Clearing-accumulation conversion cationic polymer nano-platform for targeted therapy of acute kidney injury as well as preparation method and application of clearing-accumulation conversion cationic polymer nano-platform

Abstract

The invention provides a removal-accumulation conversion cationic polymer nano-platform for targeted therapy of acute kidney injury as well as a preparation method and application of the removal-accumulation conversion cationic polymer nano-platform, and belongs to the technical field of biological medicines. The removal-accumulation conversion cationic polymer nano platform for the targeted therapy of the acute kidney injury comprises a curcumin modified 2-aminoethyl methacrylate hydrochloride polymer. On the basis of the innovative theory of kidney function state dependent delivery, a 2-aminoethyl methacrylate hydrochloride polymer with a unique clearance-accumulation conversion mechanism is adopted as a carrier specifically targeting AKI kidney, curcumin with an AKI treatment effect is modified on the carrier, specific accumulation can be achieved in the damaged kidney, and the effect of treating AKI can be achieved. And the compound can be rapidly excreted in healthy kidneys to avoid systemic toxicity, realizes a targeting effect and a controllable removal effect on AKI kidneys, and has high targeting efficiency, controllable removal characteristic and good biological safety.

Description

Technical Field

[0001] This invention relates to the field of biomedical technology, specifically to a clearance-accumulation conversion cationic polymer nanoplatform for targeted treatment of acute kidney injury, its preparation method, and its application. Background Technology

[0002] Acute kidney injury (AKI) is a common critical illness, causing more than 2 million deaths worldwide each year, posing a significant public health challenge. Existing clinical drugs have limited effectiveness in repairing damaged kidney tissue, and long-term or high-dose use may induce drug-induced kidney injury. Therefore, there is an urgent need to develop safe and effective new treatments.

[0003] Nanomedicine delivery systems offer unique advantages in improving drug bioavailability and reducing systemic toxicity, providing a new approach for AKI treatment. However, current nanomedicines still face key challenges such as insufficient kidney-targeting specificity and metabolic safety, limiting their widespread application in the treatment of kidney diseases.

[0004] In existing technologies, nanotherapies based on ligand-receptor targeted modification strategies have attracted much attention for kidney-targeted delivery of AKI due to their advantages such as simple preparation, controllable modification, and diverse carriers. However, this strategy has inherent limitations: during AKI treatment, as renal function recovers, receptor expression levels decrease significantly, which may lead to off-target effects of nanomedicines. If off-target drugs are not removed in time, it will also increase the distribution of non-target tissues and the risk of toxicity.

[0005] Therefore, developing a nanomedicine delivery system that combines efficient renal targeting and controllable clearance capabilities is of great significance for the precise and safe treatment of AKI. Summary of the Invention

[0006] In view of the technical problems existing in the background art, this application provides a clearance-accumulation conversion cationic polymer nanoplatform for targeted treatment of acute kidney injury, its preparation method and application. This nanoplatform can utilize the difference in kidney clearance rate under physiological and pathological conditions to form a unique "clearance-accumulation conversion" mechanism, which can effectively improve safety while achieving precise targeted treatment of AKI, and breaks through the limitations of traditional ligand-receptor targeted modification strategies.

[0007] In a first aspect, embodiments of this application provide a clearance-accumulation conversion cationic polymer nanoplatform for targeted treatment of acute kidney injury, comprising a 2-aminoethyl methacrylate hydrochloride polymer modified with curcumin.

[0008] In some embodiments, the modification of curcumin includes: carboxylating the curcumin to couple the carboxylated curcumin with the amino group of the 2-aminoethyl methacrylate hydrochloride polymer.

[0009] In some embodiments, the clearance-accumulation conversion cationic polymer nanoplatform for targeted treatment of acute kidney injury comprises the following structural formula: Where x and y are both positive integers, and y > x.

[0010] Secondly, embodiments of this application provide a method for preparing a clearance-accumulation conversion cationic polymer nanoplatform for targeted treatment of acute kidney injury, comprising the following steps: Using 2-aminoethyl methacrylate hydrochloride as a monomer, a polymer of 2-aminoethyl methacrylate hydrochloride was obtained through polymerization. Carboxylated curcumin was subjected to carboxylation to obtain carboxylated curcumin. The 2-aminoethyl methacrylate hydrochloride polymer was subjected to an amidation reaction with the carboxylated curcumin to obtain the reaction product; The reaction products were self-assembled to obtain nanoparticles.

[0011] In some embodiments, the polymerization reaction is a reversible addition-fragmentation chain transfer polymerization reaction; The preparation steps of the 2-aminoethyl methacrylate hydrochloride polymer include: 2-Aminoethyl methacrylate hydrochloride, RAFT reagent, initiator and solvent were mixed and reacted thoroughly. The product was collected and dried to obtain the 2-aminoethyl methacrylate hydrochloride polymer.

[0012] In some embodiments, the carboxylation treatment step includes: Curcumin was reacted with succinic anhydride, and the reaction was followed by dialysis and drying to obtain carboxylated curcumin.

[0013] In some embodiments, the amidation reaction step includes: The carboxylated curcumin, N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and solvent were mixed and reacted thoroughly. Then, the 2-aminoethyl methacrylate hydrochloride polymer was added and the reaction continued. After dialysis and drying, the reaction product was obtained.

[0014] In some embodiments, during the amidation reaction, the molar ratio of the 2-aminoethyl methacrylate hydrochloride polymer to the carboxylated curcumin is 1:(15~20).

[0015] In some embodiments, the self-assembly step includes: The reaction product is dissolved in a solvent to prepare a polymer solution; During the ultrasonic treatment, ultrapure water is added to the polymer solution to form a colloidal suspension with the Tyndall effect; The colloidal suspension was dialyzed to obtain the nanoparticles.

[0016] Thirdly, embodiments of this application provide the application of the nanoplatform described in the first aspect or the nanoplatform prepared in the second aspect in the preparation of targeted drugs for acute kidney injury.

[0017] The beneficial effects of this application are: The cationic polymer nanoplatform for targeted therapy of acute kidney injury (AKI) provided in this application utilizes a 2-aminoethyl methacrylate hydrochloride polymer with a unique "clearance-accumulation conversion" mechanism. This polymer can be rapidly excreted from healthy kidneys to avoid systemic toxicity, while specifically accumulating in damaged kidneys, with the renal accumulation concentration linearly correlated with the degree of injury. Based on this, this application achieves targeted action and controllable clearance of AKI-affected kidneys by modifying the 2-aminoethyl methacrylate hydrochloride polymer with curcumin, which has AKI therapeutic effects. This results in high targeting efficiency, controllable clearance characteristics, and good biocompatibility.

