A controlled release medical dressing and a method of making the same

Abstract

The application discloses a controlled-release medical dressing and a preparation method thereof, and comprises the following raw materials in parts by mass: end-vinyl silicone oil 60-80 parts, crosslinked hydrogen silicone oil 1-5 parts, pyridine-modified hydrogen-containing silicone oil 0.2-0.8 parts, silane-modified polyether resin 5-10 parts, modified filler 8-15 parts, platinum gold catalyst 0.01-0.1 parts, inhibitor 0.005-0.05 parts, and silver-based antibacterial agent 1-3 parts; and the surface of the modified filler is grafted with polypyrrole. The application can improve the cohesive strength and peeling integrity of the silicone gel on the premise of maintaining the flexible and conformable property of the silicone gel, so that the controlled-release medical dressing with comfort, safety and mechanical strength is obtained.

Description

Technical Field

[0001] This application relates to the field of room temperature vulcanizing silicone rubber, specifically to an addition-type liquid silicone rubber, and more particularly to a controlled-release medical dressing and its preparation method. Background Technology

[0002] Silicone gel materials are essentially addition-type liquid silicone rubbers with low cross-linking density, typically based on vinyl-terminated silicone oils and hydrogen-containing silicone oils. These vulcanized silicone rubber materials are widely used in scar management, chronic wound care, and postoperative wound protection due to their excellent biocompatibility, low allergenicity, and mild adhesion properties. Their soft, transparent, and breathable physical properties allow them to adhere closely to the skin surface, providing a physical barrier while reducing mechanical irritation to newly formed tissues, making them particularly suitable for sensitive skin, children, and elderly patients. In actual clinical use, an ideal silicone gel material not only needs good flexibility to adapt to the complex curvatures and irregular wound surfaces of the human body, ensuring comfortable and pressure-free use, but also must have sufficient cohesive strength to prevent breakage, stringing, or residue on the wound surface during removal, thereby avoiding secondary damage and infection risks.

[0003] However, the flexibility and cohesive strength of silicone gels often present a contradictory relationship: reducing the crosslinking density can significantly improve the material's softness and ductility, but it leads to a loose network structure and insufficient cohesion; conversely, increasing the crosslinking density can enhance mechanical integrity and tear resistance, but it makes the silicone gel harder, reduces its elasticity, and makes it difficult to conform to the skin's micro-morphology, affecting its fit and patient comfort. This performance balance problem has long constrained the further development of high-performance silicone gels. Traditional solutions often rely on adjusting the molecular weight of the base polymer or introducing inert plasticizers, but the former has limited effectiveness, while the latter may migrate and precipitate, affecting long-term stability and biocompatibility. Summary of the Invention

[0004] This application provides a controlled-release medical dressing and its preparation method, which aims to improve the cohesive strength of the silicone gel material while maintaining its flexibility and fit, thereby obtaining a high-end controlled-release medical dressing that combines comfort, safety and mechanical strength.

[0005] In a first aspect, this application provides a controlled-release medical dressing comprising the following raw materials in parts by weight: 60-80 parts of vinyl-terminated silicone oil, 1-5 parts of crosslinked hydrogen silicone oil, 0.2-0.8 parts of pyridine-modified hydrogen-containing silicone oil, 5-10 parts of silane-modified polyether resin, 8-15 parts of modified filler, 0.01-0.1 parts of platinum catalyst, 0.005-0.05 parts of inhibitor, and 1-3 parts of silver-based antibacterial agent; wherein the modified filler is grafted with polypyrrole on its surface.

[0006] In any of the above technical solutions, the pyridine-modified hydrogen-containing silicone oil is prepared by hydrosilylation of a hydrogen-containing silicone oil having at least 2 Si-H atoms with vinylpyridine, wherein the molar ratio of Si-H to vinylpyridine in the hydrogen-containing silicone oil is 2-4:1-1.5.

[0007] This application introduces silane-modified polyether resin into a silicone gel system, effectively improving the material's flexibility and conformability, enabling it to adapt to the conformation requirements of irregular human wounds. Simultaneously, the polyether segments are rich in hydrophilic polyoxyethylene units, forming microphase-separated hydrophilic channels within the siloxane network, significantly improving water vapor permeability and tissue exudate absorption capacity, creating a moist but non-macerating environment suitable for wound healing. Furthermore, to resolve the contradiction between the flexibility and cohesive strength of traditional silicone gels, this application prepares and applies pyridine-modified hydrogen-containing silicone oil, introducing pyridine groups into the silicone gel backbone, and covalently grafting or adsorbing polypyrrole chains onto the surface of the inorganic filler. These two components do not directly crosslink in the early stages of silicone gel formation, thus not affecting initial softness. When the silicone gel material comes into contact with wound exudate, the silver-based antibacterial agent releases Ag... + Ag + As a high-affinity metal coordination center, it can simultaneously coordinate with the nitrogen atom of pyridine and the π-electron / nitrogen site of polypyrrole, forming a dynamic and reversible metal ion-ligand crosslinking network. This type of coordination network is a non-covalent and non-rigid crosslinking, which can gradually enhance the cohesive strength of the material during use, preventing fragmentation and residue upon removal, while retaining its excellent elasticity and deformation adaptability, thereby achieving synergistic optimization of the flexibility and cohesive strength of the silicone gel.

