Double-layer microneedle delivery system for acne treatment as well as preparation method and application of double-layer microneedle delivery system

Abstract

The invention discloses a double-layer microneedle delivery system for acne treatment as well as a preparation method and application of the double-layer microneedle delivery system, and belongs to the technical field of biomedical materials and infectious skin disease treatment. According to the double-layer microneedle delivery system, a copper-tannic acid compound is packaged in a needle tip layer, and probiotic outer membrane vesicles are loaded on a backing layer, so that an intelligent delivery platform with a time-space graded release characteristic is constructed. According to the double-layer structural design, the technical problem of multi-component sequential release is solved, the organic integration of antibacterial, anti-inflammatory and repairing functions is realized, and a new treatment strategy which is efficient, low in side effect and capable of preventing scar formation is provided for acne and other complex skin inflammatory diseases.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials and treatment of infectious skin diseases, and in particular to a bilayer microneedle delivery system for acne treatment, its preparation method, and its application. Background Technology

[0002] Acne is one of the most common chronic inflammatory skin diseases worldwide, primarily affecting adolescents and young adults. Its pathogenesis is complex, mainly related to excessive sebum secretion, clogged hair follicles, *Propionibacterium acnes* infection, and excessive inflammatory response. Sebum secreted by sebaceous glands accumulates within hair follicles, creating a hypoxic microenvironment that promotes the proliferation of *Propionibacterium acnes*. The metabolic products of this bacterium can induce keratinocytes and immune cells to secrete inflammatory factors, such as tumor necrosis factor-α (TNF-α), interleukins (IL-1β, IL-8), and matrix metalloproteinases (MMPs), leading to papule and pustule formation and tissue damage.

[0003] Acne, a multifactorial chronic inflammatory skin disease, has significant limitations in clinical application with existing treatments such as topical retinoic acid, benzoyl peroxide, and antibiotics. These treatments often have a single mechanism of action and cannot simultaneously address the multiple stages of acne development, including bacterial infection, excessive inflammation, and tissue damage. For example, while antibiotics can inhibit Propionibacterium acnes, long-term use can easily lead to drug resistance and disrupt the skin's microecological balance. Retinoic acid and benzoyl peroxide, while effectively reducing inflammation and unclogging hair follicles, often cause strong irritant reactions such as dry skin, erythema, and desquamation, resulting in poor patient tolerance. The fundamental reason for this is that traditional drug formulations cannot achieve synergistic and sequential regulation of complex pathological processes.

[0004] The emergence of microneedling technology has provided a new approach to overcoming the skin barrier and improving drug delivery efficiency. However, existing microneedling systems still have significant limitations when applied to acne treatment. Most microneedles are designed to carry a single drug component (such as antibiotics or anti-inflammatory drugs), and their release behavior is usually explosive and indiscriminate, making it impossible to precisely control their release in time and space according to treatment needs. This makes it difficult to rapidly inhibit bacteria in the early stages, subsequently regulate inflammation, and promote tissue repair in the later stages, thus failing to achieve multi-stage, integrated synergistic treatment. Developing microneedle systems capable of achieving multi-component sequential release has faced technical difficulties, the key being how to construct stable delivery structures between incompatible components and precisely control the release kinetics of each component at specific stages.

[0005] Furthermore, existing microneedle systems use materials with limited functionality and lack the ability to intelligently respond to changes in the disease microenvironment (such as pH and reactive oxygen species levels). The microenvironment of acne lesions is dynamically changing, but traditional materials cannot sense and respond to these changes to adjust their therapeutic behavior (e.g., exerting a strong antibacterial effect during bacterial proliferation or efficiently scavenging free radicals under high reactive oxygen species conditions during inflammation). This "static" treatment model is mismatched with the "dynamic" disease process, which is a major reason why current microneedle therapies have short-lasting effects, fail to completely prevent recurrence, and cause scarring. Therefore, developing an intelligent microneedle system that can adapt to the complex skin microenvironment and achieve multifunctional synergy and time-sequential release has become a critical technological bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a bilayer microneedle delivery system for acne treatment, its preparation method, and its application, thereby addressing the problems existing in the prior art. This invention provides a bilayer microneedle delivery system combining probiotic outer membrane vesicles and copper-tannic acid, achieving multi-stage synergistic treatment of acne through spatiotemporal graded release characteristics. This provides a novel, highly effective, low-side-effect treatment strategy for acne and other complex inflammatory skin diseases, while also preventing scar formation.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] This invention provides a bilayer microneedle delivery system for acne treatment, comprising:

[0009] A microneedle array consisting of a tip layer and a backing layer;

[0010] The tip layer comprises a first biodegradable material and a copper-tannic acid complex;

[0011] The backing layer contains a second biodegradable material and probiotic-derived outer membrane vesicles.

