Preparation method of microneedle patch and high-penetration microneedle patch

Abstract

The application discloses a preparation method of a microneedle patch, which is carried out according to the following steps: step one, preparing a microneedle mold, the upper surface of the microneedle mold is provided with a groove, the groove bottom surface is provided with microneedle cavities which are distributed in an array, a nanocrystalline cellulose aqueous solution with a solute mass of m1 is added into the groove so as to flow into each microneedle cavity, and bubbles are removed and dried; step two, a microneedle matrix aqueous solution with a solute mass of m2 is added into the groove so as to flow into each microneedle cavity, and bubbles are removed, wherein m1:m2 = 1:800-1:100; step three, a base aqueous solution is added into the groove, bubbles are removed, and drying is carried out; and step four, the formed solid is peeled off from the microneedle mold. The application further discloses a high-penetration microneedle patch prepared by using the above method. The microneedle patch has the beneficial effects that the loading of CNC significantly improves the mechanical properties of the microneedle, the microneedle can successfully penetrate the epidermis of the skin and remain intact, the microneedle can be separated from the base part, the microneedle remains in the body, and transdermal drug release can be realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biomedical materials and devices, and particularly relates to a preparation method of a microneedle patch and a high-penetration microneedle patch. BACKGROUND

[0002] Skin is the largest organ of the human body, composed of multiple layers, including epidermis, dermis and subcutaneous tissue, accounting for about 15% of the total weight of the human body. The outermost layer of the epidermis, the stratum corneum, plays a role in the skin barrier, but also provides an obstacle for transdermal drug delivery. Transdermal drug delivery therapy has many advantages, such as avoiding liver first-pass metabolism, providing self-medication applicability, not interfering with the stomach and intestines, avoiding the inconvenience of intravenous drug administration, and avoiding various absorption conditions, such as the presence of enzymes, changes in pH, and gastric emptying time, and transdermal delivery can be easily terminated and removed when needed, thereby providing selective drug delivery to a specific site for the patient.

[0003] Compared with traditional hypodermic needle administration, MNs are very small in size, with a needle length usually below 1 mm, invisible to the naked eye, thus effectively avoiding needle phobia. Compared with ultrasound permeation or iontophoresis-based transdermal administration, which requires special electronic equipment, MNs are easy to apply without the prerequisite of complex equipment. Due to their micron-scale size, MNs can seamlessly penetrate the skin and can deliver a variety of therapeutic molecules, including therapeutic molecules with a very wide range of molecular weights, such as small molecules, biological macromolecules, and even nanoparticles. For example, Tham et al. (Tham HP, Xu KM, Lim WQ, Chen HZ, Zheng MJ, Thng TGS, et al. Microneedle-Assisted Topical Delivery of Photodynamically Active Mesoporous Formulation for Combination Therapy of Deep-Seated Melanoma. Acs Nano. 2018; 12: 11936-48.) and Ye et al. (Ye YQ, Wang JQ, Hu QY, Hochu GM, Xin HL, Wang C, et al. Synergistic Transcutaneous Immunotherapy Enhances Antitumor Immune Responses through Delivery of Checkpoint Inhibitors. Acs Nano. 2016; 10: 8956-63.) reported the treatment of melanoma with microneedle-loaded nanomedicines and vaccines. Compared with chemical agents (such as lipid nanoparticles) used to enhance transdermal drug delivery, MNs are much less expensive to manufacture and have high repeatability between batches. At the same time, the penetration depth of MNs only penetrates the epidermis without damaging neurons and capillaries in the dermis, thus minimizing the pain associated with transdermal administration and also not causing skin damage and bleeding, so the risk of infection at the application site is negligible.

[0004] It is generally believed that a single MN can penetrate the epidermis of the skin when the maximum pressure it can withstand exceeds 0.048 N. However, in actual application, it is of great significance to improve the compressive strength of the MN to ensure penetration and facilitate use. SUMMARY

[0005] Therefore, the present application provides a preparation method of a microneedle patch.

