Bionic microneedle and preparation and application thereof

Abstract

The application discloses a kind of bionic microneedle, and provides its preparation method and application.The bionic microneedle of the application is based on protein and high molecular polysaccharide composite film microneedle, specifically, the shell of the bionic microneedle is prepared by the composite film formed by protein and high molecular polysaccharide, and the hollow cavity in the middle can be used to load functional active substance.The microneedle shell formed by the composite film of the protein and high molecular polysaccharide of the application can significantly improve the mechanical strength of polymer microneedle;The hollow cavity of microneedle can be used to load functional active substance, and the loading capacity of microneedle can be significantly improved, so as to effectively improve the conversion potential of microneedle.

Description

Technical Field

[0001] This invention relates to the field of microneedle technology for drug or vaccine delivery and cosmetic purposes, specifically to the preparation and application of a biomimetic microneedle based on a composite membrane structure of protein and high molecular weight polysaccharide. Background Technology

[0002] Polymer microneedles are made from high-molecular-weight polymers and are microneedle-like structures with lengths ranging from 100 to 1000 μm. Because they can effectively penetrate the skin's stratum corneum barrier without touching nerves and blood vessels within the skin, polymer microneedles deliver functional substances with minimal pain and trauma, resulting in good patient compliance. Furthermore, after delivery, the polymer material dissolves or degrades within the skin, leaving no medical or cosmetic waste residue, thus ensuring good safety. On the other hand, the release behavior of functional active substances can be effectively modulated by adjusting the chemical properties of the polymer.

[0003] However, compared to microneedles made of metal or inorganic materials, polymer microneedles have relatively lower mechanical strength, which may lead to less than ideal skin puncture efficiency. Simultaneously, the small needle volume of microneedles severely limits their loading capacity, and the loading of functional active substances further reduces their mechanical strength. Both of these problems significantly reduce the practical application range and transformation potential of polymer microneedles. Furthermore, when loading functional active substances onto polymer microneedles, the active ingredient is generally dissolved or mixed uniformly with the polymer material before drug loading. Therefore, the loading process is relatively complex, and the dissolution and mixing steps may damage the function or structure of the active ingredient, thereby affecting its efficacy.

[0004] Generally, to improve the mechanical strength of polymer microneedles, metal nanoparticles or inorganic components can be incorporated into the polymer material, utilizing the inherent high mechanical strength of these materials to enhance the overall mechanical properties of the microneedles. However, this method has two drawbacks. First, the incorporation of these metals and inorganic materials reduces the biocompatibility of the polymer microneedles, increasing their safety risks. Second, the addition of metals and inorganic materials further impairs the loading capacity of the polymer microneedles. These two drawbacks reduce the clinical translation potential of polymer microneedles.

[0005] To improve the loading capacity of polymer microneedles, core-shell polymer microneedles can be fabricated. First, a polymer shell (such as PLGA or PVA) can be used to prepare the microneedle shell, and the functional active substance can be directly loaded into the hollow cavity of the microneedle. This strategy effectively enhances the loading capacity of the microneedle; however, the mechanical strength of core-shell polymer microneedles is significantly lower than that of solid polymer microneedles, which is detrimental to skin puncture. Alternatively, the loading capacity of polymer microneedles can be improved by directly increasing the size and number of microneedles, but this strategy significantly increases the difficulty of microneedle fabrication, and the increased microneedle size may exacerbate pain during drug administration.

[0006] Therefore, developing a novel polymer microneedle that is easy to prepare and can simultaneously improve the mechanical strength and drug loading capacity of microneedles, as well as its preparation method, has significant commercial value and scientific research significance. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a biomimetic microneedle based on proteins and high-molecular-weight polysaccharides, its preparation method, and its applications. On one hand, this invention improves the microneedle preparation materials to create a biomimetic microneedle shell, effectively enhancing the mechanical strength of the microneedle. On the other hand, the hollow cavity of the microneedle can be used to directly load powders, concentrated solutions, or suspensions of functionally active substances, significantly increasing the loading capacity. Furthermore, this drug loading method is not limited by the physicochemical properties of the functionally active substances and does not require pre-mixing of the functionally active substances with the microneedle preparation materials, improving the convenience and stability of functionally active substance loading.

