Conductive microneedle patch for diabetes wound healing as well as preparation method and application of conductive microneedle patch

Abstract

The invention discloses a conductive microneedle patch for diabetes wound healing and a preparation method and application thereof, and belongs to the technical field of biomedical materials. The conductive microneedle patch is of a nesting doll type double-layer structure formed by an inner layer and an outer layer, microneedles on the inner layer are constructed through a methacrylic anhydride modified gelatin template pouring method, and polyvinyl alcohol microneedles on the top layer are formed by the outer layer through a lining-template pouring method. Wherein the microneedle patch has remarkable conductivity and antibacterial property due to a conductive nano-material silver nanowire in the inner-layer microneedle, and the outer-layer microneedle is loaded with a hypoglycemic drug and a natural humectant betaine, so that the properties of moisturizing and continuously releasing drugs are achieved. The obtained microneedle patch can keep a wound moist environment and adjust a diabetes wound inflammation microenvironment, cell and blood vessel growth is promoted through exogenous electrical stimulation, and rapid healing of a diabetes wound can be effectively achieved by releasing a hypoglycemic drug.

Description

Technical Field

[0001] The invention belongs to the technical field of biomedical materials and relates to a conductive microneedle patch for healing diabetic wounds and a preparation method and application thereof. Background Art

[0002] Diabetes is a chronic metabolic disease characterized by insufficient insulin secretion or inefficient use of insulin by the body, leading to uncontrolled blood sugar levels. This long-term hyperglycemia not only affects the patient's daily life, but may also cause a series of serious complications, such as retinopathy, nephropathy and diabetic foot. In addition, due to the long-term influence of hyperglycemia, the wound healing process of diabetic patients becomes extremely complicated. Hyperglycemia can hinder angiogenesis and granulation tissue regeneration at the wound site, while affecting the normal function of the extracellular matrix (ECM). Compared with normal wounds, diabetic wounds heal slowly, the duration of inflammatory response is prolonged, they are more susceptible to bacterial infection, angiogenesis is blocked, and the risk of infection is increased. In the treatment of diabetic wounds, traditional wound care methods, such as the use of gauze, sponges and hydrogels, although they help to keep the wound clean and moist to a certain extent, their therapeutic effects are often limited. Therefore, the development of more effective treatments to promote the healing of diabetic wounds and reduce the risk of complications is of great significance for improving the quality of life of diabetic patients.

[0003] Microneedle Technology (MT) can penetrate the skin without touching nerves and blood vessels, thus achieving minimally invasive and painless drug delivery. Existing microneedle technology has a single function and a single therapeutic effect, and only regulates the condition by controlling the release of encapsulated therapeutic drugs. In addition, since the skin is relatively hard, the microneedles can be easily separated from the skin by eliminating the insertion pressure, which will affect the application requirements of long-term drug release of microneedles. Therefore, there is an urgent need to design and prepare multifunctional and non-detachable microneedle patches to promote their application in the medical field. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned technical problems such as the difficulty in healing diabetic chronic wounds in clinical practice and the single treatment effect of existing microneedle technology. The present invention combines electrical stimulation therapy with microneedle technology to provide a "nesting doll-style" double-layer conductive microneedle patch for healing diabetic wounds and its preparation method.

[0005] In a first aspect, the present invention provides a conductive microneedle patch for diabetic wound healing, wherein the conductive microneedle patch is composed of conductive inner microneedles containing silver nanowires and outer microneedles loaded with hypoglycemic drugs;

[0006] The bottom of the outer layer microneedle is nested in the top of the inner layer microneedle.

[0007] Furthermore, in the conductive microneedle patch provided by the present invention, the hypoglycemic drug is metformin; the diameter of the silver nanowire is 30 to 60 nm, and the length is 2 to 20 μm.

[0008] Furthermore, the conductive inner layer microneedle of the present invention has a size of 10×10 mm to 20×20 mm;

[0009] The conductive inner layer microneedle has a cone shape with a height of 400 to 600 μm and a bottom diameter of 200 to 400 μm;

[0010] The outer layer microneedles have a size of 10×10 mm to 20×20 mm;

[0011] The outer layer microneedle body is in a cone shape with a height of 400-600 μm and a bottom diameter of 200-400 μm.

