Medical dressing for resisting infection of skin wound surface and preparation method thereof

Abstract

The application discloses a medical dressing for resisting infection of a skin wound and a preparation method thereof, and relates to the fields of biological medicine materials and wound care. The medical dressing comprises a polyurethane film and antibiotics loaded on the polyurethane film. The preparation method comprises the following steps: step 1, etching processing is performed on the polyurethane film by using a 3D micro-nano laser etching instrument; and step 2, after etching, the polyurethane film is incubated with antibiotics and stored at low temperature to obtain the medical dressing. The novel dressing prepared by the application has good antibacterial effect on the basis of not affecting the original mechanical properties and moisture permeability of the polyurethane film. The application can effectively inhibit bacterial infection and inflammatory reaction of a rat skin wound, and provides an important treatment reference for clinical skin soft tissue wound, pollution and rehabilitation of other chronic skin diseases.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biomedical materials and wound care, in particular to a medical dressing for skin wound infection resistance and a preparation method thereof. BACKGROUND

[0002] Skin trauma is extremely common in daily life, whether it is a minor scratch or a deep laceration, it can cause varying degrees of infection. As the first line of defense for the human body, the integrity of the skin is once damaged, especially under chronic pollution conditions, these wounds are prone to bacterial infection, causing persistent inflammatory response, not only delaying the healing process, but in severe cases, it can lead to sepsis and its associated high medical burden.

[0003] The occurrence of skin trauma infection involves multiple links. First, microorganisms enter the tissue through the damaged skin barrier, causing an inflammatory response. These microorganisms can come from the surrounding environment, contaminated objects or the patient's own skin flora. Second, the host's immune response plays a crucial role in controlling infection. However, when the immune response is insufficient or excessive, it can lead to the spread or aggravation of infection. In addition, the types of infections caused by skin trauma are diverse, including but not limited to pyogenic infection, fungal infection, etc. Pyogenic infection is mainly manifested as local redness, swelling, pain, fever, etc. Severe cases may develop sepsis or septicemia. Fungal infection is more common in patients in a humid environment or long-term use of antibiotics, and is manifested as local itching, erythema, desquamation, etc. In clinical application, to prevent excessive inflammatory response, bacterial infection or self-infection leading to treatment failure, medical dressings are usually used locally in combination with systemic anti-inflammatory and antibacterial drugs, which may lead to the generation of antibiotic-resistant pathogens.

[0004] As a medical material, dressings are used to cover wounds to isolate the external environment and provide the appropriate environment for skin trauma healing. Global medical dressing market size data shows that the total size of the global wound dressing market in 2022 was US$13.7 billion, of which high-end dressings accounted for 54.47%, with a market size of US$7.46 billion. It is estimated that by 2030, the global wound dressing market will reach US$19 billion, with a CAGR of 4.14%, and the high-end dressing market is expected to reach US$10.6 billion, with a CAGR of 4.46%. The domestic medical dressing industry competition pattern shows that the market is mainly dominated by domestic manufacturers, focusing on traditional products, and foreign manufacturers mainly concentrate in the high-end wound dressing market, including Johnson & Johnson, 3M, Systech, Medtronic, Comfort Keepers, and ConvaTec. Therefore, there is an urgent and urgent need for advanced, cost-effective high-end medical dressings for skin trauma (including infected trauma) in the Chinese market and even the global market.

[0005] Currently, the clinically available antibacterial wound dressings are mostly achieved by spraying heavy metal elements on traditional dressing surfaces such as cotton gauze and yarn to increase the antibacterial effect, but their moisture permeability, softness and waterproofness are not ideal. Compared with traditional dressings, polyurethane medical dressings have obvious advantages in terms of sterility, transparency, softness and comfort, moisture permeability, water resistance and biocompatibility. Therefore, polyurethane dressings are widely used in the clinical treatment of various non-chronic wounds, as well as wound protection after specific surgery or treatment. However, polyurethane medical dressings have certain deficiencies in terms of hydrophilicity and antibacterial performance. Therefore, it is particularly important to develop a new type of polyurethane medical dressing with the functions of promoting wound healing and resisting infection.