[0018] In vitro experiments showed that the clearance-accumulation conversion cationic polymer nanoplatform provided in this application for targeted therapy of acute kidney injury (AKI) significantly enhances the mitochondrial repair effect of curcumin and strengthens its antioxidant and anti-inflammatory efficacy through a triple synergistic mechanism of efficient cellular uptake, lysosomal escape, and mitochondrial co-localization. Furthermore, in an AKI model, after intraperitoneal injection, intravenous administration, or oral administration, the nanoplatform specifically targeted and accumulated in the AKI pathological environment, significantly reducing serum creatinine and blood urea nitrogen to near-normal levels within 48 hours, while alleviating pathological damage and inflammatory infiltration. Long-term evaluation showed sustained repair capacity, with a 28-day survival rate of 100%, and no hepatotoxicity or hematological abnormalities were observed.

[0019] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0021] Figure 1 This is a schematic diagram of the synthetic route of the clearance-accumulation conversion cationic polymer nanoplatform used for targeted treatment of acute kidney injury in Example 1 of this application.

[0022] Figure 2 This is a schematic diagram of the self-assembled structure of AMA-Cur nanoparticles in Example 1 of this application.

[0023] Figure 3 The pAMA, Cur-COOH, and AMA-Cur prepared in Example 1 of this application 1 H NMR spectrum.

[0024] Figure 4 The size parameters, morphological characteristics, zeta potential values, and stability test results of the AMA-Cur nanoparticles prepared in Example 1 of this application are shown.

[0025] Figure 5 The results of cell viability and hemolysis experiments of the AMA-Cur nanoparticles prepared in Example 1 of this application are shown.

[0026] Figure 6 The results of the cell uptake experiment of the nanoplatform prepared in Example 1 of this application in the H2O2-induced HK-2 cell damage model are shown.

[0027] Figure 7 The results of the lysosomal escape experiment of the nanoplatform prepared in Example 1 of this application in the H2O2-induced HK-2 cell damage model.

[0028] Figure 8 The results of the mitochondrial colocalization experiment of the nanoplatform prepared in Example 1 of this application in the H2O2-induced HK-2 cell injury model.

[0029] Figure 9 The results of the DCFH-DA staining assay were obtained using the nanoplatform prepared in Example 1 of this application in an H2O2-induced HK-2 cell injury model.

[0030] Figure 10 The effect of the nanoplatform prepared in Example 1 of this application on the expression level of pro-inflammatory cytokines in an H2O2-induced HK-2 cell injury model.

[0031] Figure 11The results of cytotoxicity and anti-apoptosis tests of the nanoplatform prepared in Example 1 of this application in the H2O2-induced HK-2 cell injury model are presented.

[0032] Figure 12 This is a comparison of the metabolic differences of AMA-Cur in various organs between normal mice and AKI model mice.

[0033] Figure 13 Fluorescence imaging results of AMA-Cur carrying different fluorescent labels.

[0034] Figure 14 The results of BOD-AMA-Cur fluorescence imaging are shown for different administration routes.

[0035] Figure 15 The results of the localization analysis of BOD-AMA-Cur in the renal tubules of AKI kidneys.

[0036] Figure 16 The results show the efficacy of different doses of AMA-Cur on CDDP-induced AKI model mice.

[0037] Figure 17 The prognostic results of AMA-Cur treatment in CDDP-induced AKI model mice.

[0038] Figure 18 This is the result of the biosafety assessment of AMA-Cur.

[0039] Figure 19 Comparison results for BOD-AMA, BOD-DMAEMA, BOD-HEMA, and BOD-PEG.

[0040] Figure 20 Comparison results for BOD-AMA-HEMA, BOD-AMA-PBA, and BOD-AMA-Cur. Detailed Implementation

[0041] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0043] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0044] While existing nanotherapies based on ligand-receptor targeting modification strategies can achieve targeted delivery to the kidneys in cases of acute kidney injury (AKI), the significant decrease in receptor expression levels during AKI treatment, as kidney function recovers, can lead to off-target effects of nanomedicines. Failure to promptly remove off-target drugs can also increase the risk of distribution to non-target tissues and toxicity. In other words, current research neglects the dynamic regulation of nanomaterials' targeting behavior in the kidneys by changes in the pathological state.

[0045] As the most important excretory organ, the kidneys experience a significant reduction in metabolic function during acute kidney injury (AKI). Therefore, based on the significant differences in metabolic function of the kidneys under different physiological states, this application proposes an innovative theory of "renal function state-dependent delivery." This theory redefines the therapeutic value of renal clearance mechanisms, namely, utilizing the efficient clearance characteristics of healthy kidneys to reduce systemic toxicity, while the retention effect caused by impaired excretion function in AKI kidneys can provide a new pathway for the specific accumulation of lesions.

[0046] The targeted design approach proposed in this application, based on differences in kidney function (rapid clearance in healthy states and specific retention in pathological states), provides an innovative approach for developing novel AKI-targeted nanocarriers. Specifically, based on the aforementioned innovative theory and targeted design approach, this application, through extensive research and analysis, discovered that the 2-aminoethyl methacrylate hydrochloride polymer possesses a unique "clearance-accumulation conversion" mechanism. It exhibits a unique dynamic metabolic regulation characteristic of "retention when needed, excretion otherwise" in both AKI-affected and healthy kidneys. That is, under normal physiological conditions, the polymer can be rapidly cleared in a short time, but in the AKI model, it exhibits a "retention when needed" characteristic, and the accumulation concentration of the polymer in AKI-affected kidneys is linearly correlated with the degree of kidney damage.

[0047] Based on this, in a first aspect, embodiments of this application provide a clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of AKI, comprising a 2-aminoethyl methacrylate hydrochloride polymer modified with curcumin. The 2-aminoethyl methacrylate hydrochloride polymer can serve as a carrier with kidney-specific targeting capabilities for AKI, thereby improving the lesion-targeting precision and systemic safety of AKI therapeutic drugs. Simultaneously, since the 2-aminoethyl methacrylate hydrochloride polymer itself has no therapeutic activity, this application modifies the 2-aminoethyl methacrylate hydrochloride polymer with AKI therapeutic activity using curcumin to form a clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury, thereby achieving precise targeted therapy for AKI while simultaneously possessing high targeting efficiency, controllable clearance characteristics, and good biocompatibility.

[0048] Compared with traditional AKI nanotherapy, the "renal function state-dependent delivery" theory proposed in this application and the "clearance-accumulation conversion" cationic polymer platform designed under this theory show significant advantages. Its rapid clearance mechanism in healthy kidneys effectively avoids the risk of long-term tissue retention that may be caused by traditional nanocarriers, while its specific retention characteristics in AKI kidneys enable precise treatment. These two mechanisms complement each other, ensuring both systemic safety and therapeutic efficacy.

[0049] Furthermore, in some embodiments, the modification of curcumin includes: carboxylating curcumin to couple the carboxylated curcumin with the amino group of the 2-aminoethyl methacrylate hydrochloride polymer.