[0006] The technical scheme is as follows:

[0007] A preparation method of a microneedle patch, which is characterized by the following steps:

[0008] Step one, preparing a microneedle mold, the upper surface of which is provided with a groove, the groove bottom is provided with a microneedle cavity, and the microneedle cavities are arranged in an array;

[0009] A nanocrystalline cellulose aqueous solution with a solute mass of m1 is added to the groove so as to flow into each of the microneedle cavities, remove bubbles, and dry;

[0010] Step two, adding a microneedle matrix aqueous solution with a solute mass of m2 to the groove so as to flow into each of the microneedle cavities, remove bubbles, and suck the microneedle matrix aqueous solution that does not enter the microneedle cavities;

[0011] The microneedle matrix is made of a biodegradable material;

[0012] Wherein m1:m2 = 1:800-1:100;

[0013] Step three, adding a base aqueous solution to the groove, removing bubbles, and drying;

[0014] Step four, peeling the formed solid from the microneedle mold to obtain a microneedle patch.

[0015] As a preferred, the microneedle matrix aqueous solution is a 15-40% (w / v) hyaluronic acid solution.

[0016] As a preferred, the base aqueous solution is a 15-40% (w / v) polyvinyl alcohol solution.

[0017] As a preferred, the concentration of the nanocrystalline cellulose aqueous solution is 0.05-0.15% (w / v).

[0018] As a preferred, the concentration of the nanocrystalline cellulose aqueous solution is 0.1% (w / v).

[0019] As a preferred, the bubble removal is specifically performed in the following manner: the microneedle mold added with the aqueous solution is placed in a vacuum oven, and vacuumized to -25-30 MPa at room temperature to remove bubbles.

[0020] As a preferred, the vacuumization is to -28 MPa when removing bubbles.

[0021] As a preferred, the depth of the microneedle cavity is 300-1000 μm.

[0022] As a preferred, the step three is repeated for 3-5 times, and each time 1 / 5-1 / 3 of the total amount of the base aqueous solution is added to the groove and dried at room temperature.

[0023] The second object of the present application is to provide a high-penetration microneedle patch.

[0024] A high-penetration microneedle patch, the key of which lies in the preparation by any of the above methods. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A nanocrystalline cellulose particle size distribution chart;

[0026] Figure 2 A nanocrystalline cellulose infrared spectrum chart;

[0027] Figure 3 A microneedle actual photo loaded with 0.1% (w / v) CNC: (A) is an overall photo, and (B) is a microneedle local photo;

[0028] Figure 4 A compression resistance mechanical property of a microneedle loaded with different CNC contents;

[0029] Figure 5 A photo of a microneedle piercing a pig skin;

[0030] Figure 6 A microneedle dissolution and drug release photo, in which the light gray area is a detected drug distribution area;

[0031] Figure 7 A structural schematic diagram of a microneedle mold;

[0032] Figure 8 A Figure 7 A C-C cross-sectional view. DETAILED DESCRIPTION

[0033] The present application is further described below in conjunction with examples and drawings.

[0034] (I) Experimental material preparation

[0035] (1) Main reagent: The microneedle matrix adopts a biodegradable material, and in this embodiment, hyaluronic acid (HA, Huaxi Biological, molecular weight 45,000) is adopted, and other biodegradable materials such as gelatin can also be adopted;

[0036] Preparation of HA aqueous solution: Different mass of HA was weighed and dissolved in deionized water to prepare 15% (w / v) HA solution, 30% (w / v) HA solution, and 40% (w / v) HA solution, respectively;

[0037] In this embodiment, the substrate of the microneedle patch adopts polyvinyl alcohol (PVA, Aldrich, type 1799, CSC: 9002-89-5, solubility: 98-99% (mol / mol));

[0038] Preparation of PVA aqueous solution: Different mass of PVA was weighed and dissolved in deionized water to prepare 15% (w / v) PVA solution, 30% (w / v) PVA solution, and 40% (w / v) PVA solution, respectively.

