Preparation method of drug coating calcium peroxide aerodynamic microneedle patch

Abstract

The invention belongs to the cross technical field of the biomedical engineering field, and discloses a preparation method of a drug coating calcium peroxide aerodynamic microneedle patch, and the preparation method comprises the following specific steps: S1: CaO preparation, S2: microneedle tip mother liquor preparation, S3: backing layer preparation, S4: microneedle injection molding and vacuum filling, S5: UV cross-linking photocuring, S6: drug coating, and S7: finished product detection and packaging. The passive diffusion limitation of a traditional microneedle is broken through, an intelligent gas propulsion system is constructed through in-situ chemical reaction of CaO2 and tissue fluid, and deep targeted delivery of drugs is achieved; after the microneedle pierces the skin, the nano CaO2 embedded in the needle body is in contact with interstitial fluid to trigger an oxygen production reaction: CaO2 + 2H2O-> Ca (OH) 2 + O2 (gas), oxygen microbubbles generated by the reaction are controllably released at the speed of 0.5-1.2 mu L / mg.min, and a dynamic propulsive force field is formed in tissue gaps. The physical thrust enables drug molecules to break through a dermis reticular layer barrier, and a laser confocal microscope actually measures and displays that the penetration depth of a fluorescence-labeled drug reaches 625 microns.

Description

Technical Field

[0001] The present invention belongs to the cross-technical field of biomedical engineering, and specifically relates to a method for preparing a drug-coated calcium peroxide pneumatic microneedle patch. Background Art

[0002] Transdermal drug delivery technology delivers drugs through the skin, circumventing the first-pass effect and reducing systemic toxicity. Microneedles, a novel physical penetration enhancer, utilize arrays of micron-sized needle tips to achieve painless penetration through the stratum corneum. However, existing microneedle technology still has significant limitations: solid microneedles form only physical channels, requiring secondary drug delivery and relying on passive diffusion, resulting in low efficiency. Coated microneedles, while loaded with drugs on the tip, are limited in loading capacity, making them particularly difficult to meet high-dose requirements such as immunotherapy, and lack sufficient penetration depth for large-molecule drugs. Hollow microneedles, injected through hollow channels, are complex and prone to needle tract obstruction due to drug viscosity or skin tissue. Dissolvable microneedles, while capable of releasing drugs as the needle dissolves, still rely on passive permeation mechanisms for diffusion. More critically, conventional microneedles lack an active delivery power source, resulting in drug retention and passive diffusion within the dermis. Large-molecule drugs (such as antibodies and proteins) struggle to penetrate deep into the subcutaneous tissue. These limitations collectively limit the potential of microneedle technology for clinical applications requiring precise, deep delivery and high drug loading. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing a drug-coated calcium peroxide pneumatic microneedle patch to solve the problems raised in the above background technology.

[0004] In order to achieve the above object, the present invention provides the following technical solution: a method for preparing a drug-coated calcium peroxide pneumatic microneedle patch, the specific steps of the preparation method are as follows: S1: Preparation of CaO2: Add phenol to CaCl2 solution, add ammonia and hydrogen peroxide dropwise in an ice bath, and filter and dry to generate nano-CaO2; S2: Preparation of microneedle tip stock solution: Disperse 0.2-2 mg / mL of nano-CaO2 in anhydrous ethanol , mixed with PEGDA 3:7, and vortexed to obtain the needle tip stock solution; S3: Preparation of backing layer: Weigh 9 g of PVA and dissolve it in 41 mL of ultrapure water. Place the solution in a 70°C water bath and stir to dissolve until a uniform PVA solution is formed. This solution will serve as the flexible support backing layer of the microneedles. S4: Microneedle injection molding and vacuum filling: The needle tip mother liquid is injected into the mold, and the remaining liquid is sucked out by vacuum suction to remove bubbles, and then the PVA backing liquid is injected to ensure that the microneedle structure is intact and free of defects; S5: UV cross-linking and light curing: UV light cures PEGDA to form microneedle tips, which are then dried at room temperature and demolded to obtain the initial microneedle structure. S6: Drug coating: The drug is diluted with buffer and sprayed evenly on the surface of the microneedles, quickly frozen to -80°C, and then dried in a freeze dryer at -40°C and 0.1 Pa vacuum for 4 hours to prevent water from contacting CaO2 and inactivating the drug and maintain drug activity; S7: Finished product testing and packaging: Test the drug content, structure and gas production performance of the microneedle patch. If qualified, package it according to the standard for storage and use.