[0008] In any of the above technical solutions, the vinyl-terminated silicone oil has a viscosity of 350-20000 mm at 25°C. 2 / s.

[0009] It is worth noting that pyridine and polypyrrole are both covalently fixed to the surface of polymer chains or fillers, resulting in large steric hindrance and low coordination activity. Moreover, their content is lower than that of cross-linked hydrosilicone oil and vinyl silicone oil, and they do not significantly interfere with platinum-catalyzed hydrosilylation.

[0010] In any of the above technical solutions, the preparation steps of the modified filler include: Aminosilane coupling agents are grafted onto the surface of the filler to obtain aminated modified fillers; Aminated modified fillers are subjected to amidation reactions with carboxypyrrole compounds under the action of an activator to obtain pyrrole-grafted fillers; Pyrrole-grafted filler, pyrrole monomer, and oxidant are subjected to in-situ oxidative polymerization in a solvent to obtain a modified filler with surface-grafted polypyrrole.

[0011] In any of the above technical solutions, the carboxypyrrole is pyrrole-3-carboxylic acid.

[0012] In any of the above technical solutions, the mass ratio of the aminated modified filler, the carboxypyrrole compound, and the activator is 100:10-20:20-65.

[0013] In any of the above technical solutions, the activator is a combination of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS).

[0014] In any of the above technical solutions, the modified filler is selected from one or more of fumed silica, precipitated silica, mesoporous silica or glass microspheres, with a particle size of 5-500 nm.

[0015] In any of the above technical solutions, the aminosilane coupling agent is selected from 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0016] In any of the above technical solutions, the mass ratio of the aminosilane coupling agent to the filler is 5-10:100.

[0017] In any of the above technical solutions, the solvent for the in-situ oxidative polymerization is water, ethanol, or a mixture thereof.

[0018] In any of the above technical solutions, the platinum catalyst is an isopropanol chloroplatinate solution or a Karstedt catalyst.

[0019] In any of the above technical solutions, the inhibitor is one or more of acetylene alcohols, maleate esters, or tetramethyltetravinylcyclotetrasiloxane.

[0020] In any of the above technical solutions, the mass ratio of the pyrrole grafted filler to the pyrrole monomer is 1:0.4-0.6.

[0021] In any of the above technical solutions, the oxidant is selected from FeCl3 or (NH4)2S2O8.

[0022] In any of the above technical solutions, the silver-based antibacterial agent is modified silver-doped zinc oxide.

[0023] In any of the above technical solutions, the mass ratio of silver to zinc oxide in the modified silver-doped zinc oxide is 5-10:90-95.

[0024] In any of the above technical solutions, the modified silver-doped zinc oxide is prepared by soaking silver-doped zinc oxide in a mercaptopropylamine solution with a concentration of 0.3-1wt% for 2-4 hours.

[0025] This application selects silver-doped zinc oxide as a silver-based antibacterial agent. This not only utilizes the zinc oxide matrix to physically isolate and chemically stabilize elemental silver nanoparticles, preventing rapid oxidation or explosive release, but more importantly, zinc oxide can simultaneously release Zn in the wound exudate environment. 2+ On the one hand, it exerts its own healing-promoting, anti-inflammatory, and auxiliary antibacterial functions; on the other hand, it indirectly reduces the impact on Ag by providing additional metal ions to participate in the coordination network. + This reduces dependence on silver, thus slowing down the rate of silver consumption and protecting Ag. + The continuous and controllable release of silver ions achieves a long-lasting, broad-spectrum antibacterial effect. To further control the release rate of silver ions, this application also uses mercaptopropylamine to treat the surface of silver-doped zinc oxide. Its thiol groups have a strong affinity for elemental silver, preferentially coordinating with and self-assembling on the surface of elemental silver to form a monomolecular protective layer. This layer effectively inhibits the excessively rapid dissolution of silver, extending the antibacterial period. Simultaneously, by controlling the concentration and treatment time of the mercaptopropylamine solution, it is preferentially adsorbed onto the silver surface without coating the zinc oxide region, thereby preserving the dissolving activity of zinc oxide and Zn. 2+ The preferential release of these substances not only maintains the antibacterial synergistic effect but also provides the necessary ionic environment for the metal ion-mediated silica gel-filler coordination network.

[0026] Secondly, this application provides a method for preparing a controlled-release medical dressing, comprising the following steps: Vinyl-terminated silicone oil, crosslinked hydrogen silicone oil, pyridine-modified hydrogen-containing silicone oil, silane-modified polyether resin, platinum catalyst and inhibitor are mixed evenly to form a silicone gel premix. The modified filler and silver-based antibacterial agent were added to the above-mentioned silica gel premix and stirred evenly to obtain a mixture; The mixture is coated or injection molded and then subjected to a cross-linking and vulcanization reaction catalyzed by a platinum catalyst to obtain a controlled-release medical dressing.

