Preparation and Application of a Metal Ion-Doped Degradable Mesoporous Silica Drug Delivery System

Abstract

Preparation and application of a metal ion-doped degradable mesoporous silica drug delivery system, wherein the drug delivery system is composed of degradable metal ion-doped dendritic mesoporous silica, a photothermal agent polydopamine, and a biomacromolecule capable of supplementing the H2O2 concentration in tumor tissues. This drug delivery system generates highly toxic free radicals through catalytic Fenton reaction to kill tumor cells and has good biodegradability. The photothermal material PDA is coated on the surface of the carrier by oxidative polymerization as a dual-stimulus-responsive "gated" switch, endowing the delivery system with the characteristics of pH / NIR light dual-responsive drug release in tumor tissues. Using glucose oxidase as a model drug, it not only cuts off the nutrient supply of tumor tissues but also solves the problem that the Fenton reaction rate is limited due to the relatively limited H2O2 concentration, thereby realizing the synergistic effect of CDT / PTT and finally achieving the purpose of efficient tumor treatment and reducing the drug toxicity side effects, providing an important reference for multimodal tumor treatment.

Description

Technical Field

[0001] The present invention belongs to the field of pharmaceutical technology, and relates to the preparation and application of a metal ion-doped degradable mesoporous silica drug delivery system. Specifically, it relates to a drug-loaded system of mesoporous silica doped with metal ions coated with a photothermal material, polydopamine (PDA), and its application in the combined anti-tumor therapy of chemodynamic therapy / photothermal therapy. Background Art

[0002] Cancer has become one of the most fatal diseases today. Although current clinical treatment methods such as radiotherapy and chemotherapy can play a quite positive role in the treatment of some malignant tumors, the cytotoxicity caused by these treatment methods lacks selectivity for tumor sites extremely. This undifferentiated killing is exactly the root cause of the intractability of clinical malignant tumors.

[0003] With the rapid development of biotechnology and nanotechnology, the construction of nano-drug delivery systems has provided a new direction for the efficient treatment of cancer. Mesoporous silica nanoparticles (MSN) were first proposed as nano-carriers for transporting therapeutic agents around 2001. As a drug carrier or a carrier of functional materials, MSN has been widely used in biomedicine due to its good pore structure and particle morphology, extremely large specific surface area and pore volume, adjustable pore size and framework composition, etc. Among them, dendritic mesoporous silica (DMSN) has received extensive attention and application due to its excellent properties such as good biocompatibility, unique macroporous structure, high drug loading capacity, adjustable particle size, well-defined pore channels, and easily functionalized surface. However, due to the relatively slow degradation rate of its -Si-O-Si- framework in vivo, there are potential biosafety problems. According to relevant literature reports, common strategies for improving the degradability of DMSN: doping metal ions in the framework structure, hybridizing with organic functional groups, and introducing defects. However, although doping organic substance groups into the mesoporous silica framework structure can have good degradation characteristics, the organic functional group precursors are not only expensive, but also difficult to control in the synthesis process. In contrast, doping metal elements in the mesoporous silica framework may be a reasonable and promising strategy to improve the degradability of DMSN, which not only enhances its degradability but also endows the carrier with the ability to catalyze the Fenton reaction.

[0004] The tumor microenvironment (TME) has characteristics such as low pH value and high concentration of H2O2, which not only provides a suitable environment for the development and metastasis of tumors, but also provides a "gateway" for efficient and selective tumor treatment. In view of this situation, a large number of TME-responsive nano-delivery systems have been developed in recent years, and there are also many disadvantages, such as premature leakage that can damage normal tissues and insufficient drug loading. Therefore, this encourages researchers to explore new treatment modes.