[0005] Preferably, the specific steps of preparing CaO2 in S1 are as follows: Step 1: Solution preparation and stabilizer addition A certain amount of CaCl2 is dissolved in an appropriate amount of water, ensuring that the solution is thoroughly mixed; then, phenol is added as a stabilizer to prevent unnecessary side reactions or product degradation during the subsequent reaction process; Step 2: Reaction Slowly add NH3·H2O and H2O2 dropwise to the prepared solution while placing the reaction system in an ice bath. The ice bath helps control the reaction temperature and prevents excessive reaction or heat generation, which may affect the purity and structure of the product. The reaction is carried out in an ice bath until the reaction is complete. Step 3: Product collection and drying After the reaction is completed, the product is collected by filtration; filtration effectively removes impurities and unreacted raw materials in the solution to obtain a relatively pure CaO2 product; then, the collected product is dried at 110°C to remove residual moisture and other volatile substances, thereby generating high-purity nano-CaO2 as the power source for subsequent microneedles.

[0006] Preferably, the specific steps of preparing the microneedle tip mother solution in S2 are as follows: Step 1: Weigh an appropriate amount of prepared CaO2 powder, accurately weigh it according to the concentration range of 0.2-2 mg / mL and disperse it in anhydrous ethanol to ensure that the CaO2 is evenly suspended; Step 2: Mix the ethanol solution containing CaO2 and PEGDA in a volume ratio of 3:7. Use a pipette to accurately control the ratio to avoid imbalance. Step 3: Place the mixed solution on a vortex oscillator and oscillate at 2000-2500 rpm for 5-10 minutes until the solution becomes a uniform emulsion to form a needle tip mother solution.

[0007] Preferably, the specific steps of preparing the backing layer in S3 are as follows: Step 1: Accurately weigh 9g of polyvinyl alcohol solid powder, transfer it to a clean beaker, and add 41mL of ultrapure water; Step 2: Place the beaker in a 70°C constant temperature water bath, install a magnetic stirrer, and start stirring until the PVA particles are completely dispersed; Step 3: Continue heating and stirring for 1-2 hours until the solution becomes colorless and transparent, and filter through a 0.22μm filter membrane for later use.

[0008] Preferably, the microneedle injection molding and vacuum filling in S4 refers to slowly injecting the premixed needle tip mother liquid into the microneedle array template along the wall of the mold groove to ensure that the liquid surface covers all microporous structures; transferring the mold to a vacuum drying oven, maintaining it at a pressure of -0.08MPa for 5 minutes, and removing bubbles in the solution by negative pressure suction, with a bubble residual rate of ≤1%; using a vacuum suction device to remove the residual mother liquid on the mold surface to form a regular needle tip precursor array; then injecting the prepared PVA backing liquid at a uniform speed along the edge of the mold to completely fill the base area, and finally obtaining a layered composite structure without bubble defects.

[0009] Preferably, the UV cross-linking photocuring in S5 refers to smoothly transferring the mold carrying the needle tip mother liquid to the ultraviolet curing platform, turning on the 365nm wavelength UV lamp and irradiating it vertically at an intensity of 5mW / cm² for 10-15 minutes to initiate the photopolymerization reaction of the acrylate groups in the PEGDA molecules to form a three-dimensional network cross-linked structure; continuously monitoring the mold temperature during the curing process to ensure that it is less than 40°C to prevent thermal deformation; after the mother liquid is completely gelled, use tweezers to gently open the edge of the mold, and naturally dry it in a clean environment with a humidity of less than 40% for 2 hours to slowly separate the microneedle array from the mold base, and finally obtain a three-dimensional microneedle structure precursor with a smooth surface and a needle body verticality greater than or equal to 90%.

[0010] Preferably, the specific steps of drug coating in S6 are as follows: Step 1: Dilute the aPD-L1 antibody to the working concentration with PBS buffer and mix gently for later use; Step 2: Use a pneumatic spray device to spray the antibody working solution vertically onto the surface of the microneedle array, controlling the spray pressure to 0.5-1.0 bar to form a uniform drug film; Step 3: Immediately immerse the coated microneedles in liquid nitrogen for 30 seconds to ensure that the needle tip temperature drops to below -80°C; Step 4: Transfer to a pre-freeze dryer and vacuum dry at -40°C and 0.1 Pa for 4 hours to achieve drug fixation and water sublimation.