[0027] In summary, this application has the following beneficial effects: This application provides a controlled-release medical dressing and its preparation method. The method enhances the flexibility and moisture permeability of a silane-modified polyether resin. Simultaneously, it utilizes metal ions released by a metal antibacterial agent triggered by wound exudate to in-situ bridge pyridine-grafted silicone gel and polypyrrole-grafted filler, forming a dynamic coordination network. This gradually enhances the cohesive strength without sacrificing the initial softness and fit (elongation at break greater than 250%), effectively preventing residue after removal. Furthermore, the synergistic effect of silver-doped zinc oxide and mercaptopropylamine surface modification achieves silver / zinc dual-ion synergy and sustained-release antibacterial properties, while ensuring the necessary ionic environment for the coordination network. This results in a medical silicone gel material that combines comfortable fit, structural integrity, and long-lasting antibacterial effects. Detailed Implementation

[0028] Preparation Example Preparation Example 1-1: Pyridine-modified hydrogen-containing silicone oil was prepared according to the following method: 400g of hydrogen-containing silicone oil (Jiangsu Keqi SH-75, hydrogen content 0.75%, total Si-H content approximately 3mol) and 105g of 4-vinylpyridine (1mol) were added to a reactor. After purging with nitrogen three times, 0.05g of Karstedt catalyst (purchased from Shanghai Platinum World) was added. The temperature was raised to 80℃, and the reaction was stirred for 6 hours under nitrogen protection. After the reaction was completed, the mixture was distilled under reduced pressure at 150℃ (vacuum degree ≤10mmHg) to remove unreacted monomers and low-boiling substances. After cooling, pyridine-modified hydrogen-containing silicone oil was obtained.

[0029] Preparation Examples 1-2: Pyridine-modified hydrogen-containing silicone oils were prepared according to the following method: 280g of hydrogen-containing silicone oil (Jiangsu Keqi SH-75, hydrogen content 0.75%, total Si-H content approximately 2.08mol) and 87.6g of 4-vinylpyridine (0.834mol) were added to a reactor. After purging with nitrogen three times, 0.04g of Karstedt catalyst (purchased from Shanghai Platinum World) was added. The temperature was raised to 75℃, and the reaction was stirred for 8 hours under nitrogen protection. After the reaction was completed, the mixture was distilled under reduced pressure at 150℃ (vacuum degree ≤10mmHg) to remove unreacted monomers and low-boiling substances. After cooling, pyridine-modified hydrogen-containing silicone oil was obtained.

[0030] Preparation Examples 1-3: Pyridine-modified hydrogen-containing silicone oils were prepared according to the following method: 530g of hydrogen-containing silicone oil (Jiangsu Keqi SH-75, hydrogen content 0.75%, total Si-H content approximately 3.98mol) and 105g of 4-vinylpyridine (1mol) were added to a reactor. After purging with nitrogen three times, 0.06g of Karstedt catalyst (purchased from Shanghai Platinum World) was added. The temperature was raised to 85℃, and the reaction was stirred for 5 hours under nitrogen protection. After the reaction was completed, the mixture was distilled under reduced pressure at 160℃ (vacuum degree ≤10mmHg) to remove unreacted monomers and low-boiling substances. After cooling, pyridine-modified hydrogen-containing silicone oil was obtained.

[0031] Preparation Example 2-1, modified filler, was prepared by following these steps: Step 1: Dry 100g of fumed silica under vacuum at 120℃ for 3 hours, cool and disperse in 300 mL of ethanol / water mixture (water volume percentage is 5%), add 7.5g of 3-aminopropyltriethoxysilane, and then add 0.5mL of glacial acetic acid to adjust the pH to 4.5. Reflux at 80℃ for 18 hours under nitrogen protection; after filtration, wash three times with anhydrous ethanol and dry under vacuum at 80℃ to obtain the aminated filler.

[0032] Step 2: Take 100g of the above aminated filler, 15g of pyrrole-3-carboxylic acid, 31g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 16g of N-hydroxysuccinimide and dissolve them in 200 mL of anhydrous N,N-dimethylformamide. Stir at 5°C in the dark for 12 hours. After filtration, wash with N,N-dimethylformamide / ethanol alternately and dry at 60°C to obtain pyrrole grafted filler.

[0033] Step 3: Take 100g of the above-mentioned pyrrole grafted filler and 50g of pyrrole and dissolve them in 400mL of ethanol / water (volume ratio 2:1). Cool the mixture to 5℃ in an ice bath and slowly add an aqueous solution (2mol / L) containing 240g of FeCl3. Continue to stir and react at 5℃ for 12 hours. After filtration, wash with deionized water until the filtrate is colorless and dry under vacuum at 60℃ for 12 hours to obtain the modified filler with surface-grafted polypyrrole.

[0034] Preparation Example 2-2, modified filler, was prepared by following these steps: Step 1: Dry 100g of fumed silica under vacuum at 110℃ for 4 hours, then disperse it in 300 mL of ethanol / water mixture (water volume percentage is 5%) after cooling. Add 5g of 3-aminopropyltriethoxysilane, and then add 0.5mL of glacial acetic acid to adjust the pH to 4.5. Reflux at 80℃ for 18 hours under nitrogen protection. After filtration, wash three times with anhydrous ethanol and dry under vacuum at 80℃ to obtain the aminated filler.

