Hemostatic hydrogel microneedle as well as preparation method and application thereof

Abstract

The invention provides a hemostatic hydrogel microneedle. The diameter of the microneedle bottom surface of the hemostatic hydrogel microneedle is 50-800 [mu] m; the distance between every two adjacent microneedles ranges from 500 micrometers to 1500 micrometers. The height of the microneedle is 50 to 1000 [mu] m; the preparation method comprises the following steps: fully dissolving chitosan in a glacial acetic acid aqueous solution to obtain a chitosan solution; preparing a polyvinyl alcohol aqueous solution and a polyvinylpyrrolidone aqueous solution, and mixing to form a mixed solution; mixing the chitosan solution and the mixed solution to obtain a hydrogel prepolymerization solution; and repeatedly vacuumizing and injecting the hydrogel pre-polymerized liquid into a microneedle mold, standing to form gel, drying and demolding to obtain the hemostatic hydrogel microneedle. Chitosan macromolecules are used as a basis, the chitosan macromolecules are mixed with polyvinyl alcohol and polyvinylpyrrolidone, then the mixture is injected into a microneedle mold and cross-linked, the obtained microneedle hydrogel has good transdermal and swelling effects, and when a microneedle pierces subcutanea or absorbs chronic wound exudate, the microneedle hydrogel has an excellent hemostatic effect.

Description

Technical Field

[0001] The present invention relates to the technical field of biomedicine, and in particular to a hemostatic hydrogel microneedle and a preparation method and application thereof. Background Art

[0002] In emergency medical care and surgical procedures, rapid, effective, and safe hemostasis is crucial for saving lives and reducing complications. While traditional hemostatic methods, such as gauze, tourniquets, and physical pressure, can meet basic hemostasis needs to a certain extent, they each have significant limitations.

[0003] Hemostatic gauze, a commonly used physical hemostatic material, is often limited in its effectiveness by the amount and rate of bleeding. For wounds with heavy, rapid bleeding, hemostatic gauze struggles to quickly form an effective coagulation barrier and easily adheres to wound tissue after use. Changing the gauze not only increases the patient's pain but can also cause secondary damage, hindering wound healing.

[0004] Tourniquets are particularly suitable for temporary control of bleeding in the extremities, achieving hemostasis by compressing the arteries. However, prolonged use of tourniquets can lead to serious consequences such as limb ischemia, nerve damage, and even muscle necrosis. Therefore, their application is strictly limited and they are not suitable for controlling bleeding in the trunk or other non-extremity areas.

[0005] Although physical compression hemostasis is simple to operate and effective in stopping bleeding from superficial small wounds, its hemostasis efficiency is extremely low for deep trauma or arterial bleeding. It requires continuous human pressure, which is often difficult to achieve in emergency rescue environments, thus delaying the best time for treatment.

[0006] Although local hemostatic drugs can act directly on the wound surface, they are easily washed away by bleeding or exudate and are quickly lost, making it difficult to maintain sufficient drug concentration, especially difficult to penetrate deep tissues to exert their effects, thus limiting their hemostatic efficacy.

[0007] In view of the above-mentioned deficiencies in existing hemostatic technologies, it is particularly important to develop a new type of hemostatic material that can not only stop bleeding quickly but also avoid tissue damage, while ensuring the precise delivery of drugs to deep wounds. Hemostatic hydrogel microneedles are an innovative solution born out of this urgent need. This material combines the good biocompatibility and water absorption and retention properties of hydrogels with the painless penetration ability of microneedle technology, achieving multiple advantages of rapid coagulation, avoiding adhesion, wide applicability and deep drug delivery, providing a more efficient, safe and convenient new approach for clinical hemostasis. Therefore, the present invention aims to provide a specific method for preparing hemostatic hydrogel microneedles and their application, in order to overcome the defects of the existing technology and meet the urgent demand for efficient hemostatic materials in medical practice. Summary of the Invention

[0008] The purpose of the present invention is to provide a hemostatic hydrogel microneedle and its preparation method and application. The prepared hydrogel microneedle has good transdermal and swelling effects. When the microneedle penetrates the subcutaneous tissue or absorbs the exudate of chronic wounds, it has an excellent hemostatic effect.

[0009] In one aspect, the present invention provides a hemostatic hydrogel microneedle, wherein the bottom diameter of the hemostatic hydrogel microneedle is 50-800 μm; the spacing between the microneedles is 500-1500 μm; and the height of the microneedle is 50-1000 μm.

[0010] Furthermore, the bottom diameter of the hemostatic hydrogel microneedles is 390-410 μm; the spacing between the microneedles is 990-1010 μm; and the height of the microneedles is 490-510 μm.

[0011] Furthermore, the end of the microneedle close to the base layer is a truncated cone base, the end of the microneedle away from the base layer is a conical tip, and the cylindrical needle body is between the truncated cone base and the conical tip.

[0012] Furthermore, the raw materials for preparing the hemostatic hydrogel microneedle include chitosan, polyvinyl alcohol, and polyvinyl pyrrolidone in a weight ratio of (1-8): (1-8): (1-10).