[0011] Preferably, the finished product testing and packaging in S7 refers to the performance verification of the prepared calcium peroxide pneumatic microneedle patch: using high performance liquid chromatography to determine the drug loading of aPD-L1 antibody, observing the integrity of the needle tip morphology by optical microscopy and scanning electron microscopy, and using a pressure sensor to monitor the CaO2 The real-time gas production when reacting with water; after the three indicators are qualified, the product is packaged in a single aluminum foil bag using a medical-grade composite film, sterilized with ethylene oxide, and stored in a light-proof environment at 4°C to ensure that the product meets the requirements of sterility and stability.

[0012] The beneficial effects of the present invention are as follows: 1. This invention overcomes the limitations of passive diffusion in traditional microneedles by constructing an intelligent gas propulsion system through an in-situ chemical reaction between CaO2 and interstitial fluid, achieving deep, targeted drug delivery. Upon microneedle penetration, embedded CaO2 nanoparticles (particle size <100 nm) interact with interstitial fluid, triggering an oxygen-producing reaction: CaO2 + 2H2O → Ca(OH)2 + O2↑. The resulting oxygen microbubbles are released at a controlled rate of 0.5-1.2 μL / mg·min, forming a dynamic propulsion field within the interstitial space. This physical propulsion enables drug molecules to penetrate the dermal reticular barrier (>800 μm). Laser confocal microscopy measurements show that fluorescently labeled drugs penetrate to a depth of 625 μm, a 100% improvement compared to traditional microneedles. The innovatively designed PEGDA three-dimensional mesh structure enables sustained CaO2 reactivity, maintaining gas production for 48 hours. Combined with the gradient swelling properties of the PVA backing layer, this enables precise delivery of active ingredients to the subcutaneous fat and muscle layers, providing a revolutionary delivery platform for deep-acting drugs such as tumor immunotherapy.

[0013] 2. This invention overcomes the bottleneck in the transdermal delivery of large-molecule drugs, achieving a revolutionary breakthrough in delivery efficiency through a CaO2 gas propulsion system. When the microneedles penetrate the skin, the nano-CaO2 reacts with tissue fluid to generate oxygen microbubbles, creating a sustained and controllable physical thrust, converting "chemical energy" into "mechanical energy," effectively overcoming the steric hindrance of antibody molecules (molecular weight > 150 kDa). In vitro permeation experiments confirmed that this technology achieved a cumulative permeation per unit area of ​​2.8 μg / cm² for monoclonal antibodies (such as PD-1 / PD-L1 inhibitors), a 200% increase compared to traditional microneedles. This "chemical drive-mechanical boost" synergistic delivery model opens up a new avenue for precise localized drug delivery of high-value biologics.

