Ros-responsive hydrogel microneedles assembled by metformin and ceo2 and their application in diabetic wound treatment

Abstract

The application discloses a metformin and CeO2 assembled ROS response type hydrogel microneedle and application thereof in treatment of diabetic wound, and belongs to the technical field of biological medicine. The application utilizes mesoporous silica nanoparticles to load metformin (Met) inside and form a cerium oxide (CeO2) coating outside, thereby preparing MSN@Met-CeO2 composite nanoparticles, and loading the nanoparticles on a ROS response type hydrogel microneedle patch, so that the drug is efficiently delivered, the purpose of synchronously removing ROS of wound tissue from endogenous and exogenous is achieved, and good healing of the diabetic wound is promoted.

Description

Technical Field

[0001] This invention belongs to the field of biomedical technology, specifically, it relates to a metformin and CeO2 assembled ROS-responsive hydrogel microneedle and its application in the treatment of diabetic wounds. Background Technology

[0002] Diabetes is a complex chronic metabolic disease caused by an absolute or relative deficiency of insulin, leading to elevated blood sugar levels. It affects millions worldwide, and its prevalence has risen rapidly over the past three decades. This trend is estimated to continue, with the prevalence projected to increase from the current 5.1% to 7.7% by 2030. For individuals with diabetes, particularly those with non-healing ulcers, is a common complication that can lead to hospitalization and even amputation.

[0003] Diabetic ulcers typically appear on the lower extremities, are difficult to heal, and have a poor prognosis. The mechanisms underlying their poor healing are related to hyperglycemia, neuropathy, microvascular complications, chronic inflammation, and weakened immunity. Numerous methods exist for treating diabetic ulcers. Traditional Chinese medicine primarily employs external therapies such as fumigation, topical application, and silver iontophoresis. Western medicine, in addition to conventional treatments, includes HIF-PHD inhibitors, dressings, platelet-rich plasma (PRP), negative pressure wound therapy, and hyperbaric oxygen therapy. Current treatment methods, including wound cleaning, dressing application, vascular reconstruction, and adjuvant therapies (such as negative pressure wound therapy and oxygen therapy), often fall short of meeting the multidimensional requirements for effective healing of diabetic ulcers.

[0004] Studies have shown that excessive ROS production severely hinders wound healing because it can trigger programmed cell death and exacerbate oxidative stress damage. Therefore, efficient removal of ROS from wounds is a crucial step in restoring wound microenvironment homeostasis and achieving successful healing. Recently, hydrogels based on metal nanoparticles (NPs) have been developed as potential wound dressings. However, most metal NP-based hydrogels focus primarily on extracellular antioxidant activity while neglecting the restoration of endogenous ROS balance, thus limiting their application in the treatment of diabetic wounds. To overcome these limitations, researchers have attempted to modify NPs with various biomolecules or compounds, but due to a lack of good biocompatibility or the influence of a hypoxic microenvironment, these modified metal NPs still fail to produce ideal results in the treatment of diabetic wounds. Furthermore, diabetic wounds often have a physicochemical barrier formed by infection and necrotic tissue, affecting drug delivery and absorption, making conventional treatments ineffective. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the inventors have designed a novel wound dressing that can solve the problem of synergistic removal of endogenous and exogenous reactive oxygen species from wound tissue, while achieving efficient drug delivery and promoting good healing of diabetic wounds.

[0006] To achieve the above-mentioned technical objectives, the inventors considered that the large amount of ROS generated in the wound microenvironment is one of the important factors affecting wound healing. ROS include hydrogen peroxide (H2O2) and superoxide anion (O2). ·- hydroxyl radicals (-OH) are byproducts of intracellular oxidation reactions. Under physiological conditions, reactive oxygen species (ROS) play a crucial role in maintaining the transduction of multiple intracellular signaling pathways; under infectious conditions, ROS can exert antibacterial effects by directly disrupting the structure of biological macromolecules; excessive ROS can increase the permeability of the mitochondrial double membrane, thereby inducing apoptosis. In wound healing, substantial evidence has confirmed that excessive ROS in wound tissue is a key factor causing delayed or incomplete wound healing.