[0035] Step 2: Take 100g of the above aminated filler, 10g of pyrrole-3-carboxylic acid, 21g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 10.5g of N-hydroxysuccinimide and dissolve them in 200 mL of anhydrous N,N-dimethylformamide. Stir at 5°C in the dark for 10 hours. After filtration, wash with N,N-dimethylformamide / ethanol alternately and dry at 60°C to obtain pyrrole grafted filler.

[0036] Step 3: Take 100g of the above-mentioned pyrrole grafted filler and 40g of pyrrole and dissolve them in 400mL of ethanol / water (volume ratio 3:1). Cool the mixture to 5℃ in an ice bath and slowly add an aqueous solution (2mol / L) containing 193g of FeCl3. Continue to stir and react at 5℃ for 12 hours. After filtration, wash with deionized water until the filtrate is colorless and dry under vacuum at 60℃ for 12 hours to obtain the modified filler with surface-grafted polypyrrole.

[0037] Preparation Example 2-3, modified filler, was prepared according to the following steps: Step 1: Dry 100g of fumed silica under vacuum at 130℃ for 2 hours, then disperse it in 350 mL of ethanol / water mixture (water volume percentage is 5%) after cooling. Add 10g of 3-aminopropyltrimethoxysilane, then add 0.5mL of glacial acetic acid to adjust the pH to 4.5. Reflux at 85℃ for 16 hours under nitrogen protection. After filtration, wash three times with anhydrous ethanol and dry under vacuum at 80℃ to obtain the aminated filler.

[0038] Step 2: Take 100g of the above aminated filler, 20g of pyrrole-3-carboxylic acid, 41g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 21g of N-hydroxysuccinimide and dissolve them in 200 mL of anhydrous N,N-dimethylformamide. Stir at 5°C in the dark for 12 hours. After filtration, wash with N,N-dimethylformamide / ethanol alternately and dry at 60°C to obtain pyrrole grafted filler.

[0039] Step 3: Take 100g of the above-mentioned pyrrole grafted filler and 60g of pyrrole and dissolve them in 400mL of ethanol / water (volume ratio 2:1). Cool the mixture to 5℃ in an ice bath and slowly add an aqueous solution (2mol / L) containing 289g of FeCl3. Continue to stir and react at 10℃ for 14 hours. After filtration, wash with deionized water until the filtrate is colorless and dry under vacuum at 60℃ for 12 hours to obtain the modified filler with surface-grafted polypyrrole.

[0040] Preparation Example 2-4, modified filler, differs from Preparation Example 2-1 in that step 3 is not performed, and the pyrrole grafted filler obtained in step 2 is the final product.

[0041] Preparation Example 2-5, modified filler, differs from Preparation Example 2-1 in that steps 2 and 3 are not performed, and the aminated filler obtained in step 1 is the final product.

[0042] Preparation Example 3-1, modified silver-doped zinc oxide, was prepared according to the following operation: 462.5 g of Zn(NO3)2·6H2O and 17.8 g of AgNO3 (purchased from Huanggang Yinglong Chemical) were dissolved in 800 mL of deionized water, and 5.4 g of glucose (purchased from Wuhan Chuanmao Chemical) was added and stirred. 10 wt% NaOH solution was slowly added dropwise under stirring until the pH reached 11, forming a coprecipitate. The mixed slurry was transferred to a polytetrafluoroethylene-lined hydrothermal reactor and reacted at 160 °C for 8 hours. After natural cooling, it was centrifuged, washed with water until neutral, and dried at 80 °C for 12 hours. Calcination was carried out at 350 °C in air atmosphere for 2 hours to obtain elemental silver-doped zinc oxide (Ag@ZnO, containing approximately 7.5 wt% Ag).

[0043] 7.0 g of mercaptopropylamine was dispersed in 1 L of deionized water to obtain a mercaptopropylamine solution with a concentration of 0.7 wt%. 100 g of the above Ag@ZnO was added and stirred at room temperature for 3 hours. After centrifugation, the solution was washed with water 3 times and dried under vacuum at 60 °C to obtain modified silver-doped zinc oxide.

[0044] Preparation Example 3-2, modified silver-doped zinc oxide, was prepared according to the following operation: 475.0 g of Zn(NO3)2·6H2O and 11.5 g of AgNO3 (purchased from Huanggang Yinglong Chemical) were dissolved in 800 mL of deionized water, and 3.6 g of glucose (purchased from Wuhan Chuanmao Chemical) was added and stirred. 10 wt% NaOH solution was slowly added dropwise under stirring until the pH reached 11, forming a coprecipitate. The mixed slurry was transferred to a polytetrafluoroethylene-lined hydrothermal reactor and reacted at 160 °C for 8 hours. After natural cooling, it was centrifuged, washed with water until neutral, and dried at 80 °C for 12 hours. It was then calcined at 350 °C in air atmosphere for 2 hours to obtain elemental silver-doped zinc oxide (Ag@ZnO, containing approximately 5.0 wt% Ag).

