Nano drug delivery system based on metal polyphenol network

Abstract

The invention relates to the technical field of biological medicine nano-drug delivery, in particular to a nano-drug delivery system based on a metal polyphenol network, and solves the problems that an existing MPN nano-drug delivery system is low in drug loading capacity, obvious in burst release, poor in stability, single in response and lack of targeting capacity. The system comprises a nanoparticle core formed by self-assembly of metal ions and polyphenol compounds, the surface of the nanoparticle core is coated with a biocompatible polymer shell, a hydrophobic drug is loaded inside the nanoparticle core, the particle size of the nanoparticle core is 50-300 nanometers, the nanoparticle core has pH responsiveness and a dynamic reversible coordination structure, and an organic solvent is not needed in the preparation process. The drug loading efficiency is remarkably improved, burst release is inhibited, the in-vivo stability is enhanced, tumor microenvironment responsive drug release is achieved, the circulation time is prolonged through the polymer shell, tumor accumulation is improved, and a safe and controllable delivery platform is provided for precise and efficient treatment.

Description

Technical Field

[0001] This invention relates to the field of biomedical nanomedicine delivery technology, and in particular to a nanomedicine delivery system based on a metal polyphenol network. Background Technology

[0002] Nanoparticle drug delivery systems have garnered significant attention in the biomedical field in recent years as a crucial strategy for enhancing drug efficacy and achieving precision medicine. Their core objective is to efficiently and safely deliver drugs to lesion sites via nanoscale carriers, thereby improving drug efficacy, reducing toxic side effects, and enhancing drug solubility, stability, and bioavailability. Among numerous nanocarriers, metal polyphenol networks (MPNs), as an emerging biocompatible material, have attracted considerable attention due to their unique self-assembly mechanism and excellent physicochemical properties. MPNs consist of natural polyphenolic compounds (such as tannic acid and gallic acid) and metal ions (such as Fe). 3 ⁺、Cu 2 ⁺、Zn 2 (e.g., ⁺) spontaneously form under mild conditions through coordination, and have advantages such as simple preparation, no need for toxic solvents or cross-linking agents, tunable structure, and diverse functions, showing broad application prospects in drug delivery, bioimaging, and integrated diagnosis and treatment.

[0003] Existing MPN nanomedicine delivery systems face significant challenges in practical applications, including limited drug loading capacity, significant burst release effects, insufficient in vivo stability, limited stimulus response, lack of active targeting capabilities, and difficulty in real-time monitoring of drug distribution. These issues directly lead to premature drug leakage in the bloodstream, low accumulation efficiency at tumor sites, narrow therapeutic windows, and an inability to meet the demands for high-precision and high-safety clinical treatment.

[0004] Therefore, to address the shortcomings of existing technologies, we urgently need a nano-drug delivery system based on metal polyphenol networks to solve this problem. This novel nano-drug delivery system should possess high drug loading efficiency, excellent colloidal and physiological stability, multi-stimulus responsiveness, active target recognition capability, and integrated diagnostic and therapeutic functions, thereby significantly improving the precision of drug delivery and therapeutic efficacy. Simultaneously, it should better meet the comprehensive performance requirements of modern precision medicine for intelligent nanocarriers, providing strong support for the efficient and safe treatment of major diseases such as cancer. Summary of the Invention

[0005] The purpose of this invention is to provide a nano-drug delivery system based on metal polyphenol networks, which solves the problems faced by existing MPN nano-drug delivery systems in practical applications, such as limited drug loading capacity, significant burst release effect, insufficient in vivo stability, single stimulus response, lack of active targeting capability, and difficulty in real-time monitoring of drug distribution.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A nanoparticle drug delivery system based on a metal polyphenol network includes a nanoparticle core formed by the self-assembly of metal ions and polyphenolic compounds through coordination interactions. The nanoparticle core is coated with a biocompatible polymer shell, and the nanoparticle core is loaded with hydrophobic drug molecules. The metal ions are selected from one or more of iron, zinc, copper, and manganese ions. The polyphenolic compounds are natural or synthetic polyphenols containing catechol or pyrogallol structural units. The biocompatible polymer shell is polyethylene glycol, polylactic acid-glycolic acid copolymer, chitosan, or a transparent material. The nanoparticles contain one or more of hyaluronic acid, and the average particle size of the nanoparticle drug delivery system is 50-300 nanometers. The nanoparticle drug delivery system is pH responsive under physiological conditions and can accelerate drug release in the slightly acidic environment of tumors. The mass ratio of the nanoparticle core to the biocompatible polymer shell is 1:0.2-1:2. The nanoparticle drug delivery system achieves controlled drug release through the dynamic reversible properties of metal ligand coordination bonds. The nanoparticle drug delivery system does not require the use of organic solvents during preparation and is formed through aqueous self-assembly. It has good biocompatibility and degradability and can be metabolized into non-toxic products in vivo.

[0007] Preferably, the metal ion is ferric ion, the polyphenolic compound is tannic acid, and the molar ratio of ferric ion to tannic acid is 10:1-1:10. In the preparation process, the ferric ion solution and the tannic acid solution are first mixed at pH 7-9 to form a metal-polyphenol network core. Then, a surfactant is added, and nanoscale particles are formed under ultrasonic conditions. Unreacted substances are then removed by dialysis or ultrafiltration. Finally, a polyethylene glycol-polylactic acid block copolymer is coated onto the particles via physical adsorption or covalent coupling to form a shell. The polyethylene glycol in the polyethylene glycol-polylactic acid block copolymer has a molecular weight of 2000-5000 Da, and the polylactic acid... With a molecular weight of 5000-15000 Da, the nano-drug delivery system exhibits a cumulative drug release rate of no more than 30% within 24 hours under pH 7.4 conditions, and a cumulative drug release rate exceeding 70% within 24 hours under pH 5.5 conditions. The surface of the nano-drug delivery system can be further modified with targeting ligands, which are coupled to antibodies, peptides, or small molecule ligands via active groups at the ends of polyethylene glycol. The modification ratio of the targeting ligands is 1-10 targeting ligand molecules per 100 polyethylene glycol molecules. The nano-drug delivery system has a 2-5 times longer circulating half-life in vivo compared to unmodified nanoparticles, resulting in an enhanced tumor accumulation effect.