[0006] Laser processing, with its highly precise technical characteristics, endows thin film materials with specific patterning capabilities in the processing area. This function is achieved by precisely editing laser processing parameters, adjusting processing paths or using masks, allowing the thin film to load drugs selectively according to the inflammation of the patient's wound. Laser processing is not limited to physical processing of the thin film, but also affects the adhesion of the drug by changing the surface chemical properties of the thin film. This means that by adjusting the laser processing parameters, the drug loading capacity of the thin film can be effectively regulated to achieve more precise and personalized treatment. The micro-nano structure formed on the surface of the thin film is also believed to significantly affect the adhesion between the dressing and the antibiotic, thereby passively controlling the release speed of the drug. The application of this technology provides new ideas and methods for wound treatment and drug release in the medical field. This new type of dressing not only can be used for clinical treatment, but also has a wide application prospect in outdoor medical treatment. With the increasing demand for lightweight, intelligent and comfortable outdoor equipment, wound dressings will become particularly important for outdoor workers to quickly stop bleeding and prevent infection. SUMMARY

[0007] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a skin wound anti-infection medical dressing and a preparation method thereof. The new type of dressing prepared by the present application can have good antibacterial effect without affecting the original mechanical properties and moisture permeability of the polyurethane film. The present application can effectively inhibit bacterial infection and inflammatory response in rat skin wounds, providing an important treatment reference for the rehabilitation of clinical skin soft tissue wounds, pollution and other chronic skin diseases.

[0008] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0009] The present application provides a skin wound anti-infection medical dressing, which comprises a polyurethane film and an antibiotic loaded on the polyurethane film.

[0010] Preferably, the polyurethane film is an ultra-thin transparent material with an average film thickness of 30-100 μm.

[0011] Preferably, the drug loading of the antibiotic on the polyurethane film is 0.0625-0.625 μg / mm 2 .

[0012] Preferably, the polyurethane film has a tensile strength of 5-15 MPa, an elongation at break of 400-700%, and a Young's modulus of 5-15 MPa.

[0013] Preferably, the polyurethane film has a moisture permeability of 200-400 g / (m 2 ·24h).

[0014] Preferably, the antibiotic is selected from the group consisting of β-lactam antibiotics, macrolide antibiotics, aminoglycoside antibiotics, tetracycline antibiotics, lincomycin antibiotics, chloramphenicol antibiotics, polypeptide antibiotics, sulfonamides, and quinolones.

[0015] Further preferably, the β-lactam antibiotics include penicillins, cephalosporins, other β-lactams, β-lactamase inhibitors, and their compound preparations; the macrolide antibiotics include erythromycin, roxithromycin, azithromycin, clarithromycin, etc.; the aminoglycoside antibiotics include streptomycin, gentamicin, and etimicin, etc.; the tetracycline antibiotics include tetracycline, oxytetracycline, doxycycline, etc.; the lincomycin antibiotics include lincomycin and clindamycin; the chloramphenicol antibiotics include chloramphenicol and thiocetamide; the polypeptide antibiotics include vancomycin such as vancomycin, norvancomycin, etc., polymyxins such as polymyxin B, bacitracin, etc.; the sulfonamides and quinolones include sulfonamides, fluroquinolones, levofloxacin, moxifloxacin, etc.

[0016] The application also provides a preparation method of the medical dressing for resisting infection of skin wounds, which comprises:

[0017] Step 1: etching the polyurethane film by means of a 3D micro-nano laser etching instrument and using a continuous or interval laser etching method of point scanning patterning;

[0018] Step 2: incubating the etched film with antibiotics and storing it at low temperature to obtain the medical dressing.

[0019] Preferably, in Step 1, the continuous laser etching method comprises:

[0020] The untreated polyurethane film is fixed on a ceramic plate substrate, and the focal length is adjusted to focus the laser on the middle layer of the polyurethane film; then the ultrafast laser is used to perform 1-2 scans at a speed of 0.05-5 m / s, a power of 500-1500 mW, and a spacing of 10-80 μm to form the required pattern on the polyurethane film.