[0014] 3. This invention represents a generational leap in transdermal drug delivery systems, achieving revolutionary innovation through a three-pronged technology platform: chemical energy drive, microstructure-controlled release, and breakthroughs in biological barriers. Key technological breakthroughs include: a unique freeze-drying coating process to create a CaO2 core-drug shell gradient structure; an anhydrous ethanol-PEGDA system to ensure storage stability of nano-CaO2, addressing the challenge of reactive oxygen species inactivation; and a gas micro-thruster that generates oxygen microbubbles by reacting CaO2 with tissue fluid, creating a sustained, controllable physical thrust. This enables the penetration of large-molecule drugs such as PD-1 / PD-L1 inhibitors to a depth exceeding 625μm (a 100% increase over conventional microneedles), with a cumulative permeation per unit area of ​​2.8μg / cm² (a 200% increase), and activity retention exceeding 90%. This technology pioneers a new paradigm in which reactive oxygen species are the driving force for delivery. Supported by industrialized processes such as vacuum filling and UV curing, it ensures microneedle verticality ≥90% and batch-to-batch consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the preparation process of the present invention; Figure 2 Schematic diagram of oxygen generation curve of the present invention; Figure 3 This is a schematic diagram of the effect of the loaded simulated drug rhodamine in the present invention; Figure 4 Schematic diagram of the overall process of the preparation method of the present invention; Figure 5 The biosafety of the microneedle patch was evaluated using histological methods for the present invention; Figure 6 This is the therapeutic effect of the gas-powered microneedle of the present invention on subcutaneous tumors. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] like Figures 1 to 6 As shown, the embodiment of the present invention provides a method for preparing a drug-coated calcium peroxide pneumatic microneedle patch, characterized in that the specific steps of the preparation method are as follows: S1: Preparation of CaO2: Add phenol to CaCl2 solution, add ammonia and hydrogen peroxide dropwise in an ice bath, and filter and dry to generate nano-CaO2; S2: Preparation of microneedle tip stock solution: Disperse 0.2-2 mg / mL of nano-CaO2 in anhydrous ethanol , mixed with PEGDA 3:7, and vortexed to obtain the needle tip stock solution; S3: Preparation of backing layer: Weigh 9 g of PVA and dissolve it in 41 mL of ultrapure water. Place the solution in a 70°C water bath and stir to dissolve until a uniform PVA solution is formed. This solution will serve as the flexible support backing layer of the microneedles. S4: Microneedle injection molding and vacuum filling: The needle tip mother liquid is injected into the mold, and the remaining liquid is sucked out by vacuum suction to remove bubbles, and then the PVA backing liquid is injected to ensure that the microneedle structure is intact and free of defects; S5: UV cross-linking and light curing: UV light cures PEGDA to form microneedle tips, which are then dried at room temperature and demolded to obtain the initial microneedle structure. S6: Drug coating (freeze-drying method): The drug (such as aPD-L1 antibody) is diluted with buffer and sprayed evenly on the surface of the microneedle, quickly frozen to -80℃, and then dried in a freeze dryer at -40℃ and 0.1Pa vacuum for 4h to prevent water from contacting CaO2 and inactivating it and maintain drug activity.

[0018] S7: Finished product testing and packaging: Test the drug content, structure and gas production performance of the microneedle patch. If qualified, package it according to the standard for storage and use.

[0019] 2. The method for preparing a drug-coated calcium peroxide pneumatic microneedle patch according to claim 1, wherein the steps for preparing the CaO2 in S1 are as follows: Step 1: Solution preparation and stabilizer addition A certain amount of CaCl2 is dissolved in an appropriate amount of water, ensuring that the solution is thoroughly mixed; then, phenol is added as a stabilizer to prevent unnecessary side reactions or product degradation during the subsequent reaction process; Step 2: Reaction Slowly add NH3·H2O and H2O2 dropwise to the prepared solution while placing the reaction system in an ice bath. The ice bath helps control the reaction temperature and prevents excessive reaction or heat generation, which may affect the purity and structure of the product. The reaction is carried out in an ice bath until the reaction is complete. Step 3: Product collection and drying After the reaction is completed, the product is collected by filtration; filtration effectively removes impurities and unreacted raw materials in the solution to obtain a relatively pure CaO2 product; then, the collected product is dried at 110°C to remove residual moisture and other volatile substances, thereby generating high-purity nano-CaO2 as the power source for subsequent microneedles.

[0020] The CaO2 preparation process achieves high-performance power source production through multi-step optimization: the addition of phenol stabilizer effectively inhibits side reactions, ensures the controllable reaction path, and achieves a product purity of over 99%; NH3·H2O and H2O2 are added dropwise under ice bath conditions to precisely control the reaction exothermic rate and avoid crystal defects caused by temperature fluctuations. The resulting CaO2 particle size distribution is concentrated in the range of 50-100nm; the filtration process efficiently removes unreacted raw materials and impurities, and the residual moisture is completely removed in combination with 110°C vacuum drying to prevent hydrolysis and ineffectiveness during storage; the process ultimately produces high-purity nano-CaO2, whose gas production efficiency is 25% higher than that of conventional methods, providing continuous and controllable propulsion power for the microneedles, significantly enhancing the depth and penetration consistency of drug delivery.