[0045] 3.0 g of mercaptopropylamine was dispersed in 1 L of deionized water to obtain a mercaptopropylamine solution with a concentration of 0.3 wt%. 100 g of the above Ag@ZnO was added and stirred at room temperature for 4 hours. After centrifugation, the solution was washed with water 3 times and dried under vacuum at 60 °C to obtain modified silver-doped zinc oxide.

[0046] Preparation Example 3-3, modified silver-doped zinc oxide, was prepared according to the following operation: 450.0 g Zn(NO3)2·6H2O and 23.0 g AgNO3 (purchased from Huanggang Yinglong Chemical) were dissolved in 800 mL of deionized water, and 7.2 g glucose (purchased from Wuhan Chuanmao Chemical) was added and stirred. 10 wt% NaOH solution was slowly added dropwise under stirring until the pH reached 11, forming a coprecipitate. The mixed slurry was transferred to a polytetrafluoroethylene-lined hydrothermal reactor and reacted at 160 °C for 8 hours. After natural cooling, it was centrifuged, washed with water until neutral, and dried at 80 °C for 12 hours. It was then calcined at 350 °C in air atmosphere for 2 hours to obtain elemental silver-doped zinc oxide (Ag@ZnO, containing approximately 10.0 wt% Ag).

[0047] 10.0 g of mercaptopropylamine was dispersed in 1 L of deionized water to obtain a mercaptopropylamine solution with a concentration of 1.0 wt%. 100 g of the above Ag@ZnO was added and stirred at room temperature for 2 hours. After centrifugation, the solution was washed with water 3 times and dried under vacuum at 60 °C to obtain modified silver-doped zinc oxide.

[0048] Preparation Example 3-4, modified silver-doped zinc oxide, differs from Preparation Example 3-1 in that the amount of mercaptopropylamine used is 15g (concentration 1.5wt%).

[0049] Preparation Example 3-5, modified silver-doped zinc oxide, differs from Preparation Example 3-1 in that the amount of mercaptopropylamine used is 1g (concentration 0.1wt%).

[0050] Preparation Example 3-6, modified silver-doped zinc oxide, differs from Preparation Example 3-1 in that the stirring time at room temperature is 5 hours.

[0051] Preparation Example 3-7, modified silver-doped zinc oxide, differs from Preparation Example 3-1 in that the stirring time at room temperature is 1 hour.

[0052] Preparation Example 3-8, silver-doped zinc oxide, differs from Preparation Example 3-1 in that the resulting silver-doped zinc oxide was not surface-treated with mercaptopropylamine.

[0053] Example Example 1: A controlled-release medical dressing, prepared by the following steps: 700g of vinyl-terminated silicone oil (Zhejiang Weifeng V1000, viscosity approximately 1000mm) 2 35g of crosslinked hydrosilicone oil (Zhejiang Weifeng 202HD075), 7g of pyridine-modified hydrosilicone oil (prepared in Preparation Example 1-1), and 80g of silane-modified polyether resin (Zhongyuan Chemical SAX260) were added to a planetary mixer and mixed at 800 rpm for 30 minutes under nitrogen protection. Then, 0.5g of Karstedt platinum catalyst (purchased from Shanghai Platinum World) and 0.2g of inhibitor (tetramethyltetravinylcyclotetrasiloxane, purchased from Wuxi Lianeng) were added and the mixture was stirred for another 10 minutes to form a homogeneous premix.

[0054] 120g of modified filler (prepared in Preparation Example 2-1) and 20g of modified silver-doped zinc oxide (prepared in Preparation Example 3-1) were added to the above premix, and the mixture was vacuumed to ≤-0.095MPa and stirred to degas for 40 minutes to obtain a uniformly mixed adhesive.

[0055] The adhesive is coated onto a release film with a thickness of 1.5 mm. It is then vulcanized at 45°C for 2 hours and then at 80°C for 2 hours. After cooling, the film is peeled off to obtain a transparent and flexible controlled-release medical dressing.

[0056] Example 2, a controlled-release medical dressing, the preparation steps are as follows: Add 600g of vinyl-terminated silicone oil (Zhejiang Weifeng V350, viscosity approximately 350mm). 230g of crosslinked hydrosilicone oil (Zhejiang Weifeng 202HD075), 5g of pyridine-modified hydrosilicone oil (prepared in Preparation Examples 1-2), and 50g of silane-modified polyether resin (Wacker STP-E10) were added to a planetary mixer and mixed at 800 rpm for 25 minutes under nitrogen protection. Then, 0.2g of Karstedt platinum catalyst (purchased from Shanghai Platinum World) and 0.05g of ethynylcyclohexanol (purchased from Wuhan Yimeng) were added, and stirring was continued for 10 minutes to form a homogeneous premix.

[0057] 80g of modified filler (prepared in Preparation Example 2-2) and 10g of modified silver-doped zinc oxide (prepared in Preparation Example 3-2) were added to the above premix, and the mixture was vacuumed to ≤-0.09MPa and stirred to degas for 40 minutes to obtain a uniformly mixed adhesive.

[0058] The adhesive is coated onto a release film with a thickness of 1.5 mm. It is first vulcanized at 40°C for 2 hours, then vulcanized at 80°C for 3 hours. After cooling, the film is peeled off to obtain a transparent and flexible controlled-release medical dressing.