[0007] Mitochondria are the main source of intracellular ROS. Our previous studies found that metformin can alleviate intracellular mitochondrial stress and reduce mitochondrial division under high glucose and hypoxic conditions, thereby reducing mitochondrial ROS production. However, applying metformin alone to wounds does not reduce ROS production in tissue cells, possibly because the acidic environment within the wound tissue is unfavorable for metformin to exert its effects.

[0008] Due to its unique electron configuration, the cerium atom (Ce) has two valence states: the reduced Ce state and the cerium atom (Ce). 3+ and oxidized Ce 4+ Both of these valence states can exist in the CeO2 molecule. Under low oxygen conditions, the Ce atoms in CeO2 are reduced to Ce. 3+ The process involves the release of lattice oxygen to form oxygen vacancies, while simultaneously increasing the intermolecular distance between Ce and O atoms within CeO2, resulting in crystal distortion. Under oxygen-rich conditions, oxygen molecules can fill the oxygen vacancies on the CeO2 surface, thereby allowing Ce to... 3+ Oxidized to Ce 4+ This restores the complete crystal structure. The Ce atoms within the CeO2 molecule can undergo different valence state transitions under varying oxygen concentrations, and this property of releasing / absorbing oxygen is known as "oxygen buffering capacity (oxygen storage capacity)." When the wound contains a large amount of ROS, CeO2 mainly exists in the reduced Ce state under the action of oxygen free radicals. 3+ The presence of oxygen molecules allows them to be released into the interstitial space, thereby scavenging oxygen free radicals and releasing oxygen, thus achieving homeostasis of the wound tissue microenvironment and promoting wound healing.

[0009] Therefore, the inventors designed a method to prepare MSN@Met-CeO2 composite nanoparticles by loading metformin (Me) inside mesoporous silica nanoparticles (MSN) while forming a cerium oxide (CeO2) coating on the outside. These MSN nanoparticles were then mounted on ROS-responsive hydrogel microneedle patches to achieve the goal of simultaneously clearing ROS from wound tissue through both endogenous and exogenous means.

[0010] Specifically, the technical solution for achieving the technical objective of this invention includes: an MSN@Met-CeO2 composite nanoparticle, which has a core-shell structure, with mesoporous silica loaded with metformin in the pores as the core and cerium oxide loaded on the surface of the core as the shell.

[0011] More preferably, in the MSN@Met-CeO2 composite nanoparticles as described above, the mass ratio of metformin to cerium oxide is 1:(0.1-0.2); and the mass ratio of metformin to mesoporous silica is 1:(3-5).

[0012] More preferably, the MSN@Met-CeO2 composite nanoparticles described above have a spherical morphology and a size in the range of 60-80 nm.

[0013] In addition, the present invention also provides a ROS-responsive hydrogel microneedle containing the above-mentioned MSN@Met-CeO2 composite nanoparticles and a method for preparing the same, the method comprising the following steps:

[0014] (1) Synthesis of MSN@Met: Mesoporous silica nanoparticles were dispersed in water, metformin solution was added under stirring, the reaction was stirred at 200-600 r / min for 12-36 h, and then the product was washed by ultrafiltration with a 100 kd ultrafiltration tube to remove unloaded metformin and obtain MSN@Met.

[0015] (2) Synthesis of MSN@Met-CeO2: The MSN@Met prepared in step (1) was dispersed in ethanol, Ce(NO3)3·6H2O and hexamethyldinaphthylamine were added, stirred for 2-4 h, and then refluxed at 70-80℃ for 3-5 h. After centrifugation, the product was washed to obtain MSN@Met-CeO2.