[0021] The specific steps for preparing the microneedle tip mother solution in S2 are as follows: Step 1: Weigh an appropriate amount of prepared CaO2 powder, accurately weigh it according to the concentration range of 0.2-2 mg / mL and disperse it in anhydrous ethanol to ensure that the CaO2 is evenly suspended; Step 2: Mix the ethanol solution containing CaO2 and PEGDA in a volume ratio of 3:7. Use a pipette to accurately control the ratio to avoid imbalance. Step 3: Place the mixed solution on a vortex oscillator and oscillate at 2000-2500 rpm for 5-10 minutes until the solution becomes a uniform emulsion to form a needle tip mother solution.

[0022] The backing layer preparation process achieves performance optimization through precise quantity control and gentle processing: the precise ratio of 9g PVA to 41mL water ensures a balance between the flexibility and mechanical strength of the substrate, heating in a 70°C water bath accelerates dissolution while avoiding thermal degradation of the material, magnetic stirring for 1-2 hours ensures the uniformity of the solution, and 0.22μm filtration removes micron-sized impurities. This process controls the viscosity fluctuation range of the backing layer solution to within ±5%, significantly improving batch consistency; the thoroughly dissolved PVA molecular chains form a continuous network structure, giving the substrate a suitable elastic modulus of 15-20kPa, which can both carry the microneedle array and conform to skin deformation; the final prepared backing layer has a light transmittance of more than 90%, which facilitates quality control and reduces the risk of microneedles falling off. The specific steps for preparing the backing layer in S3 are as follows: Step 1: Accurately weigh 9 g of polyvinyl alcohol (PVA) solid powder, transfer it to a clean beaker, and add 41 mL of ultrapure water; Step 2: Place the beaker in a 70°C constant temperature water bath, install a magnetic stirrer, and start stirring until the PVA particles are completely dispersed; Step 3: Continue heating and stirring for 1-2 hours until the solution becomes colorless and transparent, and filter through a 0.22μm filter membrane for later use.

[0023] The microneedle injection molding and vacuum filling in S4 refers to slowly injecting the premixed needle tip mother liquid into the microneedle array template along the mold groove wall, ensuring that the liquid surface covers all microporous structures. The mold is transferred to a vacuum drying oven and maintained at a pressure of -0.08MPa for 5 minutes. The bubbles in the solution are removed by negative pressure suction, and the bubble residual rate is ≤1%. The residual mother liquid on the mold surface is sucked out using a vacuum suction device to form a regular array of needle tip precursors. The prepared PVA backing liquid is then injected at a uniform speed along the edge of the mold to completely fill the base area, ultimately obtaining a layered composite structure free of bubble defects.

[0024] Precise and slow injection of the mother liquid ensures complete filling of the micropores, and combined with -0.08MPa vacuum treatment, it can eliminate more than 99% of microbubbles, significantly improving the mechanical strength and structural uniformity of the needle tip; the vacuum aspiration device removes residual liquid on the surface, making the array highly regular and effectively avoiding the risk of drug leakage; the PVA backing layer is vacuum-assisted filled to form a dense layered composite structure with the microneedle layer, which not only ensures the flexibility of the substrate but also realizes drug gradient control.

[0025] Among them, the UV cross-linking photocuring in S5 refers to the smooth transfer of the mold carrying the needle tip mother liquid to the ultraviolet curing platform, turning on the 365nm wavelength UV lamp and irradiating it vertically at an intensity of 5mW / cm² for 10-15 minutes to initiate the photopolymerization reaction of the acrylate groups in the PEGDA molecules to form a three-dimensional network cross-linked structure; the mold temperature is continuously monitored during the curing process to ensure that it is less than 40°C to prevent thermal deformation; after the mother liquid is completely gelled, use tweezers to gently open the edge of the mold, and naturally dry it in a clean environment with a humidity of less than 40% for 2 hours to slowly separate the microneedle array from the mold base, and finally obtain a three-dimensional microneedle structure precursor with a smooth surface and a needle body verticality greater than or equal to 90%.

[0026] Precise control of the 365nm wavelength and 5mW / cm² irradiation intensity efficiently triggers PEGDA photopolymerization, constructing a three-dimensional network structure within 10-15 minutes and improving curing efficiency by 40%. A real-time temperature control system strictly controls the mold temperature below 40°C to avoid structural deviations caused by thermal deformation. Tweezers-assisted demolding combined with a low-humidity clean environment enables non-destructive separation of the microneedle array and the substrate, achieving a product yield of over 95%. The resulting three-dimensional microneedles have a surface roughness Ra < 0.5μm and a verticality ≥ 90%, meeting medical-grade requirements for precise puncture and significantly improving the performance of the drug delivery system.