[0008] The cuticle of insects, the shell of crustaceans, and the nacreous layer of mollusks all possess extremely high mechanical strength and hardness. Studies have found that these biological tissues contain composite membrane structures formed by chitin-like polysaccharides and proteins. Therefore, in order to improve the mechanical strength of microneedles, this invention uses proteins and high-molecular-weight polysaccharides to form a composite membrane to simulate these biological tissues in order to prepare microneedles with high mechanical strength.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A biomimetic microneedle, wherein the outer shell of the microneedle comprises proteins and high-molecular-weight polysaccharides, and the interior has a hollow cavity structure for loading functionally active substances. Preferably, the outer shell of the microneedle comprises a composite membrane formed of proteins and high-molecular-weight polysaccharides, and the interior has a hollow cavity structure for loading functionally active substances. Preferably, the functionally active substances include one or more components with cosmetic effects, drugs or vaccines with therapeutic or preventive effects.

[0011] Preferably, the protein is one or more of collagen, silk fibroin, gelatin, laminin, and albumin.

[0012] Preferably, the polysaccharide is one or more of chitosan, N-trimethyl chitosan, carboxymethyl chitosan, N-succinyl chitosan, quaternary ammonium salt chitosan, and chitosan oligosaccharide.

[0013] The thickness of the outer shell in the biomimetic microneedle can be controlled by adjusting the number of layers in the composite membrane structure.

[0014] Preferably, the composite membrane can be a multilayer membrane, and more preferably, the outer shell of the biomimetic microneedle is a double-layer membrane.

[0015] More preferably, the protein is silk fibroin and the high molecular weight polysaccharide is chitosan.

[0016] This invention provides a method for preparing biomimetic microneedles, comprising the following steps:

[0017] (1) Add the protein solution into the microneedle mold and dry it to obtain a protein membrane;

[0018] (2) Add methanol to the microneedle mold to treat the protein membrane, remove the residual methanol and then dry it;

[0019] (3) Add the polymer polysaccharide solution into the microneedle mold and dry it to obtain the double-layer membrane microneedle structure;

[0020] (4) The first three steps above can be repeated until the required number of composite membrane layers is reached;

[0021] (5) Add the functional active substance powder, solution or suspension to the hollow cavity of the above composite membrane microneedles;

[0022] (6) Finally, a polymer solution is added as a microneedle substrate, and after drying, the microneedles are peeled off to obtain biomimetic microneedles loaded with active substances.

[0023] Preferably, in the above microneedle preparation method, the solutions in steps (1) and (3) are aqueous solutions, wherein the protein concentration in the protein aqueous solution is 0.5%-20% (m / v), and the concentration of the polymeric polysaccharide in the polymeric polysaccharide aqueous solution is 0.5%-20% (m / v). More preferably, the protein concentration in the protein aqueous solution is 1%-10%, and the concentration of the polymeric polysaccharide in the polymeric polysaccharide aqueous solution is 0.5%-5%. More preferably, the protein concentration in the protein aqueous solution is 8%, and the concentration of the polymeric polysaccharide in the polymeric polysaccharide aqueous solution is 4%. More preferably, the protein is silk fibroin, and the polymeric polysaccharide is chitosan.