[0039] (2) Preparation of nanocrystalline cellulose (CNC)

[0040] ① At room temperature, 45% concentrated sulfuric acid was prepared by mixing 98% concentrated sulfuric acid and deionized water;

[0041] ② 2 g of microcrystalline cellulose (CMC, Aldrich, CSC: 9004-34-6, ≤25 um) was accurately weighed and added to 18 mL of 45% concentrated sulfuric acid, and hydrolysis was carried out at 45°C water bath constant temperature, and magnetic stirring was carried out at 400-600 RPM for 6 hours;

[0042] ③ The reaction was terminated by using 200 mL of deionized water, and the obtained suspension was centrifuged at 3000 r / min, and during the centrifugation, deionized water was repeatedly used for washing 3 times;

[0043] ④ The suspension was dialyzed for 3 days using a dialysis bag with a molecular weight cut-off of 8000-14000, and the water was changed 3 times a day until the pH of the dialysate was close to neutral;

[0044] ⑤ The dialyzed solution was frozen at -20°C, and then freeze-dried at -80°C to obtain CNC powder.

[0045] (3) Characterization of nanocrystalline cellulose (CNC)

[0046] ① Laser nanoparticle size analyzer (DLS) characterization

[0047] The particle size of the prepared CNC was measured using a dynamic light scattering nanolaser particle size analyzer. The measurement results are shown in Figure 1 The average particle size of the prepared CNC is 2270.67 nm, and the PDI is 1, indicating that the particle size distribution of the prepared CNC is relatively uniform, and the size meets the expected demand.

[0048] ② Infrared absorption spectrum (FTIR) characterization

[0049] The sample to be tested (CMC, CNC) was prepared by potassium bromide tabletting method, and the infrared absorption spectrum was measured using a Fourier infrared spectrometer.

[0050] Figure 2 The FTIR spectra of CMC and CNC are shown in Table 1. -1 The main absorption peak of CNC is 3292 cm

[0051] (ii) preparing the microneedle patch

[0052] Example 1

[0053] A method for preparing a microneedle patch, comprising the following steps:

[0054] Step 1, preparing a polydimethylsiloxane (PDMS) microneedle mold, as shown in FIGS. 1 and 2, the upper surface of the microneedle mold is provided with a groove 1, the groove 1 is provided with a microneedle cavity 2 at the bottom surface, the microneedle cavities 2 are arranged in a 15x15 array, the depth of the microneedle cavities 2 is 300 μm, the opening of the microneedle cavities 2 is a square, the opening width is 200 μm, and the spacing of the microneedle cavities 2 is 500 μm. Figure 7 8 At room temperature, nanocrystalline cellulose (CNC) is dissolved in deionized water to prepare a 0.1% (w / v) aqueous solution; 120 μL of the above CNC solution is taken into the groove 1 by a pipette, so that it flows into the microneedle cavities 2, and then it is placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-25 MPa, and the vacuum is repeatedly applied until no bubbles are generated; then it is dried at room temperature for 2 h; the residual CNC in the groove 1 is cleaned with deionized water by a pipette.

[0055] At room temperature, nanocrystalline cellulose (CNC) is dissolved in deionized water to prepare a 0.1% (w / v) aqueous solution; 120 μL of the above CNC solution is taken into the groove 1 by a pipette, so that it flows into the microneedle cavities 2, and then it is placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-25 MPa, and the vacuum is repeatedly applied until no bubbles are generated; then it is dried at room temperature for 2 h; the residual CNC in the groove 1 is cleaned with deionized water by a pipette.

[0056] Step 2, 120 μL of 15% (w / v) HA aqueous solution is taken into the groove 1 by a pipette, and then it is placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-25 MPa, and the vacuum is repeatedly applied until no bubbles are generated.

[0057] The HA solution in the microneedle mold that does not enter the microneedle cavities 2 is removed by a pipette.

[0058] Step 3, 170 μL of 15% (w / v) PVA aqueous solution is taken into the groove 1 by a pipette, and then it is placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-25 MPa, and the vacuum is repeatedly applied until no bubbles are generated.

[0059] The above PDMS mold is placed in a room temperature environment for 4 d, and 5 times of PVA aqueous solution is added, each time 170 μL.

[0060] Step 4, drying, the formed solid is peeled off from the microneedle mold to obtain a microneedle patch. The microneedle cavities 2 form microneedles of the microneedle patch, and the groove 1 forms a substrate of the microneedle patch.

[0061] In this example, the mass ratio of the raw nanocrystalline cellulose to HA is 1:150.