[0027] The specific steps of drug coating (freeze drying method) in S6 are as follows: Step 1: Dilute the aPD-L1 antibody with PBS buffer to a working concentration (e.g., 1 mg / mL) and mix gently for later use. Step 2: Use a pneumatic spray device to spray the antibody working solution vertically onto the surface of the microneedle array, controlling the spray pressure to 0.5-1.0 bar to form a uniform drug film; Step 3: Immediately immerse the coated microneedles in liquid nitrogen for 30 seconds to ensure that the needle tip temperature drops to below -80°C; Step 4: Transfer to a pre-freeze dryer and vacuum dry at -40°C and 0.1 Pa for 4 hours to achieve drug fixation and water sublimation.

[0028] Freeze-drying drug coating technology has significant advantages: first, the precise dilution of antibodies with PBS buffer can maintain protein activity and stability, ensuring drug efficacy; second, the pneumatic spray device achieves nanoscale coating uniformity through 0.5-1.0 bar pressure control, improving drug utilization by more than 30%; liquid nitrogen quick freezing technology causes the needle tip temperature to drop sharply to below -80°C, effectively inhibiting drug phase separation and microneedle structure deformation; finally, the vacuum drying process completes drug fixation at -40°C and 0.1Pa, which can not only avoid the inactivation of CaO2 by contact with water, but also maintain the mechanical strength of the microneedle.

[0029] The biosafety of microneedle patches was evaluated by histological methods. Figure 5 Shown: HE staining images show that the microneedle patch has almost no damage to various organ tissues.

[0030] Among them, the finished product testing and packaging in S7 refers to the performance verification of the prepared calcium peroxide pneumatic microneedle patch: the aPD-L1 antibody loading amount is determined by high-performance liquid chromatography, the integrity of the needle tip morphology is observed by optical microscopy and scanning electron microscopy, and the real-time gas production of the reaction between CaO2 and water is monitored by a pressure sensor; after the three indicators are qualified, a medical-grade composite film is used for single-piece aluminum foil bag packaging, sterilized with ethylene oxide, and stored in a light-proof environment at 4°C to ensure that the product meets the sterility and stability requirements.

[0031] The finished product testing and packaging process ensures product performance and safety through multi-dimensional quality control: precise detection of drug content ensures controllable efficacy, microscopic imaging verifies structural integrity to avoid usage risks, and gas production monitoring ensures stable power performance; medical-grade packaging combined with sterilization and low-temperature storage effectively maintains sterility and chemical stability to prevent drug degradation; this system not only meets medical product standards, but also extends the product shelf life through full-process quality control, ensuring safety and effectiveness at all stages from production to clinical application, and providing reliable drug delivery solutions for scenarios such as tumor immunotherapy.

[0032] The therapeutic effect of gas-powered microneedles in subcutaneous tumors Figure 6 Figure 2 shows: a) Average tumor volume changes in five groups of mice; b) Tumor inhibition rate of drug-coated calcium peroxide pneumatic microneedles in mice.

[0033] Example: Microneedle patch preparation and performance verification Preparation of CaCl2 power source Weigh 5 g of CaCl2 and dissolve it in 20 mL of deionized water, then add 0.1 g of phenol stabilizer.

[0034] Slowly add 10 mL of 25% NH3·H2O and 15 mL of 30% H2O2 dropwise under ice bath conditions and continue stirring for 2 h until the reaction is complete.

[0035] The product was collected by filtration and dried in vacuum at 110°C for 4 h to obtain CaO2 powder with a particle size of 80 nm and a yield of 85%.

[0036] Microneedle structure construction Preparation of needle tip stock solution: 1 mg CaO2 was dispersed in 1 mL ethanol, mixed with PEGDA at a volume ratio of 3:7, and vortexed at 2500 rpm for 8 min to obtain a uniform emulsion.

[0037] Preparation of backing layer: 9 g PVA was dissolved in 41 mL ultrapure water, stirred magnetically at 70°C for 1.5 h, and filtered through a 0.22 μm filter membrane for later use.

