Painless microneedle for treating alopecia and preparation method thereof
By using microneedles prepared from oleaster gum and sodium alginate, the issues of biocompatibility and limited functionality of synthetic matrix materials were resolved, enabling efficient and targeted delivery of Usma grass extract and improving the efficacy and safety of hair loss treatment.
Patent Information
- Application Number
- CN202511506281.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-21
- Publication Date
- 2026-01-09
AI Technical Summary
Existing synthetic matrix materials have poor biocompatibility, complex preparation processes, and limited functions. Usma extract has difficulty penetrating the stratum corneum of the skin, resulting in low bioavailability and limiting its application in the treatment of hair loss.
Microneedles were prepared using oleaster gum and sodium alginate as matrix materials. They were then used to physically penetrate the stratum corneum of the skin to deliver Usma grass extract to the hair follicle area. Combined with the anti-inflammatory and antioxidant properties of Usma grass extract, efficient and targeted delivery was achieved.
This method achieves highly efficient transdermal delivery of Usma grass extract, significantly improving drug bioavailability, enhancing hair follicle cell proliferation activity, and improving therapeutic efficacy. Furthermore, the materials are safe, the operation is simple, and the risk of side effects associated with traditional treatments is reduced.
Smart Images
Figure CN121287591A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of pharmaceutical preparations, and in particular to a painless microneedle for treating hair loss and its preparation method. Background Technology
[0002] As of 2025, my country had 330 million people suffering from hair loss, with men accounting for 62% and women for 38%. The main causes of hair loss are concentrated in unhealthy lifestyle habits, such as significant hair loss related to staying up late, work stress, and frequent perming and dyeing. Testing revealed that androgenetic alopecia (AGA) accounts for as much as 90%, characterized by a receding hairline and thinning hair on the crown. With increasing life pressures and environmental changes in modern society, the onset of AGA is showing a trend towards younger ages, seriously affecting patients' mental health and quality of life.
[0003] Currently, clinical treatments for AGA mainly include drug therapy, physical therapy, and surgical treatment. Drug therapy primarily involves topical minoxidil and oral finasteride. Minoxidil can dilate scalp blood vessels and prolong the hair follicle growth phase, but its transdermal penetration efficiency is low, requiring long-term use to be effective, and it easily causes side effects such as scalp itching and contact dermatitis. Finasteride, as an inhibitor of 5α-reductase, has good clinical efficacy, but some patients experience serious side effects such as sexual dysfunction and depression, deterring many patients, especially young patients. Physical and surgical treatments include low-energy laser therapy, platelet-rich plasma (PRP) injections, and hair transplantation. These methods are either expensive and lengthy, or invasive, posing a risk of infection, and require highly skilled operators, making them difficult to popularize.
[0004] In recent years, traditional Chinese medicine has shown great potential in preventing hair loss and promoting hair growth, with more natural and reliable ingredients and a lower risk of allergies. Among them, the extract of Usma grass has been confirmed by multiple studies to have excellent effects in promoting hair growth, anti-inflammation, and antibacterial properties.
[0005] Meanwhile, microneedle technology, as a novel transdermal drug delivery platform, offers a new approach to solving the absorption problem in hair loss treatment. Microneedles can instantly open microchannels in the stratum corneum of the skin through physical means, delivering drugs directly to the dermis, which can significantly improve drug penetration efficiency and achieve painless, minimally invasive, and highly efficient drug delivery.
[0006] Microneedles are often made from synthetic or semi-synthetic polymers, such as hyaluronic acid (HA), polyvinyl alcohol (PVA), and polyvinylpyrrolidone (PVP). However, these materials have some inherent drawbacks: first, degradation products may cause unknown biocompatibility issues; second, their mechanical strength and dissolution rate often require complex chemical cross-linking or formulation adjustments to achieve a balance, making the preparation process cumbersome; and third, they lack additional pharmacological activity and have limited functionality.
[0007] Due to its large molecular weight and strong hydrophilicity, Usma extract has difficulty penetrating the outermost stratum corneum barrier of human skin, resulting in extremely low bioavailability when administered topically. It cannot reach an effective therapeutic concentration at the hair follicle target tissue, thus limiting its clinical application. Summary of the Invention
[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a painless microneedle for treating hair loss and its preparation method. It overcomes the problems of poor biocompatibility, complex preparation process and single function of existing synthetic matrix materials, achieves efficient and targeted delivery of Usma grass extract, and utilizes the anti-inflammatory and antioxidant properties of the matrix material itself to synergistically exert therapeutic effects with drugs, thereby providing a safer, more effective and convenient microneedle patch for treating hair loss.