[0016] (3) Preparation of ROS-responsive hydrogel microneedles: Add MSN@Met-CeO2 prepared in step (2) to a mixed solution of PVA and PVP, mix evenly, then add TSPBA crosslinking agent and mix evenly, pour the mixture into the microneedle mold, vacuum process to fill the microneedle cavity with the mixture, and finally let it stand at room temperature for 8-12 hours, dry it thoroughly at 35-38℃, and demold.

[0017] More preferably, in the preparation method of ROS-responsive hydrogel microneedles as described above, the mesoporous silica nanoparticles in step (1) are dispersed in water at a concentration of 0.5 to 2 mg / ml, and the concentration of the metformin solution is 0.5 to 1.5 mg / ml.

[0018] More preferably, in the preparation method of ROS-responsive hydrogel microneedles as described above, the MSN@Met in step (2) is dispersed in ethanol at a concentration of 60-150 mg / ml.

[0019] More preferably, in the ROS-responsive hydrogel microneedles preparation method described above, the concentration of PVA in the mixed solution of PVA and PVP in step (2) is 10-15 wt%, and the concentration of PVP is 7-10 wt%.

[0020] Finally, since MSN@Met-CeO2 internally loads metformin and externally forms a cerium oxide coating, mounting it onto a ROS-responsive hydrogel microneedle patch can simultaneously eliminate endogenous and exogenous ROS in diabetic wound tissue, thereby solving the problem of synergistic elimination of endogenous and exogenous reactive oxygen species in wound tissue, while achieving efficient drug delivery and promoting good healing of diabetic wounds. Therefore, this invention also provides an application of the above-mentioned MSN@Met-CeO2 composite nanoparticles in the preparation of ROS-responsive hydrogel microneedles for treating diabetic wounds.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] (1) Compared with the administration of metformin and cerium oxide alone, or the administration of a mixture of the two drugs, the composite nanoparticles synthesized in this invention have significantly better effects in scavenging endogenous and exogenous ROS and promoting angiogenesis, which indicates that this invention improves the synergistic effect of the drugs.

[0023] (2) Compared with conventional drug administration methods (simply administering the drug and using a blank hydrogel), this invention significantly improves the healing speed of the wound, reduces the level of inflammation, and promotes the vascularization of the wound.

[0024] (3) Compared with traditional administration methods, the present invention is simpler to use and carry. At the same time, since metformin and cerium oxide are inexpensive, the cost of medication for patients is low. Furthermore, metformin and cerium oxide are widely used and have higher safety. Attached Figure Description

[0025] Figure 1 A schematic diagram illustrating the preparation process and mechanism of action of ROS-responsive hydrogel microneedles equipped with MSN@Met-CeO2 nanoparticles.

[0026] Figure 2 This is a schematic diagram of the synthesis of MSN@Met-CeO2 nanoparticles.

[0027] Figure 3 The following figures represent the synthesis and characterization monitoring results of MSN@Met-CeO2 nanoparticles: a) Transmission electron microscopy images of MSN, MSN@Met, and MSN@Met-CeO2; b) Changes in particle size of MSN before and after loading; c) Potential values ​​of MSN, MSN@Met, and MSN@Met-CeO2; d) UV absorbance curves of MSN, MSN@Met, and MSN@Met-CeO2; e) Drug encapsulation efficiency and loading rate of MSN@Met-CeO2 composite nanoparticles; f) Drug release curve of MSN@Met-CeO2 composite nanoparticles in a simulated human environment (37℃, PBS); g) Stability measurement results of MSN@Met-CeO2 composite nanoparticles in PBS.

[0028] Figure 4 The images show the microneedle structure under an electron microscope and the microneedle array under a microscope.

[0029] Figure 5 The swelling of the microneedles before and after contact with PBS, and the morphological changes of the microneedles in 1mM H2O2 solution.