[0024] The polymer used to prepare the microneedle substrate is at least one of polyester, PHA, PHBV, PHP, PHH, PHA-PEG, poly-4-hydroxy acid, poly-α-hydroxy acid, poly-β-hydroxy acid, poly-4-hydroxybutyrate, poly-4-hydroxyvalerate, poly-4-hydroxyhexanoate, polyesteramide, polycaprolactone, polylactide, polyglycolic acid lactide, PLGA, polydioxanone, polyorthoester, polyether ester, polyanhydride, glycolic acid-trimethylene carbonate copolymer, polyphosphate, polyphosphate urethane, polyamino acid, polycyanoacrylate, polytrimethylene carbonate, polyimino carbonate, polytyrosine carbonate, polycarbonate, polytyrosine aryl ester, polyalkylene oxalate, polyphosphocreatine, chitosan, dextran, cellulose, heparin, hyaluronic acid, alginate, inulin, starch, and glycogen.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) The composite membrane shell of the bionic microneedle of the present invention can significantly improve the mechanical strength of the microneedle, thus effectively ensuring the skin puncture efficiency of the microneedle. Traditional polymer microneedles require the polymer material to be made into a solid structure to ensure good skin puncture efficiency. The composite membrane shell of the bionic microneedle of the present invention has stronger mechanical strength than traditional solid polymer microneedles, thus effectively ensuring the skin puncture efficiency of the microneedle.

[0027] (2) The hollow cavity of the biomimetic microneedles of the present invention can be used to directly load functional active substances, thus this composite membrane microneedle can effectively increase the drug loading capacity of the microneedles. Compared with traditional polymer microneedles, the composite membrane microneedles of the present invention can increase the drug loading capacity of the microneedles by at least three times.

[0028] (3) The drug loading process of the bionic microneedles of the present invention is to directly inject the active substance powder, concentrated solution or suspension into the hollow cavity of the microneedle. No drying is required or the drying time is short. Therefore, this loading method has little impact on the function or structure of the active substance and the loading process is simple. Attached Figure Description

[0029] Figure 1 The biomimetic microneedles without active material prepared in Example 1 of this invention are shown.

[0030] Figure 2 This is a scanning electron microscope image of a cross section of the biomimetic microneedle prepared in Example 1 of the present invention.

[0031] Figure 3 This is a skin puncture diagram of the biomimetic microneedles prepared in Example 1 of the present invention.

[0032] Figure 4 The rapamycin-loaded biomimetic microneedles prepared in Example 2 of this invention.

[0033] Figure 5The results show the drug loading of rapamycin-loaded microneedles prepared in Example 2 and Comparative Example 4 of this invention.

[0034] Figure 6 This is a skin puncture diagram of the rapamycin-loaded biomimetic microneedle prepared in Example 2 of the present invention.

[0035] Figure 7 The OVA-loaded biomimetic microneedles prepared in Example 3 of this invention.

[0036] Figure 8 The biomimetic microneedles loaded with disodium methotrexate prepared in Example 4 of this invention.

[0037] Figure 9 The biomimetic microneedles carrying dendritic cells prepared in Example 5 of this invention.

[0038] Figure 10 The biomimetic microneedles prepared in Example 6 of this invention. Detailed Implementation

[0039] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention based on the content of this description. The present invention can also be implemented or applied through other specific embodiments, and various modifications and changes can be made according to different applications.

[0040] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below. The terminology used in the embodiments of the present invention is for describing specific embodiments and is not intended to limit the scope of protection of the present invention.

[0041] This invention does not limit the source of the raw materials used. Unless otherwise specified, the raw materials used in this invention are all commercially available products in this technical field.

[0042] The biomimetic microneedles disclosed in this invention have an outer shell made of a high-mechanical-strength composite membrane structure formed by proteins and high-molecular-weight polysaccharides, with a hollow cavity that can be used to load functional active substances. Therefore, this type of biomimetic microneedle can effectively improve both the mechanical strength and loading capacity of the microneedle simultaneously. This invention achieves its solution through inventive work in improving the preparation materials and active substance loading methods of polymer microneedles.

[0043] Example 1

[0044] Silk fibroin was dissolved in water to prepare an 8% (m / v) silk fibroin solution. 10 μl of the above silk fibroin solution was then pressed into a microneedle mold using pressurized gas.

[0045] The microneedle mold was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours. Then, 20 μl of methanol was added to the microneedle mold, and the methanol was forced into the mold using pressurized gas and left for 30 minutes.

