Degradable brush polymer drug carrier and application thereof

Abstract

The invention discloses a degradable brush-like polymer drug carrier and application thereof, and belongs to the technical field of high-molecular compounds, the brush-like polymer drug carrier is obtained by a click reaction of a polydisulfide main chain and a cationic side chain, the polydisulfide main chain in the structure can generate a special'sulfur-sulfur exchange 'reaction with free sulfydryl existing on cell membrane protein, the carried nucleic acid medicine is directly brought into cells through cell membranes, delivery of the nucleic acid medicine is completed, and after the nucleic acid medicine enters the body, under the action of a large amount of glutathione (GSH) existing in tumor cytoplasm, the nucleic acid medicine can be taken out from the body, so that the nucleic acid medicine can be taken out from the body. The main chain of the polydisulfide is broken and degraded, the nucleic acid medicine is released, and the method is suitable for delivery of the nucleic acid medicine.

Description

Technical Field

[0001] The invention relates to the technical field of polymer chemistry and biomedicine, and in particular to a degradable brush-shaped polymer drug carrier and application thereof. Background Art

[0002] Nucleic acid molecules show great potential in regulating gene expression. They can specifically silence target genes and are used to treat various diseases, including genetic diseases and cancer. Compared with traditional therapies, nucleic acid drugs can not only correct pathogenic gene defects, but also have the advantages of high specificity and long durability, which can minimize the frequency of administration and improve patient compliance. Important breakthroughs have been made in the treatment of genetic abnormalities, infectious diseases, tumors and other diseases. Therefore, the development of safe and efficient intracellular delivery technology is one of the keys to the development of nucleic acid molecule drugs.

[0003] The mainstream delivery vectors currently used include viral vectors and non-viral vectors. Viral vectors are still the main force in delivery tasks. Gene therapy products represented by AAV are relatively mature in production and application, but there are still problems such as insertion risk, packaging upper limit, one-time administration and liver toxicity. In order to make up for the shortcomings of viral vectors, the use of non-viral vectors for drug delivery has become a very promising alternative in recent years. Compared with traditional viral vectors, it has the advantages of low toxicity, low immune response, large vector capacity, wide source of materials, easy mass preparation and the genes carried are not integrated into the host cell genome.

[0004] In recent years, polymer-based nano-delivery systems are a relatively innovative delivery method. Reference 1 (Maximilian A. Beach, et al. Polymeric Nanoparticles for Drug Delivery. Chem Rev. 124 (9): 5505-5616, 2024, doi: 10.1021 / acs.chemrev.3c00705.) summarizes polymer-based nano-delivery systems that use dendritic macromolecules, polylactic acid-co-glycolic acid copolymers and other high molecular weight polymers as carriers to encapsulate RNA for delivery. The nano-delivery systems have physical and chemical properties such as biodegradability, biocompatibility, high water solubility, and storage stability, and are considered to be ideal drug delivery materials. The Chinese patent document with publication number CN118873512A discloses a non-liver-targeted nucleic acid drug delivery system based on electrostatic / chemical coupling dual anchoring, including a carrier core composed of a lipid nanocomplex and a nucleic acid molecule, and a carrier shell composed of albumin with good biocompatibility.

[0005] Non-viral vectors based on non-ionizable cationic lipids have also received extensive attention in the field of nucleic acid drug delivery. Since non-ionizable cationic lipid materials are highly positively charged, they can efficiently adsorb or compress nucleic acid drugs to form lipid nanoparticles, which are easy to bind to negatively charged cell membranes and enter target cells through endocytosis. However, due to the extremely high positive charge density, cationic lipid materials can cause severe cytotoxicity to target cells. At the same time, cationic carriers are easily cleared by the mononuclear phagocytic system in the body and are difficult to reach the target site.

[0006] Therefore, there is an urgent need to develop a safe, efficient and tumor-targeting nucleic acid drug delivery system to achieve efficient nucleic acid drug delivery. Summary of the invention

[0007] In view of the problems of cytotoxicity and inability to achieve responsiveness to tumor cells in polymer carriers in the prior art, the present invention provides a degradable brush-like polymer drug carrier suitable for the delivery of nucleic acid drugs.