[0009] The present invention adopts the following technical solution: On one hand, the present invention provides a method for preparing painless microneedles for treating hair loss, comprising: S1. Obtain Usma grass extract, wherein the Usma grass extract includes Isatis indigotica; S2. Preparation of Elaeagnus angustifolia resin solid; S3. Microneedle preparation: Mix a certain amount of the jujube gum solid and sodium alginate, dissolve in deionized water, add the ummar extract and stir, centrifuge to remove bubbles; drop the stirred solution into a microneedle mold, seal the microneedle mold and centrifuge, dry and demold to obtain the microneedle. Steps S1 and S2 have no specific order.
[0010] In addition to any of the possible implementations described above, another implementation is provided in which the method for preparing the jujube gum solid in step S2 includes: S21. Wash the raw jujube tree gum with deionized water to remove large pieces of bark and surface impurities, and let it air dry naturally. S22. Grind the gum in a mortar and pestle to obtain coarse jujube gum powder; S23. The coarse jujube gum powder is heated and dissolved in deionized water, and stirred magnetically to obtain a gum solution with a concentration of 1.5%-2.5%. The solution is then centrifuged to remove mechanical and organic impurities. S24. Add the resin solution to anhydrous ethanol, let stand, centrifuge and filter to obtain a precipitate; wash and decolorize the precipitate, and collect the precipitate for later use. S25. The collected precipitate is reconstituted in deionized water, heated and dried to obtain the jujube gum solid.
[0011] In addition to any of the possible implementations described above, another implementation is provided in which, in step S23, the coarse jujube gum powder is dissolved in deionized water, heated in a water bath at 60°C, and stirred with a magnetic stirrer for 40-60 minutes; then centrifuged at 4000 r / min for 3 minutes to remove impurities.
[0012] In addition to any of the possible implementations described above, another implementation is provided in which, in step S24, the jujube gum solution is added to anhydrous ethanol one tube at a time while stirring, with a volume ratio of jujube gum solution to anhydrous ethanol of 1:3; after standing in a refrigerator at 4°C for 24 hours, it is taken out and centrifuged at 4000 r / min for 3 minutes. After centrifugation and filtration, the obtained precipitate is washed and decolorized with anhydrous ethanol by centrifugation.
[0013] In addition to any of the possible implementations described above, another implementation is provided in which, in step S24, the heating and drying is performed in an oven at 50°C for 48 hours.
[0014] In addition to any of the possible implementations described above, another implementation is provided in which, in step S3, the mass ratio of the jujube gum solid, sodium alginate, and isatis indigotica is 1: (5~7): (10~15), the stirring time is not less than 24 hours, the parameters for centrifugation to eliminate foaming are 3000 rpm for 3 min, and the parameters for sealing and centrifuging the microneedle mold are 4000 rpm for 3 min.
[0015] In addition to any of the possible implementations described above, another implementation is provided in which the mass ratio of the oleaster gum solid, sodium alginate, and isatis indigotica is 4:25:50.
[0016] In addition to any of the possible implementations described above, another implementation is provided in which the microneedle mold is made of PDMS, each piece has 11*11 needles, a needle spacing of 580um, a needle bottom side length of 6.09mm, a needle height of 600um, and the microneedle patch is square in shape with a side length of 9.8mm.
[0017] On the other hand, the present invention also provides a painless microneedle for treating hair loss, wherein the painless microneedle uses jujube gum as a matrix material and is loaded with active ingredients of Usma grass extract.
[0018] In addition to any of the possible implementations described above, another implementation is provided in which the painless microneedles are prepared by the method described in any one of claims 1-8.
[0019] The beneficial effects of this invention are as follows: 1. Highly efficient transdermal delivery: Microneedles can physically penetrate the stratum corneum to deliver Usma grass extract directly to the hair follicle area, increasing hair coverage, diameter, and length, increasing the number of hair follicles, enhancing the proliferative activity of hair follicle cells, and significantly improving drug bioavailability and therapeutic effect.