[0005] Chemodynamic therapy (CDT) is an emerging cancer treatment modality first proposed by the Bu and Shi teams in 2016. It is defined as the in-situ initiation of Fenton or Fenton-like reactions within cancer cells under the catalysis of transition metals, converting the overexpressed intracellular hydrogen peroxide (H2O2) in the tumor microenvironment into highly toxic hydroxyl radicals (·OH), which are the most reactive ROS (typical reaction: Fe 2+ + H2O2 → Fe 3+ + ·OH + OH - ). This process causes the oxidative stress-induced damage of biomolecular substances such as proteins, lipids, and nucleic acids in cancer cells, thereby inducing cancer cell death. Compared with traditional cancer treatment methods, CDT has high tumor specificity and selectivity, can effectively avoid oxidative damage to normal tissues, and has low systemic toxicity and side effects. However, for in-vivo applications, the limited efficiency of Fenton or Fenton-like reactions is the main challenge restricting the clinical application of CDT. That is, factors such as catalyst efficiency, H2O2 concentration, and weakly acidic TME all determine the efficiency of ·OH generation reactions. Therefore, in recent years, researchers have designed and developed various strategies to address these issues to improve the efficacy of CDT. For example, lowering the pH value, increasing the H2O2 concentration, and improving the catalytic efficiency of the catalyst. In addition, treatment strategies can also be designed to improve the catalytic efficiency of CDT by combining with other treatment methods.

[0006] Due to the poor drug resistance and low specificity of single therapy, the desired effect cannot be achieved, so combination therapy with multiple therapies has received great attention. Compared with the single treatment mode, the multi-modal treatment plan can integrate the advantages of multiple treatment methods into a single nano-delivery system, achieve a synergistic therapeutic effect among these treatment methods (e.g., "1 + 1 > 2"), and minimize side effects. The combination of CDT with other therapies can produce obvious synergistic effects, enhance the killing effect of CDT, and reduce potential side effects. Photothermal therapy (PTT) mainly irradiates the tumor site-enriched photothermal agent with near-infrared (NIR) light with strong tissue penetration ability, which can convert light energy into heat energy, and the temperature of the tumor site can rapidly increase in a short time, resulting in apoptosis and necrosis of tumor cells. The increase in the temperature of the tumor site can accelerate the generation of ·OH, thereby improving the catalytic efficiency of the Fenton or Fenton-like reaction and enhancing the effect of tumor treatment. Therefore, the combination of CDT and PTT is an important research direction for cancer treatment. Relevant research shows that the Fenton reaction rate can be significantly increased when the environmental temperature gradually rises to 50 °C, and its reaction rate can be increased to about 3 times. Among them, the core of photothermal therapy is a photothermal agent with high photothermal conversion ability. Reports on traditional photothermal materials focus on inorganic photothermal conversion materials such as noble metal materials, metal sulfides, gold nanoparticles, and carbon nanomaterials (such as graphene and carbon nanotubes). However, these materials have potential toxicity and low biocompatibility, limiting their possible clinical applications.

[0007] Based on this, the iron-doped mesoporous silica (Fe-DMSN, abbreviated as FD) carrier with the ability to catalyze the Fenton reaction and good biodegradability designed and prepared in this invention is coated with polydopamine (PDA), a mussel-inspired material with excellent photothermal conversion efficiency, on the surface of the carrier to construct a drug-loaded system for combined CDT / PTT anti-tumor. Further, glucose oxidase (GOx), which can cut off the glucose supply in tumor tissues, is selected as the model drug and loaded into the carrier pores by the adsorption equilibrium method, aiming to solve the problem that the Fenton reaction rate is limited due to the relatively limited concentration of H2O2, thereby improving the anti-tumor efficiency.

[0008] In the prior art, there is a lack of a mesoporous silica drug-loaded system with the ability to catalyze the Fenton reaction and good degradability for combined tumor treatment. Summary of the Invention

[0009] The purpose of this invention is to provide the preparation of a metal ion-doped degradable mesoporous silica drug delivery system, aiming to achieve the synergistic anti-tumor effect of CDT / PTT, maximize the tumor treatment effect, and reduce toxic and side effects at the same time.

[0010] The technical solution adopted by the present invention is as follows: The metal ion-doped degradable mesoporous silica drug delivery system of the present invention is composed of a degradable metal ion-doped dendritic mesoporous silica, a photothermal agent polydopamine, and a biomacromolecule capable of supplementing the H2O2 concentration in tumor tissues.

