Drug delivery system and preparation method and application thereof

Abstract

The invention provides a drug delivery system, the drug delivery system is formed by cross-linking and curing hyaluronic acid conductive hydrogel and chitosan nanoparticles modified by chlorotoxin, the hyaluronic acid conductive hydrogel is formed by cross-linking and curing hyaluronic acid-methacrylic anhydride and reduced graphene oxide, and the chitosan nanoparticles modified by chlorotoxin are formed by cross-linking and curing hyaluronic acid-methacrylic anhydride and reduced graphene oxide. The chlorotoxin-modified chitosan nanoparticles are formed by loading a therapeutic drug on chitosan nanoparticles, coupling chlorotoxin by adopting an EDC / NHS activation method, and modifying by PEG (Polyethylene Glycol). The invention also provides a preparation method of the drug delivery system. The invention also provides application of the drug delivery system in preparation of drugs for treating tumors. According to the invention, two stages of carriers are used for synergistically and doubly loading therapeutic drugs, so that the conductive function, biocompatibility, drug loading stability and release controllability are considered, and the MGMT high-expression mediated tumor drug resistance is effectively reversed.

Description

Technical Field

[0001] This invention belongs to the field of materials science and relates to a hydrogel, specifically a drug delivery system, its preparation method, and its uses. Background Technology

[0002] The prior art related to this invention mainly revolves around two core directions: glioma treatment strategies and electric field-responsive drug delivery systems, as detailed below:

[0003] 1.1 Current Technologies in Glioma Treatment: The standard treatment for gliomas is currently "surgical resection + postoperative radiotherapy and chemotherapy." Simultaneously, physical therapy techniques are gradually being clinically applied, forming a multi-pronged treatment approach. This includes surgical treatment: as the preferred treatment for gliomas, the core goal is to remove the tumor mass to the greatest extent possible. However, due to the invasive growth characteristics of tumors, it is difficult to completely eliminate tumor cells diffused into normal brain tissue, leaving a risk of postoperative recurrence. Radiotherapy and chemotherapy combination therapy: Postoperative radiotherapy is routinely combined with temozolomide (TMZ) chemotherapy. TMZ is currently a first-line chemotherapy drug for glioma treatment, acting orally, while radiotherapy inhibits tumor cell proliferation through ionizing radiation. The two work synergistically to improve local control. Tumor Treating Fields (TTFields): A clinically applied physical therapy technique that interferes with tumor cell mitosis by applying a specific frequency alternating electric field to inhibit tumor growth. It is often combined with radiotherapy and chemotherapy for the treatment of recurrent or advanced gliomas, becoming an important supplement to the existing treatment system.

[0004] 1.2. Related Technologies of Electric Field-Response Drug Delivery Systems: To address the issue of low drug delivery efficiency, basic research on electric field-responsive drug delivery systems has been conducted in this field. The core focus is on carrier material design and response mechanism development, including carrier material types: Two main types of core materials are used to construct responsive carriers—first, conductive polymers (such as polyaniline and polypyrrole), which achieve electric field response due to their good conductivity, but have poor biocompatibility and in vivo degradation; second, hydrogel carriers (such as natural polysaccharide hydrogels), which possess good biocompatibility and drug loading capacity, and some are used for electric field response research after conductive modification.

[0005] The problems with existing technologies are as follows:

[0006] 2.1 Glioma treatment faces significant bottlenecks: surgery cannot completely remove invasive tumor cells, and the postoperative recurrence rate exceeds 90%; radiotherapy is prone to causing irreversible cognitive damage (occurring in 50% of elderly patients); first-line chemotherapy TMZ has low blood-brain barrier penetration, and 40% of patients develop drug resistance due to high expression of the O6-Methylguanine-DNA Methyltransferase (MGMT) gene.

[0007] 2.2 Insufficient performance of electric field responsive carriers: Traditional conductive polymers (such as polyaniline and polypyrrole) have poor biocompatibility and are difficult to degrade in vivo; single hydrogel carriers have weak targeting, insufficient BBB penetration ability, and low electric field response sensitivity, making it impossible to achieve precise and controllable drug release.