[0020] 2. Excellent mechanical properties and degradability: As a natural matrix material, the gum of Elaeagnus angustifolia has good mechanical strength and controllable degradability, without the need for complex cross-linking processes.
[0021] 3. Good biocompatibility: Elaeagnus angustifolia gum is a natural polysaccharide that is non-toxic and non-irritating, and its degradation products are safe, thus avoiding the biocompatibility risks of synthetic materials.
[0022] 4. Synergistic therapeutic effect: The gum of the jujube tree itself has anti-inflammatory, antioxidant and skin-drying effects, and has been used in hair care products. It works synergistically with the extract of Usma to enhance the anti-inflammatory and hair growth-promoting effects.
[0023] 5. Convenient to use, painless and minimally invasive: Microneedle patches are easy to operate and patients can use them themselves, avoiding the pain and infection risks of traditional injections or surgery.
[0024] 6. Low cost and easy to promote: Raw materials are widely available, the preparation process is simple, and it is suitable for large-scale production and clinical application. Attached Figure Description
[0025] Figure 1 The diagram shown is a flowchart illustrating a method for preparing a painless microneedle for treating hair loss according to an embodiment of the present invention.
[0026] Figure 2 The diagram shows the preparation process of Elaeagnus angustifolia gum solid in the example; (a) original Elaeagnus angustifolia gum; (b) Elaeagnus angustifolia gum after washing; (c) Elaeagnus angustifolia gum precipitated in anhydrous ethanol; (d) precipitate collected by centrifugation; (e) Elaeagnus angustifolia gum solid.
[0027] Figure 3 The diagram shown is a schematic of the microneedle mold in the embodiment.
[0028] Figure 4 The images show the morphology of the microneedles loaded with sodium fluorescein in the examples; (a) one; (b) another.
[0029] Figure 5 The images shown are the results of microneedles loaded with sodium fluorescein piercing pig skin in the examples; (a) one; (b) another.
[0030] Figure 6 The figure shown is a diagram illustrating the effect of microbes on HUVEC cells cultured in vitro in the embodiment.
[0031] Figure 7 The figure shown is a graph illustrating the cell survival rate of HUVEC cells after 24 hours of treatment with different concentrations of Elaeagnus angustifolia gum in the example.
[0032] Figure 8 The image shown is a diagram illustrating the scratch test results of HUVEC cells under different culture conditions in this embodiment. Detailed Implementation
[0033] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation, but can be combined with each other to achieve better technical effects.
[0034] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for preparing painless microneedles for treating hair loss, comprising: S1. Obtain Usma grass extract, wherein the Usma grass extract includes Isatis indigotica; S2. Preparation of Elaeagnus angustifolia resin solid; S3. Microneedle preparation: Mix a certain amount of the jujube gum solid and sodium alginate, dissolve in deionized water, add the ummar extract and stir, centrifuge to remove bubbles; drop the stirred solution into a microneedle mold, seal the microneedle mold and centrifuge, dry and demold to obtain the microneedle. Steps S1 and S2 have no specific order.
[0035] The reasons for using sodium alginate in this invention are as follows: 1. Enhanced mechanical strength: Sodium alginate can undergo a cross-linking reaction to form a gel network structure with a certain strength. This structure can enhance the hardness and toughness of the microneedles, making them strong enough to pierce the skin and ensuring that the microneedles will not easily break during the skin insertion process, thus successfully delivering the drug into the skin.
[0036] 2. Drug encapsulation: Sodium alginate has excellent encapsulation properties, which can encapsulate Usma extract in its gel structure; this can protect the drug from external environmental factors (such as oxygen, light, moisture, etc.), improve the stability of the drug, and reduce the loss of the drug before it reaches the site of action.
[0037] 3. Increased skin affinity: Sodium alginate has a certain affinity for the skin, which allows microneedles to better adhere to the skin surface, facilitating drug contact and absorption.
[0038] In one specific embodiment, step S2, the method for preparing the oleaster gum solid includes: S21. Wash the raw jujube tree gum with deionized water to remove large pieces of bark and surface impurities, and let it air dry naturally. S22. Grind the gum in a mortar and pestle to obtain coarse jujube gum powder; S23. The coarse jujube gum powder is heated and dissolved in deionized water, and stirred magnetically to obtain a gum solution with a concentration of 1.5%-2.5%. The solution is then centrifuged to remove mechanical and organic impurities. S24. Add the resin solution to anhydrous ethanol, let stand, centrifuge and filter to obtain a precipitate; wash and decolorize the precipitate, and collect the precipitate for later use. S25. The collected precipitate is reconstituted in deionized water, heated and dried to obtain the jujube gum solid.
