PH response chemotherapy and photo-thermal combined therapy drug delivery carrier and preparation method and application thereof

Abstract

The invention belongs to the cross field of chemistry, materials, biology and pharmacy, and particularly relates to a pH response chemotherapy and photo-thermal combined treatment drug delivery carrier and a preparation method and application thereof. The drug delivery carrier MOF-CPT-PDA-PEG constructed in the invention can realize chemotherapy-photo-thermal synergistic treatment and has good photo-thermal conversion ability, in vitro experiments show that drug release has pH and photo-thermal dual response characteristics, the hemolysis rate is lower than 5% (5-500 [mu] g / mL), the protein adsorption amount is smaller than 140 [mu] g / mg, and excellent blood compatibility is shown; cell experiments show that the survival rate of 4T1 cells is reduced to 17% through combination of MOF-CPT-PDA-PEG and illumination, the tumor inhibition effect is remarkably enhanced, and great potential is achieved in chemotherapy-photothermal combined cancer treatment. The method is green and safe, the preparation process is simple and controllable, the method is suitable for large-scale production, practical applicability is achieved, and economic and social benefits are remarkable.

Description

Technical Field

[0001] The present invention belongs to the interdisciplinary field of chemistry, materials, biology and pharmacy, and particularly relates to a pH-responsive chemotherapy and photothermal combined therapy drug delivery carrier. Background Art

[0002] Cancer is a major cause of death in humans, and chemotherapy has become an important treatment option. However, chemotherapeutic drugs used for cancer treatment have limitations, such as low bioavailability, poor selectivity, multidrug resistance, and severe side effects on normal tissues. With the application of nanomaterials in biomedicine, they show great promise in clinical development. Nanotechnology has garnered widespread attention in cancer treatment due to its unique drug delivery properties and the inherent therapeutic properties of nanomaterials.

[0003] Drug delivery systems are a research hotspot in modern biomedicine. Their core goal is to optimize drug release behavior in vivo to enhance therapeutic efficacy and minimize side effects. Traditional drug delivery vehicles (such as liposomes and polymeric nanoparticles) often face challenges such as low monotherapy efficacy, significant chemotherapy side effects, uncontrollable drug delivery, and biotoxicity, making them inadequate for the treatment of complex diseases. Metal-organic frameworks (MOFs) are an emerging class of porous materials composed of metal ions or clusters and organic ligands. Due to their significant advantages, including large surface area, high pore volume, and tunable porous structure, a variety of MOFs have been designed and prepared for diverse applications such as catalysis, gas storage, separation, adsorption, and drug delivery. Cyclodextrins (CDs) are naturally occurring macromolecules widely used as excipients in drug formulations and hold great promise for application in the pharmaceutical industry. Their unique ability to act as molecular containers by entrapping large numbers of guest molecules within their cavities makes them outstanding excipients for improving drug solubility, stability, and bioavailability, and they represent valuable tools for the assembly of novel drug delivery systems. γ-cyclodextrin-based MOFs (CD-MOFs) are a typical class of water-sensitive MOFs, containing γ-CD and potassium ions. CD-MOFs have great potential in the biomedical field due to their excellent biocompatibility. However, their backbones are destroyed before reaching target cells and tissues. Their poor hydrolytic stability severely hinders their further biomedical applications. Although many strategies have been reported to improve the hydrolytic stability of CD-MOFs, these strategies still have their own drawbacks, such as time-consuming processes, low drug loading, and harsh reaction conditions.

[0004] Photothermal therapy (PTT) is a treatment method that kills cancer cells by irradiating nanomaterials with photothermal conversion properties with near-infrared light of a specific wavelength, generating heat. Compared with traditional cancer treatments, PTT offers advantages such as fewer side effects, low toxicity, high efficiency, and non-invasiveness, and holds great potential as a new tumor treatment. Dopamine (DA) modification, as a simple and versatile method for material surface functionalization, has attracted increasing attention. Solution oxidation is the most common method for preparing polydopamine (PDA), which can be produced by spontaneous polymerization of DA under alkaline conditions. PDA has strong light absorption in the near-infrared region and can effectively convert laser energy into heat, thereby achieving PTT, promoting rapid drug release at the tumor site and effectively killing tumor cells. PDA also has good biocompatibility, making it a popular choice for tumor photothermal therapy. Patent 202310057535.1 discloses a polydopamine-cyclodextrin metal-organic framework composition that can significantly improve the water stability of CD-MOF, has a high photothermal conversion efficiency, can be used for photothermal antibacterial / anti-tumor treatment, and can also achieve controllable and long-lasting release of loaded drugs. However, its preparation process involves the control of conditions such as high temperature, organic solvents and catalysts, which increases the complexity and cost of the preparation. In addition, the solvent may chemically react with some drugs (such as camptothecin and streptomycin), resulting in low drug loading and poor in vitro activity, making it unsuitable for large-scale production applications.