[0038] Injection molding and curing: The needle tip master solution was injected into the PDMS mold. Vacuum degassing was performed at -0.08 MPa for 5 minutes. The residual liquid on the surface was then removed by suction and the PVA backing solution was injected. Irradiation was performed with a 365nm UV lamp at 5mW / cm² for 12 minutes. The mold temperature was controlled at ≤38°C. After demolding, a microneedle array with a verticality of 92% was obtained.

[0039] Drug coating and testing Freeze-dried coating: aPD-L1 antibody was diluted to 1 mg / mL with PBS and sprayed vertically with a pneumatic spray device at a pressure of 0.8 bar. After quick freezing in liquid nitrogen for 30 seconds, the sample was vacuum-dried at -40°C and 0.1 Pa for 4 hours.

[0040] Performance Verification: Drug content: HPLC determination of drug loading reached 0.98 mg / cm², RSD=2.1%.

[0041] Structural integrity: SEM showed that the tip angle was 15°±2° and there was no crack defect.

[0042] Gas production performance: The pressure sensor monitored the gas production of CaO2 reacting with water, reaching 12.5 mL / mg, which was continuously released for more than 30 minutes.

[0043] Packaging and storage Qualified products are packaged individually in medical aluminum foil bags, sterilized with ethylene oxide, and stored at 4°C in the dark. Accelerated aging tests (25°C / 60% RH) show that drug activity retention is ≥90% and gas production performance degradation is <5% within 12 months.

[0044] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0045] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a drug-coated calcium peroxide pneumatic microneedle patch, characterized by: The specific steps of this preparation method are as follows: S1: Preparation of CaO2: Add phenol to CaCl2 solution, add ammonia and hydrogen peroxide dropwise in an ice bath, and filter and dry to generate nano-CaO2; S2: Preparation of microneedle tip stock solution: Disperse 0.2-2 mg / mL of nano-CaO2 in anhydrous ethanol, mix with 3:7 PEGDA, and vortex to obtain the tip stock solution; S3: Preparation of backing layer: Weigh 9 g of PVA and dissolve it in 41 mL of ultrapure water. Place the solution in a 70°C water bath and stir to dissolve until a uniform PVA solution is formed. This solution will serve as the flexible support backing layer of the microneedles. S4: Microneedle injection molding and vacuum filling: The needle tip mother liquid is injected into the mold, and the remaining liquid is sucked out by vacuum suction to remove bubbles, and then the PVA backing liquid is injected to ensure that the microneedle structure is intact and free of defects; S5: UV cross-linking and light curing: UV light cures PEGDA to form microneedle tips, which are then dried at room temperature and demolded to obtain the initial microneedle structure. S6: Drug coating: The drug is diluted with buffer and sprayed evenly on the surface of the microneedles, quickly frozen to -80°C, and then dried in a freeze dryer at -40°C and 0.1 Pa vacuum for 4 hours to prevent water from contacting CaO2 and maintain drug activity; S7: Finished product testing and packaging: Test the drug content, structure and gas production performance of the microneedle patch. If qualified, package it according to the standard for storage and use.

2. The method for preparing a drug-coated calcium peroxide pneumatic microneedle patch according to claim 1, characterized in that: The specific steps of preparing CaO2 in S1 are as follows: Step 1: Solution preparation and stabilizer addition A certain amount of CaCl2 is dissolved in an appropriate amount of water, ensuring that the solution is thoroughly mixed; then, phenol is added as a stabilizer to prevent unnecessary side reactions or product degradation during the subsequent reaction process; Step 2: Reaction Slowly add NH3·H2O and H2O2 dropwise to the prepared solution while placing the reaction system in an ice bath. The ice bath helps control the reaction temperature and prevents excessive reaction or heat generation, which may affect the purity and structure of the product. The reaction is carried out in an ice bath until the reaction is complete. Step 3: Product collection and drying After the reaction is completed, the product is collected by suction filtration; suction filtration effectively removes impurities and unreacted raw materials in the solution to obtain a relatively pure CaO2 product; The collected product was then dried at 110°C to remove residual moisture and other volatile substances, thereby generating high-purity nano-CaO2, which served as the power source for subsequent microneedles.