[0012] Furthermore, the number of the conductive inner layer microneedles of the present invention is 10×10 to 20×20;

[0013] The number of the outer layer microneedles is 10×10 to 20×20.

[0014] Furthermore, the needle body of the conductive microneedle patch of the present invention is a double-layer structure with a height of 700 to 1000 μm and a bottom diameter of 200 to 400 μm.

[0015] In a second aspect, the present invention provides a method for preparing a conductive microneedle patch for diabetic wound healing, comprising: preparing a conductive inner layer microneedle by casting a PDMS mold with a conductive inner layer microneedle solution, UV curing and vacuum drying; preparing a conductive microneedle patch by casting a PDMS mold with an outer layer microneedle solution, placing a liner and a conductive inner layer microneedle on the PDMS mold in sequence after vacuuming, removing the liner, inserting the conductive inner layer microneedle into a PDMS mold containing an outer layer microneedle solution, and vacuum drying;

[0016] The lining layer is a hollow rectangle with an inner circle of 9×9mm to 19×19mm, an outer circle of 10×10mm to 20×20mm, and a thickness of 100 to 400μm;

[0017] The ultraviolet curing time of the conductive inner layer microneedles is 0.25 to 1 hour;

[0018] The conductive inner layer microneedle solution is prepared from methacrylic anhydride-modified gelatin, silver nanowires and photoinitiator LAP, and the outer layer microneedle solution is prepared from polyvinyl alcohol, PBS, metformin and betaine.

[0019] Furthermore, in the preparation method provided by the present invention, the mass ratio of gelatin to methacrylic anhydride in the methacrylic anhydride-modified gelatin is 5:4;

[0020] The molecular weight of the gelatin is 5 to 30 KDa.

[0021] Furthermore, the present invention provides a method for preparing a conductive inner layer microneedle solution, comprising: dissolving methacrylic anhydride modified gelatin in ultrapure water to prepare a 25% methacrylic anhydride modified gelatin solution; adding 10 to 30 mg / mL silver nanowires in an amount of 0 to 1% of the mass of the methacrylic anhydride modified gelatin solution to prepare a mixed solution; adding a photoinitiator LAP in a concentration of 3% in an amount of 0.5% of the mass of the mixed solution;

[0022] Furthermore, the present invention provides a method for preparing an outer layer microneedle solution, comprising: mixing polyvinyl alcohol and PBS at a mass ratio of 6:5, adding a metformin solution with a concentration of 5 mg / mL to prepare a mixed solution; adding betaine in an amount of 10% by mass of the mixed solution to the mixed solution, and mixing well to prepare an outer layer microneedle solution.

[0023] In the third aspect, the present invention provides the use of a conductive microneedle patch in the preparation of a diabetic wound healing drug. The conductive inner layer microneedle body has high conductivity and antibacterial properties, and its functional characteristics can serve as a carrier of exogenous electrical stimulation, regulate the microenvironment of the wound, and promote wound healing. Secondly, the outer layer microneedle body is loaded with the hypoglycemic drug metformin, and its continuous release of drugs can target the high blood sugar fluid environment of diabetic patients, provide conditions for restoring normal blood sugar signs for the healing of complex high-sugar wound environments, and further accelerate wound healing.

[0024] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0025] (1) The "nesting doll-like" double-layer conductive microneedle patch obtained by the present invention has the characteristics of mild reaction conditions, simple preparation, and easy mass production. First, its double-layer structure makes the microneedle patch needle body length 700-1000 μm, which is conducive to deeper penetration into the skin to make the drug release more effective, and the double-layer structure makes the microneedle fit more closely to the skin and is not easy to fall off.

[0026] (2) Secondly, the conductive microneedle patch efficiently combines the functional properties of the inner and outer microneedles, avoiding the excessive addition of multiple functional materials in a single medical raw material and the side effects, and significantly exhibits good antibacterial properties against Gram-positive bacteria and Gram-negative bacteria.

[0027] (3) The conductive microneedle patch prepared by the present invention has excellent biocompatibility, and can achieve a 100% drug release rate after 120 hours of administration. The conductive microneedle patch is used for chronic diabetic wounds, and has the effects of moisturizing, inhibiting bacteria and promoting healing of the wounds. At the same time, the microneedle patch has conductive properties, and the wound healing efficiency is significant under external electrical stimulation, and has a good application prospect in the field of chronic diabetic wounds.