[0013] On the other hand, the present invention provides a method for preparing hemostatic hydrogel microneedles, comprising the following steps: (1) fully dissolving chitosan in a glacial acetic acid aqueous solution to obtain a chitosan solution; (2) preparing a polyvinyl alcohol aqueous solution and a polyvinyl pyrrolidone aqueous solution and mixing them to form a mixed solution; (3) further mixing the chitosan solution and the mixed solution to obtain a hydrogel prepolymer solution; and (4) injecting the hydrogel prepolymer solution into a microneedle mold by repeated vacuuming, allowing it to stand to form a gel, and then drying and demolding to obtain the hemostatic hydrogel microneedle.

[0014] Furthermore, the volume ratio of glacial acetic acid to water in the glacial acetic acid aqueous solution is (1-5):100; the amount ratio of chitosan to glacial acetic acid aqueous solution in the chitosan solution is 1-10 g / 100 mL.

[0015] Furthermore, the ratio of polyvinyl alcohol to water in the polyvinyl alcohol aqueous solution is 1-10 g / 100 mL; the ratio of polyvinyl pyrrolidone to water in the polyvinyl pyrrolidone aqueous solution is 5-50 g / 100 mL.

[0016] Furthermore, the volume ratio of the polyvinyl alcohol aqueous solution to the polyvinyl pyrrolidone aqueous solution in the mixed solution is 1-10:1-10;

[0017] Furthermore, the volume ratio of the chitosan solution to the mixed solution is 1-10:1-10.

[0018] Furthermore, the standing time is 10-14 hours, the drying temperature is 25-40° C., and the drying time is 40-50 hours.

[0019] On the other hand, the hemostatic hydrogel microneedle or the hemostatic hydrogel microneedle prepared by the preparation method of the hemostatic hydrogel microneedle is used in hemostatic products.

[0020] The beneficial effects of the present invention are:

[0021] The present invention is based on chitosan polymer, which is mixed with polyvinyl alcohol and polyvinyl pyrrolidone, injected into a microneedle mold and cross-linked. The obtained microneedle hydrogel has good transdermal and swelling effects. When the microneedle penetrates the subcutaneous tissue or absorbs into the exudate of chronic wounds, the hydrogel microneedle swells rapidly. On the one hand, the hydrogel microneedle punctures the skin, activates coagulation factors, promotes platelet activation, enhances platelet aggregation and contraction, and thus quickly forms a coagulation barrier. On the other hand, the hydrogel microneedle swells rapidly, exerts its cationic properties, and combines with the negatively charged red blood cell membrane surface through positive charge, promoting red blood cell aggregation, thereby forming a blood clot. The blood clot is formed under the dual mechanism to achieve a hemostatic effect.

[0022] The microneedle transdermal dressing prepared by the present invention has significant advantages. In terms of size design, the coordination of bottom diameter, spacing and height ensures strength, reduces trauma, exerts functionality and is conducive to drug delivery. The raw material selection is based on chitosan, combined with polyvinyl alcohol and polyvinyl pyrrolidone. Chitosan has biocompatibility, low immunogenicity and hemostatic properties, polyvinyl alcohol enhances mechanical strength, and polyvinyl pyrrolidone regulates swelling and drug release rate. The three synergistically improve performance. The present invention also determines the mass ratio of chitosan, polyvinyl alcohol and polyvinyl pyrrolidone so that the prepared microneedle hydrogel has excellent hemostatic, mechanical, swelling and drug release properties. The preparation method of mixing raw materials, injecting them into microneedle molds and cross-linking is simple to operate, highly controllable, and conducive to industrial production. In terms of the hemostatic principle, the microneedles swell when exposed to exudate, and the positive charge of chitosan combines with the negatively charged substances of red blood cells to promote aggregation to form blood clots, providing a new solution for clinical wound management and has broad prospects in the fields of postoperative surgery and chronic wound treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a characterization diagram of the hydrogel morphology; Figure 1 (A) is a demonstration of gelation; Figure 1 (B) is the SEM image of the hydrogel;

[0024] Figure 2 is a schematic diagram of the preparation of hydrogel microneedles;

[0025] Figure 3 is a schematic diagram of the hydrogel; Figure 3 (A) is a microscopic photograph of the microneedle; Figure 3 (B) is the SEM image of the microneedle;

[0026] Figure 4 is a schematic front view of the microneedle patch;

[0027] Figure 5 is a schematic front view of the microneedle patch;

[0028] Figure 6 This is a scanning electron microscope image of microneedles of different needle types;

[0029] Figure 7 This is a test diagram of the mechanical properties of the microneedle patch;

[0030] Figure 8 This is a characterization diagram of hydrogel microneedle transdermal penetration; Figure 5 (A) is a photo of the microneedle piercing the Parafilm membrane; Figure 5 (B) shows the front and back of the first Parafilm film; Figure 5 (C) is a white light image of microneedles piercing the skin;

[0031] Figure 9 This is an OCT transdermal image of the microneedle patch;

[0032] Figure 10 It is a transdermal image of the skin pathology of the microneedle patch;

[0033] Figure 11 is a schematic top view of the structure of the microneedle patch;

[0034] Figure 12 This is a characterization diagram of the swelling performance of hydrogel microneedles; Figure 12 (A) before microneedle swelling; Figure 12 (B) after microneedle swelling; Figure 12 (C) Microneedles swollen for 6 h;

[0035] Figure 13 This is a diagram of the swelling process of microneedles with different ratios;

[0036] Figure 14 is the swelling curve graph;

[0037] Figure 15 is a graph of the hemostatic performance of the hydrogel; Figure 6 (A) Hemostasis time chart; Figure 6 (B) is the coagulation index diagram;

[0038] Figure 16 This is an observation diagram of the hydrogel hemostatic interface.