[0012] Optionally, the first biodegradable material is hyaluronic acid, and the concentration of the copper-tannic acid complex in the needle tip layer is 50 μg / mL to 70 μg / mL.

[0013] Optionally, the second biodegradable material is a mixture of polyvinyl alcohol and polyvinylpyrrolidone, and the concentration of the probiotic-derived outer membrane vesicles in the backing layer is 20 μg / mL to 30 μg / mL.

[0014] Optionally, the polyvinyl alcohol in the backing material has a mass-volume concentration of 14%-16%, and the polyvinylpyrrolidone in the backing material has a mass-volume concentration of 4%-6%.

[0015] Optionally, the individual microneedles in the microneedle array are conical in shape with a height of 700 μm to 900 μm.

[0016] The present invention also provides a method for preparing the aforementioned bilayer microneedle delivery system, comprising the following steps:

[0017] A solution of a first biodegradable material containing a copper-tannic acid complex is filled into the tip portion of the microcavity of the mold to form a needle tip layer precursor;

[0018] A second biodegradable material solution containing probiotic-derived outer membrane vesicles is applied to the surface of the mold and the remaining portion of the microcavity to form a backing layer precursor.

[0019] The mold is dried to cure the needle tip layer precursor and the backing layer precursor.

[0020] Demolding from the mold yields the dual-layer microneedle delivery system.

[0021] Optionally, prior to the filling step, the first biodegradable material solution containing the copper-tannic acid complex is degassed and centrifuged.

[0022] Optionally, the drying process is carried out at a temperature of 35°C to 40°C for 20-28 hours.

[0023] The present invention also provides the application of the aforementioned dual-layer microneedle delivery system in the preparation of products for the prevention and / or treatment of acne.

[0024] The product is configured for topical administration through the skin, wherein the copper-tannic acid complex in the needle tip layer is rapidly released in the microenvironment of acne lesions to provide early antibacterial and anti-inflammatory effects, while the probiotic-derived outer membrane vesicles in the backing layer continuously release to provide later anti-inflammatory and tissue repair effects.

[0025] Optionally, the product may include pharmaceuticals.

[0026] The present invention discloses the following technical effects:

[0027] This invention provides a bilayer microneedle delivery system combining probiotic outer membrane vesicles and copper-tannic acid. This system constructs an intelligent delivery platform with spatiotemporally graded release characteristics by encapsulating a copper-tannic acid complex in the needle tip layer and loading probiotic outer membrane vesicles onto a backing layer. The copper-tannic acid in the needle tip layer responds rapidly and is released in the acidic and hyaluronidase-rich microenvironment of acne lesions, exerting timely and potent antibacterial and early anti-inflammatory effects. Meanwhile, the probiotic outer membrane vesicles in the backing layer are continuously released, effectively regulating immune responses, scavenging reactive oxygen species, and promoting tissue repair, achieving synergistic and sequential treatment of multiple aspects of acne infection, inflammation, and tissue damage.

[0028] Compared with existing technologies, this system effectively overcomes the shortcomings of traditional therapies, such as single-effect, easy development of drug resistance, strong irritation, and neglect of tissue repair. Its dual-layer structure design solves the technical challenge of sequential release of multi-component drugs, and the microneedle delivery method significantly improves the drug accumulation efficiency at the lesion site. This design achieves the organic integration of antibacterial, anti-inflammatory, and repair functions, providing a new, highly effective, low-side-effect treatment strategy for acne and other complex inflammatory skin diseases that can prevent scar formation. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The preparation and characterization of Cu-TA / OMV MNs are shown in Figure 1. a is a schematic diagram of the preparation process of Cu-TA / OMV MNs; b is a photograph of Cu-TA / OMV MNs; c is a microscopic image of Cu-TA / OMV MNs; d is a SEM image of Cu-TA / OMV MNs at different magnifications, showing Cu-TA visible on the needle surface.