[0028] (4) The present invention can simply and massively prepare a "nesting doll-like" double-layer conductive microneedle patch through the "liner-template casting method", which exhibits significant multifunctional properties and therapeutic effects in treating chronic diabetic wounds. Its huge application potential can become an emerging medical device and treatment strategy in the biomedical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Flow chart for the preparation of double-layer microneedle patches.

[0030] Figure 2 Figure 1 is a microneedle patch morphology diagram. A is a single-layer microneedle patch morphology diagram; B is a double-layer microneedle patch morphology diagram; C is a double-layer microneedle patch array diagram.

[0031] Figure 3 The skin imprint after the double-layer microneedle patch is administered. A is the appearance of the double-layer microneedle patch; B is the skin imprint after administration.

[0032] Figure 4 This is the drug release rate diagram of the conductive microneedle patch.

[0033] Figure 5 This is a diagram showing the antibacterial effect of the conductive microneedle patch tested using the inhibition zone method.

[0034] Figure 6 The figure shows the electrical signal value of the conductive microneedle patch. A is the conductivity value image; B is the cyclic voltammetry curve image.

[0035] Figure 7 The effect diagram of the cell survival rate of the conductive microneedle patch. Among them, A is the cell survival rate of the conductive microneedle patch at 1D; B is the cell survival rate of the conductive microneedle patch at 3D; C is the cell survival rate of the conductive microneedle patch at 5D.

[0036] Figure 8 This is a diagram showing the wound healing effect of the conductive microneedle patch in a diabetic rat model with full-thickness cortical defects. DETAILED DESCRIPTION

[0037] The technical scheme of the present invention is described below in conjunction with the embodiments, but the present invention is not limited to the following embodiments. The experimental methods and detection methods described in each embodiment are conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0038] Example 1

[0039] This embodiment provides a method for preparing a single-layer microneedle patch for diabetic wound healing.

[0040] 1. Preparation of methyl propyl anhydride modified gelatin: Gelatin is modified by methacrylic anhydride, that is, methacrylic anhydride is slowly added to gelatin with a molecular weight of 5 to 30 KDa, the mass ratio of gelatin to methacrylic anhydride is 5:4, and the reaction is carried out at 60°C in the dark for 2 hours, and then PBS (phosphate buffered saline) is added to terminate the reaction to obtain a modified gelatin product. The modified gelatin product is dialyzed in ultrapure water for 72 hours, and freeze-dried for 72 hours to obtain methyl propyl anhydride modified gelatin.

[0041] 2. Preparation of single-layer microneedle solution: Dissolve methyl propyl anhydride-modified gelatin in ultrapure water to prepare a 25% methyl propyl anhydride-modified gelatin solution, and then add a 3% photoinitiator LAP (0.2% of the mass of the methyl propyl anhydride-modified gelatin solution). After ultrasonic dispersion, a single-layer microneedle solution is obtained.

[0042] 3. Preparation of single-layer microneedles: Pour the single-layer microneedle solution into the pinholes of the PDMS mold, cure it with UV light for 0.25 hours, and then dry it at room temperature and demold it to obtain a single-layer microneedle patch. The needle body of the single-layer microneedle patch is a cone with a height of 400μm and a bottom diameter of 200μm. The conical microneedles are arranged in a 10×10 array to form a 10mm×10mm (length×width) rectangular area. The conical geometry is conducive to the microneedles forming tiny perforations on the skin surface, thereby promoting the transdermal delivery of drugs or therapeutic molecules. The 10×10 array arrangement ensures that the microneedle patch can cover a larger skin area when applied, while providing a uniform therapeutic effect.

[0043] Example 2

[0044] This embodiment provides a method for preparing a "nesting doll-like" double-layer microneedle patch for diabetic wound healing.

[0045] The preparation process of the microneedle patch in this embodiment is as follows Figure 1 shown.

[0046] 1. Preparation of the outer microneedle solution: polyvinyl alcohol and PBS were mixed at a mass ratio of 6:5, and a 3 mg / mL metformin solution was added (the amount added was 5% of the total mass of polyvinyl alcohol and PBS), and the mixed solution was obtained. Betaine was added to the mixed solution at a mass ratio of 7.5% of the mixed solution, and the outer microneedle solution was obtained after mixing.