[0050] In the technical solution of this application embodiment, by first carboxylating curcumin, the carboxyl groups grafted after carboxylation can be coupled with the amino groups of the 2-aminoethyl methacrylate hydrochloride polymer, thereby improving the binding strength between curcumin and the 2-aminoethyl methacrylate hydrochloride polymer.

[0051] Furthermore, in some embodiments, the clearance-accumulation conversion cationic polymer nanoplatform for targeted treatment of AKI includes the following structural formula: Where x and y are both positive integers, and y > x.

[0052] In the technical solutions of this application embodiment, the above structural formula includes a 2-aminoethyl methacrylate hydrochloride polymer and curcumin coupled to the amino side chain of the polymer, which can achieve precise targeted treatment of AKI and effectively improve safety. More specifically, in some embodiments of this application, the value of y is 20, and the value of x ranges from 5 to 18, specifically including 5, 10, and 18, more preferably 18. In other embodiments of this application, the values ​​of x and y can be appropriately adjusted as needed.

[0053] Secondly, embodiments of this application provide a method for preparing a clearance-accumulation conversion cationic polymer nanoplatform for targeted treatment of acute kidney injury, comprising the following steps: Using 2-aminoethyl methacrylate hydrochloride as a monomer, a polymer of 2-aminoethyl methacrylate hydrochloride was obtained through polymerization. Carboxylated curcumin was subjected to carboxylation to obtain carboxylated curcumin. The 2-aminoethyl methacrylate hydrochloride polymer was subjected to an amidation reaction with carboxylated curcumin to obtain the reaction product; Nanoparticles were obtained by self-assembly of the reaction products.

[0054] In this embodiment, the carboxylated curcumin is coupled to the amino group of the 2-aminoethyl methacrylate hydrochloride polymer via the above-described method. This allows the 2-aminoethyl methacrylate hydrochloride polymer to serve as a carrier specifically targeting AKI-affected kidneys. Curcumin with AKI therapeutic effects is then stably modified onto this carrier, resulting in a nanoplatform with "clearance-accumulation conversion" characteristics. This allows for rapid excretion in healthy kidneys to avoid systemic toxicity, while also specifically accumulating in AKI-affected kidneys, thus achieving targeted action and controllable clearance of AKI-affected kidneys. Furthermore, the preparation method provided in this application is simple to operate, easy to control, and meets the needs of practical applications.

[0055] Furthermore, in some embodiments, the polymerization reaction is a reversible addition-fragmentation chain transfer (RAFT) polymerization reaction; The preparation steps of the 2-aminoethyl methacrylate hydrochloride polymer include: 2-Aminoethyl methacrylate hydrochloride (AMA), RAFT reagent, initiator and solvent were mixed and reacted thoroughly. The product was collected and dried to obtain the 2-aminoethyl methacrylate hydrochloride polymer.

[0056] In the technical solution of this application embodiment, 2-aminoethyl methacrylate hydrochloride polymer can be prepared simply and efficiently by using a reversible addition-fragmentation chain transfer polymerization reaction.

[0057] More specifically, in some embodiments, the RAFT reagent is preferably 4-cyanopentanoic acid dithiobenzoic acid (CPADB), the initiator is preferably azobisisobutyronitrile (AIBN), and the solvent is preferably N,N-dimethylformamide (DMF). The molar ratio of 2-aminoethyl methacrylate hydrochloride, RAFT reagent, and initiator is preferably 20 : (0.8~1.2) : (0.4~0.6). The reaction is preferably carried out at 70°C for 40~56 h. After the reaction is completed, the solution is preferably precipitated with n-hexane and dried under vacuum to obtain the 2-aminoethyl methacrylate hydrochloride polymer.

[0058] Furthermore, in some embodiments, the carboxylation step includes: Curcumin (Cur) was reacted with succinic anhydride, and then dialyzed and dried to obtain carboxylated curcumin (Cur-COOH).

[0059] In the technical solution of this application embodiment, curcumin can be carboxylated in a simple and efficient manner through the above method, so that the carboxylated curcumin can be coupled with the amino group of the 2-aminoethyl methacrylate hydrochloride polymer through the carboxyl group.

[0060] More specifically, in some embodiments, 4-dimethylaminopyridine (4-DMAP) is added during the carboxylation treatment, and the molar ratio of curcumin, 4-dimethylaminopyridine and succinic anhydride is preferably 1:(1.8~2.2):(1~1.4). During the carboxylation treatment, curcumin, 4-dimethylaminopyridine and succinic anhydride are preferably dissolved in anhydrous acetone. The resulting mixture is purged with argon and reacted at room temperature for 20~28h. After the reaction is completed, the acetone is removed by vacuum distillation, and the residue is dissolved in dimethyl sulfoxide (DMSO). The resulting solution is loaded into a dialysis tube with a molecular weight cutoff of 300 Daltons, dialyzed with anhydrous methanol for 24h, then dialyzed with ultrapure water for 48h, and then freeze-dried to obtain carboxylated curcumin.

[0061] Furthermore, in some embodiments, the amidation reaction step includes: Carboxylated curcumin, N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and solvent were mixed and reacted thoroughly. Then, 2-aminoethyl methacrylate hydrochloride polymer was added to continue the reaction. After dialysis and drying, the reaction product was obtained.

[0062] In the technical solution of this application embodiment, the carboxyl group in carboxylated curcumin can be coupled with the amino side chain of 2-aminoethyl methacrylate hydrochloride polymer through an amidation reaction, thereby preparing a 2-aminoethyl methacrylate hydrochloride polymer modified with curcumin.

[0063] Furthermore, in some embodiments, during the amidation reaction, the molar ratio of 2-aminoethyl methacrylate hydrochloride polymer to carboxylated curcumin is 1:(15~20).

[0064] In the technical solution of this application embodiment, by adjusting the molar ratio of 2-aminoethyl methacrylate hydrochloride polymer to carboxylated curcumin, the ratio of 2-aminoethyl methacrylate hydrochloride polymer to curcumin in the final reaction product can be controlled to achieve a better therapeutic effect.

[0065] More specifically, in some embodiments, during the amidation reaction, carboxylated curcumin, N-hydroxysuccinimide (NHS), and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) are preferably dissolved in N,N-dimethylformamide (DMF) at a molar ratio of 1:(1.8~2.2):(1.8~2.2). The reaction is carried out under argon protection at 20~30°C for 20~40 min. After the reaction continues for 24 h, 2-aminoethyl methacrylate hydrochloride polymer is added, and the reaction is continued at 20~30°C with stirring for 20~28 h. The resulting solution is dialyzed with ultrapure water through a dialysis tube (molecular weight cutoff of 3500) for 48 h, and then freeze-dried to obtain the final reaction product.

[0066] Furthermore, in some embodiments, the self-assembly step includes: The reaction products are dissolved in a solvent to prepare a polymer solution; During the ultrasonic treatment, ultrapure water is added to the polymer solution to form a colloidal suspension with the Tyndall effect; Nanoparticles were obtained by dialysis of the colloidal suspension.