[0039] Reference numerals:

[0040] 1. Basal layer; 2. Microneedle structure; 3. Diaphragm layer; 4. Isolation layer;

[0041] 21 microneedle; 211 truncated cone needle base; 212 cylindrical needle body; 213 conical needle tip; 22 plastic sealing layer. DETAILED DESCRIPTION

[0042] The following is a clear and complete description of the technical solution of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0043] Example 1

[0044] The raw materials for preparing the hemostatic hydrogel microneedles in this embodiment include chitosan, polyvinyl alcohol, and polyvinyl pyrrolidone in a weight ratio of 3:4:3;

[0045] Preparation method of this hydrogel:

[0046] (1) Chitosan was fully dissolved in water containing 2 v / v% glacial acetic acid, i.e., the volume ratio of glacial acetic acid to water was 2:98, to obtain a 5 g / 100 mL chitosan solution;

[0047] (2) dissolving polyvinyl alcohol and polyvinyl pyrrolidone in water to obtain a 5 g / 100 mL polyvinyl alcohol aqueous solution and a 40 g / 100 mL polyvinyl pyrrolidone aqueous solution, respectively; then mixing the polyvinyl alcohol aqueous solution and the polyvinyl pyrrolidone aqueous solution in a volume ratio of 1:1 to form a mixed solution;

[0048] (3) mixing the solutions in step (1) and step (2) in a certain volume ratio of 1:1 to obtain a hydrogel prepolymer solution;

[0049] (4) The prepolymer solution is reacted at room temperature for 8 hours to form a gel to obtain chitosan hydrogel.

[0050] like Figure 1 As shown in (A), when the hydrogel is inverted, it presents a concave surface similar to a hemisphere. This is because during the hydrogel formation process, the cross-linking reaction inside the hydrogel connects the polymer chains to form a three-dimensional network structure, thereby encapsulating the liquid and forming a relatively independent gel. Further scanning was used to observe the microscopic morphology of the gel, and the results are as follows Figure 1As shown in (B), pores of varying sizes and shapes exist within the hydrogel. These pores interconnect to form a three-dimensional network structure, and the pore size can range from nanometers to micrometers. Smaller pores help increase the specific surface area, improving the adsorption and loading capacity of substances. Larger pores facilitate cell invasion, nutrient transport, and the excretion of metabolic waste, which is of great significance for applications such as tissue engineering and sustained drug release. For example, a hydrogel that can be used as a wound dressing has a porous structure that can absorb wound exudate while maintaining a moist environment and promoting wound healing.

[0051] like Figure 2 As shown, the preparation method of the hydrogel microneedle includes:

[0052] (1) Prepare polydimethylsiloxane (PDMS) prepolymer and its curing agent (name: SYLGARD 184 Silicone Elastomer; brand: DOW SILICONES BELGIVMSRL, product number: 01673921), an electronic balance, a beaker, a glass rod, a vacuum drying oven, a silicon wafer master mold with a microneedle structure, and a culture dish. Pour the PDMS prepolymer and curing agent into a clean beaker at a mass ratio of 10:1 and stir with a glass rod for 10 minutes to fully mix them and ensure that there is no curing agent agglomeration. Next, the mixed solution was placed in a vacuum drying oven with a vacuum degree of -0.1 MPa for degassing for 50 minutes until there were no obvious bubbles. The degassed solution was then slowly cast into a culture dish containing a photoresin master mold to ensure uniform coverage and no new bubbles. The culture dish containing the PDMS solution and the master mold was then placed in a 60°C oven for curing for 2 hours. After complete curing, the dish was removed and the PDMS was carefully peeled off from the master mold to obtain a PDMS mold with a negative microneedle structure. Be careful not to damage the mold structure during demolding. The PDMS negative mold can be obtained by removing the positive mold.

[0053] (2) Pour the hydrogel prepolymer solution into the PDMS negative mold and degas in a vacuum drying oven at a vacuum degree of -0.1 MPa for 3 minutes at room temperature. Repeat the vacuum three times to press the hydrogel prepolymer solution into the PDMS mold.

[0054] (3) After reacting in a drying oven at 37°C for 48 hours, the hydrogel microneedle patch was demolded.