[0030] Figure 6 The following figures illustrate the wound healing promoting effect of MSN@Met-CeO2 on a diabetic mouse model: a) Construction and manipulation steps of diabetic wounds in mice; b) Wound images of different groups on days 0, 3, 7, 10, and 14; c) Wound closure status from day 0 to day 14; d) Changes in wound area in each group; e) Percentage of wound closure on day 14; f) Wound tissue results after heme staining and eosinophilic staining on days 7 and 14 (S: scab; GT: granulation tissue; E: epidermis; D: dermis; wound edges are marked with black arrows); g) Results after Masson staining on day 14. Detailed Implementation

[0031] The technical solutions and effects of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of protection of the present invention. In addition, where specific technical operation steps or conditions are not specified in the embodiments, they are all carried out in accordance with conventional techniques or conditions described in the literature in the field or in accordance with product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0032] Example 1: Preparation of ROS-responsive hydrogel microneedle patches assembled from metformin and CeO2

[0033] 1. The synthesis of MSN@Met

[0034] (1) Prepare MSN solution and Met solution with water at a concentration of 1 mg / ml respectively;

[0035] (2) Take 1 ml of MSN solution and add it to a 5 ml reaction flask. Then, add 1 ml of Met solution while stirring magnetically. Stir at 400 r / min for 24 h to load Met using the pores of MSN.

[0036] (3) After the reaction was completed, the sample was washed with a 100kd ultrafiltration tube to remove unreacted Met and obtain MSN@Met.

[0037] 2. Synthesis of MSN@Met-CeO2

[0038] MSN@Met-CeO2 was obtained by adsorbing Ce(NO3)3·6H2O and hexamethyldinaphthylamine (HMT) onto a surface and reacting them. First, 200 mg of MSN@Met was dispersed in 1.5 ml of ethanol. Then, 1.5 ml of a mixed solution containing 400 mg Ce(NO3)3·6H2O and 400 mg HMT was poured into the slurry, stirred for 2 h, and then refluxed at 75 °C for 4 h. Finally, unreacted monomers were removed by centrifugation and washing to obtain an MSN@Met-CeO2 composite nanoparticle solution.

[0039] Synthesis Principle: First, Ce(NO3)3·6H2O and hexamethyldinaphthylamine (HMT) are adsorbed onto the surface and pores of MSN@Met. Then, under heating and in the presence of oxygen, an oxidation reaction occurs, oxidizing Ce(NO3)3·6H2O to CeO2, which is then loaded onto the surface and pores of MSN@Met. The reaction formula is as follows:

[0040] Ce(NO3)3·6H2O + hexamethyldinylamine + O2 → CeO2

[0041] Figure 3 The results of characterization and monitoring related to the synthesis of MSN@Met-CeO2 composite nanoparticles are presented. Figure 3 The transmission results of a showed that the MSN@Met-CeO2 composite nanoparticles had a spherical morphology with a size of 60-80 nm. Then, using... Figure 3The changes in MSN particle size before and after loading were detected using a Malvern laser particle size analyzer. The results showed that the size of the composite nanoparticles remained around 80 nm after loading with Met and CeO2, consistent with the transmission electron microscopy (TEM) characterization results. To demonstrate the successful loading of the drug Met and nano-CeO2 onto mesoporous MSN nanoparticles, the potential values ​​of the nanoparticles were measured using a Malvern laser particle size analyzer. The test results are shown below. Figure 3 c. Compared to MSN alone, the Zeta potential values ​​of the composite nanoparticles MSN@Met and MSN@Met-CeO2 changed significantly (-27.02, -10.23, -17.88 mV), indicating that the drug Met and nano CeO2 were successfully loaded. Figure 3 The absorption peak at 233 nm in the UV absorbance curve of d further confirms the successful encapsulation of the drug Met. Figure 3 The results showed that the drug encapsulation efficiency of the MSN@Met-CeO2 composite nanoparticles was 18.19%, and the loading rate was 90.95%. Subsequently, drug release was tested in a simulated human environment (37°C, PBS), and the results were as follows... Figure 3 As shown in the release curve (f), the release of Met steadily increased over time, reaching approximately 90% at 24 hours. DLS measurements of the stability of the drug-loaded particles in PBS showed... Figure 3 The results showed that the hydrodynamic diameter of the nanoparticles remained stable at around 80 nm within 24 hours, demonstrating that the composite nanoparticles have good stability and are easy to deliver in vivo.