[0008] Preferably, the hydrophobic drug molecule is an anticancer drug, including but not limited to paclitaxel, docetaxel, camptothecin, doxorubicin, or derivatives thereof. The drug loading is 5%-30% of the total weight of the nano-drug delivery system, and the drug encapsulation efficiency is 70%-95%. The nano-drug delivery system achieves high loading through π-π stacking, hydrogen bonding, or hydrophobic interactions between the metal polyphenol network and the drug molecule. The core density of the metal polyphenol network is 1.2-1.8 g / cm³. 3 The biocompatible polymer shell has a thickness of 5-30 nanometers. The drug retention rate of the nano-drug delivery system exceeds 85% after storage at 4°C for 6 months, and there is no obvious aggregation phenomenon within 24 hours at 37°C. The nano-drug delivery system can regulate redox sensitivity by changing the type of metal ions and accelerate drug release in an environment containing high concentrations of glutathione. The surface potential of the nano-drug delivery system is -10 to -30 mV under physiological pH conditions, exhibiting good colloidal stability. The particle size change does not exceed 15% within 24 hours under 10% serum conditions. The nano-drug delivery system can be applied to treatment scenarios requiring sustained drug release via intravenous injection, subcutaneous injection, or local administration, and has the potential to reduce drug toxicity and side effects and improve the therapeutic index.

[0009] Preferably, the preparation method of the nano-drug delivery system includes the following steps: First, dissolve a metal salt in deionized water and adjust the pH to 7-9 to obtain a metal ion solution; then dissolve a polyphenol compound in deionized water to obtain a polyphenol solution; under stirring conditions, slowly add the polyphenol solution to the metal ion solution and react at room temperature for 10-60 minutes to form a metal polyphenol network prepolymer; next, dissolve a hydrophobic drug in a small amount of organic solvent, add a surfactant, and treat with probe sonication to form a drug nanoemulsion; add the drug nanoemulsion to the metal polyphenol network prepolymer solution and continue stirring for 30-120 minutes to form drug-loaded metal polyphenol network nanoparticles. The process involves dissolving a biocompatible polymer in deionized water, adding the drug-loaded nanoparticle solution, and stirring at room temperature for 2-6 hours to allow the polymer to self-assemble on the nanoparticle surface to form a shell. Finally, unbound substances are removed through dialysis, ultrafiltration, or centrifugation to obtain the final nano-drug delivery system. The entire preparation process is carried out under inert gas protection to prevent metal ion oxidation. The reaction temperature is controlled within the range of 4-40℃, and the pH value is precisely controlled using a buffer solution. This preparation method does not use toxic cross-linking agents, and the final product contains less than 0.1% residual organic solvent, meeting pharmaceutical standards. This preparation method can be scaled up to industrial production scale, with batch-to-batch variations of less than 10%.

[0010] Preferably, the surface of the nano-drug delivery system is modified with a tumor-targeting ligand, which is one or more of folic acid, transferrin, RGD peptide, or anti-EGFR antibody. The targeting ligand is coupled via an active group on the surface of a biocompatible polymer shell, which is one of a carboxyl, amino, maleimide, or azide group. The coupling reaction is carried out at pH 5-8 for 2-24 hours. The modification density of the targeting ligand is 50-500 ligand molecules per square micrometer of nanoparticle surface. The nano-drug delivery system modified with the targeting ligand exhibits significantly enhanced cellular uptake efficiency on cells expressing the corresponding receptor, and on receptor-positive cells… The uptake rate is 2-10 times higher than that of receptor-negative cells. The targeted ligand modification does not affect the basic physicochemical properties of the nano-drug delivery system. The particle size increase is no more than 20 nanometers, and the surface potential change is no more than 5 mV. In in vivo experiments, the targeted ligand-modified nano-drug delivery system exhibits enhanced tumor tissue accumulation, with drug concentration at the tumor site 1.5-3 times higher than that of the non-targeted system. At the same time, it reduces the distribution in normal tissues such as the heart and kidneys, reducing systemic toxicity. The targeted efficiency of the targeted ligand-modified nano-drug delivery system can be optimized by adjusting the ligand density. In in vitro cell experiments, the cytotoxicity is 2-5 times higher than that of free drug at the optimal ligand density, but the toxicity to normal cells is significantly reduced.

[0011] Preferably, the nano-drug delivery system exhibits multi-stimulus responsiveness, capable of releasing drugs simultaneously in response to pH changes, redox environments, and the presence of enzymes. The metallopolyphenol network core exhibits weakened coordination bonds under acidic conditions and altered metal ion valence states in reducing environments, leading to network disintegration and release of the encapsulated drug. The biocompatible polymer shell contains linkages that can be degraded by specific enzymes, such as peptides recognized by matrix metalloproteinases. When the nano-drug delivery system reaches specific tissues or cells, locally highly expressed enzymes degrade the shell, accelerating drug release. Under simulated physiological conditions (pH 7.4, 10% serum), the drug release of the nano-drug delivery system does not exceed 25% within 24 hours, and under simulated tumor microenvironment conditions (pH 6.5, 10mM glutaraldehyde), the drug release is significantly reduced. The drug release rate of glutathione reaches 50-70% within 24 hours, and exceeds 80% within 24 hours under simulated inflammation site conditions (pH 5.5, 100 μM hydrogen peroxide). The multi-stimulus responsiveness is achieved by precisely controlling the type of metal ions, polyphenol structure, and shell composition. The release kinetics of the nano-drug delivery system under different stimulation conditions can be programmed by adjusting the metal-polyphenol ratio, shell thickness, and cross-linking degree. This programmed release characteristic enables the nano-drug delivery system to selectively release drugs in specific disease microenvironments, thereby improving the therapeutic window. In in vitro cell experiments, the multi-stimulus responsive nano-drug delivery system has a 1.5-2 times higher killing effect on tumor cells than the single-response system, while significantly reducing toxicity to normal cells.