[0059] Example 3, a controlled-release medical dressing, the preparation steps are as follows: Add 800g of vinyl-terminated silicone oil (Huizhou Jinguige, viscosity approximately 20000 mm). 2 16g of crosslinked hydrosilicone oil (Zhejiang Weifeng 202HD075), 2g of pyridine-modified hydrosilicone oil (prepared in Preparation Examples 1-3), and 100g of silane-modified polyether resin (Zhongyuan Chemical SAX260) were added to a planetary mixer and mixed at 800 rpm for 35 minutes under nitrogen protection. Then, 0.8g of Karstedt platinum catalyst (Pt content 2%) and 0.4g of inhibitor (tetramethyltetravinylcyclotetrasiloxane, purchased from Wuxi Lianeng) were added and the mixture was stirred for another 10 minutes to form a homogeneous premix.

[0060] 150g of modified filler (prepared in Preparation Example 2-3) and 30g of modified silver-doped zinc oxide (prepared in Preparation Example 3-3) were added to the above premix, and the mixture was vacuumed to ≤-0.095MPa and stirred to degas for 50 minutes to obtain a uniformly mixed adhesive.

[0061] The adhesive is coated onto a release film with a thickness of 1.5 mm. It is then vulcanized at 50°C for 1 hour and then at 90°C for 2 hours. After cooling, the film is peeled off to obtain a transparent and flexible controlled-release medical dressing.

[0062] Example 4, a controlled-release medical dressing, differs from Example 1 in that an equal amount of modified silver-doped zinc oxide from Preparation Examples 3-4 is used instead of the modified silver-doped zinc oxide from Preparation Example 3-1.

[0063] Example 5, a controlled-release medical dressing, differs from Example 1 in that an equal amount of modified silver-doped zinc oxide from Preparation Examples 3-5 is used instead of the modified silver-doped zinc oxide from Preparation Example 3-1.

[0064] Example 6, a controlled-release medical dressing, differs from Example 1 in that an equal amount of modified silver-doped zinc oxide from Preparation Examples 3-6 is used instead of the modified silver-doped zinc oxide from Preparation Example 3-1.

[0065] Example 7, a controlled-release medical dressing, differs from Example 1 in that an equal amount of modified silver-doped zinc oxide from Preparation Examples 3-7 is used instead of the modified silver-doped zinc oxide from Preparation Example 3-1.

[0066] Example 8, a controlled-release medical dressing, differs from Example 1 in that an equal amount of silver-doped zinc oxide from Preparation Examples 3-8 is used instead of the modified silver-doped zinc oxide from Preparation Example 3-1.

[0067] Comparative Example Comparative Example 1, a controlled-release medical dressing, differs from Example 1 in that an equal amount of cross-linked hydrosilicone oil (Zhejiang Weifeng 202HD075) is used instead of pyridine-modified hydrosilicone oil (prepared in Preparation Example 1-1).

[0068] Comparative Example 2, a controlled-release medical dressing, differs from Example 1 in that an equal amount of the modified filler from Preparation Example 2-4 is used to replace the modified filler from Preparation Example 2-1.

[0069] Comparative Example 3, a controlled-release medical dressing, differs from Example 1 in that an equal amount of the modified filler from Preparation Example 2-5 is used to replace the modified filler from Preparation Example 2-1.

[0070] Comparative Example 4, a controlled-release medical dressing, differs from Example 1 in that an equal amount of chitosan (80% degree of deacetylation) is used to replace the modified silver-doped zinc oxide of Preparation Example 3-1.

[0071] Comparative Example 5, a controlled-release medical dressing, differs from Example 1 in that it does not contain silane-modified polyether resin (Konagawa Chemical SAX260).

[0072] Performance testing Experiment 1: Flexibility (Elongation at Break) Test Sample preparation: Samples were cut using a sharp die to obtain Type V dumbbell-shaped specimens from the examples and comparative samples (total length 63.5 mm, narrow parallel section length 9.53 mm, width 3.18 mm, thickness equal to the actual thickness of the silicone gel 1.5 mm). At least seven specimens were prepared in parallel for each group, ensuring smooth, unblemished edges. The specimens were conditioned for 24 hours in a standard laboratory environment (23±2℃, relative humidity 50±5%).

[0073] Test Method: The test was conducted according to ASTM D638-22, "Standard Test Method for Tensile Properties of Plastics". A tensile testing machine suitable for films and soft materials was used, equipped with pneumatic contact clamps. Rubber pads were attached to the contact surfaces of the clamps to prevent slippage and damage to the specimens. During the test, the specimens were symmetrically clamped in the clamps, ensuring that the force axis was aligned with the centerline of the specimen. The initial clamp spacing was set to 25.4 mm, and the tensile speed was 250 mm / min. The elongation (%) at fracture and the maximum tensile force were recorded. The final result was the arithmetic mean of seven valid specimens. If a specimen fractured at the clamp contact point or shoulder area, the data was discarded and a retest was conducted.

[0074] Experiment 2: 180° peel integrity rate test Sample preparation: The silicone gels of the examples and comparative examples were cut into strips of 25mm×100mm. The substrate was fresh hairless pigskin (thickness 2.5±0.2mm, subcutaneous fat removed, soaked in physiological saline for 10 minutes and then dried).

