An antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions.

Abstract

This invention discloses an antibacterial and anti-scarring burn dressing that provides anti-permeability and anti-infection functions, belonging to the field of medical dressing technology. The backing layer is a breathable, antibacterial, and water-resistant elastic film; the drug-release regulating layer is a porous polymer membrane with a gradient pore size structure; the core layer contains a first active pharmaceutical ingredient; the interface isolation layer is a dense polymer membrane or a water-repellent porous membrane; the wound contact layer is a silicone gel layer with a microporous structure; and the hydrophobic anti-scarring drug is only loaded on the wound-facing side of the silicone gel layer. The drug-release regulating layer of this invention has a gradient pore size structure, and the interface isolation layer allows for the rapid but not sudden release of the hydrophilic antibacterial agent during the wound healing inflammatory phase, effectively controlling infection. Simultaneously, the interface isolation layer physically isolates the core layer from the wound contact layer, ensuring the continuous release of the hydrophobic anti-scarring drug during the proliferation and remodeling phases, enabling sequential synergistic treatment of antibacterial followed by anti-scarring.

Description

Technical Field

[0001] This invention relates to the field of medical dressing technology, specifically to an antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions. Background Technology

[0002] Burns are a common type of trauma in clinical practice. Deep burn wounds often face two major problems during the healing process: wound infection and post-healing scar hyperplasia. Infection can lead to delayed wound healing, sepsis, and even endanger life, while scar hyperplasia affects appearance and function, causing long-term distress to patients. To address the problem of burn wound infection, various antibacterial dressings have been developed, such as multi-layer antibacterial dressings containing a silver ion antibacterial layer, which can effectively inhibit the growth of bacteria in the wound. To address the problem of scar hyperplasia, silicone gel drug-loaded layers have been used for scar treatment, achieving anti-scarring effects through the sealing hydration and sustained drug release of silicone gel.

[0003] The shortcomings of existing antibacterial and anti-scarring burn dressings are:

[0004] 1. Patent document CN114984301B discloses an antibacterial dressing for promoting scarless wound healing and its preparation method. "This invention discloses an antibacterial dressing for promoting scarless wound healing and its preparation method. The dressing, by weight, consists of the following components: 0.05-0.1 parts of hyperbranched polylysine anti-scarring complex, 0.1-2.0 parts of carbomer, 1-10 parts of thickener, 2-12 parts of moisturizer, 60-90 parts of water, and 1-15 parts of plant extract; and the pH is adjusted to 6.8-7.2 by alkali. This invention utilizes hyperbranched..." A novel complex synthesized by chemical grafting polylysine and an anti-scarring drug retains both the antibacterial activity of hyperbranched polylysine and the ability of the anti-scarring drug to inhibit scar formation. Simultaneously, a film-forming agent can form a breathable and moisturizing film on the skin surface, keeping the wound moist and promoting wound healing without causing scarring. However, the antibacterial dressing described in the aforementioned document is difficult to design to achieve a synergistic treatment sequence of antibacterial followed by anti-scarring, leading to interference between the release of the two drugs and hindering optimal therapeutic efficacy. Summary of the Invention

[0005] The purpose of this invention is to provide an antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions, so as to solve the technical problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions, comprising a backing layer, a drug sustained-release regulating layer, a core layer, an interface isolation layer, and a wound contact layer that are sequentially stacked and bonded together by a medical adhesive;

[0007] The backing layer is an elastic film that is breathable and has antibacterial and water-resistant properties.

[0008] The drug sustained-release control layer is a porous polymer membrane with a gradient pore size structure, wherein the pore size on the side facing the backing layer is smaller than the pore size on the side facing the core layer.

[0009] The core layer contains a first active pharmaceutical ingredient, which is a hydrophilic antibacterial agent;

[0010] The interface isolation layer is a dense polymer membrane or a water-repellent porous membrane with a thickness of 0.01-0.03 mm.

[0011] The wound contact layer contains a second active pharmaceutical ingredient, which is a hydrophobic anti-scarring drug;

[0012] The wound contact layer is a silicone gel layer with a microporous structure, and the hydrophobic anti-scarring drug is only loaded on the side of the silicone gel layer facing the wound.

[0013] Preferably, the drug sustained-release control layer is a polyurethane porous membrane, a polylactic acid porous membrane, or a polycaprolactone porous membrane, and its pore size gradually increases from the backing layer side to the core layer side along the thickness direction.

[0014] Preferably, the backing layer is a polyurethane film, a polyester film, or a polyether copolyamide film.