[0012] Preferably, the nano-drug delivery system further includes a contrast agent with fluorescence imaging or magnetic resonance imaging capabilities. The contrast agent is a near-infrared fluorescent dye, quantum dots, or magnetic nanoparticles encapsulated within a nanoparticle core, or paramagnetic metal ions chemically bonded to a polyphenol network. The fluorescent dye includes indocyanine green, Cy5.5, or derivatives thereof. The magnetic nanoparticles are iron(III) oxide with a particle size of 5-15 nanometers. The loading of the contrast agent is 0.5%-10% of the total weight of the nano-drug delivery system. The contrast agent remains stable within the nano-drug delivery system, with a leakage rate not exceeding 15% within 24 hours, while not affecting the drug loading and release characteristics. The nano-drug delivery system with imaging capabilities shows improvement compared to non-imaging nanoparticles in in vitro cell experiments. The addition of contrast agents to the system results in cellular uptake and drug release behavior comparable to those of the nano-drug delivery system. In in vivo animal models, the distribution and accumulation of the nano-drug delivery system can be tracked in real time using fluorescence imaging or magnetic resonance imaging, enabling visualized monitoring of the treatment process. The combination of imaging and therapeutic functions makes the nano-drug delivery system a diagnostic and therapeutic platform. In small animal experiments, imaging guidance can optimize the dosing regimen, and significant drug accumulation and therapeutic effects can be observed at the tumor site. The preparation method of the diagnostic and therapeutic nano-drug delivery system involves adding contrast agents only before or after the drug loading step, achieving integration through the same self-assembly process. The diagnostic and therapeutic nano-drug delivery system meets pharmaceutical requirements in terms of storage stability and biosafety, providing technical support for precision drug delivery and personalized treatment.

[0013] The present invention has the following beneficial effects: The dense three-dimensional network structure formed by the self-assembly of metal ions and polyphenolic compounds in aqueous phase effectively improves the encapsulation efficiency and drug loading of hydrophobic drugs, overcoming the problem of insufficient drug loading capacity caused by the loose structure of traditional polymer nanoparticles or liposomes. Secondly, the biocompatible polymer shell (such as PEG or hyaluronic acid) coating the core of the nanoparticles significantly enhances colloidal stability, effectively reducing serum protein adsorption and reticuloendothelial system recognition, prolonging blood circulation time, thereby improving the passive targeted accumulation efficiency at the tumor site and solving the defects of unmodified MPN nanoparticles, such as rapid in vivo clearance and low tumor enrichment rate. Thirdly, the system utilizes the pH sensitivity of the metal-polyphenol coordination bond to achieve accelerated drug release in the slightly acidic environment of the tumor, avoiding premature leakage in normal tissue (pH≈7.4), effectively inhibiting the burst release effect and expanding the therapeutic window. Fourthly, the metal... The dynamic and reversible nature of the ligand coordination bonds endows the system with inherent responsiveness, allowing drug release behavior to be adaptively adjusted according to changes in the local microenvironment. Compared to traditional MPN carriers that rely solely on a single stimulus (such as pH or a reducing environment), it possesses more precise spatiotemporal controlled release capabilities. Fifth, the entire preparation process is completed in an aqueous phase, eliminating the need for organic solvents, high temperatures, or toxic crosslinking agents. This not only simplifies the process and reduces production costs but also fundamentally avoids the biosafety risks associated with residual solvents, significantly enhancing the product's clinical translation potential. Sixth, the selected components (including metal ions, polyphenols, and polymer shell materials) all exhibit good biocompatibility and biodegradability, and the metabolites are non-toxic, meeting clinical safety requirements. Finally, the system's modular structure facilitates subsequent functional expansion (such as coupling with targeting ligands or introducing imaging probes), laying the foundation for achieving integrated diagnosis and treatment. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the preparation process of the nano-drug delivery system based on metal polyphenol networks according to the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0017] Example 1: Please see Figure 1As shown, this embodiment of a metal polyphenol network-based nano-drug delivery system includes a nanoparticle core formed by the self-assembly of metal ions and polyphenolic compounds through coordination. The surface of the nanoparticle core is coated with a biocompatible polymer shell, and the nanoparticle core is loaded with hydrophobic drug molecules. The metal ions are selected from one or more of iron ions, zinc ions, copper ions, and manganese ions. The polyphenolic compounds are natural or synthetic polyphenols containing catechol or pyrogallol structural units. The biocompatible polymer shell is polyethylene glycol, polylactic acid-glycolic acid copolymer, or chitosan. The nanoparticle delivery system comprises one or more of sugars or hyaluronic acid, with an average particle size of 50-300 nanometers. It exhibits pH responsiveness under physiological conditions, enabling accelerated drug release in the slightly acidic environment of tumors. The mass ratio of the nanoparticle core to the biocompatible polymer shell is 1:0.2-1:2. Furthermore, the nanoparticle delivery system achieves controlled drug release through the dynamic reversible properties of metal ligand coordination bonds. The system is prepared without the use of organic solvents, formed through aqueous self-assembly, and possesses good biocompatibility and degradability, capable of being metabolized into non-toxic products in vivo.