[0047] 2. Preparation of microneedle patch: After pouring the outer microneedle solution into the PDMS mold, place it in a vacuum drying oven, evacuate the outer microneedle solution to completely fill the pinholes of the PDMS mold, and then place the inner microneedle (single-layer microneedle patch) prepared in Example 1 on top of a liner with a thickness of 200 μm, then remove the liner, insert it again into the PDMS mold filled with the outer microneedle solution, and dry and demold at 50°C to prepare a microneedle patch with a "nesting doll-like" double-layer structure (inner microneedle + outer microneedle). The liner (purchased from Jiangsu Huafeng Machinery Co., Ltd., made of 304 stainless steel) is a hollow rectangle with an inner circle size of 9 mm × 9 mm (length × width) and an outer circle size of 10 mm × 10 mm (length × width). The needle body of the outer layer of microneedles is a cone with a height of 400μm and a bottom diameter of 200μm. The conical microneedles are arranged in a 10×10 array to form a rectangular area of ​​10mm×10mm (length×width). The needle body of the microneedle patch in this embodiment is a sheath structure with a height of 700μm and a bottom diameter of 700μm. In this sheath structure, the bottom of the outer layer of microneedle needle body is "nested" on the top of the inner layer of microneedle needle body. Through the adhesion of the needle body solution, the outer layer of microneedles can be firmly adhered to the inner layer of microneedles, so that they are not easy to fall off in practical applications. This sheath structure not only enhances the stability of the microneedles, but also provides an effective drug delivery method.

[0048] Example 3

[0049] This embodiment provides a method for preparing a "nesting doll-like" double-layer conductive microneedle patch for healing diabetic wounds.

[0050] 1. Preparation of methyl propyl anhydride modified gelatin: Gelatin was modified with methacrylic anhydride, that is, methacrylic anhydride was slowly added to gelatin with a molecular weight of 5 to 30 KDa, the mass ratio of gelatin to methacrylic anhydride was 5:4, and the reaction was carried out at 60°C in the dark for 2 hours, and then PBS was added to terminate the reaction to obtain a modified gelatin product. The modified gelatin product was dialyzed for 72 hours and freeze-dried for 72 hours to obtain methyl propyl anhydride modified gelatin.

[0051] 2. Preparation of inner microneedle solution: Dissolve methyl propyl anhydride modified gelatin in ultrapure water to prepare a 25% methyl propyl anhydride modified gelatin solution, then add a silver nanowire solution with a diameter of 30nm, a length of 2μm, and a concentration of 10mg / mL, the mass of the silver nanowire solution is 1% of the total mass of the methyl propyl anhydride modified gelatin solution, mix evenly, and obtain a composite solution. Add a 5% photoinitiator LAP to the composite solution, the amount added is 0.5% of the mass of the composite solution, and then ultrasonically disperse it evenly to obtain an inner microneedle solution with conductive properties.

[0052] 3. Preparation of inner layer microneedles: drip the inner layer microneedle solution into the PDMS mold, place it in a vacuum drying oven, evacuate to 1.0MPa, keep it for 45 minutes until the solution completely fills the pinholes in the PDMS mold, and after UV curing for 1 hour, dry it at room temperature and demold it to obtain a conductive inner layer microneedle. The needle body of the inner layer microneedle is a cone with a height of 400μm and a bottom diameter of 200μm. The conical microneedles are arranged in a 10×10 array to form a 10mm×10mm (length×width) rectangular area. The addition of silver nanowires makes the conductive inner layer microneedles highly conductive and antibacterial, and can serve as a carrier of exogenous electrical stimulation, regulate the microenvironment of the wound, and promote wound healing.

[0053] 4. Preparation of the outer microneedle solution: Polyvinyl alcohol and PBS were mixed at a mass ratio of 6:5, and a 5 mg / mL metformin solution was added (the amount added was 5% of the total mass of polyvinyl alcohol and PBS), and the mixed solution was obtained. Betaine was added to the mixed solution at a mass ratio of 10% of the mixed solution, and the outer microneedle solution was obtained after mixing.