[0011] Preferably, the metal ion is Cu 2+ , Mn 2+ , Fe 3+ , Fe 2+ , Mg 2+ , Ca 2+ or one of them.

[0012] Preferably, the biomacromolecule capable of supplementing the H2O2 concentration in tumor tissues includes glucose oxidase (GOx) and superoxide dismutase (SOD).

[0013] The present invention selects DMSN with larger pore size and porosity as the nanocarrier, dopes metal ions in its skeleton, such as Fe 2+ to prepare FD. The reaction process conditions are mild and the size is uniform. The iron doping into the skeleton structure still maintains a large specific surface area and pore size, and at the same time, the morphology of the carrier is not affected. The prepared FD can not only improve the biodegradability of the carrier in vivo, but also play the role of CDT therapy, and further endow the carrier with the ability to catalyze the Fenton reaction on the basis of FD as a nanodrug carrier.

[0014] The present invention coats the FD nanocarrier surface with the mussel-inspired material PDA through an oxidation-polymerization method to construct a drug-loading system with strong photothermal conversion ability, further improving the stability of the system and enhancing the tumor treatment effect.

[0015] The nanodrug delivery system constructed by the present invention coats PDA on the pore surface of FD, and at the same time loads biomacromolecules capable of supplementing the H2O2 concentration in tumor tissues, such as glucose oxidase (GOx), by the adsorption equilibrium method, in order to achieve the synergistic anti-tumor effect of CDT / PTT, maximize the tumor treatment effect and reduce the toxic and side effects.

[0016] The drug-loading system with the synergistic anti-tumor effect of CDT / PTT described in the present invention has strong stability and pH selectivity. It plays the synergistic role of CDT / PTT in the tumor microenvironment and remains inert under normal physiological conditions. At the same time, high temperature and long-term storage do not change the catalytic activity of the carrier.

[0017] The preparation method of the metal ion-doped degradable mesoporous silica drug delivery system of the present invention, taking the metal ion Fe 2+ as an example, includes the following steps:

[0018] (1) Preparation of FD:

[0019] Using cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) as structure - directing agents, tetraethyl orthosilicate (TEOS) as the silicon source, FeCl2 as the iron source, and triethanolamine (TEA) as the catalyst. DMSN was prepared by the sol - gel method. An aqueous solution of dissolved FeCl2 was added, and the mixture was transferred to a muffle furnace and reacted under hydrothermal conditions. The centrifugally collected product was dried and finally calcined in the muffle furnace to remove CTAB, obtaining FD.

[0020] (2) Preparation of FDP:

[0021] The FD carrier was dispersed in Tris buffer, and dopamine hydrochloride (DAHCl) was added. Under alkaline conditions, PDA was coated on the surface of FD.

[0022] Specifically, in the preparation of FDP described in the present invention:

[0023] In step (1): NaSal:CTAB with a molar ratio of 0.1 - 2.0 was added to 20 mL - 40 mL of distilled water, TEA was added, the reaction temperature was 60°C - 90°C, and the reaction time was 1 h - 5 h. After it was completely dissolved, 2 mL - 8 mL of TEOS was added to the system for hydrolysis. An aqueous solution of FeCl2 was added according to the molar ratio of Fe:Si of 0.5:100 - 15:100, and the reaction time was 15 min - 60 min. The obtained mixture was transferred to a muffle furnace and reacted under hydrothermal conditions. After aging for 1 h - 5 h under high - temperature and high - pressure static hydrothermal conditions at 70°C - 90°C, the reaction was stopped. The sample was dried overnight at 60°C - 80°C and finally calcined at 500°C - 600°C for 2 h - 8 h to remove CTAB, and the collected sample was FD.

[0024] In step (2): Using Tris buffer with a pH value of 8.0 - 11.0 as the reaction medium, 10 mg - 40 mg of FD was dispersed in 10 mL - 30 mL of the reaction medium, 20 mg - 50 mg of DAHCl was added, and the reaction was continuously stirred for 1 h - 24 h under a water bath condition at 20°C - 30°C. After the reaction, it was washed with water until neutral, and the precipitate was collected by centrifugation to obtain FDP.