[0015] Preferably, the core layer is an absorbent layer composed of at least one of nonwoven fabric, polyurethane foam, or sodium carboxymethyl cellulose fiber, and the hydrophilic antibacterial agent is selected from one or more of silver ion antibacterial agents, nano silver, polyhexamethylene biguanide, chlorhexidine acetate, and chitosan.

[0016] Preferably, the interface isolation layer is a polyurethane dense membrane, a polyvinyl alcohol membrane, or a polyester porous membrane treated with fluorine water repellency.

[0017] Preferably, the hydrophobic anti-scarring drug is selected from one or more of silicone, asiaticoside, tranilast and heparin sodium, and the silicone gel layer is composed of polydimethylsiloxane or polymethylvinylsiloxane.

[0018] Preferably, the microporous structure of the silicone gel layer is formed by a foaming process or a phase separation method, the average pore size of the micropores is 50-500 μm, and the porosity is 30%-80%. The hydrophobic anti-scarring drug is loaded onto the surface of the silicone gel layer by spraying, and the spraying amount is 0.1-2 mg / cm².

[0019] Preferably, it further includes a release layer disposed below the wound contact layer, the release layer being a polyester film or paper coated with a fluorine or silicone release agent.

[0020] Preferably, the total thickness of the backing layer, the drug sustained-release regulating layer, the core layer, the interface isolation layer and the wound contact layer is 1.0-6.0 mm, wherein the thickness of the wound contact layer is 0.1-2.0 mm and the thickness of the drug sustained-release regulating layer is 0.05-0.8 mm.

[0021] Preferably, the preparation steps of this antibacterial and anti-scarring burn dressing are as follows:

[0022] S1. Prepare the backing layer by selecting an elastic film substrate;

[0023] S2. Prepare a drug sustained-release control layer by forming a porous membrane with a gradient pore size structure from a polymer solution through a phase inversion method.

[0024] S3. Prepare the core layer by dissolving or dispersing the hydrophilic antibacterial agent in a solvent and loading it onto the absorbent material by spraying, impregnation or coating, and then drying to obtain the drug-loaded core layer.

[0025] S4. Prepare an interface isolation layer by forming a dense polymer film or a water-repellent porous film on the surface of the core layer, with a thickness of 0.01-0.03 mm.

[0026] S5. Prepare the wound contact layer by forming a silicone gel layer with a microporous structure by foaming or phase separation process of silicone gel precursor. Then, load the hydrophobic anti-scarring drug onto one side surface of the silicone gel layer by spraying at a spraying amount of 0.1-2 mg / cm² and then dry and cure.

[0027] S6. Composite: The backing layer, drug-release regulating layer, drug-loaded dressing core layer, interface isolation layer, and drug-loaded silicone gel wound contact layer are sequentially composited into one piece using a medical adhesive, and then die-cut, packaged, and sterilized to obtain the dressing.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. This invention employs a five-layer structural design, comprising a backing layer, a drug sustained-release regulating layer, a core dressing layer, an interface isolation layer, and a wound contact layer stacked sequentially. The drug sustained-release regulating layer has a gradient pore size structure, and the interface isolation layer has a thickness of 0.01-0.03 mm. This allows the hydrophilic antibacterial agent to be released rapidly but not abruptly during the wound healing inflammatory phase, effectively controlling infection. Simultaneously, the interface isolation layer physically isolates the core dressing layer from the wound contact layer, ensuring the continuous release of the hydrophobic anti-scarring drug during the proliferation and remodeling phases. The release pathways of the two drugs are completely independent, enabling sequential synergistic treatment of antibacterial followed by anti-scarring, overcoming the technical challenge of conflicting release sequences between antibacterial and anti-scarring drugs in existing technologies.

[0030] 2. The backing layer of the present invention uses an elastic film that is both breathable and antibacterial and water-resistant, with a breathability rate in the range of 1700-3200 g / (m²·24h) and a hydrostatic pressure resistance value of 70-100 cmH2O or higher. While effectively preventing external liquids and bacteria from invading the wound, it allows wound exudate to permeate in the form of water vapor, maintaining a suitable moist environment for the wound and achieving a balance between seepage prevention and moisture permeability, thereby avoiding secondary infection caused by the accumulation of exudate.

[0031] 3. The interface isolation layer set in this invention physically isolates the dressing layer and the wound contact layer, effectively preventing the hydrophilic antibacterial agent in the dressing layer from diffusing to the wound contact layer, and at the same time preventing the hydrophobic anti-scarring drug in the wound contact layer from diffusing to the dressing layer, ensuring that the two drugs play an independent role in their respective release pathways, and avoiding the problem of reduced efficacy caused by the mutual diffusion of drugs in different functional layers in the prior art.