[0008] A degradable brush-like polymer drug carrier, obtained by a click reaction between a polydisulfide main chain and a cationic side chain.

[0009] The structure of the polydisulfide main chain is:

[0010]

[0011] wherein x is an integer of 1 to 500, more preferably an integer of 30 to 200; y is an integer of 1 to 2000, more preferably an integer of 50 to 500; z is an integer of 1 to 1000, more preferably an integer of 1 to 10;

[0012] The structure of the cationic side chain is:

[0013]

[0014] Here, m is an integer from 10 to 60.

[0015] The present invention designs the structure of the drug carrier. Through the reaction between the polydisulfide main chain and the cationic side chain and the formed brush-like structure, the polydisulfide main chain can undergo a special "sulfur-sulfhydryl exchange" reaction with the free sulfhydryl groups on the cell membrane protein, and the carried nucleic acid drug molecules are directly brought into the cell through the cell membrane, thereby completing the delivery effect of the drug carrier.

[0016] Preferably, the molar ratio of the polydisulfide main chain to the cationic side chain is 1:1-200, more preferably 1:20-100.

[0017] Preferably, the click reaction conditions are 0-60° C., 2-48 h.

[0018] Preferably, the synthesis method of the polydisulfide backbone is as follows: under the action of a first promoter and a first catalyst, thioctic acid and a first compound containing a hydroxyl group and an azide group undergo a dehydration condensation reaction in an organic solvent to prepare a first intermediate; in an anaerobic environment, a second promoter and polyethylene glycol containing a thiol group and an azide group react to generate a thiol-containing initiator, under the action of the initiator, the first intermediate undergoes ring-opening polymerization, a quencher is added, and after the reaction is completed, post-treatment is performed to prepare the polydisulfide backbone.

[0019] Preferably, the first promoter is N,N'-carbonyldiimidazole, and the first catalyst is 4-dimethylaminopyridine; the reaction conditions of lipoic acid and the first compound containing hydroxyl and azide groups are 0-60°C and 2-48h.

[0020] Preferably, the second accelerator is tetramethylguanidine, the conditions for the ring-opening polymerization of the first intermediate are 20-40° C., 1-24 h; and the quencher is 2,2,2-trifluoroethyl acrylate.

[0021] Preferably, the synthesis method of the cationic side chain is as follows: under the action of a second catalyst and a ligand, a halogen-containing disulfide and dimethylaminoethyl methacrylate undergo an atom transfer radical polymerization reaction to prepare a second intermediate; under the action of a thiol reducing agent, the disulfide bond of the second intermediate is broken to form a terminal thiol, which is then subjected to a thiol-olefin click reaction with a second compound containing a double bond and an azadibenzocyclooctyne group to obtain a cationic side chain.

[0022] Preferably, the second catalyst is a copper salt, the ligand is 1,1,4,7,10,10-hexamethyltriethylenetetramine, the halogen-containing disulfide is bis[2-(2'-bromoisobutyryloxy)ethyl] disulfide; and the reaction conditions of the atom transfer radical polymerization are 20-40° C. and 1-24 h.

[0023] Preferably, the thiol reducing agent is tris(2-carboxyethyl)phosphine; and the reaction conditions of the thiol-olefin click reaction are 20-40° C. and 1-24 h.

[0024] The present invention also provides the use of the above-mentioned degradable brush-shaped polymer drug carrier in preparing a nucleic acid drug delivery system.

[0025] A nucleic acid drug delivery system comprises the degradable brush polymer drug carrier and a nucleic acid drug; the nucleic acid drug delivery system is a nanoscale delivery system.