[0025] The iron - doped degradable mesoporous silica drug - loaded system FDP prepared by the present invention has near - infrared photothermal conversion ability. The specific surface area of this nano - drug - loaded system is 200 m 2 / g - 400 m 2 / g, the average pore diameter is 2 nm - 6 nm, the particle size distribution is 180 nm - 250 nm, and the Zeta potential is - 15 mV to - 30 mV. (Measured in phosphate - buffered saline solution at pH = 7.4).

[0026] The PDA-coated iron-doped dendritic mesoporous silica nanodrug delivery system constructed in the present invention not only improves the stability of the nanocarrier, effectively preventing premature drug leakage, but more importantly endows the nanocarrier with the ability to synergistically enhance chemodynamic therapy / photothermal therapy and reduce toxic side effects.

[0027] Among them, the drug loading ratio relationship between FDP and the drug is: the mass ratio is between 1:1 and 10:1.

[0028] Taking GOx as the model drug:

[0029] First, load GOx into the FD prepared in step (1), and then prepare the drug-containing FDP carrier (GOx@Fe-DMSN@PDA, GFDP) according to the following steps.

[0030] Specific steps for loading GOx into FDP:

[0031] Disperse 10 mg - 40 mg of FD evenly in 5 mL - 20 mL of sodium acetate buffer solution (pH = 4.8 - 5.5), stir slowly under dark and room temperature conditions, then dissolve 2 mg - 10 mg of GOx in 1 mL - 10 mL of distilled water, and slowly add it to the system. Continue to stir for 12 h - 24 h, and then collect the product by centrifugation. Subsequently, disperse the product evenly in Tris buffer solution, add DAHCl, and stir and react at room temperature for 8 h - 24 h. The product is centrifuged to collect the precipitate, and the drug delivery system GFDP is obtained.

[0032] Advantages of the present invention:

[0033] The present invention uses FD as the drug carrier. Due to the restriction of its internal pore structure and the outer mesoporous pore wall, efficient drug loading and stable dispersion can be achieved. At the same time, the prepared carrier not only has good biodegradability, but also has strong catalytic ability for the Fenton reaction, endowing the carrier with the function of chemodynamic therapy.

[0034] The present invention introduces the mussel-inspired material PDA. It not only has a strong endogenous near-infrared absorption spectrum (650 - 900 nm), enabling it to have a good near-infrared photothermal conversion effect, but also has good biocompatibility and biodegradability. In addition, PDA also has a pH-responsive customized drug transportation function. Under normal conditions, it can respond to the acidic microenvironment of tumors, promote the targeted release of drugs, effectively prevent premature drug leakage, and achieve a more efficient tumor treatment purpose.

[0035] In the present invention, GOx is selected as the model drug, which is a natural bio-enzyme that can consume the oxygen in tumors to oxidize the substrate glucose into gluconic acid and H2O2. This will further exacerbate the heterogeneity of the tumor environment (lowering acidity and increasing the concentration of H2O2). Loading it into the carrier can not only improve its own stability but also further enhance the efficiency of the Fenton reaction. In addition, glucose oxidase consumes the nutrients (glucose) in tumors.

[0036] After the delivery system of PDA-coated iron-doped mesoporous silica loaded with GOx constructed in the present invention targets tumor cell tissues through the EPR effect, the lesion site is irradiated to a certain extent with NIR light. PDA can convert the absorbed NIR light energy into heat energy, increasing the temperature of the lesion site, thereby achieving the PTT effect. In addition, the outermost layer of the carrier, PDA, is pH-sensitive and is easily depolymerized only under the slightly acidic conditions of tumors, which can effectively prevent the leakage of drugs before reaching the lesion site to a certain extent. In tumor tissues, due to the depolymerization of the outermost layer of PDA, the inner FD loaded with drugs is also exposed. Furthermore, FD can catalyze the decomposition of H2O2 to generate highly toxic ·OH to trigger CDT. In addition, GOx can cut off the glucose supply of cancer cells and induce the amplification of tumor heterogeneity (increase in H2O2 concentration and decrease in pH). The increased H2O2 and decreased pH can just overcome the difficulty of the relatively limited concentration of H2O2 in tumor cells during the treatment of tumors by single CDT, thereby enhancing the CDT effect. Generally speaking, the nano-drug delivery system prepared in the present invention has good biocompatibility and biodegradability, and at the same time can achieve enhanced CDT / PTT synergistic anti-tumor effects.