[0054] 5. Preparation of microneedle patch: drip the outer microneedle solution into the PDMS mold, place it in a vacuum drying oven, evacuate the outer microneedle solution to completely fill the pinholes of the PDMS mold, then place the dried and demolded conductive inner microneedle on top of the 200μm liner, then remove the liner, insert it into the PDMS mold filled with the outer microneedle solution again, dry and demold at 65°C to prepare a conductive microneedle patch with a "nesting doll-like" double-layer structure (conductive inner microneedle + outer microneedle). The liner is a hollow rectangle with an inner circle size of 9mm×9mm (length×width) and an outer circle size of 10mm×10mm (length×width). The needle body of the outer microneedle is a cone with a height of 400μm and a bottom diameter of 200μm. The conical microneedles are arranged in a 10×10 array to form a 10mm×10mm (length×width) rectangular area. In this embodiment, the needle body of the microneedle patch is a sheath structure with a height of 700 μm and a bottom diameter of 700 μm.

[0055] Example 4

[0056] This embodiment provides a method for preparing a "nesting doll-like" double-layer conductive microneedle patch for healing diabetic wounds.

[0057] 1. Preparation of methyl propyl anhydride modified gelatin: Gelatin was modified with methacrylic anhydride, that is, methacrylic anhydride was slowly added to gelatin with a molecular weight of 5 to 30 KDa, the mass ratio of gelatin to methacrylic anhydride was 5:4, and the reaction was carried out at 60°C in the dark for 2 hours, and then PBS was added to terminate the reaction to obtain a modified gelatin product. The modified gelatin product was dialyzed for 72 hours and freeze-dried for 72 hours to obtain methyl propyl anhydride modified gelatin.

[0058] 2. Preparation of inner microneedle solution: Dissolve methyl propyl anhydride modified gelatin in ultrapure water to prepare a 25% methyl propyl anhydride modified gelatin solution, then add a silver nanowire solution with a diameter of 60nm, a length of 20μm, and a concentration of 30mg / mL, the mass of the silver nanowire solution is 1% of the total mass of the methyl propyl anhydride modified gelatin solution, mix evenly, and obtain a composite solution. Add a 5% photoinitiator LAP to the composite solution, the amount added is 0.5% of the mass of the composite solution, and then ultrasonically disperse it evenly to obtain an inner microneedle solution with conductive properties.

[0059] 3. Preparation of inner layer microneedles: drip the inner layer microneedle solution into the PDMS mold, place it in a vacuum drying oven, evacuate to 1.0MPa, and maintain for 45 minutes until the solution completely fills the pinholes in the PDMS mold. After UV curing for 1 hour, dry it at room temperature and demould it to obtain a conductive inner layer microneedle. The needle body of the inner layer microneedle is a cone with a height of 600μm and a bottom diameter of 400μm. The conical microneedles are arranged in a 20×20 array to form a 20mm×20mm (length×width) rectangular area.

[0060] 4. Preparation of the outer microneedle solution: Polyvinyl alcohol and PBS were mixed at a mass ratio of 6:5, and a 5 mg / mL metformin solution was added (the amount added was 5% of the total mass of polyvinyl alcohol and PBS), and the mixed solution was obtained. Betaine was added to the mixed solution at a mass ratio of 10% of the mixed solution, and the outer microneedle solution was obtained after mixing.

[0061] 5. Preparation of microneedle patch: drip the outer microneedle solution into the PDMS mold, place it in a vacuum drying oven, evacuate the outer microneedle solution to completely fill the pinholes of the PDMS mold, then place the dried and demolded conductive inner microneedle on top of the 400μm liner, then remove the liner, insert it into the PDMS mold filled with the outer microneedle solution again, dry and demold at 65°C to prepare a conductive microneedle patch with a "nesting doll-like" double-layer structure (conductive inner microneedle + outer microneedle). The liner is a hollow rectangle with an inner circle size of 19mm×19mm (length×width) and an outer circle size of 20mm×20mm (length×width). The needle body of the outer microneedle is a cone with a height of 600μm and a bottom diameter of 400μm. The conical microneedles are arranged in a 20×20 array to form a 20mm×20mm (length×width) rectangular area. In this embodiment, the needle body of the microneedle patch is a sheath structure with a height of 1000 μm and a bottom diameter of 400 μm.

[0062] The conductive microneedle patch prepared in this embodiment has high biodegradability, strong conductivity and antibacterial properties. After acting on rats with full-thickness skin defects, the wound area of ​​the rats was the smallest and the healing effect was the best at 3D, 5D and 12D compared with the blank control and single-layer microneedle groups. The wound was basically healed at 12D, which has a significant promoting effect on the healing of diabetic wounds (such as Figure 8 shown).