[0039] In one specific embodiment, in step S23, the coarse jujube gum powder is dissolved in deionized water, heated in a water bath at 60°C, and stirred with a magnetic stirrer for 40-60 minutes; then centrifuged at 4000 r / min for 3 minutes to remove impurities.
[0040] In one specific embodiment, in step S24, the jujube gum solution is added to anhydrous ethanol one tube at a time while stirring, using a dropper, with a volume ratio of jujube gum solution to anhydrous ethanol of 1:3; after standing in a refrigerator at 4°C for 24 hours, it is taken out and centrifuged at 4000 r / min for 3 min. After centrifugation and filtration, the obtained precipitate is washed and decolorized with anhydrous ethanol by centrifugation.
[0041] In one specific embodiment, in step S24, the heating and drying is performed by drying in an oven at 50°C for 48 hours.
[0042] In one specific embodiment, in step S3, the mass ratio of the jujube gum solid, sodium alginate and isatis indigotica is 1: (5~7): (10~15), the stirring time is not less than 24 hours, the parameters for centrifugation to eliminate foaming are 3000 rpm for 3 min, and the parameters for sealing and centrifuging the microneedle mold are 4000 rpm for 3 min.
[0043] In one specific embodiment, the mass ratio of the oleaster gum solid, sodium alginate, and isatis indigotica is 4:25:50.
[0044] In one specific embodiment, the microneedle mold is model TM-8, made of PDMS, with 11*11 needles per piece, a needle pitch of 580um, a needle bottom side length of 6.09mm, a needle height of 600um, and a square shape for the microneedle patch with a side length of 9.8mm.
[0045] The thickness of the human stratum corneum is about 10 - 20 μm, the total thickness of the epidermis is about 50 - 100 μm, and the key hair - generating structures of the hair follicle, the hair papilla and matrix cells, are located in the dermal papilla layer, with a depth of about 200 - 500 μm. A needle height of 600 μm can stably penetrate the stratum corneum and the epidermis and precisely act on fibroblasts and matrix cells around the hair follicle. The setting of the array density balances "stimulation effectiveness" and "skin tolerance".
[0046] In an embodiment of the present invention, a painless microneedle for treating hair loss uses tamarisk gum as a matrix material and contains an active ingredient of Lawsonia inermis extract.
[0047] In a specific embodiment, the painless microneedle is prepared by the above - mentioned method.
[0048] Embodiment 1. Microneedle mold model: TM - 8, material: PDMS, number of needles per sheet: 11 * 11, needle pitch: 580 μm, needle bottom side length: 6.09 mm, needle height: 600 μm, shape of the microneedle patch: square (side length 9.8 mm), as Figure 3 shown.
[0049] 2. Refinement of solid tamarisk gum: 2.1 The collected original tamarisk gum, [as shown in (a) of Figure 2 , is washed with deionized water to remove surface impurities and large pieces of bark, and then air - dried naturally [as shown in (b) of Figure 2 ; 2.2 It is ground with a mortar to obtain coarse gum powder; 2.3 The gum powder is heated and dissolved in deionized water (water - bath heating at 60 °C, stirred with a magnetic stirrer for 40 - 60 min) to obtain a gum solution with a concentration of about 2%. Under the condition of heat preservation, it is centrifuged at a speed of 4000 r / min for 3 min to separate and remove mechanical impurities and organic impurities, and the obtained gum solution is reserved for use; 2.4 The reserved gum solution is added drop - by - drop into anhydrous ethanol while stirring (the volume ratio of the tamarisk gum solution to ethanol is 1:3). After standing in a 4 °C refrigerator for 24 h, it is taken out, centrifuged at a speed of 4000 r / min for 3 min. After centrifugal filtration, the obtained precipitate [as shown in (c) of Figure 2 is washed and decolorized by centrifuging with anhydrous ethanol (the elution volume of anhydrous ethanol is 1.1 times that of the precipitate), and the collected precipitate is reserved for use [as shown in (d) of Figure 2 ; 2.5 The collected precipitate is redissolved in deionized water and then dried in an oven at 50 °C for 48 hours to obtain solid tamarisk gum, which is weighed and stored for use [as shown in (e) of Figure 2 .