[0055] The morphology of hydrogel microneedles was characterized. Figure 3As shown, the microneedles have a regular bullet-shaped shape, and their bottom diameter is precisely controlled within the range of 400±10μm. This dimensional accuracy ensures the stability and consistency of the microneedles in practical applications. The spacing between the microneedles is 1000±10μm. The evenly distributed spacing design is not only conducive to the rationality of the overall layout of the microneedle array, but also ensures that when they are in effect, each microneedle can act independently and efficiently on the target area to avoid mutual interference. The height of the microneedles reaches 500±10μm. Such a needle height design enables the microneedles to reach the expected depth when penetrating a specific medium to meet the corresponding functional requirements. For example, in transdermal drug delivery applications, it can accurately penetrate the skin's stratum corneum to achieve effective drug delivery while avoiding unnecessary damage to deep tissues. This fully demonstrates the scientific and practical nature of this microneedle in size design, laying a good foundation for its application in many fields.

[0056] like Figure 4 、 5 As shown in the schematic diagram, this hydrogel microneedle patch includes a base layer 1 and a microneedle structure 2. Base layer 1 is used for skin adhesion. In chronic wound treatment, long-term sustained-release drug delivery is required at the treatment site. Therefore, base layer 1 can adhere to the skin for long-term sustained-release drug delivery. Microneedle structure 2 is disposed on base layer 1 to penetrate the skin.

[0057] The microneedle structure 2 includes an array-type microneedle group, and the array-type microneedle group includes multiple rows of microneedles 21 and multiple columns of microneedles 21 .

[0058] The array-type microneedle group includes microneedles 21. The end of the microneedles 21 closest to the basal layer 1 is a truncated cone-shaped base 211, the end of the microneedles 21 away from the basal layer 1 is a conical tip 213, and between the truncated cone-shaped base 211 and the conical tip 213 is a cylindrical body 212. The microneedles 21 have high mechanical stability, thereby achieving greater puncture force. The microneedles 21 can also form an effective drug storage chamber structure, thereby increasing the drug loading capacity per unit volume of the microneedles 21. The microneedles 21 can penetrate the basal layer 1. The microneedle structure 2 can be positioned at the center of the basal layer 1.

[0059] According to an embodiment of the present invention, the microneedle patch is provided with a plurality of microneedles 21 in the microneedle structure 2. The microneedle 21 includes a truncated cone needle base 211, a conical needle tip 213, and a cylindrical needle body 212. The unique shape design of the microneedle 21 improves the puncture force of the microneedle 21 on the skin and the drug loading capacity of a single microneedle 21, thereby improving the drug penetration of the microneedle patch.

[0060] In an embodiment of the present invention, the truncated cone needle base 211 includes an upper bottom surface and a lower bottom surface. The side of the truncated cone needle base 211 close to the base layer 1 is the lower bottom surface, and the side of the truncated cone needle base 211 away from the base layer 1 is the upper bottom surface. The cylindrical needle body 212 includes an upper bottom surface and a lower bottom surface. The side of the cylindrical needle body 212 close to the truncated cone needle base 211 is the lower bottom surface, and the side of the cylindrical needle body 212 close to the conical needle tip 213 is the upper bottom surface. The conical needle tip 213 includes a bottom surface, and the side of the conical needle tip 213 close to the cylindrical needle body 212 is the bottom surface. The lower bottom surface of the truncated cone needle base 211 is in contact with the base layer 1; the upper bottom surface of the truncated cone needle base 211 is in contact with the lower bottom surface of the cylindrical needle body 212; and the upper bottom surface of the cylindrical needle body 212 is in contact with the bottom surface of the conical needle tip 213. The lower diameter of the truncated cone base 211 is 390 μm to 410 μm, and the upper diameter of the truncated cone base 211 is 190 μm to 210 μm. The upper and lower diameters of the cylindrical needle body 212 are the same as the bottom diameter of the conical needle tip 213 and the upper diameter of the truncated cone base 211.

[0061] In an embodiment of the present invention, the height of the microneedles 21 is 490 μm-510 μm.

[0062] A systematic evaluation was conducted on the optimization of the needle shape of microneedles 21. Based on the needle shape of the present invention, two microneedle arrays with different needle shapes (rivet type and cone type) were selected to carry out mechanical property testing. Scanning electron microscope images of microneedles with different needle shapes, such as Figure 6 As shown, the first column is an image of a needle-type microneedle of the present invention with a height of 500 μm, the second column is an image of a rivet-type microneedle with a height of 500 μm, and the third column is an image of a conical microneedle with a height of 500 μm.

[0063] Mechanical properties test results are as follows Figure 7 As shown, curve 1-1 is the performance curve of the needle-type microneedle 21 of the present invention with a height of 500 μm, curve 1-2 is the performance curve of the rivet-type microneedle with a height of 500 μm, and curve 1-3 is the performance curve of the conical microneedle with a height of 500 μm. The 500 μm needle-type microneedle 21 of the present invention exhibits the best mechanical stability, with a compressive strength of 900 mN, significantly higher than the conical microneedle (compressive strength of 700 mN) and the rivet-type microneedle (compressive strength of 650 mN) of the same height, and has a stronger puncture force.