[0031] Figure 2 The solubility and release properties of Cu-TA / OMV MNs are shown in Figure 1; where a is the cumulative release curve of Cu-TA from microneedles under different pH conditions (with or without HAase); and b is the cumulative release curve of OMVs from microneedles.

[0032] Figure 3 Mechanical and skin puncture resistance tests of Cu-TA / OMV MNs; where a represents the mechanical strength of MNs and Cu-TA / OMV MNs; b represents a photograph of mouse skin after application of MB-loaded Cu-TA / OMV MNs; c represents H&E staining micrographs of mouse skin after Cu-TA / OMV MNs treatment, with red arrows indicating micro-needle pores; d represents fluorescence images of mouse skin at different depths after application of Rhodamine B-loaded Cu-TA / OMV MNs.

[0033] Figure 4The in vivo therapeutic effects of Cu-TA / OMV MNs in an acne model are shown in the following figures: a) representative images of acne lesions treated with different treatment methods at different time points; b) the trajectory of acne area changes under different treatment methods over 7 days; c) bacterial plate count images collected from acne lesions on day 7 under different treatment methods; d) quantitative results of the percentage of acne area under different treatment methods; e) quantitative results of skin thickness; and f) quantitative results of bacterial count. Detailed Implementation

[0034] This invention provides a bilayer microneedle delivery system for acne treatment, comprising:

[0035] A microneedle array consisting of a tip layer and a backing layer;

[0036] The tip layer comprises a first biodegradable material and a copper-tannic acid complex;

[0037] The backing layer contains a second biodegradable material and probiotic-derived outer membrane vesicles.

[0038] The needle tip layer and the backing layer form a vertically layered structure. The needle tip layer is composed of soluble hyaluronic acid and Cu-TA. After insertion into the skin, this layer rapidly releases Cu-TA, which possesses multi-enzyme mimicry activity, including POD, SOD, CAT, and GPx-like activities. It can intelligently regulate the generation and clearance of ROS according to pH changes at the site of skin inflammation, thereby achieving a dynamic balance between antibacterial and anti-inflammatory effects and providing immediate antibacterial action on the infected site. The backing layer is composed of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and probiotic OMVs. OMVs have a sustained-release function, allowing for sustained release within the skin lesion. The bioactive molecules they contain can regulate the immune response, inhibit the expression of pro-inflammatory factors, promote the upregulation of anti-inflammatory factors, cell migration, and angiogenesis, thereby achieving sustained anti-inflammatory and tissue repair effects.

[0039] Optionally, the first biodegradable material is hyaluronic acid, and the concentration of the copper-tannic acid complex in the needle tip layer is 50 μg / mL to 70 μg / mL. In a specific embodiment of the present invention, the concentration of the copper-tannic acid complex in the needle tip layer is 60 μg / mL.

[0040] Optionally, the second biodegradable material is a mixture of polyvinyl alcohol and polyvinylpyrrolidone, and the concentration of the probiotic-derived outer membrane vesicles in the backing layer is 20 μg / mL to 30 μg / mL. In one specific embodiment of the invention, the concentration of the probiotic-derived outer membrane vesicles in the backing layer is 25 μg / mL.

[0041] Optionally, the polyvinyl alcohol in the backing material has a mass-volume concentration of 14%-16%, and the polyvinylpyrrolidone in the backing material has a mass-volume concentration of 4%-6%.

[0042] Optionally, the individual microneedles in the microneedle array are conical in shape with a height of 700 μm to 900 μm.

[0043] The present invention also provides a method for preparing the aforementioned bilayer microneedle delivery system, comprising the following steps:

[0044] A solution of a first biodegradable material containing a copper-tannic acid complex is filled into the tip portion of the microcavity of the mold to form a needle tip layer precursor;

[0045] A second biodegradable material solution containing probiotic-derived outer membrane vesicles is applied to the surface of the mold and the remaining portion of the microcavity to form a backing layer precursor.

[0046] The mold is dried to cure the needle tip layer precursor and the backing layer precursor.

[0047] Demolding from the mold yields the dual-layer microneedle delivery system.

[0048] Optionally, prior to the filling step, the first biodegradable material solution containing the copper-tannic acid complex is degassed and centrifuged.

[0049] Optionally, the drying process is carried out at a temperature of 35°C to 40°C for 20-28 hours.

[0050] The present invention also provides the application of the aforementioned dual-layer microneedle delivery system in the preparation of products for the prevention and / or treatment of acne.