[0050] 3. Microneedle preparation Accurately weigh 0.04 g of refined jujube gum and 0.25 g of sodium alginate using an analytical balance, and add them to a 100 ml Erlenmeyer flask. Take a large beaker, add hot water, and use it as a water bath to dissolve the above reagents in 50 mL of deionized water at 45°C. Then, add 0.5 g of Isatis indigotica extract to the above solution and continuously stir the mixture for 24 hours. (Seal the Erlenmeyer flask, add a magnetic stir bar or glass beads, and place it in a shaker for continuous stirring.) Next, centrifuge the stirred solution at 3000 rpm for 3 minutes to eliminate air bubbles. Mold cleaning: use an ultrasonic water bath or alcohol wash (alcohol washing can be used for the first use; for subsequent cleaning, it is best to use an ultrasonic water bath, placing the mold in a beaker containing ultrapure water for cleaning). Use a pipette (the pipette tip can be cut into a small opening) to take 1... Drop mL of the stirred solution onto the PDMS mold; seal the surface of the microneedle mold with sealing film, add wooden blocks on the top and bottom, and sandwich two microneedle molds in the middle, place it in a centrifuge tube and centrifuge at 4000 rpm for 3 min; remove the mold after drying at room temperature or in a refrigerator.
[0051] Microneedle Mechanical Testing Microneedle morphology loaded with sodium fluorescein as follows Figure 4 As shown in (a) and (b).
[0052] Fresh pigskin was purchased from a supermarket, rinsed with water, and dried. Pure microneedles loaded with sodium fluorescein were then punctured into the surface of the skin. The skin was observed and photographed using a laboratory microscope. Figure 5 As shown in (a) and (b), the yellow fluorescent puncture wounds are clearly and evenly distributed. The microneedles prepared by the microneedle formulation in this study have good mechanical properties, can effectively penetrate the skin, and are conducive to the release of drugs into the dermis.
[0053] Effects of microbes on HUVEC cells in vitro Elaeagnus angustifolia extract-loaded microneedles maintained the proliferation rate of HUVEC cells. Elaeagnus angustifolia extract-loaded microneedles were placed into HUVEC cells (Elaeagnus angustifolia group, n=3) or unloaded (control group, n=3), and stained with Calcein-AM / PI buffer at 1, 4, and 7 days post-seeding. D1, D4, and D7 represent days 1, 4, and 7 post-seeding, respectively. Cell numbers were counted, and the number at D1 was set as the starting point for proliferation. Measurement bar, 400 micrometers; n=3, ns, no significant difference, e.g. Figure 6 As shown.
[0054] Changes in cell viability of HUVEC cells after 24 hours of treatment with different degrees of Elaeagnus angustifolia gum The gum extract of Elaeagnus angustifolia was prepared at a concentration of 50 mg / mL and subsequently diluted to concentrations of 25 mg / mL, 12.5 mg / mL, 6.25 mg / mL, 3.125 mg / mL, and 15.625 mg / mL. Cell viability was assessed using a CCK8 assay after incubation with the Elaeagnus angustifolia gum extract, and the results are as follows: Figure 7 .
[0055] Scratch assays of HUVEC cells under different culture conditions The results of the scratch test are as follows Figure 8 As shown, the scratches are clearly visible.
[0056] In vitro release test of microneedles First, the release process of rhodamine was simulated by inserting SA / Gel microneedles filled with rhodamine into agarose gel, and the release behavior of the microneedles was observed under an inverted fluorescence microscope. (Observation requires 1 day) For the in vitro drug release assay, a Franz diffusion cell (C0310, Kaikai Technology Co., Ltd., Shanghai, China) with an effective area of 0.785 cm² was used. Rhodamine microneedles were introduced into agarose and then immobilized in the Franz diffusion cell. Next, 3 mL of PBS solution with a pH of 7.4 was added to the receptor. The solution was maintained at 37°C and stirred at 300 rpm. At the predetermined time, 100 μL of receptor solution was added to a 96-well plate, and the release amount of rhodamine B was quantitatively analyzed using a microplate reader. (Observation requires 3 days) Materials required: Franz diffusion cell (C0310, Kaikai Technology Co., Ltd., Shanghai, China); Rhodamine B; Agarose.