[0064] In terms of drug-loading performance, thanks to their unique geometric configuration, the needle-shaped microneedles 21 of the present invention can carry approximately 20% more drug per unit volume than conical and rivet-shaped microneedles, forming an effective drug storage chamber structure. By establishing a comprehensive evaluation system for microneedle mechanical strength and drug-loading efficiency, it was determined that the 500μm needle-shaped microneedles 21 of the present invention offer both optimal structural stability and maximum drug delivery capacity. Therefore, this needle configuration was selected as the optimal needle configuration for the hydrogel drug delivery system.

[0065] Transdermal experimental steps:

[0066] Method 1: Lay the Parafilm on the lab bench, fold it in half, and then completely soak it in a petri dish filled with water. Quickly cover with filter paper or absorbent paper to ensure close contact and no bubbles. Then press the microneedle into the Parafilm and let it sit for three minutes. Then remove the microneedle peeling paper and observe the depth of the microneedle insertion on the Parafilm. Unfold the folded Parafilm and record the number of Parafilm sections with obvious microneedle holes. Take a photo to record the front and back of the first Parafilm.

[0067] Method 2: Spread fresh pig skin on the laboratory table, then press the microneedle into the pig skin, and then let it stand for three minutes. Then remove the microneedle and observe the insertion of the microneedle on the pig skin, and take pictures to record the microneedle array on the surface of the pig skin.

[0068] The test results are as follows Figure 8 shown.

[0069] In this experiment, a single layer of Parafilm with a thickness of 127 microns was selected as a simulated medium for detecting the penetration depth of microneedles. When the microneedle acted on a sample composed of four closely stacked Parafilm sheets, careful observation clearly revealed that each Parafilm sheet showed a distinct microneedle mark, indicating that the microneedle was able to effectively penetrate each layer of Parafilm during the puncture process and leave clear traces of action. It is particularly noteworthy that on the first Parafilm sheet on the top layer, not only were there microneedle marks, but also significant puncture marks. This phenomenon strongly proves that the penetration depth of the microneedle reached at least about 120μm, fully demonstrating that the microneedle has a strong puncture ability and can penetrate to a certain target depth, meeting the penetration depth requirements in specific application scenarios. In addition, when the microneedles were applied to miniature pig skin, traces left by the microneedle array could be clearly observed on the pig skin surface. These traces showed a regular and clear array distribution pattern, which further intuitively verified the effect of the microneedles on the surface of actual biological tissues. It provides a strong practical basis and intuitive morphological evidence for the application of microneedles in related biomedical fields, and also lays the foundation for subsequent in-depth research on the interaction mechanism between microneedles and biological tissues.

[0070] In addition, through Figure 9As shown in the microneedle OCT transdermal image, the transdermal effect of the needle-type microneedle 21 of the present invention on the skin is demonstrated. The microneedle OCT transdermal image can clearly show the depth and dynamic process of the microneedle penetrating the skin. In the figure, (A) normal skin (pigskin) group; (B) hydrogel microneedle group. It can be seen from the actual results that the pigskin surface of the blank control is relatively smooth, while the pigskin surface of the experimental group can clearly see the depression left by the microneedle 21 after penetration, and the array is clear. Further observation of the subcutaneous skin state shows that the blank group is relatively flat, while the experimental group has an obvious microneedle array, and the epidermis is damaged, indicating that the needle-type microneedle 21 of the present invention has a good transdermal effect.

[0071] Through microneedle skin pathology transdermal map, such as Figure 10 As shown, the effects of the needle-type microneedles 21 of the present invention on skin pathology were examined. (A) Actual image; (B) Fluorescence image; (C) White light image. Actual images and longitudinal section results show that after the microneedles 21 penetrate the pig skin, a clear microneedle array is left. Furthermore, a clear depression caused by the penetration of the microneedles 21 is visible. The depth is approximately 80 μm, indicating that the needle-type microneedles 21 of the present invention have good skin penetration results.

[0072] like Figure 11 As shown, in an embodiment of the present invention, the number of rows of the arrayed microneedle group is 30-40, and the number of columns of the arrayed microneedle group is 20-30. Preferably, the arrayed microneedle group includes 34 rows of microneedles 21 and 24 columns of microneedles 21.

[0073] In an embodiment of the present invention, the row spacing and column spacing of the arrayed microneedle group are equal, and the row spacing and column spacing are 500 μm-1500 μm. Preferably, the row spacing and column spacing can be 1000 μm.

[0074] like Figure 5 As shown, in an embodiment of the present invention, the microneedle structure 2 further includes a plastic encapsulation layer 22, which covers the microneedle structure 2 and protects the microneedle structure 2. To prevent damage to the microneedle structure 2 during transportation, the plastic encapsulation layer 22 is longer than the microneedle structure 2 to ensure complete coverage of the microneedle structure 2. The plastic encapsulation layer 22 is disposed at the center of the base layer 1. During use, the plastic encapsulation layer 22 is removed.

[0075] In one embodiment, the length of the plastic encapsulation layer 22 in the first direction ranges from 3.5 cm to 4.5 cm; the length of the plastic encapsulation layer 22 in the second direction ranges from 4.5 cm to 5.5 cm. The length of the plastic encapsulation layer 22 in the first direction is greater than the length of the microneedle structure 2 in the first direction, and the length of the plastic encapsulation layer 22 in the second direction is greater than the length of the microneedle structure 2 in the second direction. The plastic encapsulation layer 22 can be made of PP to ensure the integrity of the needle body.