[0005] Therefore, while improving stability and biocompatibility, developing a green and safe treatment strategy with a simple and controllable preparation process suitable for large-scale production, so that nano-drug carriers have functions such as chemotherapy and photothermal therapy, and constructing a drug delivery system that responds to the tumor microenvironment and combined therapy will provide a safer and more efficient technical solution for the treatment of diseases such as tumors. Summary of the Invention

[0006] The present invention proposes a pH-responsive chemotherapy and photothermal combined therapy drug delivery carrier, its preparation method and application. Using cyclodextrin as raw material, the preparation process of the nanocarrier is ingeniously designed to construct a drug delivery carrier that combines chemotherapy and photothermal therapy. The drug delivery carrier prepared in this application is green and safe, with a simple and controllable preparation process and is suitable for large-scale production. It solves the problems of low efficacy of single tumor treatment, large toxic side effects of chemotherapy, uncontrollable drug delivery, and biological toxicity of drug carriers.

[0007] The technical solution of the present invention is achieved as follows: The present invention uses a hollow cubic structure of the γ-CD-MOF core, loaded with anti-tumor drugs (such as camptothecin), and then modifies the MOF surface with thermosensitive materials such as polydopamine (PDA) and surface modifications such as polyethylene glycol (PEG) to obtain a pH / photothermal dual-responsive, degradable nano-drug carrier with the effect of chemotherapy-photothermal synergistic therapy.

[0008] On the one hand, the present application provides a method for preparing a pH-responsive chemotherapy and photothermal combined therapy drug delivery vehicle, comprising the following steps: (1) Using surfactant as a structure-directing agent, γ-cyclodextrin and alkali metal hydroxide were added and synthesized according to the vapor diffusion method. The crystals were washed with ethanol to remove the residual surfactant, and then vacuum dried to obtain a powdered hollow cubic structure sample γ-CD-MOF (abbreviated as MOF); (2) MOF is dispersed in a mixed solution containing drugs, stirred for reaction I, and then centrifuged to obtain drug-loaded MOF-CPT. (The hollow cubic structure of MOF can transport hydrophobic chemotherapy drugs and can be degraded in the tumor microenvironment, allowing for controlled drug release.) (3) The drug-loaded MOF-CPT was dispersed in a buffer solution, and dopamine was added. After stirring for reaction II, the drug carrier MOF-CPT-PDA was obtained after centrifugation, washing, and drying. (The outer PDA layer can effectively reduce the leakage of drugs in the body. At the same time, PDA will decompose in an acidic environment and has good pH responsiveness. The good photothermal conversion ability of PDA enables the carrier to be converted into heat energy under NIR irradiation, accelerating the release of drugs and generating photothermal therapy to exert a synergistic therapeutic effect with the chemotherapy drug CPT.) (4) The drug carrier MOF-CPT-PDA was dispersed in a buffer solution, and PEG was added. After stirring for reaction III, the mixture was recovered by centrifugation, washed, and dried to obtain the drug delivery carrier MOF-CPT-PDA-PEG. (The modification of the drug carrier surface with PEG can enhance the dispersibility and biocompatibility of the drug carrier.) Preferably, the preparation method of the above-mentioned hollow cubic structure γ-CD-MOF is as follows: using surfactant cetyltrimethylammonium bromide (CTAB) as a structure-directing agent, adding γ-cyclodextrin and potassium hydroxide (KOH) and shaking to dissolve, then placing the glass bottle in a wide-mouth bottle filled with an appropriate amount of methanol (MeOH), performing methanol vapor diffusion at room temperature, washing the crystals with ethanol to remove residual surfactant CATB, and then vacuum drying to obtain a powdered hollow cubic structure sample γ-CD-MOF (abbreviated as MOF).

[0009] The methanol vapor diffusion method for preparing γ-CD-MOF is as follows: 163 mg of γ-cyclodextrin (γ-CD) was placed in a 10 mL glass vial, 5 mL of a 200 mM potassium hydroxide (KOH) solution was added, and the mixture was shaken to dissolve. The vial was then placed in a wide-mouth bottle containing an appropriate amount of methanol (MeOH) and subjected to methanol vapor diffusion at room temperature for 36 hours. The supernatant in the vial was transferred to a 50 mL centrifuge tube, and 5 mL of CTAB-MeOH solution (8 mg / mL) was added as a surfactant to rapidly precipitate the crystalline material. After standing at room temperature for 3 hours, the mixture was centrifuged at 3000 rpm for 3 minutes, the supernatant was discarded, and the crystals were washed three times with ethanol to remove residual CTAB. The resulting powdered γ-CD-MOF (abbreviated as MOF) was then dried under vacuum.