[0026] In the present invention, the polydisulfide backbone on the drug carrier can undergo a special "sulfur-sulfide exchange" reaction with the free sulfhydryl groups on the cell membrane protein, bringing the carried nucleic acid drug directly into the cell through the cell membrane to complete the delivery of the nucleic acid drug. After entering the body, under the action of glutathione (GSH) present in large quantities in the tumor cytoplasm, the polydisulfide backbone is interrupted and degraded, releasing the nucleic acid drug. The nucleic acid drug delivery system in the present invention has tumor cell responsiveness and low cytotoxicity.

[0027] Preferably, the nucleic acid drug is circular single-stranded DNA (Css DNA).

[0028] In the present invention, the circular single-stranded DNA can use the circular single-stranded DNA reported in Tang L, Tian Z, Cheng J, et al. Circular single-stranded DNA as switchable vector for gene expression in mammalian cells [J]. Nature Communications, 2023, 14. DOI: 10.1038 / s41467-023-42437-6.

[0029] Preferably, in the nucleic acid drug delivery system, the ratio of the N content in the degradable brush polymer drug carrier to the phosphate group content in the nucleic acid drug (ie, the nitrogen-to-phosphorus ratio) is 2 to 20:1.

[0030] In the present invention, when the nitrogen-phosphorus ratio of the brush-like polymer drug carrier to the nucleic acid drug is within the above range, the brush-like polymer drug carrier can completely encapsulate the nucleic acid drug to prevent the nucleic acid drug from being enzymatically hydrolyzed.

[0031] The present invention also provides a method for preparing the nucleic acid drug delivery system, which comprises the following steps: uniformly mixing the above-mentioned degradable brush-like polymer drug carrier and the nucleic acid drug to obtain the drug.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The degradable brush polymer drug carrier of the present invention is prepared by grafting a tumor cell responsive polydisulfide main chain with a cationic side chain. The drug carrier has tumor cell responsiveness and is less toxic to normal cells.

[0034] (2) The degradable brush polymer drug carrier of the present invention can be self-assembled with nucleic acid drugs through electrostatic force to prepare a nucleic acid drug delivery system, which is suitable for targeted treatment of tumor cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1Schematic diagram of the principle of nucleic acid drug delivery system.

[0036] Figure 2 The polydisulfide backbone (Poly(LPN3) in Example 1 80 )'s H NMR spectrum.

[0037] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the cationic side chain (PDMAEMA30) in Example 1.

[0038] Figure 4 This is the H NMR spectrum of the brush polymer (SS80D30) in Example 1.

[0039] Figure 5 Poly(LPN3) prepared in Example 1 80 , PDMAEMA30 and SS80D30.

[0040] Figure 6 This is a graph showing the test results of the physical properties of the nucleic acid drug delivery system, where:

[0041] A is a gel imaging image of the nucleic acid drug delivery system with different nitrogen-phosphorus ratios prepared in Examples 2 to 5 and 7;

[0042] B is a dynamic light scattering (DLS) test graph of the nucleic acid drug delivery system prepared in Example 9.

[0043] Figure 7 This is a stability test result diagram of the nucleic acid drug delivery system, where:

[0044] A and B are the particle size analysis diagrams of the nucleic acid drug delivery system prepared in Example 9 and PDMAEMA30 after incubation for 1, 3, and 5 days, respectively;

[0045] C is the degradation curve of naked DNA in 0.1U / mL DNase I enzyme;

[0046] D and E are agarose gel electrophoresis diagrams showing the degradation of nucleic acid drugs and the nucleic acid drug delivery system prepared in Example 9 by DNase I, respectively.

[0047] Figure 8 This is the GPC spectrum of the brush polymer drug carrier SS80D30 after treatment with tri(2-carboxyethyl)phosphine hydrochloride (TCEP).

[0048] Fig. 9 The figure shows the delivery ability and cytotoxicity test results of the nucleic acid drug delivery system, where:

[0049] A and C are fluorescence images and quantitative analysis images of nucleic acid drug delivery systems in human breast cancer cells (MCF7) formed by mixing PDMAEMA30, SS80D30, and B-PEI with Css DNA respectively with N / P of 10, 15, and 20;

[0050] B and D are fluorescence images and quantitative analysis images of nucleic acid drug delivery systems in normal human intestinal epithelial cells (HIEC-6) formed by mixing PDMAEMA30, SS80D30, and B-PEI with Css DNA respectively with N / P of 10, 15, and 20;

[0051] E is a statistical graph of the cell activity of nucleic acid drug delivery systems in HIEC-6 formed by mixing PDMAEMA30, SS80D30, and B-PEI with Css DNA respectively with N / P of 5, 10, 15, and 20. DETAILED DESCRIPTION

[0052] The present invention will be further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited to the following examples.