[0076] In the embodiment of the present invention, the height of the plastic sealing layer 22 ranges from 0.1 cm to 0.2 cm, and the height of the plastic sealing layer 22 is greater than the height of the microneedle structure 2 .

[0077] In the embodiment of the present invention, the base layer 1 is a hydrogel dressing; a diaphragm layer 3 is provided on the side of the base layer 1 away from the microneedle structure 2 to isolate the base layer 1. The side of the base layer 1 close to the microneedle structure 2 needs to be in contact with the skin to ensure that the microneedle patch is adsorbed on the skin for a long time, so the base layer 1 is a hydrogel dressing. Figure 2 As shown, in one embodiment, an isolation layer 4 is provided on a side of the base layer 1 close to the microneedle structure 2. When the isolation layer 4 is torn off, the side of the base layer 1 close to the microneedle structure 2 adsorbs the skin.

[0078] In one embodiment, the length of the diaphragm layer 3 in the first direction ranges from 19.5 cm to 20.5 cm; the length of the diaphragm layer 3 in the second direction ranges from 9.5 cm to 10.5 cm; and the height of the diaphragm layer 3 ranges from 0.05 cm to 0.15 cm. The length of the diaphragm layer 3 in the first direction is not less than the length of the base layer 1 in the first direction, and the length of the diaphragm layer 3 in the second direction is not less than the length of the base layer 1 in the second direction.

[0079] In the embodiment of the present invention, the height of the microneedle structure 2 is 0.05 cm-0.15 cm, and the height of the microneedle structure 2 is greater than the height of the microneedle 21 .

[0080] In one embodiment, the length of the microneedle structure 2 in the first direction is 2 cm to 3 cm; the length of the microneedle structure 2 in the second direction is 3 cm to 4 cm.

[0081] In one embodiment, the length of the base layer 1 in the first direction is 19.5 cm-20.5 cm; the length of the base layer 1 in the second direction is 9.5 cm-10.5 cm; and the height of the base layer 1 is 0.45 cm-0.55 cm.

[0082] In one embodiment, the material of the microneedles 21 includes chitosan, polyvinyl alcohol, and polyvinyl pyrrolidone, and the mass ratio of chitosan, polyvinyl alcohol, and polyvinyl pyrrolidone is 3:4:3.

[0083] Swelling experiment steps: Place the hydrogel microneedles prepared in Example 1 under a 30x microscope. Then, spray the microneedle surface with PBS solution using a sprayer. Observe and record the microneedle state under the microscope. Record and compare the microneedle state before and after swelling, and after 6 hours.

[0084] The test results are as follows Figure 12 shown.

[0085] During the swelling experiment, the microneedles exhibited significant morphological changes. Before swelling, the microneedles maintained their initial, established form. However, as the swelling reaction occurred, the microneedles began to rapidly absorb the surrounding medium, causing their volume to increase significantly. In stark contrast to pre-swelling conditions, the diameter and length of the needles showed a significant increase. This change clearly demonstrated the microneedle material's excellent absorption and responsiveness to the medium.

[0086] It is worth noting that Figure 12 As shown in (C), after 6 hours of continuous observation, although the microneedle body was in a swollen state, it still maintained an intact structure without breaking, fragmenting, or disintegrating, fully demonstrating its excellent structural stability and material integrity in the swelling environment. At the same time, the base of the microneedle underwent a significant curling phenomenon, and the originally flat base became curved and its morphology changed significantly. This curling behavior may be related to the uneven stress distribution of the microneedle material during the swelling process and the structural differences between the base and the needle body. Further research is expected to reveal the deep mechanism behind this phenomenon and its potential impact on the overall performance of the microneedle, providing a more accurate and comprehensive theoretical basis and practical guidance for the application of microneedles in related fields.

[0087] In addition, the swelling properties of the hydrogel microneedles were used to determine the material ratio of microneedles 21. Two groups of microneedles 21 with different ratios were compared: microneedles 21 with a chitosan: polyvinyl alcohol: polyvinyl pyrrolidone mass ratio of 4:3:4 (Group A) and microneedles 21 with a chitosan: polyvinyl alcohol: polyvinyl pyrrolidone mass ratio of 3:4:3 (Group B).

[0088] The water absorption and swelling of the microneedles 21 in group A and group B at different time points were recorded. The freeze-dried hydrogel was weighed, and the original mass was W0. The hydrogel microneedles were then placed in PBS (0.01M, pH 7.4). PBS is a modified phosphate buffered saline (PBS), which is a biological buffer widely used in the field of life sciences and is used in multiple fields such as cell culture, immunology research, and signal transduction. PBS solution is usually composed of sodium chloride, phosphates (such as sodium dihydrogen phosphate and potassium dihydrogen phosphate), potassium chloride, etc., and the pH value is generally adjusted to 7.4, which is suitable for a variety of biochemical experiments and cell culture. In one embodiment, the PBS solution formula is 8.0g / L sodium chloride, 0.2g / L sodium dihydrogen phosphate, 1.15g / L sodium hydrogen phosphate, and distilled water is diluted to 1L. Once the preset time interval is reached, the hydrogel microneedles 21 are removed from PBS and filter paper is used to remove excess water. The weight of the hydrogel microneedles 21 at different times is recorded as Wt until the hydrogel reaches swelling equilibrium. The swelling ratio was calculated according to the formula: swelling ratio (%) = (Wt-W0) / W0*100%.