[0037] Generally speaking, the drug delivery system constructed in the present invention generates highly toxic free radicals through catalyzing the Fenton reaction to kill tumor cells and has good biodegradability. The photothermal material PDA is coated on the surface of the carrier by oxidative polymerization as a dual-stimulus-responsive "gated" switch, endowing the delivery system with the characteristics of pH / NIR light dual-responsive drug release in tumor tissues. Using glucose oxidase (GOx) as the model drug can not only cut off the nutrient supply of tumor tissues but also solve the problem that the Fenton reaction rate is limited due to the relatively limited concentration of H2O2, thereby achieving the synergistic enhancement effect of CDT / PTT, and finally achieving the purpose of efficient tumor treatment and reducing the drug toxicity side effects, providing an important reference for tumor multimodal therapy. Description of the Drawings

[0038] Figure 1 TEM images of FD prepared in Examples 1 and 2 and FDP prepared in Example 3;

[0039] Figure 2Particle size distributions and Zeta potentials of FD prepared in Examples 1 and 2 and FDP prepared in Example 3;

[0040] Figure 3 Pore size distribution curves and nitrogen adsorption and desorption isothermal curves of FD prepared in Example 1 and FDP prepared in Example 3;

[0041] Figure 4 FT-IR data results of FD prepared in Example 1 and FDP prepared in Example 3;

[0042] Figure 5 Temperature increase data of FDP prepared in Example 3 at different concentrations under a near-infrared light power of 2 W / cm 2 below;

[0043] Figure 6 Temperature increase data of FDP prepared in Example 3 under different near-infrared light powers;

[0044] Figure 7 In vitro enzyme activity data results of the GFDP drug-loading system prepared in Example 5;

[0045] Figure 8 Data results of the in vitro catalytic performance of GFDP prepared in Example 5;

[0046] Figure 9 Results of the in vitro degradation performance of FDP prepared in Example 3;

[0047] Figure 10 Survival rates of 4T1 breast cancer cells of the FDP blank carrier and the GFDP drug-loading system under 808 nm NIR irradiation. Detailed implementation manners

[0048] Example 1

[0049] Add 68 mg of TEA to 25 mL of deionized water, sonicate evenly and place in an 80 °C water bath with slow stirring. Subsequently, add 380 mg of CTAB and 168 mg of NaSal to the flask in sequence, continue stirring and maintain the reaction for more than 1 h. After it is completely dissolved, slowly add 4 mL of TEOS to the system. After the reaction is maintained for 1 h, dissolve an appropriate amount of FeCl2 in distilled water, then drop the solution into the above mixture, and further stir at 80 °C for 15 min. Next, age the obtained mixture in a Teflon autoclave under static hydrothermal conditions at 80 °C for another 2 h and then stop. Wait for the reaction solution to cool to room temperature, wash it thoroughly with distilled water and absolute ethanol, then use the calcination method to remove the CTAB template, dry the sample overnight at 60 °C, and finally calcine it at 550 °C for 4 h. Collect the sample and set it aside.

[0050] The iron-doped dendritic mesoporous silica nanocarrier (2% FD) prepared according to the molar ratio of Fe:Si = 2:100 presents a uniform dendritic spherical morphology, with a uniform particle size, a large number of obvious mesoporous channels, a large specific surface area and pore diameter, and can achieve efficient drug loading.