[0067] In the technical solution of this application embodiment, the corresponding nanoparticles can be formed by self-assembly, and these nanoparticles can serve as a cationic polymer nanoplatform for targeted treatment of acute kidney injury.

[0068] Specifically, in some embodiments, when performing self-assembly, it is preferable to dissolve the reaction product in the solvent dimethyl sulfoxide (DMSO) to prepare a polymer solution with a concentration of 15~25 mg / mL; when dialysis of the colloidal suspension, it is preferable to use a dialysis tube with a molecular weight cutoff of 3500 and dialyze with ultrapure water for 12 hours.

[0069] Thirdly, embodiments of this application provide the application of the nanoplatform described in the first aspect or the nanoplatform prepared in the second aspect in the preparation of targeted drugs for acute kidney injury.

[0070] In the technical solution of this application embodiment, the nanoplatform has the characteristics of "clearance-accumulation conversion", which realizes the targeted effect and controllable clearance effect on AKI kidney, and has high targeting efficiency, controllable clearance characteristics and good biosafety, and can be used to prepare targeted drugs for acute kidney injury.

[0071] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0072] Example 1 This embodiment provides a method for preparing a clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury, the synthetic route of which is as follows: Figure 1 As shown (after calculation), Figure 1 The value of x is approximately 18, and the value of y is approximately 20. The specific steps include the following: Synthesis of S1,2-aminoethyl methacrylate hydrochloride polymer (pAMA) 2-Aminoethyl methacrylate hydrochloride (AMA, 331.2 mg, 20 mmol), the reversible addition-fragmentation chain transfer (RAFT) reagent 4-cyanopentanoic acid dithiobenzoic acid (CPADB, 28 mg, 1 mmol), and the initiator azobisisobutyronitrile (AIBN, 8 mg, 0.5 mmol) were dissolved in N,N-dimethylformamide (DMF, 2 mL) and placed in a reaction flask. After purging the flask with argon for 30 minutes, the mixture was heated in an oil bath at 70 °C for 48 h to carry out the polymerization reaction. After the reaction was completed, the resulting solution was precipitated three times with n-hexane and then dried under vacuum to obtain the 2-aminoethyl methacrylate hydrochloride polymer (pAMA).

[0073] S2, Synthesis of carboxylated curcumin (Cur-COOH) Curcumin (Cur, 368 mg, 1 mmol), 4-dimethylaminopyridine (4-DMAP, 244 mg, 2 mmol), and succinic anhydride (122 mg, 1.2 mmol) were dissolved in anhydrous acetone (30 mL) to obtain a mixture. This mixture was purged with argon for 40 minutes and reacted at room temperature for 24 h. After the reaction was complete, acetone was removed under reduced pressure, and the residue was dissolved in dimethyl sulfoxide (DMSO). The resulting solution was placed in a dialysis tube with a molecular weight cutoff of 300 Daltons, dialyzed against anhydrous methanol for 24 h, then against ultrapure water for 48 h, and finally freeze-dried to obtain carboxylated curcumin (Cur-COOH).

[0074] Synthesis of S3 and polymer p(AMA-co(AMA-Cur)) The Cur-COOH (153 mg, 18 mmol), NHS (75 mg, 36 mmol), and EDC (125 mg, 36 mmol) obtained in step S2 were dissolved in 2.5 mL of DMF and reacted at 25 °C for 30 minutes under argon protection. After the reaction continued for 24 hours, pAMA (60 mg, 1 mmol) obtained in step S1 was added, and the reaction was stirred at 25 °C for another 24 hours. The resulting solution was dialyzed with ultrapure water for 48 hours using a dialysis tube (molecular weight cutoff of 3500), and then freeze-dried to obtain the reaction product, denoted as p(AMA-co-(AMA-Cur)).

[0075] Synthesis of S4 nanoparticles (AMA-Cur) The p(AMA-co-(AMA-Cur)) obtained in step S3 was dissolved in dimethyl sulfoxide (DMSO) to prepare a polymer solution of 20 mg / mL. During sonication, 1.8 mL of ultrapure water was added dropwise to 200 μL of the polymer solution to form a colloidal suspension exhibiting the Tyndall effect. This colloidal suspension was dialyzed for 12 hours using a dialysis tube with a molecular weight cutoff of 3500 to obtain p(AMA-co-(AMA-Cur)) nanoparticles, which were designated AMA-Cur. A schematic diagram of the self-assembly in this step is shown below. Figure 2 As shown.

[0076] use 1 Hydrogen nuclear magnetic resonance (HNMR) spectroscopy was performed on pAMA prepared in step S1, Cur-COOH prepared in step S2, and AMA-Cur prepared in step S4 in this embodiment. The results are as follows: Figure 3 As shown. By Figure 3 As can be seen from Figure a, pAMA 1In the 1H NMR spectrum, the proton signal of the methylene group in the AMA monomer appeared in the δ 3.9-4.1 ppm range, while the proton signals of the methylene and methyl groups in the polymer backbone were located in the δ 0.7-2.0 ppm range, proving that the polymerization reaction of AMA was successfully completed. Figure 3 Figure b in the diagram (Cur-COOH) 1 The 1H NMR spectrum showed that single-terminal carboxylation disrupted the molecular symmetry of curcumin, resulting in the appearance of methoxy proton peaks at different chemical shifts (two single peaks in the δ 3.90-3.97 ppm range), proving that the synthesis of single-terminal carboxylated curcumin was successful. Figure 3 Figure c in AMA-Cur 1 The H NMR spectrum simultaneously showed characteristic signals of pAMA and Cur-COOH: the aromatic ring proton peak was located in the range of δ 6.11-7.30 ppm, the amino proton peak was located in the range of δ 1.77 ppm, and the amide bond proton peak was located in the range of δ 8.01 ppm, proving that pAMA and Cur-COOH successfully underwent an amidation reaction.

[0077] The size parameters, morphological characteristics, zeta potential, and stability of the AMA-Cur nanoparticles obtained in step S4 of this embodiment were detected, and the results are as follows: Figure 4 As shown. Among them, Figure 4 Figure a shows the hydrodynamic diameter distribution measured by a dynamic light scattering instrument, indicating a hydrodynamic diameter of 147.44 nm, confirming the successful synthesis of nanoparticles. Figure b (transmission electron microscopy image) shows that the nanoparticles are uniformly dispersed spherical or near-spherical with smooth and flat surfaces. Figure c (zeta potential detection image) shows a zeta potential of +11.53 mV, comprehensively demonstrating the success of the nanomedicine preparation. Figure d (storage stability test results) shows that after 7 days of storage in a water environment at 4°C, the particle size change rate of AMA-Cur nanoparticles is still less than 5%, exhibiting high stability.