[0089] The hydrogel microneedles in group A (chitosan: polyvinyl alcohol: polyvinyl pyrrolidone mass ratio 4:3:4) absorbed water quickly after contact with water, and the needle body expanded rapidly. During the swelling process, the microneedle body collapsed. The hydrogel microneedles in group B (chitosan: polyvinyl alcohol: polyvinyl pyrrolidone mass ratio 3:4:3) absorbed water quickly after contact with water, and the needle body gradually expanded. During the swelling process, the microneedles were able to maintain structural stability best without breaking or collapsing. The swelling process of hydrogel microneedles with different ratios is shown in the figure below. Figure 13 As shown in the figure, the row of images corresponding to 4:3:4 shows the swelling of microneedles 21 (Group A) with a chitosan:polyvinyl alcohol:polyvinyl pyrrolidone mass ratio of 4:3:4 at different time points. The different time points include 0 min, 3 min, 30 min, and 300 min. The row of images corresponding to 3:4:3 shows the swelling of microneedles 21 (Group B) with a chitosan:polyvinyl alcohol:polyvinyl pyrrolidone mass ratio of 3:4:3 at different time points. The different time points include 0 min, 3 min, 30 min, and 300 min.

[0090] The swelling properties of the gel were further tested using the bag method. The test results are as follows: Figure 14 As shown in the figure, the gel gradually absorbs water and swells in the PBS solution. After about 60 seconds, the swelling equilibrium is gradually reached. When the swelling equilibrium is finally reached, the swelling rates of the gel are about 328% and 353%, respectively. This shows that the cross-linked network of the hydrogel microneedle 21 in group B has good water absorption and mechanical maintenance capabilities. The swelling curve is shown in the figure. Figure 14 As shown in the figure, the 4:3:4 curve is the swelling curve of the microneedle 21 (group A) with a chitosan:polyvinyl alcohol:polyvinyl pyrrolidone mass ratio of 4:3:4. The 3:4:3 curve is the swelling curve of the microneedle 21 (group B) with a chitosan:polyvinyl alcohol:polyvinyl pyrrolidone mass ratio of 3:4:3.

[0091] Therefore, the microneedle patch according to an embodiment of the present invention arranges multiple microneedles in the microneedle structure. The microneedles include a truncated cone needle base, a conical needle tip, and a cylindrical needle body. Through the unique shape design of the microneedles, the puncture force of the microneedles on the skin and the drug loading capacity of a single microneedle are improved, thereby increasing the drug penetration amount of the microneedle patch, which is suitable for chronic wound treatment and long-term sustained-release drug delivery.

[0092] The hemostatic performance test of the microneedles in Example 1 was performed as follows:

[0093] Experiment 1: Hemostasis time

[0094] Take 250 μL of citrated whole blood and 25 μL of 0.1 mol / mL CaCl₂ solution, preheat at 37°C for 30 minutes, and gently mix. Apply the recalcified blood to the surface of gauze, 50 mg of xerogel, and 50 mg of hydrogel microneedles. Invert the catheter every 3 seconds to observe for clot formation. Once a clot forms, record the time to hemostasis.

[0095] Experiment 2: BCI Testing

[0096] Gauze, 50 mg of hydrogel (unshaped and dehydrated), and 50 mg of hydrogel microneedle sample were preheated in 37°C deionized water and placed in a centrifuge tube. A mixture of 0.4 mL of mouse whole blood and 0.04 mL of sodium citrate solution (concentration of 38 mg / mL) was then slowly added to cover the hydrogel. 30 μL of calcium chloride solution (concentration of 0.2 mol / L) was added to initiate coagulation. The temperature was maintained at 37°C. After 10 minutes, 10 mL of deionized water was slowly added, and 10 mL of liquid was collected and centrifuged. The supernatant obtained was transferred to a new centrifuge tube along with 20 mL of fresh deionized water and kept in a 37°C water bath for 1 hour. Finally, the absorbance of each experimental group at 540 nm (recorded as a) and the absorbance of 0.4 mL of citrated whole blood mixed with 30 mL of deionized water (recorded as b) were measured using a microplate reader. The blood coagulation index (BCI) was calculated as shown in the formula: BCI (%) = (a / b) × 100%. In addition, medical gauze was used as a blank control group.

[0097] The test results are as follows Figure 15 shown.

[0098] Precise measurements of hemostasis time revealed that the hydrogel and hydrogel microneedle groups significantly shortened their hemostasis time compared to the blank control group, clearly demonstrating their superiority in rapid hemostasis. Simultaneously, the trend of the coagulation index also showed a steady decrease over time in the hydrogel and hydrogel microneedle groups, further demonstrating the efficiency and stability of their coagulation process.