[0062] ​In step one and step two, vacuuming helps the nanocrystalline cellulose aqueous solution or the HA aqueous solution to enter the microneedle cavities 2. According to this preparation method, after the nanocrystalline cellulose aqueous solution is dried, the nanocrystalline cellulose is concentrated in the microneedles of the microneedle patch, especially in the tip part of the microneedles, so as to improve the puncture performance.

[0063] In step three, the reason for repeatedly adding the PVA aqueous solution is that, due to the volume reduction of PVA during the drying process, the repeated addition of the PVA aqueous solution can ensure the forming integrity of the final substrate and has a certain thickness and strength.

[0064] Example 2

[0065] A microneedle patch preparation method comprises the following steps:

[0066] Step one, prepare a polydimethylsiloxane (PDMS) microneedle mold, the upper surface of the microneedle mold is provided with a groove 1, the groove bottom surface of the groove 1 is provided with a microneedle cavity 2, the microneedle cavities 2 are arranged in a 15x15 array, the depth of the microneedle cavities 2 is 600 μm, the opening of the microneedle cavities 2 is a square, the opening width is 200 μm, and the spacing of the microneedle cavities 2 is 500 μm;

[0067] At room temperature, nanocrystalline cellulose (CNC) is dissolved in deionized water to prepare a 0.1% (w / v) aqueous solution; 150 μL of the above CNC solution is sucked into the groove 1 by using a pipette gun, so that it flows into the microneedle cavities 2, and then it is placed in a vacuum oven to remove bubbles at a vacuum of-28 MPa at room temperature, and the vacuuming is repeated until no bubbles are generated; then it is dried at room temperature for 2 h; and deionized water is used to clean the residual CNC in the groove 1 by using a pipette gun;

[0068] Step two, 150 μL of 30% (w / v) HA aqueous solution is sucked into the groove 1 by using a pipette gun, and then it is placed in a vacuum oven to remove bubbles at a vacuum of-28 MPa at room temperature, and the vacuuming is repeated until no bubbles are generated;

[0069] The HA solution that does not enter the microneedle cavities 2 in the microneedle mold is sucked away by using a pipette gun;

[0070] Step three, 200 μL of PVA aqueous solution is added to the groove 1 by using a pipette gun, and then it is placed in a vacuum oven to remove bubbles at a vacuum of-28 MPa at room temperature, and the vacuuming is repeated until no bubbles are generated;

[0071] The above PDMS mold is placed in a room temperature environment for 4 d, and PVA aqueous solution needs to be supplemented 4 times, 200 μL each time;

[0072] Step four, drying, the formed solid is peeled off from the microneedle mold to obtain a microneedle patch.

[0073] In this embodiment, the mass ratio of raw material nanocrystalline cellulose to HA is 1:300.

[0074] Example 3

[0075] A method for preparing a microneedle patch, comprising the following steps:

[0076] Step one, prepare a polydimethylsiloxane (PDMS) microneedle mold, the upper surface of the microneedle mold is provided with a groove 1, the groove bottom surface is provided with a microneedle cavity 2, the microneedle cavity 2 is arranged in a 15x15 array, the depth of the microneedle cavity 2 is 600μm, the opening of the microneedle cavity 2 is a square, the opening width is 200μm, and the spacing of the microneedle cavity 2 is 500μm;

[0077] At room temperature, nanocrystalline cellulose (CNC) is dissolved in deionized water to prepare a 0.05% (w / v) aqueous solution; 150μL of the above CNC solution is taken into the groove 1 with a pipette, so that it flows into the microneedle cavity 2, and then it is placed in a vacuum oven to remove bubbles at room temperature to-28MPa, and the vacuum is repeated until no bubbles are generated; then it is dried at room temperature for 2h; deionized water is used to clean the residual CNC in the groove 1 with a pipette;

[0078] Step two, 150μL of 30% (w / v) HA aqueous solution is taken into the groove 1 with a pipette, and then it is placed in a vacuum oven to remove bubbles at room temperature to-28MPa, and the vacuum is repeated until no bubbles are generated;

[0079] The HA solution that does not enter the microneedle cavity 2 in the microneedle mold is sucked away with a pipette;

[0080] Step three, 200μL of 30% (w / v) PVA aqueous solution is added to the groove 1 with a pipette, and then it is placed in a vacuum oven to remove bubbles at room temperature to-28MPa, and the vacuum is repeated until no bubbles are generated;

[0081] The above PDMS mold is placed in a room temperature environment for 4d, and PVA aqueous solution needs to be added 4 times during this period, each time 200μL;

[0082] Step four, drying, the formed solid is peeled off from the microneedle mold to obtain a microneedle patch.