[0008] 2.3 Lack of a synergistic treatment system: The integrated approach of "carrier targeted delivery + electric field controlled release + physical-chemical synergistic killing" has not been formed, resulting in significant drug toxicity and side effects, a narrow therapeutic window, and limited overall efficacy. Summary of the Invention

[0009] To address the aforementioned technical problems in the prior art, the present invention provides a drug delivery system, its preparation method, and its uses. This drug delivery system, its preparation method, and its uses aim to solve the technical problem of poor efficacy of existing drugs and methods in treating gliomas.

[0010] This invention provides a drug delivery system formed by cross-linking and solidifying hyaluronic acid conductive hydrogel and chlortoxin-modified chitosan nanoparticles. The hyaluronic acid conductive hydrogel is formed by cross-linking and solidifying hyaluronic acid-methacrylic anhydride and reduced graphene oxide. The chlortoxin-modified chitosan nanoparticles are formed by loading therapeutic drugs onto chitosan nanoparticles, coupling chlortoxin with the EDC / NHS activation method, and then modifying them with PEG. The amino acid sequence of the chlortoxin is MCMPCFTTDHQMARKCDDCCGGKGRGKCYGPQCLCR-NH2 (SEQ ID NO.1).

[0011] Specifically, chlortoxin (CTX) is a 23-peptide isolated from the venom of the Israeli golden scorpion, with a molecular weight of approximately 2.6 kDa. It was purchased from Aladdin, CAS number 56-75-7.

[0012] Furthermore, the drug is a drug for treating tumors, preferably a drug for treating gliomas.

[0013] Furthermore, the aforementioned drug for treating tumors is temozolomide.

[0014] The present invention also provides a method for preparing the above-mentioned drug delivery system, comprising the following steps:

[0015] 1) A step-by-step process for preparing a primary carrier hyaluronic acid conductive hydrogel: 200-300 kDa hyaluronic acid is selected and modified with methacrylic anhydride to obtain hyaluronic acid-methacrylic anhydride (double bond substitution degree is expected to reach 22%); then, conductive filler is added to reduce graphene oxide, and the hydrogel is cured using a two-step method of freeze-thaw pre-crosslinking + ultraviolet light crosslinking to form a three-dimensional porous network structure of hyaluronic acid conductive hydrogel with a pore size of 50-200 μm (the final hydrogel conductivity is expected to reach 1.0-1.2 S / cm).

[0016] 2) A step for preparing chloramphenicol-modified chitosan nanoparticles as a secondary carrier: 100-200 nm chitosan nanoparticles are prepared by ionogel method, and therapeutic drugs are loaded by electrostatic adsorption (the drug loading rate is expected to reach 8.5%); chloramphenicol is coupled by EDC / NHS activation method (the modification efficiency is expected to be ≥85%), wherein the amino acid sequence of the chloramphenicol is MCMPCFTTDHQMARKCDDCCGGKGRGKCYGPQCLCR-NH2, and then modified by PEG to obtain chloramphenicol-modified chitosan nanoparticles (the final product has a stable zeta potential of around +15 mV).

[0017] 3) Assembly steps of a dual-encapsulation system: Chlorine-modified chitosan nanoparticles and therapeutic drugs are co-dispersed in a hyaluronic acid-methacrylic anhydride solution, and cross-linked and cured to form a drug delivery system (the total drug loading rate of this system is expected to reach 6.8%, with a low drug leakage rate after 7 days, and it has both good drug loading stability and sustained release basis).

[0018] Further, in step 1), 200-300 kDa hyaluronic acid is dissolved in PBS buffer, then methacrylic anhydride (MAA) is added, and the reaction is carried out in an ice bath at 2-6°C for 12-36 hours. The reaction product is purified by dialysis and then freeze-dried to obtain hyaluronic acid-methacrylic anhydride. Reduced graphene oxide is added to the hyaluronic acid-methacrylic anhydride solution, and the mixture is subjected to high-frequency sonication while being cooled in an ice bath. After at least two freeze-thaw cycles for pre-crosslinking, a photoinitiator is added, and the reaction is carried out at 365 nm and 10 mW / cm. 2 Ultraviolet light irradiation curing yields a hyaluronic acid conductive hydrogel with a three-dimensional porous network structure of 50-200 μm pore size.