[0046] Use water to clean the methanol out of the mold.

[0047] Chitosan was dissolved in a 2% (v / v) aqueous acetic acid solution to prepare a 4% (m / v) chitosan solution. 10 μl of the chitosan solution was pressed into a microneedle mold using pressurized gas and then placed in a drying autoclave containing anhydrous silica gel to dry at room temperature for 2 h.

[0048] Add 10 μl of 500 mg / ml hyaluronic acid solution to the microneedle mold, dry to obtain the base, and then finally peel off the double-layer membrane biomimetic microneedle.

[0049] The prepared biomimetic microneedles without loaded functional active substances are shown Figure 1 A distinct hollow structure of the microneedles can be observed. The mechanical strength data of the prepared biomimetic microneedles are shown in Table 1, with a bursting pressure of 116.67±3.36 MPa and a Young's modulus of 1.10±0.05 GPa. Scanning electron micrographs of the cross-section of a single microneedle tip are shown in [Table 1]. Figure 2 The hollow structure of the microneedles and the silk fibroin-chitosan bilayer membrane structure are clearly visible; the effect of microneedle skin puncture is shown in [the image / description]. Figure 3 It is evident that the prepared microneedles can effectively puncture the skin, with a skin puncture efficiency exceeding 95%.

[0050] Table 1: Mechanical strength of unloaded bilayer membrane microneedles

[0051]

[0052] Example 2

[0053] Silk fibroin was dissolved in water to prepare an 8% (m / v) silk fibroin solution. 10 μl of the above silk fibroin solution was then pressed into a microneedle mold using pressurized gas.

[0054] The microneedle mold was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours. Then, 20 μl of methanol was added to the microneedle mold, and the methanol was forced into the mold using pressurized gas and left for 30 minutes.

[0055] Use water to clean the methanol out of the mold.

[0056] Chitosan was dissolved in a 2% (v / v) aqueous acetic acid solution to prepare a 4% (m / v) chitosan solution. 10 μl of the chitosan solution was pressed into a microneedle mold using pressurized gas and then placed in a glass desiccator containing anhydrous silica gel to dry at room temperature for 2 h.

[0057] Add rapamycin powder to the top of the mold and centrifuge to allow the drug to enter the hollow cavity of the microneedle.

[0058] The process of adding drug powder described above can be repeated multiple times until the drug fills the microneedle mold.

[0059] Add 10 μl of 500 mg / ml hyaluronic acid solution to the microneedle mold, dry to obtain the base, and then finally peel off to obtain the drug-loaded biomimetic microneedles.

[0060] The prepared microneedles are shown Figure 4 Rapamycin was clearly observed to be loaded into the hollow cavity of the composite membrane microneedles; the drug loading of the prepared microneedles was 167.0±11.2 μg (see...). Figure 5 Microneedle skin puncture effects are shown in [the image / document]. Figure 6 It is evident that the prepared microneedles can effectively puncture the skin, with a skin puncture efficiency exceeding 95%.

[0061] Example 3

[0062] Silk fibroin was dissolved in water to prepare an 8% (m / v) silk fibroin solution. 10 μl of the above silk fibroin solution was then pressed into a microneedle mold using pressurized gas.

[0063] The microneedle mold was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours. Then, 20 μl of methanol was added to the microneedle mold, and the methanol was forced into the mold using pressurized gas and left for 30 minutes.

[0064] Use water to clean the methanol out of the mold.

[0065] Chitosan was dissolved in water to prepare a 4% (m / v) chitosan aqueous solution. 10 μl of the chitosan solution was pressed into a microneedle mold using pressurized gas and then placed in a glass desiccator containing anhydrous silica gel to dry at room temperature for 2 hours.

[0066] Add 10 μl of 30 mg / ml ovalbumin (OVA) aqueous solution to the mold cavity, centrifuge to allow the solution to enter the hollow cavity of the microneedle, and dry at room temperature for 2 h.