[0083] In this embodiment, the mass ratio of raw material nanocrystalline cellulose to HA is 1:600.

[0084] Example 4

[0085] A method for preparing a microneedle patch, comprising the following steps:

[0086] Step one, prepare a polydimethylsiloxane (PDMS) microneedle mold, the upper surface of the microneedle mold is provided with a groove 1, the bottom surface of the groove 1 is provided with a microneedle cavity 2, the microneedle cavity 2 is arranged in a 15x15 array, the depth of the microneedle cavity 2 is 600μm, the opening of the microneedle cavity 2 is a square, the opening width of the microneedle cavity 2 is 200μm, and the spacing of the microneedle cavity 2 is 500μm;

[0087] At room temperature, nanocrystalline cellulose (CNC) is dissolved in deionized water to prepare a 0.15% (w / v) aqueous solution; 150μL of the above CNC solution is sucked into the groove 1 by a pipette, so that it flows into the microneedle cavity 2, and then it is placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-28MPa, and the vacuum is repeatedly applied until no bubbles are generated; then it is dried at room temperature for 2h; deionized water is used to clean the residual CNC in the groove 1 by a pipette;

[0088] Step two, 150μL of 30% (w / v) HA aqueous solution is sucked into the groove 1 by a pipette, and then it is placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-28MPa, and the vacuum is repeatedly applied until no bubbles are generated;

[0089] The HA solution that does not enter the microneedle cavity 2 in the microneedle mold is sucked away by a pipette;

[0090] Step three, 200μL of 30% (w / v) PVA aqueous solution is added to the groove 1 by a pipette, and then it is placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-28MPa, and the vacuum is repeatedly applied until no bubbles are generated;

[0091] The above PDMS mold is placed in a room temperature environment for 4d, and PVA aqueous solution needs to be added 4 times during this period, each time 200μL;

[0092] Step four, drying, the formed solid is peeled off from the microneedle mold to obtain a microneedle patch.

[0093] In this embodiment, the mass ratio of the raw nanocrystalline cellulose to HA is 1:200.

[0094] Example 5

[0095] A microneedle patch preparation method, comprising the following steps:

[0096] Step one, prepare a polydimethylsiloxane (PDMS) microneedle mold, the upper surface of the microneedle mold is provided with a groove 1, the bottom surface of the groove 1 is provided with a microneedle cavity 2, the microneedle cavity 2 is arranged in a 15x15 array, the depth of the microneedle cavity 2 is 1000μm, the opening of the microneedle cavity 2 is a square, the opening width of the microneedle cavity 2 is 200μm, and the spacing of the microneedle cavity 2 is 500μm;

[0097] At room temperature, nanocrystalline cellulose (CNC) was dissolved in deionized water to prepare a 0.1% (w / v) aqueous solution; 170 μL of the above CNC solution was taken by a pipette and flowed into the microneedle cavity 2 in the groove 1, and then placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-30 MPa, and the vacuum was repeatedly applied until no bubbles were generated; then dried at room temperature for 2 h; the residual CNC in the groove 1 was washed with deionized water by a pipette;

[0098] Step two, 170 μL of 40% (w / v) HA aqueous solution was taken by a pipette and added to the groove 1, and then placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-30 MPa, and the vacuum was repeatedly applied until no bubbles were generated;

[0099] The HA solution not entering the microneedle cavity 2 in the microneedle mold was removed by a pipette;

[0100] Step three, 220 μL of 40% (w / v) PVA aqueous solution was taken by a pipette and added to the groove 1, and then placed in a vacuum oven to remove bubbles at room temperature under a vacuum of-30 MPa, and the vacuum was repeatedly applied until no bubbles were generated;

[0101] The above PDMS mold was placed in a room temperature environment for 3 d, and 220 μL of PVA aqueous solution was added 3 times during the period;

[0102] Step four, drying, the formed solid was peeled off from the microneedle mold to obtain a microneedle patch.