[0051] The product is configured for topical administration through the skin, wherein the copper-tannic acid complex in the needle tip layer is rapidly released in the microenvironment of acne lesions to provide early antibacterial and anti-inflammatory effects, while the probiotic-derived outer membrane vesicles in the backing layer continuously release to provide later anti-inflammatory and tissue repair effects.

[0052] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0053] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0054] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0055] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0056] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0057] Example 1: Preparation of Cu-TA / OMV composite microneedles

[0058] Take a polydimethylsiloxane (PDMS) mold (specifications: 10×10 array, needle height 800 μm) and perform the following operations:

[0059] 1. Preparation of the needle tip solution: Dissolve 60 μg / mL of copper-tannic acid complex (Cu-TA) in a 10% (w / v) aqueous solution of hyaluronic acid (HA) to obtain a drug-containing needle tip solution. Take 100 μL of this solution and degas it under vacuum for 3 min to remove air bubbles, then centrifuge at 4000 rpm for 5 min to ensure the solution fully fills the needle tip cavity of the PDMS mold.

[0060] 2. Preparation of backing solution: The outer membrane vesicles (OMVs) of probiotics (Lactobacillus reuteri) are uniformly dispersed in a mixed aqueous solution consisting of 15% (w / v) polyvinyl alcohol (PVA) and 5% (w / v) polyvinylpyrrolidone (PVP) to form the backing solution, and the concentration is made up to 25 μg / mL.

[0061] 3. Composite microneedle molding: Carefully pour the backing layer solution prepared in step 2 onto the surface of the PDMS mold that has been filled with the needle tip layer solution, ensuring that the solution covers the entire mold and fills the backing layer space.

[0062] 4. Drying and Demolding: Place the entire composite system in a 37℃ constant temperature drying oven and allow it to dry for 24 hours. After it is completely cured, carefully peel it off from the PDMS mold to obtain the Cu-TA / OMV composite microneedle patch. Store it in a desiccator for later use. Detailed process flow is as follows: Figure 1 As shown in a.

[0063] 5. Preparation of control microneedles: Using the same method, except omitting one or both of Cu-TA or OMVs, blank microneedles (Blank MNs), microneedles loaded with only Cu-TA (Cu-TA MNs), and microneedles loaded with only OMVs (OMV MNs) were prepared respectively.

[0064] 6. Morphological Characterization: The macroscopic morphology, array integrity, and microscopic surface morphology of the obtained microneedles were observed using a smartphone camera, an optical microscope, and a scanning electron microscope (SEM, GeminiSEM 300). The characterization results showed that the obtained Cu-TA / OMV MNs formed a regular 10×10 array, with each microneedle being conical in shape and 800 μm in height. Figure 1 (b and c). High-magnification SEM images reveal nanoflower-like Cu-TA structures embedded within the hyaluronic acid matrix. Figure 1 d).

[0065] Example 2: In vitro dissolution and release performance test of microneedles

[0066] 1. Determination of Cu-TA release behavior

[0067] Since Propionibacterium acnes (C. acnes) secretes hyaluronidase (HAase), creating a hyaluronidase-rich environment in the acne microenvironment, the release characteristics of Cu-TA were further evaluated under different conditions.

[0068] The prepared Cu-TA / OMV MNs were immersed in 1.5 mL of phosphate-buffered saline (PBS). Four different release conditions were set to simulate different microenvironments: pH 7.4 (enzyme-free), pH 7.4 (containing 100 U / mL hyaluronidase, HAase), pH 5.5 (enzyme-free), and pH 5.5 (containing 100 U / mL HAase).

[0069] At predetermined time points, 0.2 mL of the release medium was collected and immediately replenished with an equal volume of fresh PBS at the same temperature. The absorbance of the collected sample at the characteristic absorption wavelength of Cu-TA was measured using a UV-Vis spectrophotometer. The concentration of Cu-TA was calculated based on a pre-plotted standard curve, and its cumulative release curve was then plotted. The results showed that under pH 7.4 and pH 5.5 (with and without HAase), the release rates of hyaluronic acid reached 45.56%, 57.13%, 70.85%, and 95.90% within 5 min, respectively. Figure 2 (a) Cu-TA is released most rapidly at pH 5.5 in the presence of HAase, indicating that it can be rapidly released in the acidic and HAase-rich microenvironment of acne lesions.