[0053] The raw materials used in the present invention are all commercially available.

[0054] Example 1: Preparation of degradable brush polymer drug carrier

[0055] (1) Synthesis of Lipoic Acid Derivative Monomers

[0056]

[0057] Take lipoic acid (compound 1, 7 g, 33.98 mmol, 1 eq) and 3-azidopropanol (compound 2, 3.13 mL, 33.98 mmol, 1 eq) in a 500 mL round-bottom flask, add 100 mL of tetrahydrofuran (THF) to dissolve under nitrogen protection, and slowly add N, N'-carbonyldiimidazole (CDI) (7.7 g, 47.57 mmol, 1.4 eq) and 4-dimethylaminopyridine (DMAP) dropwise under ice bath conditions. The mixture was added with 100 mL of dichloromethane solution of (5.8 g, 47.57 mmol, 1.4 eq), and the temperature was naturally raised to room temperature. After reacting for 12 h, 100 mL of saturated saline was added to the reaction solution for washing and extraction, which was repeated three times. A certain amount of anhydrous sodium sulfate was added to the obtained organic phase, dried, filtered, and concentrated under reduced pressure to obtain a crude product. The crude product was separated and purified by silica gel column chromatography (petroleum ether: dichloromethane = 3:1) to obtain a yellow viscous liquid 3 (7.2 g, yield 82%).

[0058] (2) Synthesis of polydisulfide backbone

[0059]

[0060] Compound 3 (878.6 mg, 3.04 mmol, 1 eq) in step (1) was placed in a 2 mL sample bottle, tetramethylguanidine (5.5 μL, 0.04 mmol, 0.0125 eq) was added and mixed thoroughly, and then 100 μL of ultra-dry THF solution of azidopolyethylene glycol thiol (N3-PEG2000-SH) (86.9 mg, 0.04 mmol, 0.0125 eq) was added to the reaction solution. After the reaction reached the target degree of polymerization, 100 μL of THF solution of 2,2,2-trifluoroethyl acrylate ((101 μL, 0.80 mmol, 0.125 eq)) was added thereto to terminate the polymerization reaction. After stirring the reaction for 1 h, the reaction solution was repeatedly precipitated in ice ether three times and vacuum dried to obtain a colorless slurry compound 4 (abbreviated as Poly(LPN3) 80 , 715 mg, yield 74%), the H NMR spectrum of compound 4 is as follows Figure 2 Shown

[0061] (3) Synthesis of poly (2-dimethylaminoethyl methacrylate)

[0062]

[0063] Bis[2-(2'-bromoisobutyryloxy)ethyl]disulfide (compound 5, 30.1 mg, 0.066 mmol, 1 eq) was dissolved in anisole, cuprous bromide (9.5 mg, 0.066 mmol, 1 eq) and ligand 1,1,4,7,10,10-hexamethyltriethylenetetramine (15.3 mg, 0.066 mmol, 1 eq) were dissolved in 100 μL N,N-dimethylformamide, dimethylaminoethyl methacrylate (compound 6, 314.2 mg, 2 mmol, 30 eq) was removed from the polymerization inhibitor, and then deoxygenated with nitrogen for 30 min. The above solutions were mixed in a 5 mL reaction bottle and reacted in a nitrogen environment for 5 hours. The reaction solution was dialyzed in ethylenediaminetetraacetic acid tetrasodium salt solution and ultrapure water for 24 hours, respectively, and then freeze-dried to obtain poly(2-dimethylaminoethyl methacrylate) (334 mg, yield 97%) with a degree of polymerization of 60.