[0032] 4. The wound contact layer of this invention uses a silicone gel layer with a microporous structure, which is soft, has mild adhesion, is painless when changing dressings, does not damage new tissue, and the anti-scarring drug is only loaded on the side of the silicone gel layer facing the wound, which can avoid the drug carrier from irritating the wound. At the same time, the results of cytotoxicity test show that it is non-cytotoxic, no infection occurred in animal experiments, and the scar inhibition rate is as high as 78%-92%, which has good biocompatibility and safety. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the antibacterial and anti-scarring burn dressing of the present invention.

[0034] In the diagram: 1. Backing layer; 2. Drug sustained-release control layer; 3. Core layer; 4. Interface isolation layer; 5. Wound contact layer; 6. Hydrophobic anti-scarring drug; 7. Silicone gel layer. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] Example 1: Please refer to Figure 1 An antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions includes a backing layer 1, a drug sustained-release regulating layer 2, a core layer 3, an interface isolation layer 4, and a wound contact layer 5, which are stacked in sequence and bonded together with a medical adhesive.

[0039] Preparation of backing layer 1: A polyurethane film with a thickness of 0.03 mm was used. The moisture permeability of the film was 2500 g / (m²·24h). The test conditions were 38℃, 90% relative humidity, and hydrostatic pressure resistance ≥80cmH2O. Before use, plasma treatment was performed with a power of 100W and a time of 30 seconds.

[0040] Preparation of drug sustained-release control layer 2: Polyurethane resin was dissolved in dimethylformamide to prepare a 15wt% polymer solution. A film with a thickness of 0.5 mm was formed on a glass plate. The film was then immersed in a deionized water coagulation bath at 25°C for 30 minutes. By controlling the coagulation bath temperature and immersion time, solvent and non-solvent exchange was achieved to form a gradient pore structure. The formed porous membrane was then fully immersed in deionized water for 24 hours to remove residual solvent and dried at room temperature. Scanning electron microscopy showed that the average pore size on the side facing the backing layer 1 was 5 μm, and the average pore size on the side facing the core layer 3 was 50 μm. The pore size gradually increased along the thickness direction. The control layer thickness was 0.2 mm, and the porosity was 70%.

[0041] Preparation of core layer 3: Polyurethane foam was selected as the substrate. It was medical grade, 2 mm thick, and had a liquid absorption capacity of 15 times its own weight. Nano-silver antibacterial agent was ultrasonically dispersed in anhydrous ethanol. The nano-silver particle size was 20-50 nm. The ultrasonic power was 200 W and the time was 30 minutes to prepare a dispersion of 0.5 mg / mL. The dispersion was uniformly loaded onto the surface and pores of the polyurethane foam by spraying. The spraying pressure was 0.3 MPa, the spraying distance was 20 cm, and the spraying amount was 1.0 mg / cm². The core layer 3 was dried at 50 °C for 3 hours to obtain the drug-loaded core layer 3. The nano-silver loading was detected by ICP-MS to be 0.95 mg / cm².

[0042] Preparation of interface isolation layer 4: Polyurethane resin was dissolved in dimethylformamide to prepare a 10wt% solution, and a dense film was formed on the surface of the core layer 3 by coating. The coating thickness was 0.05mm, and the film thickness after drying was 0.02mm. The drying conditions were 60℃ for 2 hours.

[0043] Preparation of wound contact layer 5: Polydimethylsiloxane and foaming agent azodicarbonamide were mixed evenly with a foaming agent addition of 1 wt%. The mixture was coated onto the release film with a thickness of 1 mm and foamed at 130℃ for 10 minutes to form a microporous structure. Scanning electron microscopy showed that the average pore size of the micropores was 200 μm and the porosity was 60%. The anti-scarring drug silicone was dissolved in isopropanol to prepare a 2 wt% solution, which was loaded onto one side of the silicone gel layer 7 by spraying. This side was the opposite side of the release film. The spraying pressure was 0.2 MPa, the spraying distance was 15 cm, and the spraying amount was 0.5 mg / cm². The layer was dried and cured at 50℃ for 2 hours to obtain the drug-loaded wound contact layer 5. The silicone loading amount was measured to be 0.48 mg / cm² by weighing. The release layer was retained below the wound contact layer 5 and was peeled off before use.