[0010] Preferably, the drug in step (2) is camptothecin (CPT); the concentration of the mixed solution is 0.2-2 mg / mL, and the mixed solution is composed of water and phosphate buffer solution, and the volume ratio of water to phosphate buffer solution is 1:9; the stirring reaction I is carried out under the condition of stirring at room temperature in the dark for 2 h.

[0011] Preferably, in the above step (3), the mass ratio of the drug-loaded MOF-CPT to dopamine is 1:1-6; and the stirring reaction II is carried out at room temperature for 2-6 h.

[0012] Preferably, the concentration of the buffer solution after adding the drug carrier MOF-CPT-PDA in the above step (4) is 0.5-2 mg / mL, and the mass ratio of the drug carrier MOF-CPT-PDA to PEG is 0.5-4:1.

[0013] Preferably, the molecular weight of PEG in the above step (4) is 3000-20000; and the stirring condition for reaction III is stirring at room temperature for 1-6 h.

[0014] Preferably, the buffer is Tris-HCl buffer, with a pH of 8.0-10.5 and a molar concentration of 10 mM; the centrifugation speed is 20,000 rpm and the time is 10 min.

[0015] In the second aspect, the drug delivery carrier MOF-CPT-PDA-PEG prepared by the above preparation method.

[0016] Thirdly, a pH / photothermal dual-responsive, degradable nanodrug delivery system was constructed using the above-mentioned drug delivery carrier MOF-CPT-PDA-PEG.

[0017] Fourthly, the application of the above-mentioned pH / photothermal dual-responsive, degradable nano drug delivery system in the preparation of tumor treatment drugs.

[0018] Preferably, the above drug delivery system is applied to cervical cancer or breast cancer.

[0019] The present invention has the following beneficial effects: 1. The drug delivery carrier MOF-CPT-PDA-PEG constructed by the present invention can improve the stability and biocompatibility of MOF after modification with PDA and give it photothermal conversion function; it also cleverly utilizes the alkaline preparation conditions of MOF in combination with the preparation conditions of polydopamine to complete the surface polydopamine modification of MOF in a weakly alkaline aqueous solution, and can maintain the structure of MOF. The preparation method provided in this application is green and safe, the preparation process is simple and controllable, the process reaction conditions are mild, the cost is low, the drug loading capacity is high, it is easy to actually mass-produce, has practical applicability, and significant economic and social benefits.

[0020] 2. Photothermal experiments demonstrated that MOF-PDA-PEG possessed excellent photothermal conversion capacity (29.3%), meeting the needs of photothermal therapy. Drug release experiments revealed that the CPT release profile exhibited a distinct pH- and photothermal-responsive release pattern. Within a concentration range (5-500 μg / mL), the hemolysis rate of MOF-PDA-PEG was less than 5%. The protein adsorption capacity of MOF-PDA-PEG for various proteins (BSA, OVA, HSA, and mixed proteins) was less than 140 μg / mg, demonstrating the carrier's excellent biocompatibility. At a CPT concentration of 15 μg / mL, MOF-CPT-PDA-PEG and CPT exhibited cell viability of 38.3% and 51.3% on HeLa cells, respectively. Cell-based experiments demonstrated that combined chemotherapy and photothermal therapy significantly enhanced tumor suppression compared to chemotherapy alone. MOF-CPT-PDA-PEG, with its excellent biocompatibility and cytotoxicity, holds great promise for combined chemotherapy and photothermal therapy of cancer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 The synthesis route of photothermal responsive MOF drug carriers and their drug release mechanism in cancer cells.

[0023] Figure 2Transmission electron microscopy images of the drug carrier prepared in Example 3 of the present invention; wherein A is a TEM image of MOF, B is a TEM image of MOF-PDA, C is a TEM image of MOF-PDA-PEG, D is a particle size distribution diagram of MOF, E is a particle size distribution diagram of MOF-PDA, and F is a particle size distribution diagram of MOF-PDA-PEG.

[0024] Figure 3 This is the Zeta potential diagram of the drug carrier prepared in Example 3 of the present invention; wherein a is MOF, b is MOF-PDA, and c is MOF-PDA-PEG.