[0064] (4) Cationic side chain

[0065]

[0066] Compound 7 (100 mg, 0.02 mmol, 1 eq) was dissolved in 1 mL of tetrahydrofuran, and 68 μL of tri(2-carboxyethyl)phosphine aqueous solution (TCEP) (0.5 M, pH = 7.0) was added. After stirring for 30 min, dibenzocyclooctylmaleimide (25.6 mg, 0.06 mmol, 3 eq) was added and reacted overnight. The reaction solution was extracted with water and ether, the upper ether was discarded, passed through a desalting column, and freeze-dried to obtain a side chain with a polymerization degree of 30 (compound 8, referred to as PDMAEMA30, 87 mg, yield 80%). The H NMR spectrum of compound 8 is shown as follows: Figure 3 shown.

[0067] (5) Synthesis of degradable brush polymer drug carriers

[0068]

[0069] Poly(LPN3) obtained in step (2) 80 (2 mg, 0.086 μmol, 1 eq) and PDMAEMA30 (20.7 mg, 0.0068 mmol, 80 eq) obtained in step (4) were dissolved in 1 mL N,N-dimethylformamide and stirred at room temperature overnight. After dialysis for 24 hours, a 10 mL ultrafiltration centrifuge tube with a molecular weight cut-off of 50 kDa was used to remove the remaining PDMAEMA30. The product was collected and freeze-dried to obtain a degradable brush-like polymer drug carrier with a degree of polymerization of 80 (compound 9, referred to as SS80D30, 12 mg, yield 52%). The H NMR spectrum of compound 9 is shown in FIG. Figure 4 shown.

[0070] Example 2: Preparation of nucleic acid drug delivery system

[0071] Take 0.4 μg of SS80D30 prepared in Example 1 to prepare a 1 mg / mL aqueous solution, and mix it with 0.5 μg of Css DNA (using Tang L, Tian Z, Cheng J, et al. Circular single-stranded DNA as switchable vector for gene expression in mammalian cells [J]. Nature Communications, 2023, 14. DOI: 10.1038 / s41467-023-42437-6. reported circular single-stranded DNA), vortex mix, and let stand for 30 minutes to obtain a nucleic acid drug delivery system with a nitrogen-phosphorus ratio of 1: 2.

[0072] Embodiments 3 to 10

[0073] The preparation method is similar to that of Example 2, with the differences shown in the following table.

[0074] Table 1: Reaction conditions of Examples 2 to 10

[0075]

[0076] Sample analysis

[0077] 1. GPC analysis

[0078] Poly(LPN3) prepared in Example 1 80 , PDMAEMA30 and SS80D30 were analyzed using gel permeation chromatography (GPC).

[0079] Figure 5 Poly(LPN3) prepared in Example 1 80 , PDMAEMA30 and SS80D30, among which the molecular weight of SS80D30 is significantly greater than that of Poly(LPN3) 80 、PDMAEMA30, indicating that through Poly(LPN3) 80 SS80D30 was successfully prepared by click reaction with PDMAEMA30.

[0080] 2. Physical properties analysis of nucleic acid drug delivery systems

[0081] (1) Encapsulation capacity analysis

[0082] The nucleic acid drug delivery systems with different nitrogen-phosphorus ratios prepared in Examples 2 to 5 and 7 were subjected to horizontal electrophoresis experiments at 120 V for 30 minutes using 1% agarose gel to verify the encapsulation of nucleic acids in the nanoparticles, and the images were obtained using a gel imager.

[0083] Figure 6 A in FIG. 1 is a gel imaging image of the nucleic acid drug delivery system with different nitrogen-phosphorus ratios prepared in Examples 2 to 5 and 7. The results show that when the nitrogen-phosphorus ratio is 2, the brush-like polymer drug carrier can completely encapsulate the nucleic acid drug, and the larger the nitrogen-phosphorus ratio, the better the encapsulation effect.

[0084] (2) Particle size and zeta potential analysis

[0085] The particle size and potential of the nucleic acid drug delivery system prepared in Example 9 were tested using dynamic light scattering (DLS).