[0018] First, 0.5 g of ferric chloride (FeCl3·6H2O) was dissolved in 20 mL of deionized water, and the pH was adjusted to 8.0 with 1 M NaOH solution to obtain a 0.1 M ferric ion solution. Simultaneously, 0.3 g of tannic acid was dissolved in 10 mL of deionized water to obtain a 0.05 M tannic acid solution. Under magnetic stirring (500 rpm), the tannic acid solution was slowly added dropwise to the ferric ion solution, and the reaction was allowed to proceed at room temperature for 30 minutes. The solution color changed from yellow to deep blue, indicating the formation of an iron-tannic acid network. Next, 10 mg of paclitaxel was dissolved in 1 mL of anhydrous ethanol, and 0.1 g of poloxamer 188 was added as a surfactant. A transparent paclitaxel nanoemulsion was formed by probe sonication (100 W power, 2 sec / 1 sec pulse, total time 5 minutes). This emulsion was added to the aforementioned iron-tannic acid solution, and stirring was continued for 1 hour to form drug-loaded nanoparticles. Subsequently, 0.2 g of methoxy polyethylene glycol-polylactic acid (mPEG-PLA, molecular weight 5000-10000) was dissolved in 10 mL of deionized water, and the drug-loaded nanoparticle solution was added. The mixture was stirred at room temperature for 4 hours, allowing the polymer to self-assemble on the nanoparticle surface to form a shell. Finally, the mixed solution was placed in a dialysis bag with a molecular weight cutoff of 10000 and dialyzed against deionized water for 24 hours (water changed every 4 hours). The solution was then filtered through a 0.22 μm filter membrane to obtain the final nano-drug delivery system. Dynamic light scattering analysis showed that the average particle size of this nano-drug delivery system was 125 ± 15 nm, the polydispersity index (PDI) was 0.12, and the surface potential was -22 ± 3 mV. Transmission electron microscopy revealed spherical particles with a clearly visible core-shell structure. High-performance liquid chromatography (HPLC) determined the drug loading to be 18.5% and the encapsulation efficiency to be 87.3%. In vitro release experiments showed that the drug release rate was 25.6% after 24 hours in phosphate buffer at pH 7.4, while it reached 78.4% at pH 5.5, demonstrating good pH responsiveness. After storage at 4°C for 6 months, the particle size increased by no more than 10%, and the drug retention rate exceeded 90%, indicating that the system has good stability.

[0019] The workflow of the metal polyphenol network-based nano-drug delivery system described in this invention is as follows: First, in an aqueous environment, one or more selected metal ions, such as iron, zinc, copper, or manganese ions, are mixed with natural or synthetic polyphenolic compounds containing catechol or pyrogallol structural units, such as tannic acid or gallic acid. Under mild conditions, a nanoparticle core with a three-dimensional network structure is spontaneously formed through metal-ligand coordination. This corresponds to the nanoparticle core formed by the self-assembly of metal ions and polyphenolic compounds through coordination in the corresponding technical solution. This process does not require the introduction of organic solvents or toxic cross-linking agents and is carried out entirely in a physiologically compatible aqueous system. Subsequently, during or after the self-assembly process... Hydrophobic drug molecules, such as the anti-tumor drugs paclitaxel and doxorubicin, are simultaneously or subsequently loaded into the core of nanoparticles. The hydrophobic drug molecules are loaded into the nanoparticle core, and efficient encapsulation is achieved using the hydrophobic microregions and coordination cavities of the MPN network. Next, a biocompatible polymer, such as one or more of polyethylene glycol, PLGA, chitosan, or hyaluronic acid, is added to the system. This polymer coats the nanoparticle core surface through physical adsorption or weak interactions, forming a stable polymer shell. This biocompatible polymer shell not only shields the surface charge of the nanoparticles and reduces protein adsorption but also prolongs their residence time in the bloodstream. Finally, a... A complete nano-drug delivery system with an average particle size controlled within the range of 50–300 nanometers was obtained. The average particle size of the nano-drug delivery system is 50–300 nanometers, and the mass ratio of the nanoparticle core to the polymer shell is controlled between 1:0.2 and 1:2, corresponding to a mass ratio of the nanoparticle core to the biocompatible polymer shell of 1:0.2–1:2, to balance drug loading capacity and stability. The system maintains structural stability under physiological conditions, but in the slightly acidic environment (pH≈6.5–6.8) at tumor sites, the metal-polyphenol coordination bonds partially dissociate due to proton competition. Therefore, the nano-drug delivery system exhibits pH responsiveness under physiological conditions, enabling accelerated drug release in the slightly acidic environment of tumors. The drug is released, thereby triggering a controlled release of the drug. Simultaneously, thanks to the inherent dynamic reversibility of the metal ligand coordination bond, the nano-drug delivery system achieves controlled drug release through this dynamic reversibility. The drug release rate can be dynamically adjusted according to changes in the local microenvironment, avoiding burst release. The entire preparation process employs an aqueous self-assembly strategy, meaning the nano-drug delivery system does not require the use of organic solvents during preparation. It is formed through aqueous self-assembly, resulting in a product with good biocompatibility and degradability. It can be metabolized in vivo into non-toxic small molecule products, making it suitable for clinical administration routes such as intravenous injection.

[0020] Example 2: Please see Figure 1 As shown in this embodiment, a nano-drug delivery system based on a metal polyphenol network is described. The metal ion is ferric ion, and the polyphenol compound is tannic acid. The molar ratio of ferric ion to tannic acid is 10:1 to 1:10. In the preparation process, a ferric ion solution and a tannic acid solution are first mixed at pH 7-9 to form a metal polyphenol network core. Then, a surfactant is added, and nanoscale particles are formed under ultrasonic conditions. Unreacted substances are then removed by dialysis or ultrafiltration. Finally, a polyethylene glycol-polylactic acid block copolymer is coated onto the particles through physical adsorption or covalent coupling to form a shell. The polyethylene glycol in the polyethylene glycol-polylactic acid block copolymer has a molecular weight of 2000. The molecular weight of polylactic acid is 5000-15000 Da. The cumulative drug release rate of the nano-drug delivery system does not exceed 30% within 24 hours under pH 7.4 conditions, while it exceeds 70% within 24 hours under pH 5.5 conditions. The surface of the nano-drug delivery system can be further modified with a targeting ligand. The targeting ligand is coupled to an antibody, peptide, or small molecule ligand through the active group at the end of the polyethylene glycol. The modification ratio of the targeting ligand is 1-10 targeting ligand molecules per 100 polyethylene glycol molecules. The circulating half-life of the nano-drug delivery system in vivo is 2-5 times longer than that of unmodified nanoparticles, and it has an enhanced tumor accumulation effect.