[0078] The cell viability of the AMA-Cur nanoparticles prepared in step S4 of this embodiment was detected, and a hemolysis experiment was performed. The test results are as follows: Figure 5 As shown in the figure. The cell viability assay method included: seeding human renal proximal tubular epithelial cells (HK-2) into 96-well plates and incubating overnight at 37°C. Different concentrations of Cur and AMA-Cur gradient dilutions were prepared using culture medium and added to different wells. After incubation at 37°C for 24 hours, 10 μL of CCK-8 solution was added to each well, and incubation continued for 2 hours. Cell viability was then measured, and the results are shown in the figure. Figure 5As shown in Figure a. The hemolysis experiment involved collecting fresh mouse blood, centrifuging for 10 minutes, washing three times with physiological saline, and resuspending the precipitated red blood cells in physiological saline to prepare a 10% (v / v) suspension. 50 μL of the red blood cell suspension was aliquoted into centrifuge tubes and incubated with 950 μL of pAMA or AMA-Cur at different concentrations. The negative control group consisted of red blood cells mixed with 950 μL of physiological saline, while the positive control group was treated with 950 μL of ultrapure water. After incubation at 37°C for 2 hours, the cells were centrifuged again for 10 minutes. The percentage of hemolysis was calculated by detecting the absorbance of the supernatant at 576 nm. The test structure is shown in Figure a. Figure 5 The bc diagram is shown in the figure.

[0079] Depend on Figure 5 As shown in Figure a, compared with an equivalent dose of free curcumin (Cur), the AMA-Cur prepared in this example significantly reduced cytotoxicity and exhibited higher cell viability; Figure 5 As can be seen from the BC diagram, the AMA-Cur prepared in this embodiment did not cause hemolysis in the concentration range of 6.25-100 μg / mL, proving that it has good blood compatibility.

[0080] The AMA-Cur nanoparticles prepared in this embodiment can serve as a clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury, and can be used in the preparation of targeted drugs for acute kidney injury. To demonstrate its application effect, the following provides a detailed description of the nanoplatform's in vitro cell experiments, specific targeting effects, efficacy evaluation, and in vivo biosafety assessment.

[0081] I. In vitro cell experiments 1. Cellular uptake and mitochondrial targeting This application uses the human proximal tubular epithelial cell line HK-2, which maintains a differentiation phenotype similar to natural proximal tubular epithelial cells, as an in vitro model system. To establish a kidney injury model, HK-2 cells were seeded in 24-well plates and cultured overnight, followed by pretreatment with 200 μM hydrogen peroxide for 4 hours. Subsequently, the hydrogen peroxide-stimulated HK-2 cells were co-incubated with BOD-nanoparticles (BOD, BOD-AMA-Cur, BOD concentration 0.1 μg / mL) labeled with the green fluorescent dye boron dipyrrole methylene (BODIPY). Cellular uptake of BOD and BOD-AMA-Cur was assessed at 0.5 hours and 1 hour after incubation, respectively. The results are as follows: Figure 6 As shown.

[0082] Figure 6Figures a and b in the diagram are cell uptake images and fluorescence intensity quantitative analysis diagrams, respectively. As can be seen from figures a and b, BOD-AMA-Cur showed a significantly higher cell internalization rate 1 hour after treatment compared with BOD, which may be attributed to the cell uptake-promoting effect of the AMA polymer in BOD-AMA-Cur. Figure 6 Figures c and d show the quantitative analysis of BOD and BOD-AMA-Cur uptake in hydrogen peroxide-damaged HK-2 cells using flow cytometry. Figures c and d also demonstrate that, compared to BOD, BOD-AMA-Cur exhibits stronger time-dependent fluorescence enhancement and higher cellular uptake efficiency. That is, from... Figure 6 It can be concluded that AMA polymers can effectively improve cell internalization efficiency.

[0083] Given the central role of mitochondria in the pathophysiological mechanisms of AKI, maintaining or restoring their integrity has become a key objective of novel AKI therapies. Since drug carriers must achieve lysosomal escape to complete intracellular delivery, this application first investigated the intracellular lysosomal escape capability of AMA-Cur. The lysosomal escape experiment involved: H2O2-damaged HK-2 cells were seeded in 24-well plates and cultured overnight; then, the cells were treated with BOD-AMA-Cur for 0.5 hours or 1 hour; followed by washing three times with PBS buffer; then staining with Lyso-Tracker Red (75 nM) for 30 minutes; after removing the staining solution, fresh culture medium was added. Images of lysosomal escape were acquired using a fluorescence microscope and analyzed using ImageJ software. The results are shown below. Figure 7 As shown. By Figure 7 It can be seen that the lysosomal colocalization coefficient (Pearson correlation coefficient) of BOD-AMA-Cur decreased significantly from 0.88 at 0.5 hours to 0.67 at 1 hour, proving that it has a highly efficient escape ability.

[0084] Further mitochondrial colocalization assays were performed. The method included: H2O2-damaged HK-2 cells were seeded in 24-well plates and incubated overnight. Cells were then treated with BOD-AMA-Cur for 1 hour, washed three times with PBS buffer, stained with mitochondrial tracing agent (100 nM) for 30 minutes, fixed with 4% paraformaldehyde for 10 minutes, and stained with DAPI for 10 minutes. Mitochondrial colocalization was observed under a fluorescence microscope and analyzed using ImageJ software. The results are shown below. Figure 8 As shown. Figure 8In the figures, Figures a and b show the results of mitochondrial colocalization analysis. These results further reveal a significant colocalization between BOD-AMA-Cur (green fluorescence) and mitochondrial markers (red fluorescence) (P=0.82), verifying its ability to deliver Cur to mitochondria to exert a therapeutic effect. Figures c and d show the fluorescence staining images detected by JC-10 fluorescent dye and the fluorescence intensity of various substances in the cells. As can be seen from Figures c and d, H2O2 stimulation leads to a significant decrease in mitochondrial membrane potential, which is manifested as a decrease in fluorescence intensity. AMA-Cur co-incubation can effectively restore mitochondrial dysfunction.

[0085] comprehensive Figure 6-8 The experimental results show that AMA-Cur prepared in Example 1 of this application effectively enhances the mitochondrial repair effect of curcumin through a triple synergistic mechanism of efficient cellular uptake, lysosomal escape and mitochondrial colocalization.

[0086] 2. In vitro studies on antioxidant and anti-inflammatory effects In acute kidney injury, mitochondrial dysfunction leads to excessive production of reactive oxygen species (ROS), which weakens cellular antioxidant defenses and triggers oxidative stress, ultimately activating the inflammatory cascade and apoptosis pathway. To evaluate the effect of AMA-Cur prepared in Example 1 on the antioxidant stress of H2O2-damaged HK-2 cells, this application used DCFH-DA staining to quantitatively detect intracellular ROS levels. The results are as follows: Figure 9 As shown. By Figure 9 It can be seen that the fluorescence intensity of the H2O2 treatment group was significantly higher than that of the control group, indicating that the oxidative stress injury model was successfully established. In contrast, the fluorescence intensity of the AMA-Cur treatment group was significantly lower than that of the free Cur group and close to that of the normal control group, indicating that AMA-Cur can effectively reduce ROS accumulation in H2O2-damaged HK-2 cells.