[0067] The process of adding the protein solution described above can be repeated multiple times until the protein fills the microneedle mold.

[0068] Add 10 μl of 500 mg / ml hyaluronic acid solution to the microneedle mold, dry to obtain the base, and then finally peel off the protein-carrying biomimetic microneedles.

[0069] The prepared microneedles are shown Figure 7 .

[0070] Example 4

[0071] Silk fibroin was dissolved in water to prepare an 8% (m / v) silk fibroin solution. 10 μl of the silk fibroin solution was then injected into a microneedle mold using pressurized gas.

[0072] The microneedle mold containing the silk fibroin solution was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours. Then, 20 μl of methanol was added, and the methanol was forced into the microneedle mold using pressurized gas and left for 30 minutes.

[0073] Use water to clean the methanol out of the microneedle mold.

[0074] Chitosan was dissolved in a 2% (v / v) aqueous acetic acid solution to prepare a 4% (m / v) chitosan aqueous solution. 10 μl of the chitosan solution was pressed into a microneedle mold using pressurized gas and then placed in a glass desiccator containing anhydrous silica gel to dry at room temperature for 2 h.

[0075] Add 10 μl of 50 mg / ml methotrexate disodium salt aqueous solution to the top of the mold, and centrifuge to allow the solution to enter the hollow cavity of the microneedle.

[0076] The process of adding the drug solution described above can be repeated multiple times until the drug fills the microneedle mold.

[0077] Add 10 μl of 500 mg / ml hyaluronic acid solution to the above microneedle mold, dry to obtain the base, and then finally peel off to obtain the biomimetic microneedles loaded with methotrexate disodium salt.

[0078] The prepared microneedles are shown Figure 8 It was clearly observed that methotrexate disodium salt was loaded into the microneedle body; the drug loading of the microneedle was 129.7±9.6μg.

[0079] Example 5

[0080] Silk fibroin was dissolved in water to prepare an 8% (m / v) silk fibroin solution. 10 μl of the silk fibroin solution was then injected into a microneedle mold using pressurized gas.

[0081] The microneedle mold containing the silk fibroin solution was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours. Then, 20 μl of methanol was added, and the methanol was forced into the microneedle mold using pressurized gas and left for 30 minutes.

[0082] Use water to clean the methanol out of the microneedle mold.

[0083] Chitosan was dissolved in a 2% (v / v) aqueous acetic acid solution to prepare a 4% (m / v) chitosan aqueous solution. 10 μl of the chitosan solution was pressed into a microneedle mold using pressurized gas and then placed in a glass desiccator containing anhydrous silica gel to dry at room temperature for 2 h.

[0084] Add 100 μl of green fluorescently labeled mouse bone marrow-derived dendritic cells (1 × 10⁻⁶) to the top of the mold. 8 (cells / ml), let stand for 1 hour to allow the cells to settle into the tip of the microneedle.

[0085] Remove excess liquid from the microneedle base.

[0086] Add 10 μl of 500 mg / ml hyaluronic acid solution to the microneedle mold, dry it to obtain the base, and then finally peel off the biomimetic microneedles carrying dendritic cells.

[0087] The prepared microneedles are shown Figure 9 It can be clearly observed that 293T cells are encapsulated within the microneedle body.

[0088] Example 6

[0089] Silk fibroin was dissolved in water to prepare an 8% (m / v) silk fibroin solution. 10 μl of the silk fibroin solution was then injected into a microneedle mold using pressurized gas.

[0090] The microneedle mold containing the silk fibroin solution was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours. Then, 20 μl of methanol was added, and the methanol was forced into the microneedle mold using pressurized gas and left for 30 minutes.

[0091] Use water to clean the methanol out of the microneedle mold.

[0092] Chitosan was dissolved in a 2% (v / v) aqueous acetic acid solution to prepare a 4% (m / v) chitosan aqueous solution. 10 μl of the chitosan solution was pressed into a microneedle mold using pressurized gas and then placed in a glass desiccator containing anhydrous silica gel to dry at room temperature for 2 h.