[0057] The results of microneedle release are shown in Table 1: Table 1 It can be seen that about 80% of the drug can be released within half an hour.
[0058] The microneedles of this invention overcome the problems of poor biocompatibility, complex preparation process, and single function of existing synthetic matrix materials, and achieve efficient and targeted delivery of Usma grass extract. By utilizing the anti-inflammatory and antioxidant properties of the matrix material itself, it can work synergistically with drugs to exert a therapeutic effect, thereby providing a safer, more effective and convenient microneedle patch for treating hair loss.
[0059] While several embodiments of the present invention have been provided herein, those skilled in the art should understand that modifications can be made to these embodiments without departing from the spirit of the invention. The above embodiments are merely exemplary and should not be construed as limiting the scope of the invention.
Claims
1. A method for preparing painless microneedles for treating hair loss, characterized in that, The method includes: S1. Obtain Usma grass extract, wherein the Usma grass extract includes Isatis indigotica; S2. Preparation of Elaeagnus angustifolia resin solid; S3. Microneedle preparation: Mix a certain amount of the jujube gum solid and sodium alginate, dissolve in deionized water, add the ummar extract and stir, centrifuge to remove bubbles; drop the stirred solution into a microneedle mold, seal the microneedle mold and centrifuge, dry and demold to obtain the microneedle. Steps S1 and S2 have no specific order.
2. The method for preparing painless microneedles for treating hair loss as described in claim 1, characterized in that, In step S2, the method for preparing the oleaster gum solid includes: S21. Wash the raw jujube tree gum with deionized water to remove large pieces of bark and surface impurities, and let it air dry naturally. S22. Grind the gum in a mortar and pestle to obtain coarse jujube gum powder; S23. The coarse jujube gum powder is heated and dissolved in deionized water, and stirred magnetically to obtain a gum solution with a concentration of 1.5%-2.5%. The solution is then centrifuged to remove mechanical and organic impurities. S24. Add the resin solution to anhydrous ethanol, let stand, centrifuge and filter to obtain a precipitate; wash and decolorize the precipitate, and collect the precipitate for later use. S25. The collected precipitate is reconstituted in deionized water, heated and dried to obtain the jujube gum solid.
3. The method for preparing painless microneedles for treating hair loss as described in claim 2, characterized in that, In step S23, the coarse jujube gum powder is dissolved in deionized water, heated in a water bath at 60°C, and stirred with a magnetic stirrer for 40-60 minutes; then centrifuged at 4000 r / min for 3 minutes to remove impurities.
4. The method for preparing painless microneedles for treating hair loss as described in claim 2, characterized in that, In step S24, the jujube gum solution is added to anhydrous ethanol one tube at a time while stirring using a dropper, with a volume ratio of jujube gum solution to anhydrous ethanol of 1:
3. After standing in a refrigerator at 4°C for 24 hours, the solution is taken out and centrifuged at 4000 r / min for 3 minutes. After centrifugation and filtration, the precipitate is washed and decolorized with anhydrous ethanol by centrifugation.
5. The method for preparing painless microneedles for treating hair loss as described in claim 2, characterized in that, In step S24, the heating and drying process involves drying in an oven at 50°C for 48 hours.
6. The method for preparing painless microneedles for treating hair loss as described in claim 1, characterized in that, In step S3, the mass ratio of the jujube gum solid, sodium alginate and isatis indigotica is 1: (5~7): (10~15), the stirring time is not less than 24 hours, the parameters for centrifugation to eliminate foaming are 3000 rpm for 3 min, and the parameters for sealing and centrifuging the microneedle mold are 4000 rpm for 3 min.
7. The method for preparing painless microneedles for treating hair loss as described in claim 6, characterized in that, The mass ratio of the oleaster resin solid, sodium alginate, and isatis indigotica is 4:25:
50.
8. The method for preparing painless microneedles for treating hair loss as described in claim 1, characterized in that, The microneedle mold is made of PDMS, with 11*11 needles per piece, a needle spacing of 580um, a needle bottom side length of 6.09mm, a needle height of 600um, and a square shape for the microneedle patch with a side length of 9.8mm.
9. A painless microneedling method for treating hair loss, characterized in that, The painless microneedles use jujube gum as a matrix material, which is loaded with active ingredients from Usma grass extract. The painless microneedles are prepared by the method described in any one of claims 1-8.