[0044] Composite and Sterilization: The backing layer 1, drug sustained-release regulating layer 2, dressing core layer 3, interface isolation layer 4, and drug-loaded silicone gel wound contact layer 5 are stacked in sequence and laminated using medical acrylate pressure-sensitive adhesive at a pressure of 0.3 MPa and a temperature of 50°C. The dressing is then die-cut into 10cm×10cm sizes, sealed in polyethylene and aluminum foil composite bags, and sterilized by Cobalt-60 irradiation with an irradiation dose of 20 kGy to obtain the finished dressing.

[0045] Example 2: Please refer to Figure 1 An antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions, the specific implementation method is the same as in Example 1, except that:

[0046] Preparation of backing layer 1: Polyester film with a thickness of 0.025 mm, a moisture permeability of 1800 g / (m²·24h), and a hydrostatic pressure resistance value ≥100 cmH2O is used;

[0047] Preparation of drug sustained-release regulating layer 2: Polylactic acid resin with a molecular weight of 200 kDa was used to replace polyurethane. Polylactic acid was dissolved in dichloromethane to prepare a 12 wt% solution. The coagulation bath was a mixture of deionized water and ethanol at 25°C with a volume ratio of 7:3. The resulting porous membrane had an average pore size of 2 μm on the side facing backing layer 1 and an average pore size of 40 μm on the side facing core layer 3, a thickness of 0.15 mm, and a porosity of 65%.

[0048] Preparation of core layer 3: Sodium carboxymethyl cellulose fiber nonwoven fabric was used as the substrate, hydrocolloid fiber, with a basis weight of 100 g / m². The antibacterial agent was polyhexamethylene biguanide with a purity of ≥99%, which was dissolved in deionized water to prepare a solution of 0.3 mg / mL. The solution was loaded by impregnation for 10 minutes. After removal, excess solution was squeezed out and dried at 50°C for 4 hours. The loading amount was detected by ultraviolet spectrophotometry and was 0.78 mg / cm².

[0049] Preparation of interface isolation layer 4: Polyvinyl alcohol film is used instead of polyurethane film. Polyvinyl alcohol is dissolved in deionized water to prepare an 8 wt% solution, which is then coated onto the surface of core layer 3 to form a film with a thickness of 0.015 mm after drying.

[0050] Preparation of wound contact layer 5: Polymethylvinylsiloxane was used instead of polydimethylsiloxane. The anti-scarring drug was asiaticoside with a purity of ≥98%, which was dissolved in ethanol to prepare a 1wt% solution. The spraying amount was 1.0 mg / cm², and the loading amount was 0.95 mg / cm² as determined by HPLC.

[0051] Example 3: Please refer to Figure 1 An antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions, the specific implementation method is the same as in Example 1, except that:

[0052] Preparation of backing layer 1: A polyether copolyamide film with a thickness of 0.03 mm, a moisture permeability of 3200 g / (m²·24h), and a hydrostatic pressure resistance of ≥70 cmH2O is used.

[0053] Preparation of drug sustained-release regulating layer 2: Polycaprolactone resin with a molecular weight of 80 kDa was used to replace polyurethane. Polycaprolactone was dissolved in a mixture of dichloromethane and acetone with a volume ratio of 8:2 to prepare a 10 wt% solution. The coagulation bath was deionized water at 15 °C. The resulting porous membrane had an average pore size of 1 μm on the side facing backing layer 1 and an average pore size of 30 μm on the side facing core layer 3, a thickness of 0.25 mm, and a porosity of 72%.

[0054] Preparation of core layer 3: Polyurethane foam was used as the substrate, the same as in Example 1. Chitosan was used as the antibacterial agent, with a degree of deacetylation ≥90% and a molecular weight of 100kDa. It was dissolved in 1% acetic acid solution to prepare a solution of 2.0 mg / mL. The solution was loaded by spraying at a rate of 1.5 mg / cm². It was dried at 50°C for 4 hours. The loading amount was measured to be 1.45 mg / cm² by ultraviolet spectrophotometry.

[0055] Preparation of interface isolation layer 4: A polyester porous membrane treated with fluorine water repellency was used. The polyester porous membrane with a pore size of 0.5 μm and a thickness of 0.02 mm was selected and impregnated in fluorine water repellency agent with a concentration of 2% for 5 minutes. After removal, it was cured at 120℃ for 3 minutes. The treated porous membrane was then laminated to the surface of the core layer 3 with medical adhesive.

[0056] Preparation of wound contact layer 5: The anti-scarring drug is a compound of silicone and asiaticoside. Silicone and asiaticoside are mixed at a mass ratio of 3:1 and dissolved in a mixture of ethanol and isopropanol with a volume ratio of 1:1 to prepare a 3wt% solution. The spraying amount is 1.5 mg / cm², and the loading amount is 1.45 mg / cm² as determined by HPLC.