[0086] Figure 6 B is a dynamic light scattering (DLS) test chart of the nucleic acid drug delivery system prepared in Example 9. The results show that the average particle size of the nucleic acid drug delivery system is 190.3 nm and the zeta potential is +37.8 mV.

[0087] 3. Stability Analysis of Nucleic Acid Drug Delivery System

[0088] (1) Particle size stability analysis

[0089] The PDMAEMA30 prepared in Example 1 and the nucleic acid drug delivery system prepared in Example 9 were incubated in a PBS buffer solution at pH 7.4 for 1, 3 and 5 days, and the particle sizes of the polymer nanoparticles were detected.

[0090] Figure 7 A and B are the particle size analysis diagrams of the nucleic acid drug delivery system prepared in Example 9 and PDMAEMA30 after incubation for 1, 3, and 5 days, respectively. The results show that after the nucleic acid drug delivery system and PDMAEMA30 are incubated in PBS buffer, the particle size of the nucleic acid drug delivery system is more stable.

[0091] (2) DNA degradation analysis

[0092] DNase I enzyme was added to the nucleic acid drug delivery system solution prepared in Example 9 at a working concentration of 0.1 unit / mL, and the mixture was incubated for 0, 5, 10, 20, 60, 120 and 240 minutes, respectively. EDTA was used to terminate the enzymatic hydrolysis, and 2 μL of 1 mg / mL sodium heparin aqueous solution was added to the nucleic acid drug delivery system as a control group. Agarose gel was used to characterize the degradation, and Imagej was used to quantitatively analyze the degradation rate.

[0093] Figure 7 Figure C is the degradation curve of naked DNA in 0.1U / mL DNase I enzyme. The results show that as the DNase I enzyme treatment time increases, the DNA is gradually enzymatically hydrolyzed and is completely enzymatically hydrolyzed after 20 minutes.

[0094] Figure 7 D and E in the figure are agarose gel electrophoresis diagrams of the degradation of nucleic acid drugs and the nucleic acid drug delivery system prepared in Example 9 by DNase I enzyme, respectively. The results show that the nucleic acid drug will be gradually enzymatically hydrolyzed under DNase I enzyme treatment, while the nucleic acid drug delivery system can protect the nucleic acid drug from being degraded for a long time.

[0095] 4. Analysis of disulfide responsiveness of brush polymer drug carriers

[0096] The SS80D30 prepared in Example 1 was dissolved in N,N-dimethylformamide containing 1.3 mM tri(2-carboxyethyl)phosphine hydrochloride (TCEP), and the relative molecular weight change was tested using a gel permeation chromatography (GPC).

[0097] Figure 8This is the GPC spectrum of SS80D30 after treatment with tri(2-carboxyethyl)phosphine hydrochloride (TCEP). The results show that under the action of TCEP, the disulfide main chain of SS80D30 can be broken and the molecular weight is reduced.

[0098] 5. Delivery Capacity and Cytotoxicity Analysis of Nucleic Acid Drug Delivery System

[0099] (1) Delivery capability analysis

[0100] Commercial transfection reagents branched B-PEI (Mw = 25000) and PDMAEMA30 were mixed with CssDNA to form nucleic acid drug delivery systems with N / P of 10, 15 and 20 as the control group. The nucleic acid drug delivery systems prepared in Examples 8 to 10 were used for transfection experiments in human breast cancer cells (MCF7) and normal human intestinal epithelial cells (HIEC-6), respectively, and the transfection conditions were studied using fluorescence microscopy and flow cytometry.

