparation method of the nanogel targeting cardiac radiation damage includes the following steps: The composite delivery carrier and circNCX1 plasmid were dissolved in water and then added dropwise to a CaCl2 solution to react and obtain the nanogel. The concentration of the CaCl2 solution is 1 mM to 10 mM; the ratio of the composite delivery vector, circNCX1 plasmid, water and CaCl2 solution is 1 mg to 20 mg: 10 μg to 100 μg: 1 mL: 2 mL.

2. The nanogel as described in claim 1, characterized in that, The ratio of the composite delivery vector to the circNCX1 plasmid is 1 mg to 10 mg: 15 μg to 25 μg.

3. The nanogel as described in claim 1, characterized in that, In step (2), the pH of the reaction system is 5-6; and / or, In step (2), the reaction temperature is room temperature and the reaction time is 12 hours; and / or, In step (1), the mass ratio of the polyethylene glycol-modified sodium alginate to 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide is 1:1~5:1~5; and / or, In step (1), the reaction time is 20 min to 30 min.

4. The nanogel according to any one of claims 1-3, characterized in that, The preparation method of the polyethylene glycol-modified sodium alginate includes the following steps: (a) Oxidizing sodium alginate to obtain oxidized sodium alginate; (b) Sodium alginate oxide, polyethylene glycol monomethyl ether amino, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide were subjected to amidation reaction to obtain polyethylene glycol-modified sodium alginate oxide.

5. The nanogel as described in claim 4, characterized in that, The preparation method of the oxidized sodium alginate includes the following steps: Sodium alginate was reacted with sodium periodate solution to obtain the reaction product; The sodium alginate oxide was obtained by precipitating the reaction product with ethanol.

6. The nanogel as described in claim 5, characterized in that, The mass ratio of sodium alginate to sodium periodate is 1~10:1~10; and / or, The concentration of the sodium periodate solution is 0.1 g / mL to 0.5 g / mL; and / or, In the system where sodium alginate and sodium periodate solution react, the reaction temperature is room temperature and the reaction time is 12 hours. In the step of precipitating the reaction product with ethanol, the reaction temperature is -10°C to 10°C.

7. The nanogel according to claim 1, characterized in that, In the step of dissolving the composite delivery carrier and circNCX1 plasmid in water and then adding them dropwise to a CaCl2 solution to obtain the nanogel, the pH value of the reaction is 4-9; and / or, The reaction temperature is 0°C to 50°C, and the reaction time is 1 hour to 72 hours.

8. The use of the nanogel targeting cardiac radiation injury according to any one of claims 1-7 in the preparation of medicaments for the prevention and / or treatment of cardiac radiation injury.

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