[0093] Following the above method, one layer each of silk fibroin membrane and chitosan membrane were prepared, ultimately resulting in a four-layer membrane structure.

[0094] Add 10 μl of 500 mg / ml hyaluronic acid solution to the above microneedle mold, dry to obtain the base, and then finally peel off the silk fibroin-chitosan four-layer membrane microneedles.

[0095] The prepared microneedles are shown Figure 10 The hollow structure of the microneedles is clearly visible. The mechanical strength data of the prepared four-layer membrane microneedles are shown in Table 2, with a burst pressure of 163.37 ± 3.47 MPa and a Young's modulus of 1.48 ± 0.05 GPa. Compared to the bilayer membrane microneedles prepared in Example 1, the mechanical strength of the four-layer membrane microneedles is further improved.

[0096] Table 2: Mechanical Strength of Silk Fibroin-Chitosan Four-Layer Membrane Microneedles

[0097]

[0098] Examples 7-14

[0099] The biomimetic microneedle patches provided in Examples 7-14 were prepared in the same way as in Example 1, except for the types of proteins and high molecular weight polysaccharides. Several microneedle patches as shown in Table 3 were prepared in Examples 7-14 respectively.

[0100] Table 3: Types, concentrations, and amounts of proteins and high-molecular-weight polysaccharides used in the biomimetic microneedles prepared in Examples 7-14

[0101]

[0102]

[0103] The mechanical strength of the biomimetic microneedles prepared in Examples 7-14 was measured, and the test results are shown in Table 4.

[0104] Table 4: Mechanical strength of the biomimetic microneedles prepared in Examples 7-14

[0105]

[0106] Experimental results show that biomimetic microneedles with high mechanical strength can be obtained using silk fibroin, collagen, gelatin, chitosan, N-trimethyl chitosan, and carboxymethyl chitosan.

[0107] Examples 15-19

[0108] The biomimetic microneedle patches provided in Examples 15-19 were prepared in the same way as in Example 1, except for the concentration of silk fibroin and chitosan solution. Several microneedle patches as shown in Table 5 were prepared in Examples 15-19 respectively.

[0109] Table 5: Concentrations of biomimetic microneedle silk fibroin and chitosan prepared in Examples 15-19

[0110]

[0111] The mechanical strength of the biomimetic microneedles prepared in Examples 15-19 was measured, and the test results are shown in Table 6.

[0112] Table 6: Mechanical strength of the biomimetic microneedles prepared in Examples 15-19

[0113]

[0114] Experimental results show that when using silk fibroin and chitosan to prepare biomimetic microneedles, the mechanical strength of the prepared biomimetic microneedles increases significantly with the increase of the concentration of silk fibroin and chitosan solution.

[0115] Comparison of microneedle mechanical strength and drug loading capacity:

[0116] Comparative Example 1

[0117] Hyaluronic acid was dissolved in water to prepare a hyaluronic acid solution with a concentration of 500 mg / ml.

[0118] 20 μl of the above hyaluronic acid solution was injected into the microneedle mold using pressurized gas.

[0119] The microneedle mold was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours.

[0120] Add 20 μl of hyaluronic acid solution as a base and dry at room temperature for 2 hours.

[0121] By peeling the microneedles out of the mold, blank hyaluronic acid microneedles can be obtained.

[0122] The bursting pressure of the prepared hyaluronic acid solid microneedles was 57.30±5.54 MPa, and the Young's modulus was 0.50±0.05 GPa, as shown in Table 7. By comparing the results of Examples 1, 6-19 and the present comparative example, it can be found that the mechanical strength of the biomimetic microneedles of the present invention is significantly higher than that of traditional hyaluronic acid solid microneedles.

[0123] Table 7: Mechanical strength of the prepared hyaluronic acid microneedles

[0124]

[0125] Comparative Example 2

[0126] Chitosan was dissolved in a 2% (v / v) aqueous acetic acid solution to prepare a 4% (m / v) chitosan solution.