[0021] The hydrophobic drug molecule is an anticancer drug, including but not limited to paclitaxel, docetaxel, camptothecin, doxorubicin, or their derivatives. The drug loading is 5%-30% of the total weight of the nano-drug delivery system, and the drug encapsulation efficiency is 70%-95%. The nano-drug delivery system achieves high loading through π-π stacking, hydrogen bonding, or hydrophobic interactions between the drug molecule and the metal polyphenol network. The core density of the metal polyphenol network is 1.2-1.8 g / cm³. 3 The biocompatible polymer shell has a thickness of 5-30 nanometers. The drug retention rate of the nano-drug delivery system exceeds 85% after storage at 4°C for 6 months, and there is no obvious aggregation phenomenon within 24 hours at 37°C. The nano-drug delivery system can regulate redox sensitivity by changing the type of metal ions and accelerate drug release in an environment containing high concentrations of glutathione. The surface potential of the nano-drug delivery system is -10 to -30 mV under physiological pH conditions, exhibiting good colloidal stability. The particle size change does not exceed 15% within 24 hours under 10% serum conditions. The nano-drug delivery system can be applied to treatment scenarios requiring sustained drug release via intravenous injection, subcutaneous injection, or local administration, and has the potential to reduce drug toxicity and side effects and improve the therapeutic index.

[0022] The preparation method of the nano-drug delivery system includes the following steps: First, a metal salt is dissolved in deionized water, and the pH is adjusted to 7-9 to obtain a metal ion solution; then, a polyphenol compound is dissolved in deionized water to obtain a polyphenol solution; under stirring conditions, the polyphenol solution is slowly added dropwise to the metal ion solution, and the reaction is carried out at room temperature for 10-60 minutes to form a metal polyphenol network prepolymer; next, a hydrophobic drug is dissolved in a small amount of organic solvent, a surfactant is added, and the mixture is ultrasonically treated with a probe to form a drug nanoemulsion; the drug nanoemulsion is added to the metal polyphenol network prepolymer solution, and the reaction is continued with stirring for 30-120 minutes to form drug-loaded metal polyphenol network nanoparticles; The biocompatible polymer was then dissolved in deionized water, and the above-mentioned drug-loaded nanoparticle solution was added. The mixture was stirred at room temperature for 2-6 hours to allow the polymer to self-assemble on the surface of the nanoparticles to form a shell. Finally, unbound substances were removed by dialysis, ultrafiltration, or centrifugation to obtain the final nano-drug delivery system. The entire preparation process was carried out under inert gas protection to avoid oxidation of metal ions. The reaction temperature was controlled within the range of 4-40℃, and the pH value was precisely controlled by a buffer solution. The preparation method does not use toxic crosslinking agents, and the organic solvent residue in the final product is less than 0.1%, which meets pharmaceutical standards. The preparation method can be scaled up to industrial production scale, with batch-to-batch differences of less than 10%.

[0023] First, 0.4 g of zinc sulfate (ZnSO4·7H2O) was dissolved in 20 mL of deionized water, and the pH was adjusted to 7.5 with ammonia to obtain a 0.08 M zinc ion solution. 0.25 g of EGCG was dissolved in 10 mL of deionized water, and a 0.04 M MEGCG solution was obtained under light-protected conditions. Under nitrogen protection, the EGCG solution was slowly added dropwise to the zinc ion solution, and the reaction was carried out at room temperature in the dark for 45 minutes to form a light brown zinc-EGCG network solution. 15 mg of docetaxel was dissolved in 1.5 mL of DMSO, and 0.15 g of Tween 80 was added. The mixture was sonicated (120 W, 5 minutes) to form a nanoemulsion. This emulsion was added to the zinc-EGCG solution and stirred for 90 minutes to form drug-loaded nanoparticles. 0.25 g of carboxymethyl chitosan was dissolved in 15 mL of deionized water, and the above drug-loaded nanoparticles were added. The mixture was stirred for 5 hours to form a shell. After dialysis purification, 1 mL of the nano-drug delivery system solution was taken and 0.5 mL of EDC / NHS activation solution (0.1 MEDC, 0.05 MNHS, pH 6.0) was added. Activation was performed at room temperature for 30 minutes. Then, 5 mg of folic acid-polyethylene glycol-amino (FA-PEG-NH2, molecular weight 3400) was added, the pH was adjusted to 7.0, and the reaction was carried out at 4°C for 12 hours to complete the folic acid targeted modification. Unreacted substances were removed by dialysis to obtain the targeted nano-drug delivery system. Characterization results showed that the particle size after targeted modification was 158 ± 18 nm, an increase of approximately 25 nm compared to the unmodified state, and the surface potential changed from -18 mV to -15 mV. The folic acid modification density was approximately 85 molecules per 100 square nanometers surface area. In vitro cell experiments using MCF-7 (folate receptor positive) and A549 (folate receptor low expression) cell lines showed that, at the same drug concentration, the targeted nano-drug delivery system exhibited a 1.8-fold higher inhibition rate against MCF-7 cells compared to the non-targeted system, while the inhibition rate against A549 cells was only 1.2-fold higher, demonstrating receptor-mediated selective uptake. Under conditions containing 10 mM glutathione, the drug release rate reached 65.7% after 24 hours, indicating that the system also possesses redox sensitivity. In vivo pharmacokinetic studies showed that the targeted nano-drug delivery system had a half-life of 18.5 hours in rats, approximately 1.7 times longer than the non-targeted system, and the drug concentration in tumor tissue reached its peak 12 hours after administration, 2.3 times that of the non-targeted system.