3. The method for preparing a drug-coated calcium peroxide pneumatic microneedle patch according to claim 1, characterized in that: The specific steps for preparing the microneedle tip mother solution in S2 are as follows: Step 1: Weigh an appropriate amount of prepared CaO2 powder, accurately weigh it according to the concentration range of 0.2-2 mg / mL and disperse it in anhydrous ethanol to ensure that the CaO2 is evenly suspended; Step 2: Mix the ethanol solution containing CaO2 and PEGDA in a volume ratio of 3:

7. Use a pipette to accurately control the ratio to avoid imbalance. Step 3: Place the mixed solution on a vortex oscillator and oscillate at 2000-2500 rpm for 5-10 minutes until the solution becomes a uniform emulsion to form a needle tip mother solution.

4. The method for preparing a drug-coated calcium peroxide pneumatic microneedle patch according to claim 1, characterized in that: The specific steps for preparing the backing layer in S3 are as follows: Step 1: Accurately weigh 9g of polyvinyl alcohol solid powder, transfer it to a clean beaker, and add 41mL of ultrapure water; Step 2: Place the beaker in a 70°C constant temperature water bath, install a magnetic stirrer, and start stirring until the PVA particles are completely dispersed; Step 3: Continue heating and stirring for 1-2 hours until the solution becomes colorless and transparent, and filter through a 0.22μm filter membrane for later use.

5. The method for preparing a drug-coated calcium peroxide pneumatic microneedle patch according to claim 1, characterized in that: The microneedle injection molding and vacuum filling in S4 refers to slowly injecting the premixed needle tip mother liquid into the microneedle array template along the wall of the mold groove to ensure that the liquid surface covers all microporous structures; transferring the mold to a vacuum drying oven and maintaining it at a pressure of -0.08MPa for 5 minutes, removing bubbles in the solution by negative pressure suction, and the bubble residual rate is ≤1%; using a vacuum suction device to remove the residual mother liquid on the mold surface to form a regular needle tip precursor array; then injecting the prepared PVA backing liquid at a uniform speed along the edge of the mold to completely fill the base area, and finally obtaining a layered composite structure without bubble defects.

6. The method for preparing a drug-coated calcium peroxide pneumatic microneedle patch according to claim 1, characterized in that: The UV cross-linking photocuring in S5 refers to the smooth transfer of the mold carrying the needle tip mother liquid to the UV curing platform, turning on the 365nm wavelength UV lamp with an intensity of 5mW / cm² vertical irradiation for 10-15 minutes to initiate the photopolymerization reaction of the acrylate groups in the PEGDA molecules to form a three-dimensional network cross-linked structure; the mold temperature is continuously monitored during the curing process to ensure that it is less than 40°C to prevent thermal deformation; after the mother liquid is completely gelled, use tweezers to gently open the edge of the mold, and naturally dry it in a clean environment with a humidity of less than 40% for 2 hours to slowly separate the microneedle array from the mold base, and finally obtain a three-dimensional microneedle structure precursor with a smooth surface and a needle body verticality greater than or equal to 90%.

7. The method for preparing a drug-coated calcium peroxide pneumatic microneedle patch according to claim 1, characterized in that: The specific steps of drug plating in S6 are as follows: Step 1: Dilute the aPD-L1 antibody to the working concentration with PBS buffer and mix gently for later use; Step 2: Use a pneumatic spray device to spray the antibody working solution vertically onto the surface of the microneedle array, controlling the spray pressure to 0.5-1.0 bar to form a uniform drug film; Step 3: Immediately immerse the coated microneedles in liquid nitrogen for 30 seconds to ensure that the needle tip temperature drops to below -80°C; Step 4: Transfer to a pre-freeze dryer and vacuum dry at -40°C and 0.1 Pa for 4 hours to achieve drug fixation and water sublimation.

8. The method for preparing a drug-coated calcium peroxide pneumatic microneedle patch according to claim 1, characterized in that: The finished product testing and packaging in S7 refers to the performance verification of the prepared calcium peroxide pneumatic microneedle patch: the drug loading of aPD-L1 antibody is determined by high performance liquid chromatography, the integrity of the needle tip morphology is observed by optical microscopy and scanning electron microscopy, and the CaO2 is monitored by pressure sensor. The real-time gas production when reacting with water; after the three indicators are qualified, the product is packaged in a single aluminum foil bag using a medical-grade composite film, sterilized with ethylene oxide, and stored in a light-proof environment at 4°C to ensure that the product meets the requirements of sterility and stability.

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