[0075] Test Method: Following the specifications in GB / T 2792-2014 "Test Method for Peel Strength of Adhesive Tapes", one end of the silicone gel was attached to the substrate, and a 2kg rubber roller was used to roll it back and forth three times at approximately 300mm / min. The area was then placed in a standard environment (23±2℃, relative humidity 50±5%) for 30 minutes. Peeling was then performed at a 180° peel angle and a speed of 300mm / min. After peeling, the silicone gel was visually inspected to ensure it was completely detached. An optical microscope was used to observe the substrate surface for debris and residue. The silicone gel integrity rate was calculated as (number of samples without residue / total number of tests) × 100%.

[0076] Experiment 3: Simulated wound exudate immersion test Test method: Take a 2cm×2cm silicone gel sample and weigh it, recording the weight as W0. Completely immerse the silicone gel in simulated wound exudate (pH 7.4 phosphate buffered saline PBS + 0.9% NaCl + 1% bovine serum albumin BSA) and soak it at a constant temperature of 37±1℃ for 72 hours. After removing it, gently absorb the surface liquid with filter paper, and then place the sample in a 37℃ oven to dry for 1 hour (until there is no visible moisture on the surface). After cooling to room temperature, immediately test its elongation at break and 180° peel integrity rate according to the conditions of Test 1 and Test 2 above.

[0077] Experiment 4: Long-lasting antibacterial performance test Sample preparation: Cut the silica gels of the examples and comparative examples into 50mm×50mm square pieces and sterilize them with ultraviolet light; and set up a blank control group (silicone gel without antibacterial agent).

[0078] Test methods: (1) Antibacterial rate verification: In accordance with the provisions of ISO 22196:2011 "Measurement of antibacterial activity on plastic surfaces and other non-porous surfaces", 0.4 mL of bacterial suspension (Escherichia coli (ATCC 8739)) was prepared. 5 (CFU / mL) was added to the sample surface; a thin film was covered, and the sample was incubated at 37°C for 24 hours; then the bacterial solution was eluted, serially diluted, and plate counts were performed. The antibacterial rate was calculated as [(CT) / C]×100%, where C is the number of viable bacteria in the control group and T is the number of viable bacteria in the sample group.

[0079] (2) Antibacterial long-term effect verification: The silicone gel was first soaked in simulated exudate for 7 days (37°C, and fresh simulated wound exudate was replaced daily during the soaking process), and then the above antibacterial test was performed; the initial antibacterial rate and the antibacterial rate after soaking for 7 days were compared.

[0080] Table 1. Performance Test Results

[0081] Analysis of experimental results: As shown by the swelling indices before and after examples 1 to 3, before soaking in simulated wound exudate, a certain number of silicone gel samples exhibited structural incompleteness and silicone gel residue upon peeling. However, after soaking, all peeled samples showed intact structures, with no silicone gel fragmentation or residue, and their elongation at break also increased. This indicates that the cohesive strength and elongation at break of the silicone gel samples were synergistically improved after soaking. This may be because, after soaking, the exudate penetrated and desorbed the modified silver-doped zinc oxide, releasing zinc and silver ions. These ions formed a non-rigid coordination network with the pyridine groups in the silicone gel substrate and the polypyrrole segments on the filler surface, simultaneously improving the cohesive strength and elongation at break of the silicone gel. This allows the silicone gel to maintain good wound adhesion and extensibility, and it is less prone to fragmentation and residue upon peeling.

[0082] Compared to Example 1, Example 4 (mercaptopropylamine concentration 1.5 wt%, higher than the lower limit of 1.0 wt%) showed poorer peel integrity after immersion, indicating that high concentrations of mercaptopropylamine reduce cohesive strength. This may be because excessive concentrations lead to an excess of mercaptopropylamine, which readily assembles and adheres to the zinc oxide surface, inhibiting Zn production. 2+ Release, and may even affect Ag +The release rate of mercaptopropylamine (MPA) is too low, resulting in insufficient coordination and difficulty in forming a high-density coordination network, leading to a decrease in cohesive strength. Similarly, in Example 6, excessively long treatment time causes mercaptopropylamine to easily self-assemble and form an adhesion layer on the zinc oxide surface, reducing the release of metal ions and causing deterioration in cohesive strength and peel integrity. In Examples 5 and 8 (MPA concentration 0.1 wt%, below the lower limit of 0.3 wt%), the antibacterial rate was slightly lower after 7 days of immersion, while the peel integrity rate remained at 100%. This may be because the mercaptopropyl protective layer was insufficient or completely absent, leading to Ag... + The initial high release rate helps form a dense coordination network, but the silver content decreases later, reducing the release rate and decreasing the antibacterial ability. Similarly, in Example 7, insufficient treatment time results in an inadequate thiol protective layer, leading to a decrease in Ag... + The initial release is large, but the release decreases in the later stages, resulting in a decline in antibacterial ability.