[0087] In the H2O2-induced HK-2 cell injury model, the expression levels of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α were further detected, and the results are as follows: Figure 10 As shown. By Figure 10 It can be seen that the expression levels of 1L-1β, 1L-6 and TNF-α were significantly increased in the H2O2 treatment group, but after AMA-Cur treatment, the concentrations of these three inflammatory factors were significantly lower than those in the H2O2 treatment group and the free Cur treatment group, indicating that AMA-Cur may enhance the anti-inflammatory effect of curcumin by improving intracellular drug delivery efficiency.

[0088] Further cytotoxicity and anti-apoptosis assays were performed, and the results were as follows: Figure 11 As shown. By Figure 11Figure a shows that after co-culturing AMA-Cur with H2O2-damaged HK-2 cells, the cell survival rate increased to over 90%, indicating that AMA-Cur is non-cytotoxic and has the ability to restore cell function. Figure 11 As shown in Figure b, based on the Giemsa staining results, cells treated with H2O2 exhibited typical apoptotic morphological characteristics, such as cell shrinkage and fragmentation; while cells treated with AMA-Cur maintained a near-normal morphology, with clear boundaries and intact structure, indicating that cell damage was effectively restored. Figure 11 As shown in Figure c, flow cytometry analysis confirms that AMA-Cur treatment can significantly reduce H2O2-induced apoptosis, lowering the proportion of apoptotic cells to near the control level.

[0089] comprehensive Figure 9-11 The results show that AMA-Cur can effectively protect renal cells from H2O2 damage by inhibiting oxidative stress and inflammatory response, thereby reducing apoptosis and promoting functional recovery.

[0090] II. Specific Targeting Effect This application uses in vivo fluorescence imaging technology to compare and analyze the metabolic differences of AMA-Cur in the kidneys of normal mice and AKI model mice. The results are as follows: Figure 12 As shown. The AKI model was established in 8-week-old male C57BL / 6J mice by intraperitoneal injection of 20 mg / kg cisplatin. Figure 12 It can be seen that BOD-AMA-Cur in healthy mice is rapidly excreted through the kidneys with extremely low retention; while in AKI model mice, BOD-AMA-Cur shows significant accumulation in the kidneys, reaching peak concentration 4 hours after administration, and the retention time is prolonged to 24 hours. At 4, 8, and 10 hours after administration, the fluorescence intensity in the kidneys of AKI model mice was 4.1 times, 5.3 times, and 3.2 times higher than that in healthy mice at the corresponding time points, respectively.

[0091] To verify the multifunctionality of AMA-Cur as an AKI nanocarrier, this application loaded three fluorescent dyes with different structures (BOD, Cy5.5, and ICG) into AMA-Cur, and evaluated their tissue distribution in AKI model mice using in vivo imaging technology. The results are as follows: Figure 13 As shown. By Figure 13It can be seen that free ICG and Cy5.5 mainly accumulate in the liver, while BOD is distributed in small amounts in both the liver and kidneys; while ICG-AMA-Cur, Cy5.5-AMA-Cur and BOD-AMA-Cur all show specific accumulation in the kidneys of AKI, indicating that AMA-Cur can reshape the distribution pattern of the dye in vivo, confirming its targeting advantage.

[0092] Given that intraperitoneal injection, oral administration, and intravenous injection are the three main routes affecting drug bioavailability, this application used these three methods to administer BOD-AMA-Cur to AKI model mice to evaluate its effect on renal targeting. In vivo imaging results are as follows: Figure 14 As shown. By Figure 14 It can be seen that BOD-AMA-Cur achieved kidney-specific targeting of AKI after intraperitoneal injection, oral administration, and intravenous injection. This targeting characteristic, which is independent of the route of administration, provides important value for the treatment of kidney diseases.

[0093] During acute kidney injury (AKI), renal tubular cells are the primary site of damage, and the pathway by which BOD-AMA-Cur enters these cells determines its therapeutic efficacy. Fluorescence localization analysis of renal tissue revealed the distribution of BOD-AMA-Cur as follows: Figure 15 As shown. By Figure 15 As can be seen, the boundaries of the renal tubules labeled with AQP1 show clear outlines (red), the BOD signal is evenly distributed in the renal tubular cells (green), and the significant co-localization with the edge of AQP1 (yellow) confirms the precise delivery and intracytoplasmic accumulation of the fluorescent label BOD in the renal tubular cells, providing morphological evidence for targeted therapy of AKI kidney.

[0094] comprehensive Figure 12-15 The results show that the AMA-Cur prepared in this embodiment can achieve AKI-specific targeting through a pathologically dependent differential clearance mechanism. Specifically, it is rapidly cleared from healthy kidneys to prevent long-term toxicity, but specifically enriched in damaged kidneys to ensure precise drug release and targeted repair within the pathological microenvironment. This metabolically adaptive, pathologically responsive targeting mechanism provides a more precise and safer guarantee for AKI treatment compared to traditional ligand-receptor binding-based targeting strategies.

[0095] III. Evaluation of the efficacy of AMA-Cur in cisplatin (CDDP)-induced AKI model 1. The efficacy of AMA-Cur in treating AKI A CDDP-induced AKI model was established and drug administration was performed. The efficacy of each treatment group was evaluated based on changes in key indicators of kidney injury. The results are as follows: Figure 16 As shown.

[0096] Specifically, Figure 16 Figure a in the figure shows the method and administration regimen for establishing the CDDP-induced AKI model. After establishing the corresponding AKI model, free curcumin (Cur, 6 mg / kg) and AMA-Cur at doses of 2 mg / kg, 4 mg / kg, and 6 mg / kg were administered via intraperitoneal injection. The administration methods for each treatment group are represented as Cur, AMA-Cur-2, AMA-Cur-4, and AMA-Cur-6, respectively. Serum and kidney samples were collected for testing 48 hours after administration.

[0097] Depend on Figure 16 As shown in Figure b, the kidneys of AKI mice were grayish-white. After AMA-Cur intervention, the appearance of the kidneys was significantly improved, and their color became close to that of the normal kidneys in the control group. To assess the histopathological damage in the model mice, the kidney tissues were stained with hematoxylin and eosin (H&E), periodic acid and Schiff (PAS), and CD68 antibody macrophage immunostaining. The results are as follows: Figure 16 The results are shown in Figure ch. Specifically, Figure c shows extensive vacuolar degeneration of renal tubules in the AKI group, Figure d shows structural damage such as brush border detachment, and Figure e shows an approximately 2-fold increase in macrophage infiltration. All of these pathological changes showed significant dose-dependent improvement in the AMA-Cur treatment group, with better results than the free Cur group. The quantitative pathological scoring results in Figure fh are also consistent with these conclusions. These results indicate that compared with the AKI model group, the AMA-Cur group showed significantly reduced renal tubular damage, effective alleviation of cast formation and tubular dilation, and pathological changes approaching normal levels. This demonstrates that the AMA carrier can improve the bioavailability of Cur and significantly enhance its anti-inflammatory and tissue repair efficacy, proving that AMA-Cur has a positive therapeutic effect on alleviating CDDP-induced AKI.