[0057] Comparative Example 1: The specific implementation method is the same as Example 1, except that: the drug sustained-release control layer 2 is not set, and the core layer 3 is directly bonded to the backing layer 1 through a medical adhesive.

[0058] Comparative Example 2: The specific implementation method is the same as that in Example 1, except that: no interface isolation layer 4 is set, and the core layer 3 and the wound contact layer 5 are directly bonded together by medical adhesive.

[0059] Comparative Example 3: Using a combination of commercially available products:

[0060] Antibacterial dressing: Silver ion antibacterial dressing;

[0061] Anti-scarring patches: silicone patches;

[0062] Instructions for use: Cover the wound with silver ion antibacterial dressing from day 1 to day 7, and change it every 2 days. From day 8 to day 28, replace it with silicone patch, and change it every 2 days.

[0063] Performance testing:

[0064] Test 1: Thickness test: According to GB / T 6672-2001 standard, the thickness of each layer and the total thickness of the dressing were measured using a thickness gauge with an accuracy of 0.001 mm. Five points were measured for each sample, and the average value was taken.

[0065] Test 2: Moisture permeability test: The moisture permeability tester was used. The test conditions were 38℃ and 90% relative humidity. Each sample was measured 3 times and the average value was taken.

[0066] Test 3: Hydrostatic pressure test: The hydrostatic pressure tester was used. The test conditions were room temperature. Each sample was tested 3 times and the average value was taken.

[0067] Test 4: Pore size and porosity test: The cross-sectional structure of the membrane was observed using a scanning electron microscope, and the average pore size and pore size distribution were analyzed using Image-ProPlus software. The porosity was determined using the ethanol displacement method: The sample was weighed and recorded as W1, immersed in anhydrous ethanol for 24 hours, removed and dried, and weighed again and recorded as W2. The porosity was calculated using the formula (W2-W1) / (ρethanol×V)×100%, where ρethanol is the density of ethanol and V is the sample volume.

[0068] Test 5: Drug loading test: Nano silver: ICP-MS was used to detect the drug-loaded core layer 3. The core layer 3 was cut into pieces, digested with aqua regia, and the concentration of silver ions was detected after adjusting the volume.

[0069] Polyhexamethylene biguanide: Detected by ultraviolet spectrophotometry at a wavelength of 236 nm. The drug-loaded core layer 3 was cut into pieces, soaked in 0.1 M hydrochloric acid for 24 hours, and the supernatant was taken for detection.

[0070] Chitosan: Ultraviolet spectrophotometry was used for detection at a wavelength of 210 nm. The drug-loaded core layer 3 was cut into pieces, soaked in 1% acetic acid for 24 hours, and the supernatant was taken for detection.

[0071] Silicone: The weight of the drug-loaded wound contact layer 5 is determined by weighing the drug-loaded layer 5 and subtracting the weight of the unloaded silicone gel layer 7.

[0072] asiaticoside: Detected by HPLC with a C18 column, a mobile phase of acetonitrile and water at a volume ratio of 35:65, and a detection wavelength of 220 nm;

[0073] Test 6: Cytotoxicity Assay: Following ISO 10993-5, the MTT assay was used to detect the viability of human fibroblasts (HSF cells). Dressing samples were cut into 1cm × 1cm pieces and immersed in DMEM medium at an extraction ratio of 1cm² / mL for 24 hours at 37°C. HSF cells were then added at a concentration of 1 × 10⁻⁶ cells / mL. 4Each cell was seeded into a 96-well plate and cultured for 24 hours. Extraction medium was added, and the cells were cultured for another 24 hours. MTT solution (5 mg / mL) was added and cultured for 4 hours. The supernatant was discarded, and DMSO was added to dissolve formazan. The absorbance at 570 nm was measured using a microplate reader, and cell viability was calculated. The cell viability calculation formula was: experimental group OD value divided by control group OD value multiplied by 100%. Six wells were tested for each sample, and the average value was taken. The toxicity grading criteria were: cell viability ≥90% was non-toxic, 60%-89% was mild toxicity, 30%-59% was moderate toxicity, and <30% was severe toxicity.

[0074] Test 7: Animal experiment: Healthy SD rats, half male and half female, weighing 200-250g, 8-10 weeks old, were selected. After 1 week of acclimatization, 3% sodium pentobarbital was injected intraperitoneally at a dose of 30 mg / kg to anesthetize them. The hair on the back was removed and the area was disinfected. A self-made burn instrument was used to contact the skin on the back for 10 seconds to establish a deep second-degree burn model. The self-made burn instrument was a 2cm diameter copper rod heated in a 100℃ water bath. The wound was confirmed by pathological sectioning to have reached the reticular layer of the dermis.