[0103] In this embodiment, the mass ratio of the raw nanocrystalline cellulose to HA was 1:400.

[0104] Comparative Example 1

[0105] The microneedle patch preparation method of Reference Example 2 was referred to, except that no CNC aqueous solution was added in step one, and step two was directly performed. A microneedle patch without CNC was prepared.

[0106] It was found in actual observation that for the HA aqueous solution and the PVA aqueous solution, a solution with a concentration of 15% (w / v) was too dilute, and the drying process was more likely to solidify, and the formability was poor, and the final microneedle was too thin and soft, and the mechanical property was insufficient. A solution with a concentration of 40% (w / v) was too thick, and the liquid was viscous, and the solution was not easy to enter the mold pores during the vacuum process, which also led to poor formability. Therefore, the preferred concentration of the HA aqueous solution and the PVA aqueous solution was both 30% (w / v).

[0107] (Three) Characterization of the Microneedle Patch

[0108] (1) Appearance of the Microneedle

[0109] The microneedle patch prepared in Example 2 was observed under an optical microscope, and a real picture of the microneedle is shown in Figure 3 It can be seen that the microneedles are arranged in an array on the substrate. The single microneedle is in the shape of a quadrangular prism with regular morphology.

[0110] (2) Compression modulus test of microneedle

[0111] The microneedle patches prepared in Example 2, Example 3, Example 4 and Comparative Example 1 were respectively taken, and the compression modulus of the samples was tested by using an electronic universal testing machine. According to the parameters given by the polydimethylsiloxane (PDMS) mold, the test was carried out at a compression rate of 1 mm / min within a displacement range of 0.6 μm.

[0112] According to the test results, the compression modulus of the entire microneedle patch was converted into the compression modulus of a single needle.

[0113] The compression modulus of the microneedle is shown in Figure 4 Compared with the microneedle patch prepared in Comparative Example 1, the compression modulus of the microneedle loaded with CNC is improved.

[0114] Comparing microneedles with different CNC loading amounts, the microneedle loaded with 0.1% CNC is pressed to the position of half of the needle tip, and the single needle can bear a maximum pressure of 0.24 N, which is better than the microneedles loaded with 0.05% CNC and 0.15% CNC.

[0115] Existing studies have shown that a single microneedle can penetrate the epidermis layer of the skin when the maximum pressure it can bear exceeds 0.048 N. However, increasing the compression modulus of the microneedle can ensure that the microneedle penetrates the epidermis layer. Since the microneedle loaded with 0.1% CNC has a much higher pressure than that required to penetrate the epidermis layer of the skin, it has more advantages in clinical use.

[0116] (3) Skin penetration test of microneedle

[0117] The microneedle patch prepared in Example 2 was taken, and was forced (about 20 N) into the skin of a pig to observe the penetration. Figure 5 The penetration result of the microneedle is shown, which indicates that the microneedle can penetrate the epidermis layer of the skin.

[0118] (4) Degradation and drug release of microneedle

[0119] Hyaluronic acid (HA) is a glycosaminoglycan (GAG) with repeating disaccharide units (a-1,4-D-glucuronic acid and β-1,3-N-acetyl-D-glucosamine). Because HA exhibits excellent biocompatibility and biodegradability, HA and its derivatives have been widely used as tissue engineering temporal scaffolds and drug delivery devices for therapeutic agents. The present application selects HA as the microneedle matrix material, that is, it takes advantage of its excellent biomedical properties. If necessary, the drug can be dispersed in the HA aqueous solution in advance, and the HA aqueous solution containing the drug is added to the groove 1 in step two of preparing the microneedle, thereby obtaining a drug-loaded microneedle patch. According to the properties of the drug, drying can be selected in step three in a dark environment at room temperature.

[0120] The microneedle was prepared according to the method of Example 2, and the desalted hydrophobic doxorubicin hydrochloride (Dox) was loaded as a drug into the microneedle patch for drug release experiments.

[0121] The microneedle patch prepared in Example 2 was used to observe the changes in the microneedle after being inserted into the pig skin. As shown in Figure 6 (A), after the microneedle was inserted into the skin for 1 min, the structure gradually became incomplete, and after 5 min, no complete microneedle structure was observed, and after 30 min, no microneedle structure was observed.