[0098] Depend on Figure 16 As shown in the figure, serum creatinine (SCr) and blood urea nitrogen (BUN) levels, important clinical markers of renal function impairment, were significantly elevated in the AKI model. Compared with the AKI model group, the SCr and BUN levels in the AMA-Cur treatment group were significantly reduced in a dose-dependent manner. Specifically, the AMA-Cur-6 group, with a dose of 6 mg / kg, approached the levels of the healthy control group and was significantly better than the free Cur group with the same dose. Figure 16The KM plot shows the effect of AMA-Cur treatment on key pro-inflammatory factors (TNF-α, IL-1β, and IL-6). Specifically, due to the systemic inflammatory response accompanying AKI, the expression levels of various pro-inflammatory factors in the serum of the AKI model were significantly increased. Compared with the AKI model group, AMA-Cur treatment dose-dependently reduced the expression levels of these pro-inflammatory factors. Among them, the AMA-Cur-6 group had the best anti-inflammatory effect, restoring them to near-normal levels, which was superior to the free Cur group with the same dose. This indicates that the AMA carrier achieves an effective therapeutic concentration of Cur at the site of injury through targeted delivery, overcoming the deficiency of insufficient renal accumulation of free drugs. It also demonstrates that AMA-Cur can effectively inhibit the systemic inflammatory response associated with AKI, and AMA-Cur-6 can rapidly inhibit the inflammatory response to block the progression of AKI.

[0099] 2. Prognostic observation of AMA-Cur treatment for AKI A CDDP-induced AKI model was established, and the drug was administered. The renal prognosis of AKI was then assessed. The results are as follows: Figure 17 As shown.

[0100] Specifically, Figure 17 Figure a in the figure shows the method for establishing the CDDP-induced AKI model and the drug administration and prognostic observation protocol. After establishing the corresponding AKI model, free curcumin (Cur, 6 mg / kg) and AMA-Cur at doses of 2 mg / kg, 4 mg / kg and 6 mg / kg, respectively, were administered via intraperitoneal injection. The drug administration methods for each treatment group are represented as Cur, AMA-Cur-2, AMA-Cur-4 and AMA-Cur-6, respectively. Serum and kidney samples were collected at different time points after drug administration for testing.

[0101] Depend on Figure 17 As shown in Figure b, the survival rate of CDDP-induced AKI model mice was significantly reduced, indicating successful model establishment and high lethality. In contrast, free Cur treatment only slightly improved survival, while different doses of AMA-Cur treatment groups all showed significant survival advantages, with survival rates significantly higher than the AKI and Cur groups. Furthermore, the survival rate of the AMA-Cur-6 group was consistent with the healthy control group, indicating that AMA-Cur effectively protects AKI mice from death, with a significantly better effect than free Cur. Figure 17As shown in Figure c, the body weight of AKI mice was significantly lower than that of the healthy control group, reflecting a severe systemic disease state. The free Cur treatment group had limited effect on improving weight recovery, while the AMA-Cur treatment group, especially the AMA-Cur-4 and AMA-Cur-6 groups, showed a significantly smaller decrease in body weight and recovered to near the level of the healthy control group more quickly. This indicates that targeted therapy with AMA-Cur can effectively increase the drug concentration in the kidneys compared to free Cur, thereby improving survival rate and effectively alleviating the systemic consumption and toxicity caused by AKI, significantly improving the overall health of the animals.

[0102] Figure 17 Figure d in the figure shows the H&E staining results of kidney tissue in each group after 14 and 28 days of treatment. As can be seen from the figure, the proximal tubule cells of mice in the AMA-Cur-6 group have regular morphology, uniform staining of the brush border villi of the lumen, few cell cytoplasmic swelling, no nuclear fragmentation, and proliferating and repaired renal tubule cells. The renal tubule damage and inflammation are significantly reduced compared with the AKI group.

[0103] Figure 17 The ef graph shows the results of four renal function indicators (BUN, Scr, Glu, and UA) after 14 and 28 days of treatment. The ef graph shows that the levels of BUN, Scr, Glu, and UA in the AMA-Cur-6 group were close to those in the healthy control group, indicating that AMA-Cur effectively restores renal filtration and excretion functions, and this effect is sustained. Furthermore, because AKI is accompanied by a strong inflammatory response, the expression levels of pro-inflammatory factors IL-6, IL-1β, and TNF-α in serum are significantly increased. Figure 17 As shown in the g-plot, the AMA-Cur-6 group reduced pro-inflammatory factors to levels close to those of the healthy control group, demonstrating a significant anti-inflammatory effect with long-term stability. To assess the systemic safety of AMA-Cur treatment, this application also measured serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels 28 days after treatment. The results are as follows: Figure 17 The h-plot shows that AST and ALT levels in the AMA-Cur-6 group were within the normal range after treatment, indicating that AMA-Cur treatment does not cause significant liver damage and has good liver safety.

[0104] Long-term observation has confirmed that the kidneys treated with AMA-Cur exhibit continuous repair characteristics, and renal function indicators are stably maintained within the physiological range. None of the animals in the AMA-Cur-6 group progressed to chronic kidney disease, and no fibrotic lesions or atrophic changes were observed in the kidney tissue. The 28-day survival rate reached 100%, and there were no statistically significant differences in the activity status, weight gain trend, and healthy control group of the experimental animals. This proves that AMA-Cur can not only achieve complete recovery from acute damage, but also effectively block the pathological process of AKI transforming into chronic disease.

[0105] IV. In vivo biosafety assessment of AMA-Cur After administering the prescribed dose of free Cur and AMA-Cur to mice at a dose of 6 mg / kg, biosafety assessments were performed, and the results are as follows: Figure 18 As shown.

[0106] Specifically, H&E staining was used to assess the tissue integrity of major organs (heart, liver, spleen, lungs, and kidneys). Figure 18 Figure a in the diagram shows the detection of renal function using serum biochemical indicators. Figure 18 (bc diagram in the image), and analyzed hematological parameters using whole cell count (CBC). Figure 18 (See dg graph). As shown in graph a, no significant pathological changes were observed in any of the tested organs; as shown in graphs b and c, the measured values ​​of uric acid nitrogen (BUN), creatinine (SCr), uric acid (UA), and glucose (Glu) were all within the normal physiological range; as shown in graph dg, there were no significant differences in hematological parameters between the treatment group and the control group.