[0070] 2. Measurement of OMVs release behavior

[0071] Bilayer microneedles (Dil-Cu-TA / OMV MNs) with Dil fluorescent dye labeling were prepared.

[0072] Immerse Dil-Cu-TA / OMV MNs in 1.5 mL PBS (pH 7.4), take 0.2 mL samples at predetermined time points and replenish with an equal amount of fresh PBS.

[0073] The fluorescence intensity of Dil in the sample was measured using a fluorescence spectrophotometer (excitation wavelength: 549 nm, emission wavelength: 565 nm). The simulated release concentration of OMVs was calculated based on the standard curve, and the cumulative release curve was plotted.

[0074] The results showed that OMVs were continuously released from the PVA / PVP backing layer, with a cumulative release rate of up to 97.7% within 48 hours. Figure 2 (b).

[0075] Overall, the rapid release of Cu-TA from the MNs tip provides immediate antibacterial action and early inflammation control, while the sustained release of OMVs from the backing layer alleviates persistent inflammation and promotes tissue regeneration. This biphasic release behavior is synchronized with each stage of acne healing, thus enabling precise and efficient treatment management.

[0076] Example 3: Mechanical properties and skin puncture capability testing of microneedles

[0077] 1. Mechanical strength test

[0078] The mechanical strength of blank MNs and Cu-TA / OMV MNs was evaluated using a universal testing machine (Instron 5943, USA).

[0079] The microneedle patch was fixed to the test platform with the needle tip pointing vertically upwards. After calibrating and zeroing the loaded sensor, a downward compressive force was applied to the microneedle array at a constant rate of 0.1 mm / min until the force value dropped significantly (indicating that the needle body broke or bent).

[0080] Force-displacement data were recorded throughout the process, and curves were plotted. Test results show that the breaking force of Cu-TA / OMV MNs is far higher than the critical force required for a single microneedle to pierce the skin (0.058 N / needle), possessing sufficient mechanical strength to penetrate the skin. Figure 3 (a).

[0081] 2. Ex vivo skin puncture experiment

[0082] Take fresh mouse skin, remove the hair, and fix it.

[0083] Macroscopic puncture verification: Cu-TA / OMV MNs loaded with methylene blue (MB) were applied to the skin surface, gently pressed, and held for 5 minutes before removal. The skin surface was photographed using a digital camera to observe the distribution of blue spots, demonstrating that the microneedles successfully pierced the stratum corneum and released the dye. Figure 3 (b).

[0084] Histological verification: Skin tissue treated with microneedles (using unloaded Cu-TA / OMV MNs) was fixed in 4% paraformaldehyde, routinely embedded in paraffin, sectioned (5 μm thick), and stained with hematoxylin and eosin (H&E). The sections were observed under an optical microscope, and the depth of the microneedle channels was measured. The results showed that the microneedles penetrated the epidermis and entered the dermis, to a depth of approximately 200-300 μm. Figure 3 (c).

[0085] Fluorescence Tracing Penetration Depth: Cu-TA / OMV MNs loaded with Rhodamine B were prepared and applied to mouse skin for 5 min before removal. Skin tissue from the treated area was collected, and the fluorescence distribution of Rhodamine B in the skin tissue was observed using a confocal laser scanning microscope (CLSM, Leica TCS SP8). The results showed that fluorescence signals were still observed at 320 μm in the tissue, consistent with the histological analysis results, confirming that the drug was effectively released to the target skin layer. Figure 3 As shown in d.

[0086] Example 4: Evaluation of the in vivo therapeutic effect of microneedling in acne model mice

[0087] 1. Establishment of animal models

[0088] Male Balb / c mice aged 6-8 weeks and weighing 20-25 g were used in the experiment. All procedures were approved by the Laboratory Animal Ethics Committee (Approval No.: ZJCLA-IACUC-20011395).

[0089] Mice were anesthetized with isoflurane, and their back hair was shaved off. The skin was then disinfected with 75% ethanol.

[0090] In each mouse, 50 μL of a suspension of Propionibacterium acnes (C. acnes) was injected intradermally into a selected area on the back. (Concentration: 1 × 10⁻⁶) 8 (CFU / mL) to induce acne-like lesions and establish an acne model.