[0042] 3. Preparation of gel microneedles:

[0043] 3.1 Preparation of N1-(4-bromobenzyl)-N3-(4-bromophenyl)-N1,N1,N3,N3-tetramethylpropane-1,3-diamine (TSPBA):

[0044] (1) Dissolve 4.6 mmol / L 4-(bromomethyl)phenylboronic acid (1 g) and 1.5 mmol / L TMPA (0.2 g) in 40 mL of DMF;

[0045] (2) Stir the solution at 60℃ for 24 hours;

[0046] (3) Pour the mixture into 100 mL of tetrahydrofuran and filter it, then wash it with tetrahydrofuran three times.

[0047] (4) Freeze-dry the product overnight to obtain approximately 0.6g of pure TSPBA, which is then prepared with pure water to the required concentration.

[0048] 3.2 Preparation of microneedles:

[0049] (1) Dissolve polyvinyl alcohol (PVA, type 1799) solid in an oil bath at 90℃ and prepare a concentration of 12wt%. Then take 10mL of 12wt% PVA solution and add 0.9g of polyvinylpyrrolidone (PVP40) solid under stirring to form a mixed solution of PVA and PVP.

[0050] (2) Mix the MSN@Met-CeO2 composite nanoparticle solution (1 mg / ml) with the PVA and PVP mixed solution at a volume ratio of 1:1 until homogeneous;

[0051] (3) The mixed solution containing nanoparticles prepared in step (2) was mixed with 5 wt% TSPBA crosslinking agent at a volume ratio of 1:1. The mixture was then quickly poured into a microneedle mold (conical holes, 15*15 array), and vacuumed for 1 min. This process was repeated 3 times (the vacuum treatment ensured that the solution filled the holes). Finally, the mixture was left to stand at room temperature overnight, and then dried in a 37°C oven for 48 h.

[0052] (4) After the microneedle patch is fully dried, demold to obtain the drug-loaded microneedle patch. The blank microneedles are prepared as above, except that the same volume of nano solution is replaced with an aqueous solution.

[0053] Figure 4 The images show the structure of the microneedles under an electron microscope and the microneedle array under a microscope. It was observed that each microneedle patch consists of 225 (15×15) needles on a substrate, with a height of 600±10 micrometers, a base width of 165±10 micrometers, and a center space of 400±10 micrometers between adjacent needles.

[0054] Figure 5 To observe the swelling of microneedles before and after contact with PBS under a microscope, as well as the morphological changes of microneedles in 1mM H2O2 solution, the results showed that the microneedles have ROS responsiveness.

[0055] Example 2: Experimental study on the effect of hydrogel microneedle patches on promoting wound healing in diabetic mice

[0056] 1.1 Animal preparation

[0057] Male animals were selected because females contain hormones that affect modeling efficiency. Studies have shown that female animals have a lower modeling success rate and may have a higher mortality rate than males, especially for type I.

[0058] Type I diabetes can generally be induced by body weight. Select 6-8 week old C57 mice with a body weight of 17-22g. After 1-2 weeks of acclimatization feeding, inject STZ on an empty stomach. The success rate of modeling is relatively ideal.

[0059] 1.2 Feeding before modeling

[0060] Feeding before membrane formation: Type 1 diabetes models are established relatively quickly. Mice can usually begin modeling after being acclimatized to a normal diet for 2 weeks.

[0061] 1.3 Preparation of reagents

[0062] Preparation of STZ-sodium citrate buffer

[0063] Preparation of solutions A and B: Weigh 2.1g of citric acid (MW: 210.14) and add it to 100mL of double-distilled water to prepare solution A; weigh 2.94g of sodium citrate (MW: 294.10) and add it to 100mL of double-distilled water to prepare solution B.