[0107] The results above show that AMA-Cur administration can maintain all detected physiological parameters within the normal range, demonstrating good biocompatibility.

[0108] In summary, the scavenging-accumulation switching cationic polymer nanoplatform (AMA-Cur) prepared in this application successfully achieves targeted and efficient repair of AKI. This nanoplatform utilizes the unique "scavenging-accumulation switching" renal response characteristics of AMA polymers. Under normal physiological conditions, it can be rapidly cleared by the kidneys to avoid systemic toxicity, while in the pathological environment of AKI, it can achieve specific targeting of damaged areas through a retention effect. Furthermore, this nanoplatform can significantly improve the bioavailability of curcumin. In vitro models have confirmed that it can promote cellular uptake efficiency, enable lysosomal escape and precise delivery to mitochondria, thereby effectively scavenging reactive oxygen species, inhibiting pro-inflammatory cytokines, and blocking apoptosis pathways. In a cisplatin-induced AKI model, after administration of AMA-Cur (6 mg / kg) via intraperitoneal, intravenous, or oral routes, the drug specifically accumulated in the damaged kidneys, significantly reducing serum creatinine and uric acid nitrogen to near-normal levels within 48 hours, while simultaneously alleviating pathological damage and inflammatory infiltration. Long-term evaluation showed sustained recovery capabilities, with a 28-day survival rate of 100%, stable renal function indicators, persistently low levels of inflammatory cytokine expression, and no hepatotoxicity or hematological abnormalities. Overall, the clearance-accumulation conversion cationic polymer nanoplatform (AMA-Cur) designed based on the theory of "renal function state-dependent delivery" for targeted AKI therapy in this application provides a nanotherapy platform that combines high efficacy and safety, while advancing precision treatment strategies.

[0109] Comparative Example To demonstrate that the "clearance-accumulation conversion" renal response characteristic of the AMA polymer used in this application is a unique effect of this substance, and not common to any polymer, this application uses cationic monomer DMAEMA, neutral monomer HEMA, and neutral monomer PEG as monomers in the comparative examples to prepare corresponding polymers via RAFT polymerization, and compares them with the AMA polymer synthesized in Example 1 of this application. Using the green fluorescent dye BOD as a fluorescent label, BOD-AMA, BOD-DMAEMA, BOD-HEMA, and BOD-PEG were synthesized respectively, and comparative experiments were conducted. The results are as follows. Figure 19 As shown.

[0110] Specifically, Figure 19 Figure a in the diagram shows the structural schematics of the above substances. A cisplatin-induced AKI mouse model was established, and the accumulation of each of the above substances was detected in various organs. The results are as follows: Figure 19As shown in Figure BC, 2 hours after injection, BOD-AMA exhibited a significant enrichment effect in the kidneys of patients with AKI, with its renal fluorescence intensity being 2-4 times higher than that of BOD-DMAEMA, BOD-HEMA, and BOD-PEG, demonstrating that the polymer of AMA has a targeted accumulation effect that other polymers do not possess.

[0111] To verify whether the targeting ability of AKI could still be retained after chemical modification, AKI was modified with the functional monomers HEMA and PBA, respectively, and compared with AMA-Cur prepared in Example 1 of this application. Using the green fluorescent dye BOD as a fluorescent label, BOD-AMA-HEMA, BOD-AMA-PBA, and BOD-AMA-Cur were synthesized and compared. The results are as follows. Figure 20 As shown.

[0112] Specifically, Figure 20 Figure a in the diagram shows the structural schematics of the above substances. A cisplatin-induced AKI mouse model was established, and the accumulation of each of the above substances was detected in various organs. The results are as follows: Figure 20 As shown in Figure 2bc, BOD-AMA-HEMA, BOD-AMA-PBA, and BOD-AMA-Cur all maintained their specific targeting ability to the kidneys in cases of AKI, demonstrating that AMA is the core functional molecule for achieving kidney targeting in AKI, and that the renal fluorescence intensity of BOD-AMA-Cur is higher than that of the other substances.

[0113] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury, characterized in that, This includes 2-aminoethyl methacrylate hydrochloride polymers modified with curcumin.

2. The clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury according to claim 1, characterized in that, The modification of curcumin includes: carboxylating the curcumin to couple the carboxylated curcumin with the amino group of the 2-aminoethyl methacrylate hydrochloride polymer.

3. The clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury according to claim 2, characterized in that, Including the following structural formulas: Where x and y are both positive integers, and y > x.

4. A method for preparing a clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury, characterized in that, Includes the following steps: Using 2-aminoethyl methacrylate hydrochloride as a monomer, a polymer of 2-aminoethyl methacrylate hydrochloride was obtained through polymerization. Carboxylated curcumin was subjected to carboxylation to obtain carboxylated curcumin. The 2-aminoethyl methacrylate hydrochloride polymer was subjected to an amidation reaction with the carboxylated curcumin to obtain the reaction product; The reaction products were self-assembled to obtain nanoparticles.

5. The method for preparing the clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury according to claim 4, characterized in that, The polymerization reaction is a reversible addition-fragmentation chain transfer polymerization reaction; The preparation steps of the 2-aminoethyl methacrylate hydrochloride polymer include: 2-Aminoethyl methacrylate hydrochloride, RAFT reagent, initiator and solvent were mixed and reacted thoroughly. The product was collected and dried to obtain the 2-aminoethyl methacrylate hydrochloride polymer.

6. The method for preparing the clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury according to claim 4, characterized in that, The carboxylation treatment step includes: Curcumin was reacted with succinic anhydride, and the reaction was followed by dialysis and drying to obtain carboxylated curcumin.

7. The method for preparing the clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury according to claim 4, characterized in that, The amidation reaction includes the following steps: The carboxylated curcumin, N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and solvent were mixed and reacted thoroughly. Then, the 2-aminoethyl methacrylate hydrochloride polymer was added and the reaction continued. After dialysis and drying, the reaction product was obtained.

8. The method for preparing the clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury according to claim 4, characterized in that, During the amidation reaction, the molar ratio of the 2-aminoethyl methacrylate hydrochloride polymer to the carboxylated curcumin is 1:(15~20).

9. The method for preparing the clearance-accumulation conversion cationic polymer nanoplatform for targeted therapy of acute kidney injury according to claim 4, characterized in that, The self-assembly steps include: The reaction product is dissolved in a solvent to prepare a polymer solution; During the ultrasonic treatment, ultrapure water is added to the polymer solution to form a colloidal suspension with the Tyndall effect; The colloidal suspension was dialyzed to obtain the nanoparticles.

10. The use of a nanoplatform according to any one of claims 1-3 or a nanoplatform prepared by the preparation method according to any one of claims 4-9 in the preparation of targeted drugs for acute kidney injury.

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