[0063] Example 5

[0064] This embodiment provides detection data of a "nesting doll-like" double-layer conductive microneedle patch for diabetic wound healing.

[0065] Figure 2 The morphology of single-layer microneedle patches and double-layer microneedle patches. Figure 2 A in the figure is the morphology of the single-layer microneedle patch needle body obtained in Example 1. Figure 2 B is a morphological diagram of the double-layer microneedle patch needle body prepared in Example 2. It can be observed from the figure that the bottom of the outer microneedle needle body is nested in the top of the inner microneedle needle body, which enhances the overall stability of the microneedle patch. This sheath structure enables the outer microneedles to penetrate the skin more effectively under the guidance of the inner microneedles, while maintaining the integrity of the microneedle patch and the consistency of drug delivery. Figure 2 C in the figure is the array arrangement of the double-layer microneedle body prepared in Example 2.

[0066] Figure 3 This is an electronic image of the double-layer microneedle patch after it penetrated the subject's skin. Figure 3 A in FIG. 1 is an appearance diagram of the conductive microneedle patch prepared in Example 3. Figure 3B in the figure is the skin mark of the subject after using the conductive microneedle patch. It can be found from the figure that the conductive microneedle patch can minimize skin damage and almost no wounds are left after use. The conductive microneedle patch prepared by the present invention is minimally invasive and can penetrate the surface layer of the skin without causing significant pain or bleeding.

[0067] Figure 4 The drug release rate of the conductive microneedle patch prepared in Example 3. Within 0 to 3 hours, the drug release rate of the conductive microneedle patch rises in a straight line, and the drug release rate of the conductive microneedle patch is relatively fast. This is because the drug is at the tip or surface of the microneedle, which is easy to dissolve or release quickly. In 3 to 120 hours, the drug release rate of the conductive microneedle patch slows down. This is because the drug has been released from the surface of the microneedle, and the remaining drug needs to be gradually dissolved or diffused from the inside or deeper structure of the microneedle. At 120 hours, the drug release rate of the conductive microneedle patch reaches 100%, indicating that the conductive microneedle patch can achieve complete release of the drug and ensure that the therapeutic effect of the drug is fully exerted. This drug release mode can provide rapid initial drug release to quickly respond to treatment needs, and then maintain the drug concentration within the effective range through slow release, thereby reducing the number of dosing times, improving patient compliance, and also helping to reduce drug waste and potential side effects.

[0068] Figure 5 The results of the antibacterial test of the conductive microneedle patch using the inhibition zone method. As can be seen from the figure, the conductive microneedle patch with added nanosilver wire has a strong and effective antibacterial effect on Escherichia coli and Staphylococcus aureus compared with the blank group and the single-layer microneedle patch group, with almost no aseptic growth, confirming its antibacterial effect and the potential to inhibit bacterial reproduction on diabetic wounds.

[0069] Figure 6 This is a numerical diagram of the electrical signal of the conductive microneedle patch. Figure 6 A in the figure is the conductivity of the conductive microneedle patch with different amounts of silver nanowire added. The conductivity of the conductive microneedle patch with the best addition group reaches 9.6S / m, which meets the conditions for forming a conductive path with human skin. Figure 6 B in the figure is the cyclic voltammetry curve of the conductive microneedle patch. After the conductive microneedle patch forms a conductive path, the internal electrical signal can circulate continuously and uninterruptedly twice. The conductive microneedle patch has excellent conductive properties.

[0070] Figure 7 The effect diagram of the cell survival rate of the conductive microneedle patch was shown. L929 cells were co-cultured with the conductive microneedle patch for 1D ( Figure 7 A), 3D( Figure 7 B) and 5D( Figure 7 C), the number of live cells was significantly greater than that of dead cells, and the cells showed a gradual proliferation phenomenon, indicating that the conductive microneedle patch has strong biocompatibility.

[0071] Figure 8 The wound healing effect of the conductive microneedle patch in the full-thickness cortical defect mouse model. In the wound healing study of the full-thickness cortical defect mouse model, the effects of different treatments on the wound healing effect can be seen. In the blank group of mice without intervention, the wounds were still large after 12 days, and the natural healing process of the wounds in the hyperglycemic mice was slow without external treatment intervention. After the administration of the single-layer microneedle patch, the wound surface gradually shrank after 12 days, indicating that the single-layer microneedle patch can promote the wound healing process. After 12 days of administration of the conductive microneedle patch, the wound healed faster. The conductive properties of the conductive microneedle patch can better promote cell migration and proliferation, and accelerate wound healing. The conductive microneedle patch can provide more effective drug delivery and electrical stimulation therapy, which shows great potential in promoting wound healing.