[0051] Example 2

[0052] Add 70 mg of TEA to 30 mL of deionized water, ultrasonically mix evenly and place it in an 80 °C water bath and stir slowly. Subsequently, add 400 mg of CTAB and 200 mg of NaSal to the flask in sequence, continue stirring and keep the reaction for more than 1 h. After it is completely dissolved, slowly add 6 mL of TEOS to the system. After the reaction is maintained for 1 h, then dissolve an appropriate amount of FeCl2 in distilled water, and then drop the solution into the above mixture and further stir at 80 °C for 30 min. Next, the obtained mixture is aged in a Teflon autoclave under static hydrothermal conditions at 80 °C for another 4 h and then stopped. After the reaction solution is cooled to room temperature, it is thoroughly washed with distilled water and absolute ethanol. Then, the CTAB template is removed by the calcination method. The sample is dried overnight at 60 °C and finally calcined at 550 °C for 6 h. The sample is collected and reserved for use.

[0053] The iron-doped dendritic mesoporous silica nanocarrier (5% FD) is prepared according to the molar ratio of Fe:Si = 5:100.

[0054] Example 3

[0055] Disperse 16 mg of FD in 15 mL of pH 8.0 Tris buffer solution, add 30 mg of dopamine hydrochloride, and stir and react at 600 rpm at room temperature for 12 h. The product is centrifuged (8000 rpm, 10 min) to collect the precipitate, which is FDP, and washed with distilled water and absolute ethanol for standby.

[0056] The prepared FDP has a uniform particle size and good dispersion stability. At the same time, the prepared FDP can be locally heated under near-infrared light irradiation, and has good heating ability ( Figures 5 - 6 ), and can achieve photothermal therapy for tumors.

[0057] Figure 1 Figure (a) is the TEM image of FD prepared in Examples 1 and 2 and FDP prepared in Example 3; it can be seen from the figure that FD has an obvious pore structure. As the Fe doping ratio increases, the pores become blurred, and the PDA coating on the surface of FD causes the pores to become blurred, proving that PDA is coated on the surface of FD. Figure 2 Figure (b) is the particle size distribution and Zeta potential of FD prepared in Examples 1 and 2 and FDP prepared in Example 3; the doping of Fe and the coating of PDA result in an increase in particle size and a change in potential. Figure 3Pore size distribution curves of FD prepared in Example 1 and FDP prepared in Example 3, and isothermal curves of nitrogen adsorption and desorption; after PDA coating, the pore channels were blocked, resulting in a decrease in the specific surface area of FD and the disappearance of the pore size distribution. Figure 4 FT-IR data results of FD prepared in Example 1 and FDP prepared in Example 3; compared with DMSN, in the FD spectrum, the energy band shifted slightly, indicating that some Fe ions were incorporated into the Si-O-Si framework; compared with FD, new absorption peaks appeared in the spectrum of FDP after PDA coating, proving that PDA had been coated on the surface of the FD carrier.

[0058] Example 4

[0059] Disperse 20 mg of FD in 30 mL of Tris buffer solution with pH 8.0, then add 40 mg of hydrochloric acid dopamine and stir at 600 rpm at room temperature for 12 h. The product was collected by centrifugation (8000 rpm, 10 min) to obtain the precipitate, which was FDP, and washed with distilled water and absolute ethanol for standby.

[0060] Example 5

[0061] Disperse 16 mg of FD evenly in 6 mL of sodium acetate buffer solution (pH = 5.2) and stir slowly under dark and room temperature conditions. Then dissolve 4 mg of GOx in 4 mL of distilled water and slowly add it to the system. Continue to stir for 12 h and then collect the product by centrifugation. Subsequently, disperse the product evenly in 15 mL of Tris buffer solution, then add 30 mg of hydrochloric acid dopamine and stir at 600 rpm at room temperature for 12 h. The product was collected by centrifugation (8000 rpm, 10 min) to obtain the drug-loaded system GFDP, and washed with distilled water and absolute ethanol for standby.

[0062] Example 6

[0063] Disperse 20 mg of FD evenly in 10 mL of sodium acetate buffer solution (pH = 5.2) and stir slowly under dark and room temperature conditions. Then dissolve 6 mg of GOx in 8 mL of distilled water and slowly add it to the system. Continue to stir for 18 h and then collect the product by centrifugation. Subsequently, disperse the product evenly in 15 mL of Tris buffer solution, then add 40 mg of hydrochloric acid dopamine and stir at 600 rpm at room temperature for 12 h. The product was collected by centrifugation (8000 rpm, 10 min) to obtain the drug-loaded system GFDP, and washed with distilled water and absolute ethanol for standby.