[0019] Further, in step 2), chitosan is dissolved in acetic acid solution to obtain chitosan solution; sodium tripolyphosphate solution is added, stirred and collected by centrifugation; therapeutic drugs are added for easy adsorption and then purified by centrifugation; after activation by EDC / NHS, chlorine toxin is added, wherein the amino acid sequence of chlorine toxin is MCMPCFTTDHQMARKCDDCCGGKGRGKCYGPQCLCR-NH2, and mPEG-SS is added for surface modification, finally obtaining chlorine toxin modified chitosan nanoparticles.

[0020] Furthermore, in step 3), chlortoxin-modified chitosan nanoparticles are dispersed in a hyaluronic acid-methacrylic anhydride solution, and a drug for treating tumors is added to obtain a drug delivery system.

[0021] Furthermore, the aforementioned drug for treating tumors is temozolomide.

[0022] The present invention also provides the use of the above-described drug delivery system in the preparation of drugs for treating tumors.

[0023] Furthermore, the drug delivery system contains temozolomide.

[0024] The specific technical features of this invention are as follows:

[0025] 1.1 Hierarchical Dual-Encapsulation Drug Delivery System: A macroscopic-microscopic hierarchical loading structure is constructed using a macroscopic conductive hydrogel of hyaluronic acid (HA) and a dual encapsulation technology of modified chitosan nanoparticles (CSNPs). The primary carrier is a composite reduced graphene oxide (rGO) HA conductive hydrogel, which endows the system with conductivity and a basis for sustained drug release. The secondary carrier is chlortoxin-modified CSNPs. Through the synergistic dual loading of TMZ by the two carriers, conductivity, biocompatibility, drug loading stability, and controllable release are all taken into account.

[0026] 1.2 Synergistic Targeting and BBB Penetration Mechanism: Integrating the triple effects of CSNPs cationic penetration (enhancing cross-barrier affinity + chlorine toxin receptor-mediated (precisely identifying tumor cells) + polyethylene glycol (PEG) invisibility (prolonging in vivo circulation time), simultaneously improving BBB penetration efficiency and tumor site targeted enrichment ability.

[0027] 1.3 Low-voltage intelligent electric field controlled release module: Adapted to 1-3V safe low voltage and 200kHz alternating electric field, it supports two modes: continuous power-on and intermittent power-on (power-on for 10min / pause for 20min). Through the effects of electric field-induced electroswelling and charge rearrangement, it realizes real-time and precise control of drug release rate.

[0028] 1.4 Electric field-chemotherapy synergistic killing mechanism: Breaking through the traditional "single carrier + single treatment" framework, it integrates multidisciplinary technologies to form an integrated solution of "targeted delivery + electric field controlled release + synergistic killing". It synergistically integrates the physical killing effect of electric field (interfering with tumor cell mitosis and destroying spindle structure) with the DNA damage effect of TMZ chemotherapy to form a "physical-chemical" dual killing pathway, which effectively reverses tumor drug resistance mediated by high expression of MGMT.

[0029] 2. Electric Field Control Module Design

[0030] 2.1 Core parameters: It is compatible with alternating electric fields with a voltage range of 1-3V and a frequency of 200kHz, and an electric field strength of 50-150V / m; it uses platinum wire electrodes with a diameter of 0.5mm and an electrode spacing of 2cm to ensure that the electric field accurately covers the target area.

[0031] 2.2 Control Mode: Supports two modes: continuous power supply and intermittent power supply (power supply for 10 min / pause for 20 min). The intermittent mode matches the 24-hour division cycle of tumor cells, enabling pulsed drug release and adapting to the rhythm of tumor treatment.

[0032] 2.3 Equipment compatibility: Compatible with portable DC power supplies with a volume of <1000g, easy to operate and highly portable, meeting the needs of clinical scenarios such as postoperative bedside treatment.

[0033] 3. Application Method

[0034] 3.1 Administration method: The intracranial local implantation or targeted delivery mode is adopted. The dual-encapsulation system can efficiently penetrate the BBB and specifically accumulate at the tumor site through the triple synergistic mechanism of "CSNPs cation penetration + chlorine toxin receptor mediation + PEG invisibility".