[0025] Figure 4 The photothermal effect of the drug carrier prepared in Example 3 of the present invention is characterized; wherein A is different materials under 808 nm near-infrared laser (2.0 Wcm -2 ) for 10 min, B is the photothermal curve of MOF-PDA-PEG (5.0 mg / mL) after irradiation with 808 nm near-infrared laser power for 10 min, C is the photothermal curve of MOF-PDA-PEG with different concentrations irradiated with 808 nm near-infrared laser power (2.0 Wcm -2 Figure 5. Photothermal curves of MOF-PDA-PEG nanoparticles irradiated with 808 nm near-infrared laser at different powers for 10 min. Figure 5. D is the near-infrared thermal image of MOF-PDA-PEG nanoparticles irradiated with 808 nm near-infrared laser at different powers for 10 min. Figure 5. E is the temperature change of MOF-PDA-PEG under four consecutive on / off irradiations. Figure 5. F is the system time constant obtained by applying the ratio of the linear cooling time to -lnθ. Data are expressed as the mean ± SD (n = 3).

[0026] Figure 5 These are the absorption comparison diagrams of the free drug and the carrier-bound drug in Example 3 of the present invention under ultraviolet absorption and fluorescence spectra; A is the ultraviolet absorption spectrum diagram, and B is the fluorescence spectrum diagram.

[0027] Figure 6 The release curve of the drug carrier at different pH in Example 3 of the present invention is the cumulative release curve of CPT from MOF-CPT-PDA-PEG under different conditions at 37°C; where a is pH 5.0+NIR, b is pH 5.0, and c is pH 7.4; the data are expressed as mean ± SD (n = 3).

[0028] Figure 7This is a graph evaluating the blood compatibility of the drug carrier in Example 3 of the present invention; wherein A is the protein adsorption capacity of MOF-PDA-PEG and different proteins at different ratios, B is the protein adsorption capacity when the ratio of different carriers to protein is 4:1, C is the hemolysis percentage of MOF-PDA-PEG at different concentrations, and D is the hemolysis percentage of MOF-PDA at different concentrations; data are expressed as mean ± SD (n = 3).

[0029] Figure 8 This is a cytotoxicity experiment of the drug carrier prepared in Example 3 of the present invention, where A is the cell survival rate of HeLa cells after incubation with different concentrations of the carrier for 48 h, B is the cell survival rate of HeLa cells after near-infrared light irradiation with different concentrations of the carrier, and C is the cytotoxicity test results of free CPT and MOF-CPT-PDA-PEG at different concentrations; data are expressed as mean ± SD (n = 3).

[0030] Figure 9 The cell migration results of 4T1 cells in Example 3 of the present invention after incubation with PBS, CPT and MOF-CPT-PDA-PEG for 24 h.

[0031] Figure 10 Figure 3 shows the fluorescence images and survival status of 4T1 cells after incubation with different carriers in Example 3 of the present invention; A is the cell fluorescence image of 4T1 cells after incubation with different carriers for 24 h, B is the survival area of ​​4T1 cells after incubation with different carriers for 24 h, and C is the cell survival rate after incubation with 4T1 cells at different concentrations of CPT for 48 h; MOF-CPT-PDA-PEG and MOF-CPT-PDA-PEG+NIR are expressed as NP and NPL, respectively, and the data are expressed as mean ± SD (n = 3). DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; the materials and reagents used are commercially available reagents and materials unless otherwise specified.

[0034] The present invention provides a method for constructing a pH-responsive nano drug delivery carrier for combined chemotherapy and photothermal therapy. The preparation method of the drug delivery carrier is simple, low in cost, and has a large drug loading capacity. After being modified with PDA, the stability and biocompatibility of MOF can be improved and it can be endowed with photothermal conversion function. The reaction conditions of the preparation process of the present invention are mild and easy to actually mass-produce. The present invention can solve the difficult problem of polydopamine surface modification of hydrophilic cyclodextrin-metal ion coordination MOF. The present invention cleverly utilizes the alkaline preparation conditions of MOF in combination with the preparation conditions of polydopamine to complete the surface polydopamine modification of MOF in a weakly alkaline aqueous solution, and can maintain the structure of MOF. The drug carrier prepared by the present invention can solve the problems of low efficacy of single tumor treatment, large toxic side effects of chemotherapy, uncontrollable drug delivery, etc., and provide a new technical method for the treatment of tumors with significant economic and social value; the synthesis route of the photothermal responsive MOF drug carrier of the present application and its drug release mechanism in cancer cells are as follows: Figure 1 shown.