[0064] Example 7

[0065] FDP (Example 3) and GFDP (Example 5) with the same concentration were dispersed in PBS containing glucose (10 mM) (pH = 7.4), incubated at 37 °C in the dark, and the pH values at different time points were detected using a portable pH meter. Meanwhile, the concentration of H2O2 was determined by the xylenol orange method.

[0066] The results showed that the pH value of the FDP solution in PBS (pH = 7.4) containing glucose (10 mM) remained basically unchanged at around 7.40; while the pH value of the GFDP solution decreased significantly within 90 min, from 7.40 to 4.32 significantly, which was mainly due to the formation of gluconic acid. In addition, no change in the H2O2 concentration was detected in the FDP + glucose (10 mM) group solution, while the amount of H2O2 produced in the GFDP group increased significantly within 4 h and finally reached the highest value (63.4 μM). However, since a part of the H2O2 catalyzed by GOx to produce glucose will be catalytically decomposed, the amount of H2O2 detected will be somewhat lower to a certain extent. The relevant data are shown in Figure 7 .

[0067] Example 8

[0068] A certain concentration of GFDP (Example 5) was dispersed in ammonium acetate buffer (pH = 5.0) containing TMB (0.8 mM) and H2O2 (0.1 mM) or glucose (10 mM) that initiated the catalytic reaction, and the total volume of the reaction was 3 mL. It was incubated in a constant temperature shaker at 37 °C for 10 min, centrifuged to take the supernatant, and the absorbance at 652 nm was detected by an ultraviolet-visible spectrophotometer.

[0069] The results showed that the TMB + H2O2 + GFDP mixed solution had a strong absorption peak at 652 nm, and the color of the reaction solution was dark blue, indicating that GFDP catalyzed the decomposition of H2O2 to generate ·OH, thereby oxidizing TMB to blue oxTMB. Then, the production of ·OH by self-supplied H2O2-enhanced acid-treated GFDP was further studied. Unexpectedly, the TMB + glucose + GFDP mixed solution also had a strong absorption peak at 652 nm, which indicated that triggering the release of GOx by GFDP under acidic conditions could catalyze glucose to produce H2O2, and then GFDP could catalyze H2O2 to generate ·OH, thus overcoming the problem of relatively limited H2O2 concentration in tumor cells and realizing enhanced chemodynamic therapy. The relevant data are shown in Figure 8 .

[0070] Example 9

[0071] 10 mg of FDP was separately placed in 2 mL of simulated body fluids (SBF) with pH 7.4 and 5.0, and ultrasonicated to completely dissolve it. Subsequently, it was separately transferred into dialysis bags, placed in centrifuge tubes, and 38 mL of simulated body fluid was added. Finally, it was placed in a shaker (37 °C, 150 rpm), timed, and 5 mL of supernatant was taken out at different times for quantitative determination by an ultraviolet spectrophotometer.

[0072] The results showed that in SBF with pH 7.4, there was almost no degradation product silicate ion before 2 h, and the amount of degradation product gradually increased with the extension of time after 2 h. In contrast, in SBF with pH 5.0, degradation started gradually from the beginning, indicating that the constructed nano-drug delivery system could be rapidly degraded in vivo. In addition, according to the UV-Vis-NIR scanning results, it was also shown that the degradation rate of FDP in SBF with pH 5.0 was significantly faster than that in SBF with pH 7.4. At the same time, it was also shown that it could prevent the easy leakage of drugs before reaching the tumor tissue, thus improving the biosafety. The relevant data are shown in Figure 9 .