[0024] Example 3: Please see Figure 1As shown in this embodiment, a nano-drug delivery system based on a metal polyphenol network is described. The surface of the nano-drug delivery system is modified with a tumor-targeting ligand, which is one or more of folic acid, transferrin, RGD peptide, or anti-EGFR antibody. The targeting ligand is coupled to an active group on the surface of a biocompatible polymer shell, which is one of a carboxyl, amino, maleimide, or azide group. The coupling reaction is carried out at pH 5-8 for 2-24 hours. The modification density of the targeting ligand is 50-500 ligand molecules per square micrometer of nanoparticle surface. The nano-drug delivery system modified with the targeting ligand exhibits significantly enhanced cellular uptake efficiency on cells expressing the corresponding receptor. The uptake rate on receptor-positive cells is 2-10 times higher than that on receptor-negative cells. The targeted ligand modification does not affect the basic physicochemical properties of the nano-drug delivery system. The particle size increase is no more than 20 nanometers, and the surface potential change is no more than 5 mV. In in vivo experiments, the targeted ligand-modified nano-drug delivery system exhibits enhanced tumor tissue accumulation, with drug concentration at the tumor site 1.5-3 times higher than that of the non-targeted system, while reducing distribution in normal tissues such as the heart and kidneys, thus reducing systemic toxicity. The targeted efficiency of the targeted ligand-modified nano-drug delivery system can be optimized by adjusting the ligand density. In in vitro cell experiments, at the optimal ligand density, cytotoxicity is 2-5 times higher than that of free drug, but toxicity to normal cells is significantly reduced.

[0025] The nano-drug delivery system exhibits multi-stimulus responsiveness, simultaneously releasing drugs in response to pH changes, redox environments, and the presence of enzymes. The metallopolyphenol network core exhibits weakened coordination bonds under acidic conditions and altered metal ion valence states in reducing environments, leading to network disintegration and the release of the encapsulated drug. The biocompatible polymer shell contains linkages that can be degraded by specific enzymes, such as peptides recognized by matrix metalloproteinases. When the nano-drug delivery system reaches specific tissues or cells, locally highly expressed enzymes degrade the shell, accelerating drug release. Under simulated physiological conditions (pH 7.4, 10% serum), the drug release of the nano-drug delivery system does not exceed 25% within 24 hours, and under simulated tumor microenvironment conditions (pH 6.5, 10mM glutathione), the drug release is significantly reduced. The drug release rate of the peptide reaches 50-70% within 24 hours, and exceeds 80% within 24 hours under simulated inflammation site conditions (pH 5.5, 100 μM hydrogen peroxide). The multi-stimulus responsiveness is achieved by precisely controlling the type of metal ions, polyphenol structure, and shell composition. The release kinetics of the nano-drug delivery system under different stimulation conditions can be programmed by adjusting the metal-polyphenol ratio, shell thickness, and cross-linking degree. The programmed release characteristics enable the nano-drug delivery system to selectively release drugs in specific disease microenvironments, thereby improving the therapeutic window. In in vitro cell experiments, the multi-stimulus responsive nano-drug delivery system has a 1.5-2 times higher killing effect on tumor cells than the single-response system, while significantly reducing toxicity to normal cells.

[0026] The nano-drug delivery system also includes a contrast agent with fluorescence imaging or magnetic resonance imaging capabilities. The contrast agent is a near-infrared fluorescent dye, quantum dots, or magnetic nanoparticles encapsulated within a nanoparticle core, or paramagnetic metal ions chemically bonded to a polyphenol network. The fluorescent dye includes indocyanine green, Cy5.5, or derivatives thereof. The magnetic nanoparticles are iron(III) oxide with a particle size of 5-15 nanometers. The loading of the contrast agent is 0.5%-10% of the total weight of the nano-drug delivery system. The contrast agent remains stable within the nano-drug delivery system, with a leakage rate not exceeding 15% within 24 hours, without affecting the drug loading and release characteristics. The imaging-enabled nano-drug delivery system shows improved performance compared to the unadded system in in vitro cell experiments. The contrast agent system exhibits remarkable cellular uptake and drug release behavior. In in vivo animal models, the distribution and accumulation of the nano-drug delivery system can be tracked in real time using fluorescence imaging or magnetic resonance imaging, enabling visualized monitoring of the treatment process. The combination of imaging and therapeutic functions makes the nano-drug delivery system a diagnostic and therapeutic platform. In small animal experiments, imaging guidance can optimize the dosing regimen, and significant drug accumulation and therapeutic effects can be observed at the tumor site. The preparation method of the diagnostic and therapeutic nano-drug delivery system involves adding the contrast agent only before or after the drug loading step, achieving integration through the same self-assembly process. The diagnostic and therapeutic nano-drug delivery system meets pharmaceutical requirements in terms of storage stability and biosafety, providing technical support for precision drug delivery and personalized treatment.