[0035] Example 1 A method for preparing a pH-responsive nano drug delivery carrier for combined chemotherapy and photothermal therapy, comprising the following steps: (1) Preparation of hollow cubic γ-CD-MOF: γ-CD-MOF was synthesized by vapor diffusion using the surfactant cetyltrimethylammonium bromide as a structure-directing agent, γ-cyclodextrin as an organic ligand, potassium hydroxide (KOH) as a metal ion, and methanol (MeOH) as a vapor diffusion agent. 163 mg of γ-cyclodextrin (γ-CD) was dissolved in a 10 mL glass vial with 5 mL of a 200 mM potassium hydroxide (KOH) solution, shaken, and then placed in a wide-mouth bottle containing an appropriate amount of methanol (MeOH) for methanol vapor diffusion at room temperature for 36 hours. To obtain a small-sized CD-MOF, the supernatant was transferred to a 50 mL centrifuge tube and 5 mL of CTAB-MeOH solution (8 mg / mL) was added as a surfactant to rapidly precipitate the crystalline material. After standing at room temperature for 3 hours, the sample was centrifuged at 3000 rpm for 3 minutes, the supernatant discarded, washed three times with ethanol to remove residual CTAB, and then vacuum dried to obtain a powdered γ-CD-MOF sample (abbreviated as MOF).

[0036] (2) Drug loading: 10 mg of MOF was dispersed in 10 mL of a 0.25 mg / mL CPT-ethanol solution and stirred at room temperature in the dark for 2 hours. After drug loading, the mixture was centrifuged at 20,000 rpm for 10 minutes, and the precipitate was collected and washed three times with anhydrous ethanol to obtain camptothecin-loaded MOF-CPT. The supernatant was collected and the CPT content in the supernatant was measured using a UV-visible spectrophotometer at 370 nm to calculate the drug loading.

[0037] (3) Polydopamine PDA encapsulation: 10 mg of MOF-CPT was dispersed in Tris-HCl buffer (pH 8.0, 10 mM). Then, 10 mg of DA was added and stirred at room temperature for 6 h. Finally, the PDA-coated MOF-CPT-PDA was centrifuged at 20,000 rpm for 10 min and washed three times with deionized water to remove excess dopamine. The mixture was dried at 60°C to obtain black polydopamine-modified MOF-CPT-PDA. The supernatant was collected and its absorbance at 370 nm was measured.

[0038] (4) PEG surface modification: 8 mg of the polydopamine-modified drug carrier MOF-CPT-PDA obtained in step (3) and 20 mL of ethanol were added to a round-bottom flask. 2 mL of a 1.0 mg / mL deionized water solution of PEG (MW = 3000-20000) was added while stirring. The mixture was stirred for 1 h in a sealed, light-proof state. Unencapsulated PEG was removed by centrifugation, and then washed three times with 95% ethanol to obtain the PEG-modified drug carrier MOF-CPT-PDA-PEG. All supernatants were collected, the absorbance of the supernatant at 370 nm was measured, and the CPT loading was calculated to be 117 μg / mg.

[0039] Example 2 A method for preparing a pH-responsive nano drug delivery carrier for combined chemotherapy and photothermal therapy, comprising the following steps: (1) The preparation of hollow cubic structured γ-CD-MOF was the same as in Example 1.

[0040] (2) Drug loading: 10 mg of MOF was dispersed in 10 mL of a 0.5 mg / mL CPT-ethanol solution and stirred at room temperature in the dark for 2 hours. After drug loading, the mixture was centrifuged at 20,000 rpm for 10 minutes, and the precipitate was collected and washed three times with anhydrous ethanol to obtain camptothecin-loaded MOF-CPT. The supernatant was collected and the CPT content in the supernatant was measured at 370 nm using a UV-visible spectrophotometer to calculate the drug loading.

[0041] (3) Polydopamine PDA encapsulation: 10 mg of MOF-CPT was dispersed in 20 mg of Tris-HCl (pH 9.5) buffer containing DA. The mixture was stirred for 2 hours in the dark and open to the atmosphere. Dopamine oxidized to polydopamine in the presence of air and then self-aggregated onto the MOF-CPT surface. Unencapsulated PDA was removed by centrifugation, and the mixture was washed three times with 95% ethanol to obtain the polydopamine-modified drug carrier MOF-CPT-PDA. The supernatant was collected and its absorbance at 370 nm was measured.

[0042] (4) PEG surface modification: 6 mg of the polydopamine-modified drug carrier MOF-CPT-PDA obtained in step (3) and 20 mL of ethanol were added to a round-bottom flask. 2 mL of a 1.0 mg / mL deionized water solution of PEG (MW = 3000-20000) was added while stirring. The mixture was stirred for 2 h in a sealed, light-proof state. Unencapsulated PEG was removed by centrifugation, and then washed twice with 95% ethanol to obtain the PEG-modified drug carrier MOF-CPT-PDA-PEG. All supernatants were collected, and the absorbance value of the supernatant at 370 nm was measured. The CPT drug loading was calculated to be 232 μg / mg.