[0075] Rats were randomly divided into 7 groups, with 10 rats in each group:

[0076] Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Blank Control Group;

[0077] Furthermore, the blank control group was covered with sterile gauze, and all dressings were changed every 2 days for 28 consecutive days.

[0078] Wound healing rate determination: The wound was photographed with a digital camera on days 3, 7, 14, 21, and 28. The wound area was calculated using Image-Pro Plus software. The wound healing rate was calculated as follows: original wound area minus current wound area, then divided by the original wound area, and multiplied by 100%.

[0079] Infection assessment: Observe the wound for signs of infection such as redness, swelling, exudation, and pus at each dressing change. On the 7th day, collect wound secretions for bacterial culture and count the colony-forming units, which are recorded as CFU.

[0080] Scar scoring: On day 28, the Vancouver Scar Scale was used to assess the scars. The assessment included:

[0081] Color: 0 points indicates normal skin tone, 1 point indicates light pink, 2 points indicates pink, and 3 points indicates dark red;

[0082] Thickness: 0 points indicates normal, 1 point indicates less than 2mm, 2 points indicates 2-5mm, and 3 points indicates greater than 5mm;

[0083] Softness: 0 points indicates normal, 1 point indicates soft, 2 points indicates bendable, and 3 points indicates hard.

[0084] Blood vessel distribution: 0 points indicates normal, 1 point indicates mild, 2 points indicates moderate, and 3 points indicates severe.

[0085] The total score ranges from 0 to 12 points. The higher the score, the more severe the scar. At the same time, the scar height is measured using calipers. The scar height is the difference between the scar height and the normal skin height. The scar inhibition rate is calculated by subtracting the scar height of the experimental group from the scar height of the blank control group, dividing by the scar height of the blank control group, and then multiplying by 100%.

[0086] Performance test results:

[0087] Table 1 Physical Performance Data

[0088]

[0089] Table 2 Results of Cytotoxicity Tests

[0090]

[0091]

[0092] The results showed that the cell survival rate of Examples 1-3 was greater than 90% and there was no cytotoxicity. Comparative Example 1 showed a significant decrease in cell survival rate due to the burst release of nano-silver and exhibited mild cytotoxicity. Comparative Example 2 also showed mild cytotoxicity.

[0093] Table 3. Animal experiment results: Wound healing rate (%)

[0094]

[0095] Table 4. Animal Experiment Results: Infection Assessment

[0096]

[0097] Table 5. Animal Experiment Results: Scar Assessment Results (Day 28)

[0098]

[0099] Furthermore, the mechanism of action of the gradient pore size control layer: The comparison between Examples 1-3 and Comparative Example 1 shows that the gradient pore size control layer can effectively control the release rate of hydrophilic antibacterial agents. In Comparative Example 1 without the control layer, nanosilver experienced severe burst release, resulting in significant cytotoxicity and a cell survival rate of 65.3%. In contrast, Example 1 avoided the cytotoxicity caused by burst release through the gradient pore size control layer, achieving a cell survival rate of 92.5% and realizing long-lasting antibacterial effect.

[0100] The mechanism of the gradient pore size control layer is as follows: the small pore size facing the backing layer 1 is 1-5μm, forming a dense layer, which forms a diffusion barrier for the hydrophilic antibacterial agent and slows down the initial release rate; the large pore size facing the core layer 3 is 30-50μm, forming a loose layer, which is conducive to the uniform distribution and subsequent release of the antibacterial agent in the control layer.

[0101] Mechanism of action of interface isolation layer 4: The comparison between Examples 1-3 and Comparative Example 2 shows that interface isolation layer 4 can effectively prevent the mutual diffusion of hydrophilic antibacterial agent and hydrophobic anti-scarring drug 6. In Comparative Example 2 without isolation layer, the release of the two drugs interferes with each other, while in Example 1, through interface isolation layer 4, the release paths of the two drugs are completely independent.

[0102] Synergistic effect of time-release: Animal experimental data from Examples 1-3 show a precise match with the physiological stages of wound healing:

[0103] Inflammatory phase (0-7 days): Hydrophilic antibacterial agents effectively control wound infection. As shown in Table 4, in Examples 1-3, the bacterial count was less than 100 CFU / cm² on day 7, and no infection occurred.

[0104] Proliferation phase (7-21 days): Hydrophobic anti-scarring drug 6 begins to be released significantly, promoting wound healing. As shown in Table 3, the wound healing rate of Examples 1-3 reached over 89% in 14 days.