[0101] Fig. 9 A to D in the figure are fluorescence images and quantitative analysis images of nucleic acid drug delivery systems with N / P of 10, 15 and 20 formed by mixing PDMAEMA30, SS80D30 and B-PEI with Css DNA respectively in human breast cancer cells (MCF7) and normal human intestinal epithelial cells (HIEC-6). The results show that the transfection efficiency of the cationic side chain PDMAEMA30 is lower than that of the nucleic acid drug delivery system prepared in Examples 8 to 10, indicating that the design of the polydisulfide main chain structure and the brush structure can improve the delivery efficiency of nucleic acid drugs; the transfection efficiency of the nucleic acid drug delivery system prepared in Examples 8 to 10 in MCF7 is equivalent to that of B-PEI, while the transfection efficiency in HIEC-6 is significantly lower than that of B-PEI, which is about 1 / 4 times that of B-PEI, indicating that the nucleic acid drug delivery system has tumor cell responsiveness.

[0102] (2) Cytotoxicity analysis

[0103] PDMAEMA30, SS80D30, and B-PEI were mixed with CssDNA to form nucleic acid drug delivery systems with N / P of 5, 10, 15, and 20, respectively. After being cultured in normal human intestinal epithelial cells (HIEC-6) for 24 hours, the cell viability was evaluated using the CCK-8 detection kit.

[0104] Fig. 9 E in the figure is a statistical chart of cell activity in HIEC-6 of nucleic acid drug delivery systems formed by mixing PDMAEMA30, SS80D30, and B-PEI with Css DNA respectively, with N / P of 5, 10, 15, and 20. The results show that the toxicity of the nucleic acid drug delivery system is significantly lower than that of the B-PEI group.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A degradable brush polymer drug carrier, characterized in that: It is obtained by click reaction between the polydisulfide main chain and the cationic side chain. The structure of the polydisulfide main chain is: Wherein, x is an integer of 1 to 500; y is an integer of 1 to 2000; z is an integer of 1 to 1000; The structure of the cationic side chain is: Here, m is an integer from 10 to 60.

2. The degradable brush polymer drug carrier according to claim 1, characterized in that: The molar ratio of the polydisulfide main chain to the cationic side chain is 1:1-200.

3. The degradable brush polymer drug carrier according to claim 1, characterized in that: The click reaction conditions are 0-60° C., 2-48 h.

4. The degradable brush polymer drug carrier according to claim 1, characterized in that: The synthesis method of the polydisulfide main chain is as follows: under the action of a first promoter and a first catalyst, thioctic acid and a first compound containing a hydroxyl group and an azide group undergo a dehydration condensation reaction in an organic solvent to prepare a first intermediate; in an oxygen-free environment, a second promoter and polyethylene glycol containing a thiol group and an azide group react to generate a thiol-containing initiator, under the action of the initiator, the first intermediate undergoes ring-opening polymerization, and then a quencher is added. After the reaction is completed, post-treatment is performed to prepare the polydisulfide main chain.

5. The degradable brush polymer drug carrier according to claim 1, characterized in that: The synthesis method of the cationic side chain is as follows: under the action of a second catalyst and a ligand, a halogen-containing disulfide and dimethylaminoethyl methacrylate undergo an atom transfer radical polymerization reaction to prepare a second intermediate; under the action of a thiol reducing agent, the disulfide bond of the second intermediate is broken to form a terminal thiol, and then a thiol-olefin click reaction is carried out with a second compound containing a double bond and an azadibenzocyclooctyne group to obtain a cationic side chain.

6. Use of the degradable brush polymer drug carrier according to any one of claims 1 to 5 in the preparation of a nucleic acid drug delivery system.

7. A nucleic acid drug delivery system comprising the degradable brush polymer drug carrier according to any one of claims 1 to 5 and a nucleic acid drug.

8. The nucleic acid drug delivery system according to claim 7, characterized in that: The nucleic acid drug is a circular single-stranded DNA.

9. The nucleic acid drug delivery system according to claim 7, characterized in that: In the nucleic acid drug delivery system, the nitrogen-phosphorus ratio of the degradable brush-shaped polymer drug carrier and the nucleic acid drug is 2 to 20:

1.

10. The method for preparing a nucleic acid drug delivery system according to any one of claims 7 to 9, characterized in that: The method comprises the following steps: uniformly mixing the degradable brush-shaped polymer drug carrier according to any one of claims 1 to 5 and the nucleic acid drug to obtain the drug.

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