[0043] Example 3 A method for preparing a pH-responsive nano drug delivery carrier for combined chemotherapy and photothermal therapy, comprising the following steps: (1) The preparation of hollow cubic structured γ-CD-MOF was the same as in Example 1.

[0044] (2) Drug loading: 10 mg of MOF was dispersed in 10 mL of a 1 mg / mL CPT-ethanol solution and stirred at room temperature in the dark for 2 hours. After drug loading, the mixture was centrifuged at 20,000 rpm for 10 minutes, and the precipitate was collected and washed three times with anhydrous ethanol to obtain camptothecin-loaded MOF-CPT. The supernatant was collected and the CPT content in the supernatant was measured using a UV-visible spectrophotometer at 370 nm to calculate the drug loading.

[0045] (3) Polydopamine PDA encapsulation: 10 mg of MOF-CPT was dispersed in a Tris-HCl (pH 10.0) buffer solution containing 30 mg of DA. The solution was stirred for 4 hours in the dark and open to the atmosphere. Dopamine oxidized to polydopamine in the presence of air and then self-aggregated onto the MOF-CPT surface. Unencapsulated PDA was removed by centrifugation, and the solution was washed three times with 95% ethanol to obtain the polydopamine-modified drug carrier MOF-CPT-PDA. The supernatant was collected and its absorbance at 370 nm was measured.

[0046] (4) PEG surface modification: 4 mg of the polydopamine-modified drug carrier MOF-CPT-PDA obtained in step (3) and 20 mL of ethanol were added to a round-bottom flask. 2 mL of a 1.0 mg / mL deionized water solution of PEG (MW = 3000-20000) was added while stirring. The mixture was stirred for 2 h in a sealed, light-proof state. Unencapsulated PEG was removed by centrifugation, and then washed three times with 95% ethanol to obtain the PEG-modified drug carrier MOF-CPT-PDA-PEG. All supernatants were collected, the absorbance of the supernatant at 370 nm was measured, and the CPT loading was calculated to be 685 μg / mg.

[0047] Example 4 A method for preparing a pH-responsive nano drug delivery carrier for combined chemotherapy and photothermal therapy, comprising the following steps: (1) The preparation of hollow cubic structured γ-CD-MOF was the same as in Example 1.

[0048] (2) Drug loading: Disperse 10 mg of MOF in 10 mL of a 2 mg / mL CPT-ethanol solution at room temperature with stirring for 2 hours in the dark. After drug loading, centrifuge at 20,000 rpm for 10 minutes, collect the precipitate, and then wash with anhydrous ethanol until the supernatant is nearly colorless, yielding camptothecin-loaded MOF-CPT. Collect the supernatant and measure the CPT content in the supernatant using a UV-visible spectrophotometer at 370 nm to calculate the drug loading.

[0049] (3) Polydopamine PDA encapsulation: 10 mg of MOF-CPT was dispersed in a Tris-HCl (pH 10.5) buffer solution containing 60 mg of DA. The mixture was stirred for 2 hours in the dark and open to the atmosphere. Dopamine oxidized to polydopamine in the presence of air and then self-aggregated onto the MOF-CPT surface. Unencapsulated PDA was removed by centrifugation, and the mixture was washed twice with 95% ethanol to obtain the polydopamine-modified drug carrier MOF-CPT-PDA. The supernatant was collected and its absorbance at 370 nm was measured.

[0050] (4) PEG surface modification: 1 mg of the polydopamine-modified drug carrier MOF-CPT-PDA obtained in step (3) and 20 mL of ethanol were added to a round-bottom flask. 2 mL of a 1.0 mg / mL deionized water solution of PEG (MW = 3000-20000) was added while stirring. The mixture was stirred for 2 h in a sealed, light-proof state. Unencapsulated PEG was removed by centrifugation, and then washed twice with 95% ethanol to obtain the PEG-modified drug carrier MOF-CPT-PDA-PEG. All supernatants were collected, the absorbance of the supernatant at 370 nm was measured, and the CPT loading was calculated to be 1343 μg / mg.

[0051] Implementation effect examples To prove the success of sample preparation, the obtained samples were characterized. The method of the present invention has achieved consistent results after repeated experiments. The relevant application test data are as follows: Experiment 1: The morphology of the carrier was characterized by transmission electron microscopy (TEM). The drug carrier prepared in Example 3 was characterized by TEM. Figure 2 As shown, the particle size distribution is uniform and the morphology is controllable, which is suitable for large-scale production.