[0105] Remodeling period (21-30 days): Hydrophobic anti-scarring drug 6 is continuously released, effectively inhibiting scar hyperplasia. As shown in Table 5, Examples 1-3 achieved a scar inhibition rate of 78%-92% at 28 days, which is significantly better than the control group.

[0106] This time-sequenced release pattern is precisely matched with the physiological stages of wound healing, achieving synergistic treatment of antibacterial followed by anti-scarring;

[0107] Through a five-layer structural design, including a backing layer 1, a drug sustained-release regulating layer 2, a core dressing layer 3, an interface isolation layer 4, and a wound contact layer 5, the following functions are achieved:

[0108] Synergistic release of time: The gradient pore size control layer controls the rapid but not sudden release of hydrophilic antibacterial agents during the inflammatory phase, while the interface isolation layer 4 ensures the continuous release of hydrophobic anti-scarring drugs 6 during the proliferation and remodeling phases, achieving synergistic treatment of antibacterial followed by anti-scarring.

[0109] Anti-seepage and anti-infection: Backing layer 1 is breathable and antibacterial and water-resistant, effectively preventing the invasion of external liquids and bacteria, while allowing wound exudate to seep out;

[0110] To avoid drug interference: the interface isolation layer 4 physically isolates the dressing core layer 3 from the wound contact layer 5, ensuring that the two drugs can work independently;

[0111] Good biocompatibility: The silicone gel wound contact layer 5 is soft, has gentle adhesion, is painless when changing dressings, and is non-cytotoxic;

[0112] The preparation method is simple: each layer can be prepared by conventional processes, the composite process is mature, and it is suitable for large-scale production;

[0113] Therefore, it can effectively solve the technical problems of existing burn dressings, such as single function, functional conflict, sudden release of antibacterial agents, and drug cross-diffusion.

[0114] The working principle utilizes a five-layer structure, including a backing layer 1, a drug-releasing control layer 2, a core layer 3, an interface isolation layer 4, and a wound contact layer 5, stacked sequentially. The drug-releasing control layer 2 features a gradient pore size structure, and the interface isolation layer 4 has a thickness of 0.01-0.03 mm. This allows for the rapid but non-abrupt release of hydrophilic antibacterial agents during the wound healing and inflammatory phase, effectively controlling infection. Simultaneously, the interface isolation layer 4 physically isolates the core layer 3 from the wound contact layer 5, ensuring the continuous release of hydrophobic anti-scarring drugs 6 during the proliferation and remodeling phases. The release pathways of the two drugs are completely independent, enabling sequential synergistic treatment of antibacterial followed by anti-scarring. This overcomes the technical challenge of conflicting release sequences between antibacterial and anti-scarring drugs in existing technologies. The backing layer 1 uses a breathable yet antibacterial and water-resistant elastic film with a permeability of 1700-3200 ppm. Within the range of g / (m²·24h), the hydrostatic pressure tolerance value is above 70-100cmH2O. While effectively preventing external liquids and bacteria from invading the wound, it allows wound exudate to permeate in the form of water vapor, maintaining a suitable moist environment for the wound. This achieves a balance between impermeability and permeability, thereby avoiding secondary infection caused by exudate accumulation. The interface isolation layer 4 physically isolates the dressing layer 3 from the wound contact layer 5, effectively preventing the hydrophilic antibacterial agent in the dressing layer 3 from diffusing into the wound contact layer 5, while simultaneously preventing the hydrophobic anti-scarring drug 6 in the wound contact layer 5 from diffusing into the dressing layer 3, ensuring the safety of both drugs. Each layer functions independently within its respective release pathway, avoiding the reduced efficacy caused by cross-diffusion of drugs in different functional layers in existing technologies. The wound contact layer 5 uses a silicone gel layer 7 with a microporous structure, which is soft, has gentle adhesion, and is painless when changing dressings without damaging new tissue. The anti-scarring drug is only loaded on the side of the silicone gel layer 7 facing the wound, avoiding stimulation of the wound by the drug carrier. At the same time, cytotoxicity test results show no cytotoxicity, no infection occurred in animal experiments, and the scar inhibition rate is as high as 78%-92%, demonstrating good biocompatibility and safety.