[0122] The dissolution experiment of the microneedle also confirmed the above changes. The microneedle was immersed in PBS buffer and observed under a microscope. As shown in Figure 6 (B), after 10 s of immersion, the microneedle structure began to collapse, the tip part began to erode, the microneedle gradually dissolved, and by 5 min, only a small amount of the microneedle base was visible.

[0123] The drug-loaded microneedle was inserted into the pig skin, and under the laser confocal microscope, the drug distribution was observed by layer-by-layer scanning, wherein the excitation light wavelength was 475-485 nm and the emission light wavelength was 575-585 nm. Figure 6 The distribution of the drug in the skin was shown, and it could be seen that the drug content gradually increased within a depth of 0-40 μm; within a depth of 40-120 μm, the drug concentration was relatively high; below 120 μm, the drug distribution gradually decreased, and at 200 μm, almost no drug was observed. The drug delivery depth of the soluble microneedle is usually 150-400 μm, which proves that the prepared microneedle patch meets the requirements of microneedle drug delivery.

[0124] The present application prepared nanocrystalline cellulose (CNC) by acid hydrolysis of microcrystalline cellulose (CMC), and this material loaded in the HA+PVA microneedle improved the mechanical properties of the microneedle, especially using 0.1% (w / v) CNC to prepare the microneedle, which made the prepared microneedle have good mechanical properties and drug release performance.

[0125] The present application has the following beneficial effects:

[0126] (1) The mechanical property of the prepared CNC-loaded HA+PVA microneedle is significantly higher than that of the microneedle without CNC, which can successfully penetrate the epidermis of the skin and keep the microneedle intact;

[0127] (2) The microneedle is separable from the base part, the microneedle is left in the body, and the transdermal drug release can be realized;

[0128] (3) No pain and bleeding are caused, and the risk of infection is extremely low and almost negligible.

[0129] Finally, it should be noted that the above description is only for the preferred embodiments of the present application, and those of ordinary skill in the art can make various similar expressions under the inspiration of the present application without departing from the purpose and claims of the present application. Such changes fall within the scope of the present application.

Claims

1. A microneedle patch preparation method characterized by The following steps are taken: Step one, preparing a microneedle mold, the upper surface of which is provided with a groove (1), the groove (1) is provided with a microneedle cavity (2) at the bottom surface, and the microneedle cavities (2) are arranged in an array; A nanocrystalline cellulose aqueous solution with a solute mass of m1 is added to the groove (1) to flow into each of the microneedle cavities (2), remove bubbles, and dry; Step two, adding a microneedle matrix aqueous solution with a solute mass of m2 to the groove (1) to flow into each of the microneedle cavities (2), remove bubbles, and absorb the microneedle matrix aqueous solution that does not enter the microneedle cavities (2); The microneedle matrix is made of biodegradable material; Wherein m1:m2 = 1:800-1:100; Step three, adding a base aqueous solution to the groove (1), removing bubbles, and drying; Step four, peeling the formed solid from the microneedle mold to obtain a microneedle patch; The nanocrystalline cellulose is concentrated at the microneedle tip of the microneedle patch; The concentration of the nanocrystalline cellulose aqueous solution is 0.1% (w / v); The microneedle matrix aqueous solution is a 15-40% (w / v) hyaluronic acid solution, and the base aqueous solution is a 15-40% (w / v) polyvinyl alcohol solution.

2. The method of claim 1, wherein: The bubbles are removed by placing the microneedle mold with the added aqueous solution in a vacuum oven, and vacuumizing to -25 to -30 MPa at room temperature to remove the bubbles.

3. The method of claim 2, wherein the microneedle patch is prepared by: When removing bubbles, vacuumize to -28 MPa.

4. The method of claim 1, wherein: The depth of the microneedle cavities (2) is 300-1000 μm.

5. The method of claim 1, wherein: The step three is repeated 3-5 times, and each time 1 / 5-1 / 3 of the total amount of the base aqueous solution is added to the groove (1) and dried at room temperature.

6. A high penetration microneedle patch characterized by The method is prepared by any one of claims 1-5. The method is prepared by any one of claims 1-5.

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