[0052] The surface charge of the carrier was measured using a Zeta particle size analyzer. Figure 3 As shown, the surface potential of MOF (a) is -15.9 mV. After being wrapped with dopamine, the potential of the carrier MOF-PDA (b) becomes -22.9 mV. After the introduction of PEG, the surface potential of the carrier MOF-PDA-PEG (c) is -25.9. The surface potential of the carrier changes significantly, proving that the surface modification is successful. The prepared drug carrier was characterized for its photothermal effect. First, the photothermal conversion capacity of MOF-PDA-PEG at different concentrations was measured. MOF-PDA-PEG was dispersed in a PBS (10 mM) buffer solution at pH 7.4, and the concentrations were 1, 2, 5, and 10 mg / mL. A PBS buffer solution without the carrier was used as a control group. MOF-CPT-PDA-PEG at different concentrations was irradiated for 10 minutes at an 808 nm infrared laser with a power of 2 W. The temperature change of the solution was measured using a thermocouple thermometer, and a photothermal curve was plotted. The photothermal conversion capacity of MOF-PDA-PEG at different powers was then measured. MOF-PDA-PEG was dispersed in a 10 mM PBS buffer solution at pH 7.4 to a concentration of 10 mg / mL. The 10 mg / mL MOF-PDA-PEG solution was irradiated with infrared lasers at powers of 0.6, 1.4, and 2.0 W cm for 10 minutes, respectively. The temperature change of the solution was measured using a thermocouple thermometer, and a photothermal curve was plotted. To investigate the photothermal stability of MOF-PDA-PEG nanoparticles, a 10 mg / mL MOF-PDA-PEG nanoparticle solution was irradiated with an 808 nm infrared laser at 2 W for 10 minutes. The laser was then turned off and the sample was allowed to cool at room temperature for 15 minutes. Four cycles of photothermal curves were repeated, and the temperature change was recorded. The photothermal conversion efficiency of the material was calculated based on the temperature change over one cycle. Figure 4 The constructed drug carrier showed good photothermal response (29.3%). The above results indicate that MOF-PDA-PEG has good photothermal conversion ability, and the photothermal effect becomes more obvious with increasing carrier concentration and radiation density.

[0053] Experiment 2 The prepared drug carrier was characterized by spectrometry, such as Figure 5 The drug carrier shown in the figure shows the characteristic peak after loading the CPT drug. The prepared drug carrier was subjected to in vitro simulated release evaluation, as shown in Figure 2. Figure 6The cumulative release curves of CPT from the drug carrier MOF-CPT-PDA-PEG under different conditions are shown: pH 5.0+NIR (a), pH 5.0 (b), and pH 7.4 (c). In pH 5.0 buffer, the cumulative release rate of MOF-CPT-PDA-PEG was 44.3%, while in pH 7.4 buffer, the cumulative release rate was 33.3%. It is also noteworthy that drug release was more rapid in pH 5.0 buffer, with more CPT released from the carrier in the same timeframe. This is because PDA degrades under acidic conditions, destroying the PDA layer on the MOF surface, leading to more and faster drug release. When the carrier was exposed to light for a specific period of time under acidic conditions, the cumulative release rate increased to 52.4%. This is likely due to the fact that the increased temperature accelerated the movement of drug molecules, enhancing the CPT release rate. Drug release results indicate that the surface carrier exhibits excellent pH- and photothermal-responsive drug release behavior.

[0054] Experiment 3 The prepared drug carrier was subjected to hemolysis test evaluation, such as Figure 7 The prepared drug delivery vehicle exhibits excellent blood compatibility. Within a certain concentration range (5-500 μg / mL), the hemolysis rate of MOF-PDA-PEG is less than 5%, and the protein adsorption capacity of MOF-PDA-PEG for different proteins (BSA, OVA, HSA, and mixed proteins) is less than 140 μg / mL. Blood compatibility experiments demonstrate the carrier's good biocompatibility.

[0055] Experiment 4 The cytotoxicity test was performed by MTT method. The prepared drug carrier was subjected to in vitro cytotoxicity evaluation, such as Figure 8 The unloaded drug carriers (a, b) showed minimal toxicity to HeLa tumor cells, but irradiation with infrared light (808 nm) significantly increased their toxicity. (c) At a drug loading concentration of 15 μg / mL and 808 nm laser irradiation, the cell survival rate was only 23.8%. However, the cell survival rates of MOF-CPT-PDA-PEG and CPT for HeLa cells were 38.3% and 51.3%, respectively.