[0035] 3.2 Electric field initiation and drug release regulation: After carrier implantation, a low voltage electric field of 1-3V is applied. Drug release is precisely regulated through electroswelling, electroosmosis and charge rearrangement effects. The drug release rate is higher at 2V voltage for 24 hours.

[0036] 3.3 Synergistic therapy: The electric field exerts a physical killing effect by interfering with the mitosis of tumor cells, which synergizes with the DNA damage effect of TMZ chemotherapy, killing tumor cells through a dual pathway, while reversing drug resistance mediated by high expression of MGMT.

[0037] This invention possesses five core advantages, precisely addressing the core pain points in glioma treatment, and combining efficacy, safety, and clinical translational value:

[0038] 1. High targeted delivery efficiency: Through a triple synergistic mechanism, BBB achieves efficient penetration, increasing the drug concentration at the tumor site compared to free TMZ, and significantly exceeding that of normal brain tissue, resulting in outstanding targeted enrichment effect;

[0039] 2. Precise and controllable drug release: Relying on a 1-3V low-voltage electric field, it supports a pulsed drug release mode, adapts to the tumor cell division cycle, and can adjust the drug release rate in real time, effectively avoiding the development of drug resistance.

[0040] 3. Significant synergistic therapeutic effect: The synergistic effect of electric field physical killing and TMZ chemotherapy has a high tumor inhibition rate against U87 glioma cells, can reverse drug resistance mediated by MGMT high expression, and prolong the median survival time of model mice.

[0041] 4. Excellent biocompatibility: With natural endogenous HA as the core material, the degradation products are non-toxic, the survival rate of nerve cells after 72 hours of co-culture is high, there is no obvious inflammatory reaction after implantation in vivo, and the safety is high.

[0042] 5. Strong clinical applicability: Focusing on gliomas, it is suitable for intracranial implantation and postoperative bedside treatment. It specifically addresses the problems of difficulty in penetrating the blood-brain barrier (BBB) ​​and drug resistance. It is compatible with portable electric field devices, is easy to operate, and can be used for the treatment of residual and recurrent tumors after glioma surgery. Moreover, the core technology architecture can be extended to other cross-barrier or precise controlled-release treatment scenarios. It has broad application potential for solid tumors that need to cross physiological barriers or for the treatment of chronic diseases requiring precise controlled release.

[0043] This invention focuses on the intersection of drug delivery systems and tumor treatment, targeting the precision treatment of gliomas. With low-voltage electric field response as its core, it constructs an integrated precision treatment technology system to address the bottlenecks in glioma treatment. Through an integrated design of "synergistic BBB penetration + precise tumor enrichment + on-demand pulsed drug release + electric field-chemotherapy synergistic killing", it overcomes treatment bottlenecks such as difficulty in penetrating the blood-brain barrier and strong tumor drug resistance. It provides a safe, efficient and precise treatment plan for gliomas, especially postoperative residual, recurrent and MGMT-high expression drug-resistant tumors, while also providing technical support for tumor-targeted therapy across physiological barriers. Attached Figure Description

[0044] Figure 1This is a schematic diagram of the hyaluronic acid conductive hydrogel of the present invention. At the center of the image is the core matrix of chitosan nanoparticles (CSNPs), which encapsulate temozolomide (TMZ) drug particles. The drug can be released through the pores of the nanoparticles. The surface of the nanoparticles is modified with PEG, significantly extending the circulation time of the carrier in vivo. The outermost conjugated chloramphenicol can simultaneously bind to surface receptors on glioma cells and blood-brain barrier endothelial cells, providing core support for the carrier's cross-blood-brain barrier and tumor-specific enrichment. Green represents CSNPs; blue represents PEG; pink represents chloramphenicol; and light green represents chitosan nanoparticles.