[0027] First, 0.35 g of copper sulfate was dissolved in 20 mL of deionized water, and the pH was adjusted to 8.2 with triethanolamine to obtain a 0.07 M copper ion solution. 0.3 g of proanthocyanidins was dissolved in 10 mL of deionized water to obtain a 0.06 M proanthocyanidin solution. Under stirring, the proanthocyanidin solution was added dropwise to the copper ion solution, and the reaction was carried out at room temperature for 40 minutes to form a dark green copper-proanthocyanidin network solution. 5 mg of indocyanine green (ICG) and 12 mg of camptothecin were dissolved together in 1.2 mL of a DMSO / ethanol mixture (1:1, v / v), and 0.12 g of lecithin was added. The mixture was sonicated (150 W, 6 minutes) to form a dual-drug-loaded nanoemulsion. This emulsion was added to the copper-proanthocyanidin solution and stirred for 100 minutes to form a nanoparticle core simultaneously loaded with both drug and contrast agent. 0.3 g of hyaluronic acid (molecular weight 50 kDa) was dissolved in 15 mL of deionized water, and the above-mentioned nanoparticles were added. The mixture was stirred at room temperature for 6 hours to form a shell. After dialysis purification, a nano-drug delivery system with near-infrared imaging function was obtained. Characterization results showed that the system had an average particle size of 182 ± 22 nm, a surface potential of -28 ± 4 mV, a camptothecin loading of 15.8%, an encapsulation efficiency of 82.5%, an ICG loading of 3.2%, and a 24-hour ICG leakage rate of 12.7%. In vitro release experiments showed that the 24-hour release rate of camptothecin was 28.3% at pH 7.4, 75.8% at pH 6.0, and 89.2% at pH 6.0 with 20 μM hydrogen peroxide, exhibiting dual pH / ROS response characteristics. Near-infrared imaging experiments showed that the nano-drug delivery system exhibited strong fluorescence signals under 808 nm laser excitation. In vitro cell imaging revealed significant endocytosis in HT-29 colon cancer cells, with the fluorescence signal increasing over time. In an in vivo mouse tumor model experiment, a significant fluorescence signal was observed at the tumor site 4 hours after intravenous injection, with the strongest signal at 12 hours, consistent with the drug accumulation time. Treatment experiments showed that, under the same dose of camptothecin, the nano-drug delivery system significantly inhibited tumor growth (76.5%) compared to the free drug group (48.2%) and the control group (12.3%), while showing no significant decrease in mouse body weight, indicating that the system improved drug efficacy and reduced toxic side effects.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A nano-drug delivery system based on a metal polyphenol network, characterized in that, include: The nanomedicine delivery system comprises a nanoparticle core formed by the self-assembly of metal ions and polyphenolic compounds through coordination. The nanoparticle core is coated with a biocompatible polymer shell, and the nanoparticle core is loaded with hydrophobic drug molecules. The metal ions are selected from one or more of iron, zinc, copper, and manganese ions. The polyphenolic compounds are natural or synthetic polyphenols containing catechol or pyrogallol structural units. The biocompatible polymer shell is one or more of polyethylene glycol, polylactic-co-glycolic acid, chitosan, or hyaluronic acid. The average particle size of the nano-drug delivery system is 50-300 nanometers. The nano-drug delivery system is pH responsive under physiological conditions and can accelerate drug release in the slightly acidic environment of tumors. The mass ratio of the nanoparticle core to the biocompatible polymer shell is 1:0.2-1:

2. The nano-drug delivery system achieves controlled drug release through the dynamic reversible properties of metal ligand coordination bonds. The nano-drug delivery system does not require the use of organic solvents during preparation and is formed through aqueous self-assembly. It has good biocompatibility and degradability and can be metabolized into non-toxic products in vivo.

2. The nano-drug delivery system based on a metal polyphenol network according to claim 1, characterized in that, The metal ion is ferric ion, and the polyphenolic compound is tannic acid. The molar ratio of ferric ion to tannic acid is 10:1 to 1:

10. In the preparation process, the ferric ion solution and the tannic acid solution are first mixed at pH 7-9 to form a metal-polyphenol network core. Then, a surfactant is added, and nanoscale particles are formed under ultrasonic conditions. Unreacted substances are removed by dialysis or ultrafiltration. Finally, a polyethylene glycol-polylactic acid block copolymer is coated onto the particles via physical adsorption or covalent coupling to form a shell. The polyethylene glycol in the polyethylene glycol-polylactic acid block copolymer has a molecular weight of 2000-5000 Da, and the polylactic acid has a molecular weight of... The amount is 5000-15000 Da. The cumulative drug release rate of the nano-drug delivery system does not exceed 30% within 24 hours under pH 7.4 conditions, while it exceeds 70% within 24 hours under pH 5.5 conditions. The surface of the nano-drug delivery system can be further modified with a targeting ligand. The targeting ligand is coupled to an antibody, peptide, or small molecule ligand through an active group at the end of polyethylene glycol. The modification ratio of the targeting ligand is 1-10 targeting ligand molecules per 100 polyethylene glycol molecules. The circulating half-life of the nano-drug delivery system in vivo is 2-5 times longer than that of unmodified nanoparticles, and it has an enhanced tumor accumulation effect.

3. The nano-drug delivery system based on a metal polyphenol network according to claim 2, characterized in that, The hydrophobic drug molecule is an anticancer drug, including but not limited to paclitaxel, docetaxel, camptothecin, doxorubicin, or their derivatives. The drug loading is 5%-30% of the total weight of the nano-drug delivery system, and the drug encapsulation efficiency is 70%-95%. The nano-drug delivery system achieves high loading through π-π stacking, hydrogen bonding, or hydrophobic interactions between the drug molecule and the metal polyphenol network. The core density of the metal polyphenol network is 1.2-1.8 g / cm³. 3 The biocompatible polymer shell has a thickness of 5-30 nanometers. The drug retention rate of the nano-drug delivery system exceeds 85% after storage at 4°C for 6 months, and there is no obvious aggregation phenomenon within 24 hours at 37°C. The nano-drug delivery system can regulate redox sensitivity by changing the type of metal ions and accelerate drug release in an environment containing high concentrations of glutathione. The surface potential of the nano-drug delivery system is -10 to -30 mV under physiological pH conditions, exhibiting good colloidal stability. The particle size change does not exceed 15% within 24 hours under 10% serum conditions. The nano-drug delivery system can be applied to treatment scenarios requiring sustained drug release via intravenous injection, subcutaneous injection, or local administration, and has the potential to reduce drug toxicity and side effects and improve the therapeutic index.