[0056] Experiment 5 The prepared drug carrier was subjected to cell migration and live / dead staining studies, e.g. Figure 9 、 Figure 10 The prepared drug carrier was more efficiently engulfed by cells. The survival rate of 4T1 cells in the MOF-CPT-PDA-PEG+NIR group dropped to 17%, demonstrating the carrier's potential for photothermal therapy. Live / dead staining experiments demonstrated the significant potential of MOF-CPT-PDA-PEG for tumor therapy.

[0057] PDA encapsulation imparts photothermal conversion capabilities to the carrier, while PEG surface modification enhances its biocompatibility. Photothermal experiments demonstrate that MOF-PDA-PEG possesses excellent photothermal conversion capacity (29.3%), meeting the requirements of photothermal therapy. Drug release experiments using MOF-CPT-PDA-PEG reveal that the CPT release profile exhibits a distinct pH- and photothermal-responsive release pattern. Within a concentration range (5-500 μg / mL), the hemolysis rate of MOF-PDA-PEG is less than 5%, and the protein adsorption capacity of MOF-PDA-PEG for various proteins (BSA, OVA, HSA, and mixed proteins) is less than 140 μg / mL. Hemocompatibility experiments demonstrate the carrier's excellent biocompatibility. At a CPT concentration of 15 μg / mL, the cell viability of HeLa cells treated with MOF-CPT-PDA-PEG and CPT was 38.3% and 51.3%, respectively. Cellular experiments demonstrate that combined chemotherapy and photothermal therapy significantly enhances tumor inhibition compared to chemotherapy alone. MOF-CPT-PDA-PEG has good biocompatibility and cytotoxicity, and has great potential in chemotherapy-photothermal combined cancer therapy.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a pH-responsive chemotherapy and photothermal combined therapy drug delivery carrier, characterized in that: The steps are: (1) MOF is dispersed in a mixed solution containing a drug, stirred for reaction I, and then centrifuged to obtain drug-loaded MOF-CPT; (2) The drug-loaded MOF-CPT was dispersed in a buffer solution, and dopamine was added. After stirring for reaction II, the mixture was recovered by centrifugation, washed, and dried to obtain the drug carrier MOF-CPT-PDA. (3) The drug carrier MOF-CPT-PDA was dispersed in a buffer solution, and PEG was added. After stirring for reaction III, the mixture was recovered by centrifugation, washed, and dried to obtain a pH-responsive chemotherapy and photothermal combined therapy drug delivery carrier, namely MOF-CPT-PDA-PEG.

2. The method for preparing a pH-responsive chemotherapy and photothermal combined therapy drug delivery vector according to claim 1, characterized in that: In step (1), the drug is camptothecin; the concentration of the mixed solution is 0.2-2 mg / mL, and the solution is composed of water and phosphate buffer solution, with a volume ratio of water to phosphate buffer solution of 1:9; and the stirring reaction I is carried out under the condition of stirring at room temperature in the dark for 2 h.

3. The method for preparing a pH-responsive chemotherapy and photothermal combined therapy drug delivery carrier according to claim 2, characterized in that: In step (2), the mass ratio of the drug-loaded MOF-CPT to dopamine is 1:1-6; and the stirring reaction II is carried out at room temperature for 2-6 h.

4. The method for preparing a pH-responsive chemotherapy and photothermal combined therapy drug delivery vector according to claim 3, characterized in that: The concentration of the buffer solution after adding the drug carrier MOF-CPT-PDA in step (3) is 0.5-2 mg / mL, and the mass ratio of the drug carrier MOF-CPT-PDA to PEG is 0.5-4:

1.

5. The method for preparing a pH-responsive chemotherapy and photothermal combined therapy drug delivery carrier according to claim 4, characterized in that: The molecular weight of PEG in step (3) is 3000-20000; the stirring reaction III is carried out at room temperature for 1-6 hours.

6. The method for preparing a pH-responsive chemotherapy and photothermal combined therapy drug delivery vector according to claim 5, characterized in that: The buffer solution is Tris-HCl buffer solution with a pH of 8.0-10.5 and a molar concentration of 10 mM; the centrifugal speed is 20,000 rpm and the time is 10 min.

7. The pH-responsive chemotherapy and photothermal therapy drug delivery carrier MOF-CPT-PDA-PEG prepared by the preparation method according to any one of claims 1 to 6.

8. A pH / photothermal dual-responsive, degradable nanodrug delivery system constructed using the pH-responsive chemotherapy and photothermal combined therapy drug delivery carrier MOF-CPT-PDA-PEG according to claim 7.

9. Use of the nano drug delivery system according to claim 8 in the preparation of drugs for treating tumors.

10. The use according to claim 9, characterized in that: The tumor is cervical cancer or breast cancer.

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