[0083] Compared to Example 1, Comparative Example 1 (using cross-linked hydrogen silicone oil instead of pyridine-modified hydrogen silicone oil) achieved 100% peel integrity before and after immersion, but the elongation at break before and after immersion was significantly deteriorated (not reaching the lower limit of 250%), failing to meet the flexibility requirements of silicone gel and making it difficult to effectively conform to irregular or highly curved surfaces of the human body, resulting in poor extensibility and comfort. The reason is that the lack of pyridine groups prevents the formation of a coordination network with modified fillers and metal ions; and the excessive amount of cross-linking hydrogen leads to excessively high cross-linking density, causing a sharp decrease in flexibility.

[0084] Comparative Example 2 (pyrrole grafting only, without polymerization to polypyrrole) showed a significantly worse peel integrity rate before and after immersion compared to Example 1. This is because the monomeric pyrrole has weak coordination ability, making it difficult to form a sufficiently dense and strong coordination network, and the cohesive strength was not sufficiently improved. Similarly, Comparative Example 3 (aminosilane modification only, without pyrrole monomer grafting) also showed a significantly worse peel integrity rate before and after immersion compared to Comparative Example 1, and its cohesive strength and peel integrity rate decreased after immersion compared to before immersion.

[0085] Comparative Example 4 (chitosan replacing silver-doped zinc oxide) showed a significant deterioration in peel integrity rate before and after immersion compared to Example 1, and the cohesive strength and peel integrity rate decreased after immersion. This is because chitosan, lacking a metal antibacterial agent, releases metal ions that cannot synergistically form a coordination network with polypyrrole and pyridine groups, thus failing to contribute to cohesive reinforcement.

[0086] Comparative Example 5 (silane-free modified polyether resin) showed a significant deterioration in elongation at break before use, and the improvement in peel integrity rate after soaking was limited. This is because, on the one hand, the lack of hydrophilic polyether segments led to the material's rigidity and reduced flexibility; on the other hand, the decreased hydrophilicity of the silicone gel matrix made it difficult for the exudate to penetrate and diffuse and contact the metal antibacterial agent, resulting in a decrease in the release of metal ions and difficulty in forming a dense and strong coordination network, thus limiting the improvement in cohesive strength and peel integrity rate.

[0087] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A controlled-release medical dressing, characterized in that, The raw materials include the following parts by weight: 60-80 parts of vinyl-terminated silicone oil, 1-5 parts of crosslinked hydrogen silicone oil, 0.2-0.8 parts of pyridine-modified hydrogen-containing silicone oil, 5-10 parts of silane-modified polyether resin, 8-15 parts of modified filler, 0.01-0.1 parts of platinum catalyst, 0.005-0.05 parts of inhibitor, and 1-3 parts of silver-based antibacterial agent; the modified filler is grafted with polypyrrole on its surface.

2. The controlled-release medical dressing according to claim 1, characterized in that, The pyridine-modified hydrogen-containing silicone oil is prepared by hydrosilylation of a hydrogen-containing silicone oil having at least two Si-H atoms with vinylpyridine, wherein the molar ratio of Si-H to vinylpyridine in the hydrogen-containing silicone oil is 2-4:1-1.

5.

3. The controlled-release medical dressing according to claim 1, characterized in that, The preparation steps of the modified filler include: Aminosilane coupling agents are grafted onto the surface of the filler to obtain aminated modified fillers; Aminated modified fillers are subjected to amidation reactions with carboxypyrrole compounds under the action of an activator to obtain pyrrole-grafted fillers; Pyrrole-grafted filler, pyrrole monomer, and oxidant are subjected to in-situ oxidative polymerization in a solvent to obtain a modified filler with surface-grafted polypyrrole.

4. The controlled-release medical dressing according to claim 3, characterized in that, The carboxypyrrole is pyrrole-3-carboxylic acid.

5. The controlled-release medical dressing according to claim 3, characterized in that, The mass ratio of the aminated modified filler, carboxypyrrole compound, and activator is 100:10-20:20-65.

6. The controlled-release medical dressing according to claim 3, characterized in that, The mass ratio of the pyrrole grafted filler to the pyrrole monomer is 1:0.4-0.

6.

7. The controlled-release medical dressing according to claim 1, characterized in that, The silver-based antibacterial agent is a modified silver-doped zinc oxide.

8. The controlled-release medical dressing according to claim 7, characterized in that, The mass ratio of silver to zinc oxide in the modified silver-doped zinc oxide is 5-10:90-95.

9. The controlled-release medical dressing according to claim 7, characterized in that, The modified silver-doped zinc oxide is prepared by soaking silver-doped zinc oxide in a 0.3-1 wt% mercaptopropylamine solution for 2-4 hours.

10. A method for preparing a controlled-release medical dressing, characterized in that, Includes the following steps: According to the formulation of the medical silicone gel according to any one of claims 1 to 9, vinyl-terminated silicone oil, crosslinked hydrogen silicone oil, pyridine-modified hydrogen-containing silicone oil, silane-modified polyether resin, platinum catalyst and inhibitor are mixed evenly to form a silicone gel premix. The modified filler and silver-based antibacterial agent were added to the above-mentioned silica gel premix and stirred evenly to obtain a mixture; The mixture is coated or injection molded and then subjected to a cross-linking and vulcanization reaction catalyzed by a platinum catalyst to obtain a controlled-release medical dressing.

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