[0064] Preparation of sodium citrate buffer: Mix solutions A and B in a certain ratio (1:1.32 or 1:1), adjust the pH to 4.2-4.5, and filter with a 0.22μm filter membrane for sterilization. This is the required sodium citrate buffer. It is recommended to prepare it fresh for use.

[0065] Weigh out the STZ lyophilized powder, place it in a dry sterile bottle, wrap it with aluminum foil, place it on ice, add pre-cooled sodium citrate buffer (1% w / v) to dissolve it, and filter it through a 0.22 μm filter membrane for sterilization.

[0066] Note: ① After removing the STZ lyophilized powder from the -20℃ freezer, allow it to thaw completely at room temperature in a dry, dark place for about 10 minutes (very important). ② STZ is unstable and easily inactivated. After rapid weighing, any remaining reagent must still be dried and protected from light; wrapping it in dry aluminum foil (or tin foil) is recommended. ③ If you are not experienced with the procedure, do not dissolve all the STZ at once. It is recommended to dissolve STZ in groups according to your proficiency, such as 10 or 15 mice per group. Alternatively, you can weigh the required amount of STZ in advance according to the animal group and dispense it into smaller containers.

[0067] 1.4 Injection

[0068] Administer the drug intraperitoneally or via the tail vein according to the animal's fasting body weight. Tail vein injection has higher drug utilization efficiency compared to intraperitoneal injection, but it is more difficult to perform. If the injection technique is not proficient, the two groups should be injected alternately, and the injection should be completed within 30 minutes. For type 1 diabetes models: multiple low-dose injections of 50-60 mg / kg for five consecutive days are recommended.

[0069] 1.5 Wound Modeling

[0070] A type 1 diabetic mouse model induced by streptozotocin (STZ) was established to evaluate the in vivo effects of MSN@Met-CeO2 MN on wound healing. After successful induction of diabetes, hair was shaved from the back region, and a 1 cm diameter full-thickness resection wound was created on day 0. Figure 6 a).

[0071] 1.6 Evaluation Indicators for the Modeling Effect of STZ-Induced Diabetes Model

[0072] (1) General indicators: polydipsia, polyphagia, polyuria, and weight loss occur;

[0073] (2) Other indicators: fasting blood glucose, fasting serum insulin level, serum insulin level, insulin sensitivity, glucose tolerance, etc.

[0074] (3) Serum biochemical indicators: T-Cho, TG, HDL-C, LDL-C, CR, BUN, Alt, etc.;

[0075] (4) Pathological sections: pathological sections of pancreatic tissue.

[0076] 1.7 Results

[0077] Solutions of Met (1 mg / ml), CeO2 (0.1 mg / ml), MSN+Met+CeO2 (1 mg / ml Met + 0.5 mg / ml MSN + 0.1 mg / ml CeO2), and MSN@Met-CeO2 composite nanoparticles (1 mg / ml) were mixed with PVA and PVP solutions at a volume ratio of 1:1. The nanoparticle-containing solution prepared in the above steps was then mixed with 5 wt% TSPBA crosslinking agent at a volume ratio of 1:1. This mixture was rapidly poured into a microneedle mold (conical orifices, 15*15 array), and vacuum-evacuated for 1 min, repeated 3 times (vacuum treatment ensured the solution filled the orifice cavity). Finally, the mixture was allowed to stand overnight at room temperature, and then dried in a 37°C oven for 48 h. After the microneedle patch was fully dried, it was demolded to obtain the drug-loaded microneedle patch. Blank microneedles were prepared as described above, except that the same volume of nanoparticle solution was replaced with pure water. The drug-loaded microneedle patches were obtained with drug loading amounts of Met MN (1 mg), CeO2MN (0.1 mg), MSN (0.5 mg) + Met (0.5 mg) + CeO2 (0.1 mg) MN and MSN@Met-CeO2 MN (1 mg) per patch.