[0099] Based on the above results, we can know that both hydrogels and hydrogel microneedles have extremely obvious hemostatic effects, which provides a solid and powerful experimental basis and broad application prospects for their application in hemostasis-related fields, and is expected to become an important research direction for new hemostatic materials.

[0100] As can be seen from the hemostasis time, the hemostasis time of the hydrogel and hydrogel microneedle groups was significantly reduced compared to the blank group. At the same time, the coagulation index also gradually decreased over time. These results indicate that both the hydrogel and hydrogel microneedle groups have a significant hemostatic effect.

[0101] The hydrogel hemostatic interface was observed by scanning electron microscopy. Figure 16 As shown in the figure, further observation of cell adsorption on the hydrogel surface using scanning electron microscopy revealed a large number of cells adsorbed on the gel surface. From their concave morphology, it can be inferred that most of the cells are red blood cells. This discovery not only intuitively demonstrates the hydrogel's ability to adsorb red blood cells, but also provides a microscopic basis for studying the mechanism of action of hydrogels in blood-related applications, helping to promote the further development of hydrogels in fields such as hemostasis and blood purification.

[0102] Further observation of the adsorption of cells on the hydrogel surface using a scanning electron microscope revealed that a large number of cells were adsorbed on the gel surface, and judging from the concave morphology, most of the cells were red blood cells.

[0103] The parts of the embodiment herein that are not exhaustive of the midpoint values of the technical scope claimed for protection by the present invention and the new technical solutions formed by equivalent replacement of single or multiple technical features in the technical solutions of the embodiments are also within the scope claimed for protection by the present invention: at the same time, in all the listed or unlisted embodiments of the scheme of the present invention, each parameter in the same embodiment merely represents an example of its technical solution (i.e., a feasible solution), and there is no strict coordination and limitation relationship between the parameters, wherein the parameters can be replaced with each other without violating the axioms and the claims of the present invention, unless otherwise stated.

[0104] The technical means disclosed in the solutions of the present invention are not limited to the technical means disclosed in the above technical means, but also include technical solutions composed of any combination of the above technical features. The above is a specific embodiment of the present invention. It should be noted that for those skilled in the art, various improvements and modifications can be made without departing from the principles of the present invention, and such improvements and modifications are also considered to be within the scope of protection of the present invention.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A hemostatic hydrogel microneedle, characterized in that: The bottom diameter of the hemostatic hydrogel microneedles is 50-800 μm; the spacing between the microneedles is 500-1500 μm; and the height of the microneedles is 50-1000 μm.

2. The hemostatic hydrogel microneedle according to claim 1, characterized in that: The bottom diameter of the microneedle is 390-410 μm; the spacing between the microneedles is 990-1010 μm; and the height of the microneedle is 490-510 μm.

3. The hemostatic hydrogel microneedle according to claim 1, characterized in that: The end of the microneedle close to the base layer is a truncated cone needle base, the end of the microneedle away from the base layer is a conical needle tip, and the cylindrical needle body is between the truncated cone needle base and the conical needle tip.

4. The hemostatic hydrogel microneedle according to claim 1, characterized in that: The raw materials for preparing the hemostatic hydrogel microneedle include chitosan, polyvinyl alcohol and polyvinyl pyrrolidone in a weight ratio of (1-8): (1-8): (1-10).

5. A method for preparing a hemostatic hydrogel microneedle according to any one of claims 1 to 4, characterized in that the steps include: (1) fully dissolving chitosan in a glacial acetic acid aqueous solution to obtain a chitosan solution; (2) preparing a polyvinyl alcohol aqueous solution and a polyvinyl pyrrolidone aqueous solution and mixing them to form a mixed solution; (3) further mixing the chitosan solution and the mixed solution to obtain a hydrogel prepolymer solution; (4) injecting the hydrogel prepolymer solution into a microneedle mold by repeatedly vacuuming, allowing it to stand to form a gel, and then drying and demolding to obtain a hemostatic hydrogel microneedle.

6. The method for preparing a hemostatic hydrogel microneedle according to claim 5, characterized in that: The volume ratio of glacial acetic acid to water in the glacial acetic acid aqueous solution is (1-5):100; the dosage ratio of chitosan to the glacial acetic acid aqueous solution in the chitosan solution is 1-10 g / 100 mL.

7. The method for preparing a hemostatic hydrogel microneedle according to claim 5, characterized in that: The ratio of polyvinyl alcohol to water in the polyvinyl alcohol aqueous solution is 1-10 g / 100 mL; the ratio of polyvinyl pyrrolidone to water in the polyvinyl pyrrolidone aqueous solution is 5-50 g / 100 mL.

8. The method for preparing a hemostatic hydrogel microneedle according to claim 5, characterized in that: The volume ratio of the polyvinyl alcohol aqueous solution to the polyvinyl pyrrolidone aqueous solution in the mixed solution is 1-10:1-10.

9. The method for preparing a hemostatic hydrogel microneedle according to claim 5, characterized in that: The volume ratio of the chitosan solution to the mixed solution is 1-10:1-10.

10. Use of the hemostatic hydrogel microneedle according to any one of claims 1 to 4 in preparing a hemostatic product.

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