[0127] 10 μl of the chitosan solution was pressurized into the microneedle mold using pressurized gas.

[0128] The microneedle mold was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours.

[0129] Add 10 μl of 500 mg / ml hyaluronic acid solution to the microneedle mold and dry at room temperature for 2 hours to obtain the base.

[0130] By peeling the microneedles from the mold, chitosan film microneedles can be obtained.

[0131] The rupture pressure of the prepared chitosan film microneedles was 32.64±2.40 MPa, and the Young's modulus was 0.26±0.03 GPa, as shown in Table 8.

[0132] Table 8: Mechanical strength of the prepared chitosan film microneedles

[0133]

[0134] Comparing the results of Example 1 with those of this comparative example, it can be found that the mechanical strength of the silk fibroin-chitosan biomimetic microneedles is significantly higher than that of the chitosan film microneedles after the addition of silk fibroin. Therefore, adding silk fibroin membrane to chitosan film microneedles to prepare composite membrane structures can significantly improve the mechanical strength of the microneedles.

[0135] Comparative Example 3

[0136] Dissolve silk fibroin in water to prepare an 8% (m / v) silk fibroin solution.

[0137] 10 μl of the silk fibroin solution was pressurized into the microneedle mold using pressurized gas.

[0138] The microneedle mold was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours.

[0139] Add 10 μl of 500 mg / ml hyaluronic acid solution to the microneedle mold and dry at room temperature for 2 hours to obtain the base.

[0140] By peeling the microneedles from the mold, silk fibroin film microneedles can be obtained.

[0141] The rupture pressure of the prepared silk fibroin film microneedles was 43.15 ± 3.71 MPa, and the Young's modulus was 0.34 ± 0.04 GPa (see Table 9). Comparing the results of Example 1 with this comparative example, it can be found that the mechanical strength of the silk fibroin-chitosan biomimetic microneedles is significantly higher than that of the silk fibroin film microneedles after the addition of chitosan. This shows that adding a chitosan membrane to silk fibroin film microneedles to prepare composite membrane structure microneedles can significantly improve the mechanical strength of the microneedles. In summary, proteins and high-molecular-weight polysaccharides have a synergistic effect, and their combination can significantly improve the mechanical strength of the microneedles.

[0142] Table 9: Mechanical strength of the prepared silk fibroin film microneedles

[0143]

[0144] Comparison of drug loading capacity on microneedles:

[0145] Comparative Example 4

[0146] Hyaluronic acid was dissolved in water to prepare a hyaluronic acid solution with a concentration of 500 mg / ml.

[0147] Rapamycin was added to the above solution and stirred thoroughly to prepare a hyaluronic acid suspension containing 50 mg / ml rapamycin.

[0148] 20 μl of the drug-loaded hyaluronic acid suspension was injected into the microneedle mold using pressurized gas.

[0149] The microneedle mold was placed in a glass desiccator containing anhydrous silica gel and dried at room temperature for 2 hours.

[0150] Add 20 μl of hyaluronic acid solution as a base and dry at room temperature for 2 hours.

[0151] By peeling the microneedles from the mold, hyaluronic acid microneedles loaded with rapamycin can be obtained.

[0152] The prepared microneedles had a drug loading capacity of 48.8 ± 7.4 μg. Comparing Example 2 with this comparative example, it is evident that the biomimetic microneedles of the same size as traditional polymer solid microneedles have a 3.4-fold increased drug loading capacity, significantly improving the drug loading capacity. The difference is shown in the comparison below. Figure 5 .