[0115] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions, characterized in that: It includes a backing layer (1), a drug release control layer (2), a core layer (3), an interface isolation layer (4), and a wound contact layer (5) that are stacked in sequence and bonded together with a medical adhesive. The backing layer (1) is an elastic film that is breathable and has antibacterial and water-resistant properties; The drug sustained-release control layer (2) is a porous polymer membrane with a gradient pore size structure, and the pore size on the side facing the backing layer (1) is smaller than the pore size on the side facing the core layer (3). The core layer (3) contains a first active pharmaceutical ingredient, which is a hydrophilic antibacterial agent; The interface isolation layer (4) is a dense polymer membrane or a porous membrane with water-repellent treatment, with a thickness of 0.01-0.03 mm; The wound contact layer (5) contains a second active pharmaceutical ingredient, which is a hydrophobic anti-scarring drug (6). The wound contact layer (5) is a silicone gel layer (7) with a microporous structure, and the hydrophobic anti-scarring drug (6) is loaded only on the side of the silicone gel layer (7) facing the wound.

2. The antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions according to claim 1, characterized in that: The drug sustained-release control layer (2) is a polyurethane porous membrane, a polylactic acid porous membrane or a polycaprolactone porous membrane, and the pore size gradually increases from the backing layer (1) side to the core layer (3) side along the thickness direction.

3. The antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions according to claim 1, characterized in that: The backing layer (1) is a polyurethane film, a polyester film, or a polyether copolyamide film.

4. The antibacterial and anti-scarring burn dressing according to claim 1, characterized in that: The core layer (3) is an absorbent layer composed of at least one of nonwoven fabric, polyurethane foam or sodium carboxymethyl cellulose fiber, and the hydrophilic antibacterial agent is selected from one or more of silver ion antibacterial agents, nano silver, polyhexamethylene biguanide, chlorhexidine acetate and chitosan.

5. The antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions according to claim 1, characterized in that: The interface isolation layer (4) is a polyurethane dense membrane, a polyvinyl alcohol membrane, or a polyester porous membrane treated with fluorine water repellency.

6. The antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions according to claim 1, characterized in that: The hydrophobic anti-scarring drug (6) is selected from one or more of silicone, asiaticoside, tranilast and heparin sodium, and the silicone gel layer (7) is composed of polydimethylsiloxane or polymethylvinylsiloxane.

7. The antibacterial and anti-scarring burn dressing according to claim 1, characterized in that: The microporous structure of the silicone gel layer (7) is formed by foaming process or phase separation method. The average pore size of the micropores is 50-500μm and the porosity is 30%-80%. The hydrophobic anti-scarring drug (6) is loaded onto the surface of the silicone gel layer (7) by spraying, and the spraying amount is 0.1-2mg / cm².

8. The antibacterial and anti-scarring burn dressing that provides anti-seepage and anti-infection functions according to claim 1, characterized in that: It also includes a release layer disposed below the wound contact layer (5), the release layer being a polyester film or paper coated with a fluorine or silicone release agent.

9. The antibacterial and anti-scarring burn dressing according to claim 1, characterized in that: The total thickness of the backing layer (1), drug release control layer (2), core layer (3), interface isolation layer (4) and wound contact layer (5) is 1.0-6.0 mm, the thickness of the wound contact layer (5) is 0.1-2.0 mm, and the thickness of the drug release control layer (2) is 0.05-0.8 mm.

10. A method for preparing an antibacterial and anti-scarring burn dressing with anti-seepage and anti-infection functions according to any one of claims 1-9, characterized in that, The preparation steps of this antibacterial and anti-scarring burn dressing are as follows: S1. Prepare the backing layer (1), and select an elastic film substrate; S2. Preparation of drug sustained-release control layer (2): The polymer solution is transformed into a porous membrane with a gradient pore size structure by phase inversion method; S3. Preparation of the core layer (3): The hydrophilic antibacterial agent is dissolved or dispersed in a solvent and loaded onto the absorbent material by spraying, impregnation or coating. After drying, the drug-loaded core layer (3) is obtained. S4. Prepare an interface isolation layer (4) to form a dense polymer film or a water-repellent porous film on the surface of the core layer (3) with a thickness of 0.01-0.03 mm. S5. Prepare the wound contact layer (5). Form a silicone gel layer (7) with a microporous structure by foaming or phase separation process of silicone gel precursor. Then load the hydrophobic anti-scarring drug (6) onto one side surface of the silicone gel layer (7) by spraying. The spraying amount is 0.1-2 mg / cm². Dry and cure. S6. Composite: The backing layer (1), drug sustained-release control layer (2), drug-loaded dressing core layer (3), interface isolation layer (4) and drug-loaded silicone gel wound contact layer (5) are sequentially composited into one piece using a medical adhesive, and then die-cut, packaged and sterilized to obtain the dressing.

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