[0045] Figure 2 This is a schematic diagram of the electric field-targeted controlled release principle of the hyaluronic acid conductive hydrogel of the present invention. The upper half of the image shows a three-dimensional network of hyaluronic acid (HA) conductive hydrogel. The HA molecular chains cross-link to form a porous scaffold, and functionalized chitosan nanoparticles are present in the pores, completing the second-level encapsulation of the drug-loaded nanoparticles and constructing a hierarchical dual drug-loading system of "hydrogel-nanoparticle". Chlorine toxin coupled to the surface of the hydrogel can simultaneously bind to the surface receptors of glioma cells and blood-brain barrier endothelial cells, providing core support for the specific enrichment of the carrier at the lesion site. The lower half of the image shows the secondary drug-loading unit, namely temozolomide (TMZ) chitosan nanoparticles that have been PEGylated and functionalized with chlorine toxin. After a safe low-voltage alternating electric field of 1-3V is applied to the system, the release behavior of the drug in the pores can be precisely driven by the electro-response characteristics of the conductive hydrogel. Detailed Implementation

[0046] The specific implementation of this invention includes the preparation of a dual-encapsulated drug delivery system, the construction of an electric field modulation module, and in vivo and in vitro application verification. The detailed steps are as follows:

[0047] Example 1: Preparation of a double-encapsulated drug delivery system

[0048] 1.1 HA-MA (Hyaluronic Acid-Methacrylamide) Modification:

[0049] Dissolve 200 kDa hyaluronic acid (HA) in PBS buffer at pH 7.4 to prepare a 2% (w / w) HA solution.

[0050] In the above HA solution, MAA (methacrylic anhydride) was slowly added dropwise at a molar ratio of 3:1 to the repeating unit of HA, and the reaction was carried out in an ice bath at 4°C for 24 hours. The reaction product was purified by dialysis and then freeze-dried to obtain a double bond substitution degree of 22% (using...). 1 HA-MA was obtained by 1H-NMR nuclear magnetic resonance hydrogen spectroscopy.

[0051] Double bond substitution degree (%) = A C=C / 2AHA / n ×100%;

[0052] Where A C=C For the integral area of ​​the double-bonded carbon, A HA Let n be the integral area of ​​the characteristic hydrogen of HA, and n be the number of hydrogen atoms corresponding to the characteristic hydrogen of HA.

[0053] 1.2 Preparation of rGO composite hydrogel:

[0054] Weigh the above-mentioned HA-MA and prepare a 10% (w / w) HA-MA solution. Add reduced graphene oxide (rGO) to make its (w / w) concentration in the HA-MA solution 2%. Perform high-frequency sonication for 30 minutes (simultaneously, cool in an ice bath to prevent material degradation). After three freeze-thaw cycles for pre-crosslinking, add the photoinitiator Irgacure 2959 (2-hydroxy-4′-(2-hydroxyethoxy)-2-methylphenylacetone, 98% purchased from Shanghai Maclean Chemical Reagent). After addition, the final (w / w) concentration of the photoinitiator in the HA-MA solution is 0.1%. Use a wavelength of 365 nm and a wavelength of 10 mW / cm². 2 After being irradiated with ultraviolet light for 30 seconds, the HA-rGO conductive hydrogel was finally obtained.

[0055] Its conductivity was measured to be 1.2 S / cm using a conductivity meter.

[0056] 1.3 Preparation of CTX-PEG-CSNPs:

[0057] 100 kDa chitosan was dissolved in a 1% (w / w) acetic acid solution to prepare a 2 mg / mL chitosan solution. A 1 mg / mL sodium tripolyphosphate (TPP) solution was added dropwise, with a TPP to chitosan solution mass ratio of 1:10. After stirring for 30 min, CSNPs (Chitosan-based CSNPs) were collected by centrifugation. Chitosan nanoparticles were added to a TMZ solution at a mass ratio of 10:1 (chitosan to TMZ), and the mixture was adsorbed for 2 hours before centrifugation and purification. After activation with EDC / NHS (a combination of carbodiimide and N-hydroxysuccinimide), chlorine toxin was coupled to CSNPs at a molar ratio of 50:1 (approximately 1 mL of chlorine toxin was added to 3 mL of CSNPs). The amino acid sequence of the chlorine toxin was MCMPCFTTDHQMARKCDDCCGGKGRGKCYGPQCLCR-NH2 (SEQ ID NO.1). Then, mPEG-SS (composed of polyethylene glycol (PEG) chains and succinimide succinate (SS) groups) was added for surface modification to finally obtain PEG-CTX-TMZ-CSNPs.