[0073] Example 10

[0074] 4T1 cells were inoculated into 96-well plates and cultured for 24 h. At the same time, sterile PBS was added to the edge wells of each 96-well plate as a blank group, and cultured in an incubator for 24 h. After the cells adhered to the wall, the original culture medium was discarded, and the blank FDP carrier of Example 3 and GFDP of Example 5 with a series of concentrations were added and cultured for another 24 h. For the NIR laser irradiation group, GFDP was irradiated with an 808 nm NIR laser at a power of 2 W / cm 2 for 3 min. After culturing for another 24 h, 50 μL of 2 mg / mL MTT solution was added, and incubation was continued (37 °C, 4 h). The old culture medium was aspirated, and 150 μL of DMSO was added. It was shaken in the dark for 15 min, and the absorbance of each well was measured at a wavelength of 570 nm, and the relative cell viability was calculated.

[0075] The results showed that the FDP blank carrier had a certain effect on the cell viability within the tested concentration range, and the cell viability decreased significantly with the increase in the carrier concentration. It could be considered that the blank nanoparticles prepared in the present invention had certain cytotoxicity, which proved that the prepared FDP had a CDT effect. Under NIR light irradiation, the temperature of the carrier increased, which would also have a certain toxic side effect on the cells. For the GFDP drug-loaded system under 808 nm NIR light irradiation, the cell inhibition rate was the highest and the toxicity was the greatest, indicating that the constructed drug-loaded system could achieve the synergistic effect of CDT / ST / PTT multimodal therapy. At the same time, the cell viability decreased significantly with the increase in glucose concentration. The relevant data are shown in the appendix Figure 10 .

Claims

1. A metal ion-doped degradable mesoporous silica drug delivery system, characterized in that, It is composed of biodegradable metal ion-doped dendritic mesoporous silica, the photothermal agent polydopamine, and a biological macromolecule capable of replenishing the H2O2 concentration in tumor tissues; this drug delivery system has the ability to catalyze the Fenton reaction and biodegradability; the metal ion is Fe 2+ ; the biological macromolecule capable of replenishing the H2O2 concentration in tumor tissues is glucose oxidase.

2. The preparation method of the metal ion-doped degradable mesoporous silica drug delivery system according to claim 1, characterized in that, It includes the following steps: (1) Preparation of FD: Using CTAB and NaSal as structure-directing agents, with a molar ratio of NaSal:CTAB = 0.1 - 2.0, TEOS as the silicon source, FeCl2 as the iron source, and TEA as the catalyst; adopting the sol-gel method, reacting at 60 °C - 90 °C for 1 h - 5 h to obtain DMSN, adding an aqueous solution of dissolved FeCl2 according to the molar ratio of Fe:Si = 0.5:100 - 15:100, transferring the obtained mixture to a muffle furnace and reacting under hydrothermal conditions for 1 h - 5 h; centrifuging and collecting the product, drying, and finally calcining in a muffle furnace at 500 °C - 600 °C for 2 h - 8 h to remove CTAB, thus obtaining metal ion-doped dendritic mesoporous silica, denoted as FD; (2) Preparation of FDP: Dispersing the FD carrier in Tris buffer, adding dopamine hydrochloride, and coating PDA on the surface of FD under alkaline conditions to obtain a drug-loaded system of PDA-coated iron-doped dendritic mesoporous silica, denoted as FDP; (3) Preparation of GFDP: Dispersing FD in a sodium acetate buffer solution with pH = 4.8 - 5.5, dissolving glucose oxidase in distilled water, and then slowly adding it to the system of the sodium acetate buffer solution, stirring for 12 h - 24 h under dark and room temperature conditions, subsequently dispersing the product in Tris buffer, adding dopamine hydrochloride, and stirring and reacting at room temperature for 8 h - 24 h, centrifuging and collecting the precipitate, and washing to obtain the drug-loaded system GFDP.

3. The preparation method according to claim 2, wherein The specific process of step (2) is: dispersing 10 mg - 40 mg of FD in Tris buffer with a pH value of 8.0 - 11.0, adding 20 mg - 50 mg of dopamine hydrochloride, continuously stirring and reacting under a water bath condition of 20 °C - 30 °C for 1 h - 24 h, and centrifuging and collecting the precipitate, which is FDP.

4. Use of the metal ion-doped degradable mesoporous silica drug delivery system according to claim 1 in the preparation of a combined anti-tumor drug for chemodynamic therapy / photothermal therapy.

Images