[0091] 2. Grouping and Treatment

[0092] Two days after bacterial injection, acne nodules (approximately 2 mm thick) were confirmed to have formed. Mice that successfully modeled the condition were randomly divided into 6 groups (n=6 per group):

[0093] (1) Model control group (no treatment);

[0094] (2) Positive control group (treated with commercially available salicylic acid microneedle patches);

[0095] (3) Blank microneedle group (Blank MNs);

[0096] (4) Cu-TA microneedle group (Cu-TA MNs);

[0097] (5) OMV microneedle group (OMV MNs);

[0098] (6) Cu-TA / OMV composite microneedle group (Cu-TA / OMV MNs).

[0099] During treatment, the corresponding microneedle patch is applied to the acne lesion site, gently pressed to ensure adhesion, and then secured with medical tape.

[0100] 3. Efficacy evaluation

[0101] Lesion morphology and thickness: Before treatment (day -2), on the day of treatment (day 0), and on days 1, 3, 5, and 7 after treatment, photographs of the lesions were taken using a digital camera, and the thickness of the lesion area was measured using calipers. Changes in relative acne area were calculated using image analysis software.

[0102] In vivo antibacterial effect: On day 7 after treatment, exudate from acne lesions in mice of each group was aseptically collected. The exudate was serially diluted and cultured using the plate spread method, and the number of colonies (CFU) formed was counted to calculate the bacterial reduction rate of each treatment group.

[0103] 4. Results

[0104] In vivo experimental data showed that, compared with the model control group and other treatment groups, the Cu-TA / OMV MNs treatment group showed the fastest regression of acne lesions, the smallest abscesses, and the most significant reduction in lesion thickness in mice. Figure 4 (a and e). Analysis of the relative acne area further confirmed these results, showing that Cu-TA / OMV MNs accelerated the healing process ( Figure 4 (b and d). Bacterial counting results showed that, compared with the model control group, the bacterial count of Cu-TA MNs decreased to 1.477%, while the bacterial count of the Cu-TA / OMV MNs group decreased to 0.2133% (b and d). Figure 4 The results (c and f) were significantly better than those of the single-component microneedle group and the positive control group.

[0105] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A bilayer microneedle delivery system for acne treatment, characterized in that, include: A microneedle array consisting of a tip layer and a backing layer; The tip layer comprises a first biodegradable material and a copper-tannic acid complex; The backing layer contains a second biodegradable material and probiotic-derived outer membrane vesicles.

2. The dual-layer microneedle delivery system according to claim 1, characterized in that, The first biodegradable material is hyaluronic acid, and the concentration of the copper-tannic acid complex in the needle tip layer is 50 μg / mL to 70 μg / mL.

3. The dual-layer microneedle delivery system according to claim 1, characterized in that, The second biodegradable material is a mixture of polyvinyl alcohol and polyvinylpyrrolidone, and the concentration of the probiotic-derived outer membrane vesicles in the backing layer is 20 μg / mL to 30 μg / mL.

4. The dual-layer microneedle delivery system according to claim 3, characterized in that, The polyvinyl alcohol has a mass-volume concentration of 14%-16% in the backing material, and the polyvinylpyrrolidone has a mass-volume concentration of 4%-6% in the backing material.

5. The dual-layer microneedle delivery system according to claim 1, characterized in that, The individual microneedles in the microneedle array are conical in shape and have a height of 700 μm to 900 μm.

6. A method for preparing a bilayer microneedle delivery system as described in any one of claims 1-5, characterized in that, Includes the following steps: A solution of a first biodegradable material containing a copper-tannic acid complex is filled into the tip portion of the microcavity of the mold to form a needle tip layer precursor; A second biodegradable material solution containing probiotic-derived outer membrane vesicles is applied to the surface of the mold and the remaining portion of the microcavity to form a backing layer precursor. The mold is dried to cure the needle tip layer precursor and the backing layer precursor. Demolding from the mold yields the dual-layer microneedle delivery system.

7. The method according to claim 6, characterized in that, Prior to the filling step, the first biodegradable material solution containing the copper-tannic acid complex is degassed and centrifuged.

8. The method according to claim 6, characterized in that, The drying process is carried out at a temperature of 35°C to 40°C for 20-28 hours.

9. The use of a bilayer microneedle delivery system as described in any one of claims 1-5 in the preparation of products for the prevention and / or treatment of acne.

10. The application according to claim 9, characterized in that, The products include pharmaceuticals.

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