[0058] 1.4 Dual System Assembly:

[0059] PEG-CTX-TMZ-CSNPs were dispersed in a 10% (w / w) HA-MA solution at a mass ratio of 1:10. TMZ was then added again (the experiment involved adding TMZ twice to construct a dual delivery system through "intra-nanoparticle loading + hydrogel loading," achieving graded release, improving drug loading efficiency, and combining the advantages of local sustained release and targeted delivery to optimize drug delivery and therapeutic effects), resulting in a final TMZ concentration of 8%. After treatment with the aforementioned cross-linking and curing process (freeze-thaw pre-crosslinking + photocrosslinking two-step method), a composite hydrogel carrier with a high total drug loading rate was obtained, the specific structure of which is shown below. Figure 1 As shown.

[0060] Example 2: Electric Field Control Module and Application Implementation:

[0061] Electric field equipment setup:

[0062] The control system is constructed using a combination of a signal generator and a high-voltage amplifier. The signal generator outputs a 200kHz, 2V alternating electrical signal, which is then processed by a high-voltage amplifier with an amplification factor of 10 and applied to the drug-loaded system through platinum wire electrodes with an electrode spacing of 2cm. The actual applied electric field strength is 100V / m.

[0063] The signal generator is powered by a DC power supply with an output voltage of 12-24V and a current of ≥1A. The signal generator is set to an alternating signal mode and outputs an electrical signal with a frequency of 200kHz and a peak value of 2V. The signal is transmitted to a high-voltage amplifier with an amplification factor of 10 through a 50Ω coaxial cable. The amplified 20Vpp signal is connected to two platinum wire electrodes (anode and cathode) with a diameter of 0.5mm and a length of 5cm through shielded wires. The two electrodes are vertically fixed with an insulating clamp at a distance of 2cm and applied to the drug-loaded system, ultimately forming a uniform alternating electric field with an actual electric field strength of 100V / m.

[0064] In vitro release experiment: The drug-loaded gel obtained in Example 1 was immobilized on a Franz diffusion cell membrane (the membrane was a standard scientific research consumable with a molecular weight cutoff of 10 kDa; during immobilization, it was ensured that the gel and the membrane were tightly adhered without air bubbles; then 2 mL of pH 7.4 sterile PBS buffer was added to the Franz diffusion cell and the supply cell, and 10 mL of PBS buffer containing 0.02% sodium azide (for antibacterial and anti-contamination purposes) was added to the receiving cell; then, platinum wire electrodes were deployed according to the aforementioned electric field control system parameters, a uniform alternating electric field was applied, and the drug concentration in the release solution was measured periodically to complete the in vitro release behavior analysis). The cell was placed in a constant temperature environment of 37°C with a low voltage electric field of 2V applied; samples were taken at time intervals (0.5h, 1h, 2h, 4h, 8h, 12h, 24h, 48h, 72h) to measure the temozolomide (TMZ) concentration in the release solution at different times.

[0065]

[0066] In vivo application validation: Using a U87 glioma orthotopic transplantation mouse model (purchased from Shanghai Ruitaimos Biotechnology Co., Ltd.) to demonstrate the effective reversal of MGMT-mediated tumor drug resistance, U87 cells were labeled with a fluorescent dye (e.g., DiR) before transplantation. Weekly imaging after transplantation showed a gradual increase in brain-specific fluorescence signal, confined to the intracranial region (excluding ectopic implantation). Simultaneously, T2-weighted MRI showed a high-signal space-occupying lesion in the brain, with enhanced tumor margin enhancement on contrast-enhanced scans (consistent with glioma imaging characteristics) (purchased from Shanghai Ruitaimos Biotechnology Co., Ltd.). After intracranial implantation of the drug-loaded gel obtained in Example 1, a 2V electric field was continuously applied for 7 days. MRI monitoring results showed that 21 days after inoculation, the tumor volume in the model control group reached (125.6±12.5) mm.3 The tumor volume in the treatment group was only (28.5±5.3) mm. 3 The tumor volume in the treatment group mice was smaller than that in the model group; the median survival time in the treatment group was significantly prolonged to 56 days, an increase of 100% compared to the model control group, with two mice surviving for more than 80 days and no obvious tumor residue found after autopsy. The median survival time was extended from 28 days (for details, please refer to [link to relevant documentation]). Figure 2 ).