4. The nano-drug delivery system based on a metal polyphenol network according to claim 3, characterized in that, The preparation method of the nano-drug delivery system includes the following steps: First, a metal salt is dissolved in deionized water, and the pH is adjusted to 7-9 to obtain a metal ion solution; then, a polyphenol compound is dissolved in deionized water to obtain a polyphenol solution; under stirring conditions, the polyphenol solution is slowly added dropwise to the metal ion solution, and the reaction is carried out at room temperature for 10-60 minutes to form a metal polyphenol network prepolymer; next, a hydrophobic drug is dissolved in a small amount of organic solvent, a surfactant is added, and the mixture is ultrasonically treated with a probe to form a drug nanoemulsion; the drug nanoemulsion is added to the metal polyphenol network prepolymer solution, and the reaction is continued with stirring for 30-120 minutes to form drug-loaded metal polyphenol network nanoparticles; The biocompatible polymer was then dissolved in deionized water, and the above-mentioned drug-loaded nanoparticle solution was added. The mixture was stirred at room temperature for 2-6 hours to allow the polymer to self-assemble on the surface of the nanoparticles to form a shell. Finally, unbound substances were removed by dialysis, ultrafiltration, or centrifugation to obtain the final nano-drug delivery system. The entire preparation process was carried out under inert gas protection to avoid oxidation of metal ions. The reaction temperature was controlled within the range of 4-40℃, and the pH value was precisely controlled by a buffer solution. The preparation method does not use toxic crosslinking agents, and the organic solvent residue in the final product is less than 0.1%, which meets pharmaceutical standards. The preparation method can be scaled up to industrial production scale, with batch-to-batch differences of less than 10%.

5. The nano-drug delivery system based on a metal polyphenol network according to claim 3, characterized in that, The nano-drug delivery system is surface-modified with a tumor-targeting ligand, which is one or more of folic acid, transferrin, RGD peptide, or anti-EGFR antibody. The targeting ligand is coupled via an active group on the surface of a biocompatible polymer shell, which is one of a carboxyl, amino, maleimide, or azide group. The coupling reaction is carried out at pH 5-8 for 2-24 hours. The modification density of the targeting ligand is 50-500 ligand molecules per square micrometer of nanoparticle surface. The nano-drug delivery system modified with the targeting ligand exhibits significantly enhanced cellular uptake efficiency on cells expressing the corresponding receptor, and in receptor-positive cells… The targeting efficiency is 2-10 times higher than that of receptor-negative cells. The targeted ligand modification does not affect the basic physicochemical properties of the nano-drug delivery system. The particle size increase is no more than 20 nanometers, and the surface potential change is no more than 5 mV. In in vivo experiments, the targeted ligand-modified nano-drug delivery system exhibits enhanced tumor tissue accumulation, with the drug concentration at the tumor site being 1.5-3 times higher than that of the non-targeted system. At the same time, it reduces the distribution in normal tissues such as the heart and kidneys, reducing systemic toxicity. The targeted efficiency of the targeted ligand-modified nano-drug delivery system can be optimized by adjusting the ligand density. In in vitro cell experiments, the cytotoxicity is 2-5 times higher than that of free drug at the optimal ligand density, but the toxicity to normal cells is significantly reduced.

6. The nano-drug delivery system based on a metal polyphenol network according to claim 5, characterized in that, The nano-drug delivery system exhibits multi-stimulus responsiveness, simultaneously releasing drugs in response to pH changes, redox environments, and the presence of enzymes. The metallopolyphenol network core exhibits weakened coordination bonds under acidic conditions and altered metal ion valence states in reducing environments, leading to network disintegration and the release of the encapsulated drug. The biocompatible polymer shell contains linkages that can be degraded by specific enzymes, such as peptides recognized by matrix metalloproteinases. When the nano-drug delivery system reaches specific tissues or cells, locally highly expressed enzymes degrade the shell, accelerating drug release. Under simulated physiological conditions (pH 7.4, 10% serum), the drug release of the nano-drug delivery system does not exceed 25% within 24 hours, and under simulated tumor microenvironment conditions (pH 6.5, 10mM glutathione), the drug release is significantly reduced. The drug release rate of the peptide reaches 50-70% within 24 hours, and exceeds 80% within 24 hours under simulated inflammation site conditions (pH 5.5, 100 μM hydrogen peroxide). The multi-stimulus responsiveness is achieved by precisely controlling the type of metal ions, polyphenol structure, and shell composition. The release kinetics of the nano-drug delivery system under different stimulation conditions can be programmed by adjusting the metal-polyphenol ratio, shell thickness, and cross-linking degree. The programmed release characteristics enable the nano-drug delivery system to selectively release drugs in specific disease microenvironments, thereby improving the therapeutic window. In in vitro cell experiments, the multi-stimulus responsive nano-drug delivery system has a 1.5-2 times higher killing effect on tumor cells than the single-response system, while significantly reducing toxicity to normal cells.

7. The nano-drug delivery system based on a metal polyphenol network according to claim 1, characterized in that, The nano-drug delivery system also includes a contrast agent with fluorescence imaging or magnetic resonance imaging capabilities. The contrast agent is a near-infrared fluorescent dye, quantum dots, or magnetic nanoparticles encapsulated within a nanoparticle core, or paramagnetic metal ions chemically bonded to a polyphenol network. The fluorescent dye includes indocyanine green, Cy5.5, or derivatives thereof. The magnetic nanoparticles are iron(III) oxide with a particle size of 5-15 nanometers. The loading of the contrast agent is 0.5%-10% of the total weight of the nano-drug delivery system. The contrast agent remains stable within the nano-drug delivery system, with a leakage rate not exceeding 15% within 24 hours, without affecting the drug loading and release characteristics. The imaging-enabled nano-drug delivery system shows improved performance compared to the unadded system in in vitro cell experiments. The contrast agent system exhibits remarkable cellular uptake and drug release behavior. In in vivo animal models, the distribution and accumulation of the nano-drug delivery system can be tracked in real time using fluorescence imaging or magnetic resonance imaging, enabling visualized monitoring of the treatment process. The combination of imaging and therapeutic functions makes the nano-drug delivery system a diagnostic and therapeutic platform. In small animal experiments, imaging guidance can optimize the dosing regimen, and significant drug accumulation and therapeutic effects can be observed at the tumor site. The preparation method of the diagnostic and therapeutic nano-drug delivery system involves adding the contrast agent only before or after the drug loading step, achieving integration through the same self-assembly process. The diagnostic and therapeutic nano-drug delivery system meets pharmaceutical requirements in terms of storage stability and biosafety, providing technical support for precision drug delivery and personalized treatment.

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