[0153] In summary, the biomimetic microneedles prepared by this invention can significantly improve both the mechanical strength and loading capacity of polymer microneedles. On one hand, the composite membrane shell of the microneedle has stronger mechanical strength than traditional solid polymer microneedles, effectively ensuring the skin puncture efficiency of the microneedle. On the other hand, the hollow cavity of the microneedle can be used to directly load functional active substances, significantly increasing the loading capacity of the microneedle; compared to traditional polymer microneedles, the biomimetic microneedles of this invention can increase the drug loading capacity of the microneedle by at least three times. Furthermore, the drug loading process of the biomimetic microneedles of this invention involves directly injecting active substance powder, concentrated solution, or suspension into the hollow cavity of the microneedle, requiring no drying or requiring only a short drying time. Therefore, this loading method has minimal impact on the function or structure of the active substance, the loading process is simple, the properties of the active substance are more diverse, and the application range is wider.

[0154] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A biomimetic microneedle, characterized in that, The outer shell of the microneedle contains protein and high molecular weight polysaccharide, and the interior is a hollow cavity structure for loading functional active substances; the protein is one or more of collagen, silk fibroin, and gelatin; the high molecular weight polysaccharide is one or more of chitosan, N-trimethyl chitosan, carboxymethyl chitosan, N-succinyl chitosan, and quaternary ammonium chitosan; the protein and high molecular weight polysaccharide form a composite membrane, the composite membrane is a multilayer membrane, and the preparation method of the composite membrane includes the following steps: (1) adding a protein solution to a microneedle mold and drying it to obtain a protein membrane; (2) adding methanol to the microneedle mold to treat the protein membrane, removing the residual methanol and drying it; (3) adding a high molecular weight polysaccharide solution to the microneedle mold and drying it to obtain a composite membrane microneedle structure formed by protein and high molecular weight polysaccharide; (4) repeating the above three steps until the required number of composite membrane layers is reached; the functional active substances include one or more of components with cosmetic effects, drugs or vaccines with therapeutic or preventive effects.

2. The biomimetic microneedle according to claim 1, characterized in that, The thickness of its outer shell is controlled by adjusting the number of layers in the composite membrane structure.

3. A method for preparing the biomimetic microneedles according to any one of claims 1-2, characterized in that, The preparation method of the bionic microneedles includes the following steps: (1) Add the protein solution into the microneedle mold and dry it to obtain a protein membrane; (2) Add methanol to the microneedle mold to treat the protein membrane, remove the residual methanol and then dry it; (3) Add the polymer polysaccharide solution into the microneedle mold and dry it to obtain the composite membrane microneedle structure formed by protein and polymer polysaccharide; (4) The first three steps above can be repeated until the required number of composite membrane layers is reached; (5) Add the functional active substance into the hollow cavity of the above composite membrane microneedles and dry it; (6) Finally, a polymer solution is added as a substrate for the microneedles, and the microneedles are peeled off after drying.

4. The method for preparing the biomimetic microneedles according to claim 3, characterized in that, The protein concentration in the protein solution is 0.5%-20% m / v, and the concentration of the high molecular weight polysaccharide in the high molecular weight polysaccharide solution is 0.5%-20% m / v.

5. The method for preparing biomimetic microneedles according to claim 3, characterized in that, The polymer used to prepare the microneedle substrate is at least one selected from PHBV, PHP, PHH, PHA-PEG, poly-4-hydroxy acid, poly-α-hydroxy acid, poly-β-hydroxy acid, poly-4-hydroxybutyrate, poly-4-hydroxyhexanoate, polyesteramide, polycaprolactone, polylactide, polyglycolic acid, PLGA, polydioxanone, polyorthoester, polyanhydride, glycolic acid-trimethylene carbonate copolymer, polyphosphate, polyphosphate urethane, polyamino acid, polycyanoacrylate, polytrimethylene carbonate, polyimino carbonate, polytyrosine carbonate, polycarbonate, polytyrosine aryl ester, polyalkylene oxalate, polyphosphocreatine, chitosan, dextran, cellulose, heparin, hyaluronic acid, alginate, inulin, starch, and glycogen.

6. The biomimetic microneedle according to any one of claims 1-2 or the biomimetic microneedle prepared by any one of claims 3-5, characterized in that... The prepared microneedles are loaded with small molecule, macromolecule, cellular and viral drugs, adjuvants and / or cosmetic components.

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