Claims

1. A drug delivery system, characterized in that, The drug delivery system is formed by cross-linking and solidifying hyaluronic acid conductive hydrogel and chlortoxin-modified chitosan nanoparticles. The hyaluronic acid conductive hydrogel is formed by cross-linking and solidifying hyaluronic acid-methacrylic anhydride and reduced graphene oxide. The chlortoxin-modified chitosan nanoparticles are formed by loading therapeutic drugs onto chitosan nanoparticles, coupling chlortoxin with the EDC / NHS activation method, and then modifying them with PEG. The amino acid sequence of the chlortoxin is: MCMPCFTTDHQMARKCDDCCGGKGRGKCYGPQCLCR-NH2.

2. The drug delivery system according to claim 1, characterized in that, The drug mentioned is a drug for treating tumors.

3. The drug delivery system according to claim 2, characterized in that, The drug mentioned for treating tumors is temozolomide.

4. A method for preparing a drug delivery system according to claim 1, characterized in that, Includes the following steps: 1) A step for preparing a primary carrier hyaluronic acid conductive hydrogel: Select hyaluronic acid with a capacity of 200-300 kDa, modify it with methacrylic anhydride to obtain hyaluronic acid-methacrylic anhydride; then add conductive filler to reduce graphene oxide, and use a two-step method of freeze-thaw pre-crosslinking + ultraviolet light crosslinking to solidify it, forming a hyaluronic acid conductive hydrogel with a three-dimensional porous network structure with a pore size of 50-200 μm; 2) A step for preparing chloramphenicol-modified chitosan nanoparticles as a secondary carrier: 100-200 nm chitosan nanoparticles are prepared by ionogel method, and a drug for treating tumors is loaded by electrostatic adsorption; chloramphenicol is coupled by EDC / NHS activation method, wherein the amino acid sequence of the chloramphenicol is MCMPCFTTDHQMARKCDDCCGGKGRGKCYGPQCLCR-NH2, and then modified by PEG to obtain chloramphenicol-modified chitosan nanoparticles; 3) Assembly steps of a dual-encapsulation system: Chlorine-modified chitosan nanoparticles and anti-tumor drugs are co-dispersed in a hyaluronic acid-methacrylic anhydride solution, and then cross-linked and cured to form a drug delivery system.

5. The method for preparing a drug delivery system according to claim 4, characterized in that, In step 1), 200-300 kDa hyaluronic acid was dissolved in PBS buffer, and then methacrylic anhydride was added. The mixture was reacted in an ice bath at 2-6°C for 12-36 hours. The reaction product was purified by dialysis and then freeze-dried to obtain hyaluronic acid-methacrylic anhydride. Reduced graphene oxide was added to the hyaluronic acid-methacrylic anhydride solution, and the mixture was subjected to high-frequency sonication while being cooled in an ice bath. After at least two freeze-thaw cycles for pre-crosslinking, a photoinitiator was added, and the reaction was carried out at 365 nm and 10 mW / cm. 2 Ultraviolet light irradiation curing yields a hyaluronic acid conductive hydrogel with a three-dimensional porous network structure of 50-200 μm pore size.

6. The method for preparing a drug delivery system according to claim 4, characterized in that, In step 2), chitosan is dissolved in acetic acid solution to obtain chitosan solution; sodium tripolyphosphate solution is added, stirred and collected by centrifugation; therapeutic drugs are added for easy adsorption and then purified by centrifugation; after activation by EDC / NHS, chlorine toxin is added, wherein the amino acid sequence of chlorine toxin is MCMPCFTTDHQMARKCDDCCGGKGRGKCYGPQCLCR-NH2, and then mPEG-SS is added for surface modification, finally obtaining chlorine toxin modified chitosan nanoparticles.

7. A method for preparing a drug delivery system according to claim 4, characterized in that, In step 3), chlortoxin-modified chitosan nanoparticles are dispersed in a hyaluronic acid-methacrylic anhydride solution, and a drug for treating tumors is added to obtain a drug delivery system.

8. A method for preparing a drug delivery system according to claim 7, characterized in that, The drug mentioned for treating tumors is temozolomide.

9. Use of the drug delivery system of claim 1 in the preparation of a medicament for treating tumors.

10. The use according to claim 9, characterized in that, The drug delivery system described contains temozolomide.

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