[0078] Mice were divided into five treatment groups (n=10 per group) and treated with microneedle patches 6 hours after wound modeling. Wound area was assessed on days 3, 7, 10, and 14 post-traumatic stress. Results clearly showed that, compared to the blank MN group, wounds treated with Met MN, CeO2 MN, MSN+Met+CeO2 MN, and MSN@Met-CeO2 MN exhibited faster wound healing, crust formation, and hemostasis. Figure 6 b). Among them, diabetic wounds treated with MSN@Met-CeO2 MN achieved 50% closure the fastest, and 95% closure was achieved by day 14. Figure 6c and 6d). Conversely, on day 14, 56.34%, 45.35%, 30.21%, and 25.13% of the wounds in the blank MN group, Met MN group, CeO2 MN group, and MSN+Met+CeO2 MN group, respectively, remained unclosed. Figure 6 e). Furthermore, we histologically evaluated wound bed granulation and re-epithelialization at 7 and 14 days post-treatment using hematoxylin and eosin (HE) staining. Specifically, the MSN@Met-CeO2MN group exhibited the best degree of epithelialization at day 7 and formed a more complete epidermal layer structure at day 14. Figure 6 f). By observing the extracellular matrix of the tissue, we observed that, compared with other groups, the collagen fibers in the MSN@Met-CeO2MN group were arranged in an orderly manner, forming a mature basement membrane under the entire epidermis of the healing tissue. Figure 6 g). In summary, these results confirm that MSN@Met-CeO2 MN has a significant promoting effect on healing in diabetic wounds.

[0079] The embodiments given above are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions or substitutions made by those skilled in the art based on the technical features of the present invention are within the protection scope of the present invention.

Claims

1. A ROS-responsive hydrogel microneedle containing MSN@Met-CeO2 composite nanoparticles, characterized in that, The MSN@Met-CeO2 composite nanoparticles have a core-shell structure, with mesoporous silica loaded with metformin in the pores as the core and cerium oxide loaded on the surface of the core as the shell. The mass ratio of metformin to cerium oxide is 1:(0.1~0.2). The mass ratio of metformin to mesoporous silica is 1:(3~5). The MSN@Met-CeO2 composite nanoparticles are spherical in shape with a size of 60-80 nm.

2. The method for preparing ROS-responsive hydrogel microneedles according to claim 1, characterized in that, The method includes the following steps: (1) Synthesis of MSN@Met: Mesoporous silica nanoparticles were dispersed in water, metformin solution was added under stirring, and the reaction was stirred at 200~600 r / min for 12~36 h. The product was then washed by ultrafiltration with a 100 kd ultrafiltration tube to remove unloaded metformin and obtain MSN@Met. (2) Synthesis of MSN@Met-CeO2: The MSN@Met prepared in step (1) was dispersed in ethanol, Ce(NO3)3 •6H2O and hexamethyldinaphthylamine were added, stirred for 2-4 h, and then refluxed at 70-80℃ for 3-5 h. After centrifugation, the product was washed to obtain MSN@Met-CeO2. (3) Preparation of ROS-responsive hydrogel microneedles: Add MSN@Met-CeO2 prepared in step (2) to a mixed solution of PVA and PVP, mix evenly, then add TSPBA crosslinking agent and mix evenly, pour the mixture into the microneedle mold, vacuum process to fill the microneedle cavity with the mixture, and finally let it stand at room temperature for 8-12 hours, dry it thoroughly at 35~38℃, and demold.

3. The method for preparing ROS-responsive hydrogel microneedles according to claim 2, characterized in that, The mesoporous silica nanoparticles mentioned in step (1) are dispersed in water at a concentration of 0.5~2 mg / ml, and the concentration of the metformin solution is 0.5~1.5 mg / ml.

4. The method for preparing ROS-responsive hydrogel microneedles according to claim 2, characterized in that, The MSN@Met mentioned in step (2) is dispersed in ethanol at a concentration of 60~150mg / ml.

5. The method for preparing ROS-responsive hydrogel microneedles according to claim 2, characterized in that, In step (2), the concentration of PVA in the mixed solution of PVA and PVP is 10-15 wt% and the concentration of PVP is 7-10 wt%.

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