[0072] The embodiments described above are part of the embodiments of the present invention, but not all of them. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but only represents selected embodiments of the present invention. All other embodiments obtained without creative work and related deductions and substitutions made by ordinary technicians in the field under the conditions of the concept of the present invention belong to the scope of protection of the present invention.

Claims

1. A conductive microneedle patch for diabetic wound healing, characterized in that: The conductive microneedle patch is composed of conductive inner microneedles containing silver nanowires and outer microneedles loaded with hypoglycemic drugs; The bottom of the outer layer microneedle is nested in the top of the inner layer microneedle.

2. The conductive microneedle patch for diabetic wound healing according to claim 1, characterized in that: The hypoglycemic drug is metformin; The diameter of the silver nanowire is 30-60 nm, and the length is 2-20 μm.

3. The conductive microneedle patch for diabetic wound healing according to claim 1, characterized in that: The size of the conductive inner layer microneedles is 10×10 mm to 20×20 mm; The conductive inner layer microneedle has a cone shape with a height of 400 to 600 μm and a bottom diameter of 200 to 400 μm; The outer layer microneedles have a size of 10×10 mm to 20×20 mm; The outer layer microneedle body is in a cone shape with a height of 400-600 μm and a bottom diameter of 200-400 μm.

4. The conductive microneedle patch for diabetic wound healing according to claim 1, characterized in that: The number of the conductive inner layer microneedles is 10×10 to 20×20; The number of the outer layer microneedles is 10×10 to 20×20.

5. The conductive microneedle patch for diabetic wound healing according to claim 1, characterized in that: The needle body of the conductive microneedle patch is a double-layer structure with a height of 700-1000 μm and a bottom diameter of 200-400 μm.

6. A method for preparing a conductive microneedle patch for diabetic wound healing, characterized in that: include: The conductive inner layer microneedle is prepared by casting the conductive inner layer microneedle solution into a PDMS mold, UV curing and vacuum drying; The conductive microneedle patch is made by pouring the outer microneedle solution into a PDMS mold, placing a liner and a conductive inner microneedle on the PDMS mold in turn after vacuum, removing the liner, inserting the conductive inner microneedle into the PDMS mold containing the outer microneedle solution, and vacuum drying; The lining layer is a hollow rectangle with an inner circle of 9×9mm to 19×19mm, an outer circle of 10×10mm to 20×20mm, and a thickness of 100 to 400μm; The conductive inner layer microneedle solution is prepared from methacrylic anhydride-modified gelatin, silver nanowires and photoinitiator LAP, and the outer layer microneedle solution is prepared from polyvinyl alcohol, PBS, metformin and betaine.

7. The preparation method according to claim 6, characterized in that: The mass ratio of gelatin to methacrylic anhydride in the methacrylic anhydride modified gelatin is 5:4; The molecular weight of the gelatin is 5 to 30 KDa.

8. The preparation method according to claim 6, characterized in that: The conductive inner layer microneedle solution comprises: dissolving methacrylic anhydride modified gelatin in ultrapure water to prepare a 25% methacrylic anhydride modified gelatin solution; adding 10-30 mg / mL silver nanowires in an amount of 0-1% of the mass of the methacrylic anhydride modified gelatin solution to prepare a mixed solution; adding a photoinitiator LAP in a concentration of 3% in an amount of 0.5% of the mass of the mixed solution; The ultraviolet curing time of the conductive inner layer microneedles is 0.25 to 1 hour.

9. The preparation method according to claim 6, characterized in that: The outer layer microneedle solution comprises: polyvinyl alcohol and PBS are mixed evenly at a mass ratio of 6:5, and then a metformin solution with a concentration of 5 mg / mL is added to prepare a mixed solution; betaine is added to the mixed solution at a mass percentage of 10% of the mixed solution to prepare an outer layer microneedle solution after mixing evenly.

10. Use of the conductive microneedle patch prepared by the preparation method according to any one of claims 6 to 9 in preparing a diabetic wound healing drug.

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