[0021] Preferably, in step 1, the interval laser etching method comprises:

[0022] The untreated polyurethane film is fixed on a ceramic plate substrate, and the focal length is adjusted to focus the laser on the middle layer of the polyurethane film; then the ultrafast laser is used to perform X-axis linear scanning at a speed of 0.1-0.5 m / s, a power of 800-1200 mW, and a spacing of 10-20 μm, and after waiting for 0-4 minutes for the bubbles generated by etching to disappear, the Y-axis is moved by 5-10 μm for re-laser etching to form the required pattern on the polyurethane film.

[0023] Further preferably, the heat accumulation time in the interval laser etching method is 1-3 minutes.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The present application successfully creates a controllable drug release technology based on polyurethane film ultrafast laser surface treatment, which successfully realizes the customization of polyurethane film surface micro-nano structure by fine adjustment of laser processing parameters (such as processing power, scanning line spacing, intermittent scanning mode, etc.), and can adjust and optimize the drug loading. The beneficial effects of this technology include customized drug release process, enhanced drug loading effect, maintained or improved film performance, widened application field, and high efficiency and energy saving. These advantages make this technology have wide application prospect and potential in the fields of medical treatment, biology, and medicine. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the stress-strain curve of the polyurethane dressing with antibiotic combination assisted by 3D micro-nano laser etching technology. Figure 1 a in the formula is the film thickness characterization (SEM image) of the polyurethane film, Figure 1 b in the formula is the surface morphology (SEM image) of the polyurethane film with high drug loading, Figure 1 c in the formula is the surface morphology (SEM image) of the polyurethane film with low drug loading.

[0027] Figure 2 is the stress-strain curve of the polyurethane dressing with antibiotic combination assisted by 3D micro-nano laser etching technology.

[0028] Figure 3 is the moisture permeability of the polyurethane dressing with antibiotic combination assisted by 3D micro-nano laser etching technology.

[0029] Figure 4 The influence of 3D micro-nano laser intensity on the drug loading of polyurethane dressings; wherein, Figure 4 a, d in the figure are the two-dimensional plane and three-dimensional fluorescence confocal images of laser scanning power 730 mW, respectively, Figure 4 b, e in the figure are the two-dimensional plane and three-dimensional fluorescence confocal images of laser scanning power 790 mW, respectively, Figure 4 c, f in the figure are the two-dimensional plane and three-dimensional fluorescence confocal images of laser scanning power 850 mW, respectively.

[0030] Figure 5 The influence of 3D micro-nano laser etching distance on the drug loading of polyurethane dressings; wherein, Figure 5 a in the figure is a fluorescence confocal image with a scanning line distance of 22 μm, Figure 5 b in the figure is a fluorescence confocal image with a scanning line distance of 20 μm, Figure 5 c in the figure is a fluorescence confocal image with a scanning line distance of 18 μm, Figure 5 d in the figure is a fluorescence confocal image with a scanning line distance of 16 μm, Figure 5 e in the figure is a fluorescence confocal image with a scanning line distance of 14 μm, Figure 5 f in the figure is a fluorescence confocal image with a scanning line distance of 12 μm.

[0031] Figure 6 The influence of 3D micro-nano laser etching interval time on the drug loading of polyurethane dressings; wherein, Figure 6 a in the figure is a fluorescence confocal image of continuous scanning, Figure 6 b in the figure is a fluorescence confocal image of interval scanning for 0 minutes, Figure 6 c in the figure is a fluorescence confocal image of interval scanning for 1 minute, Figure 6 d in the figure is a fluorescence confocal image of interval scanning for 2 minutes, Figure 6 e in the figure is a fluorescence confocal image of interval scanning for 3 minutes, Figure 6 f in the figure is a fluorescence confocal image of interval scanning for 4 minutes.

[0032] Figure 7 The degree of improvement of the drug loading of polyurethane dressings assisted by 3D micro-nano laser etching technology combined with antibiotics.

[0033] Figure 8 The degree of bacterial inhibition of in vitro experiments of polyurethane dressings assisted by 3D micro-nano laser etching technology combined with antibiotics; wherein, Figure 8 a in the figure is the actual picture of the bacteriostatic circle of the polyurethane dressing without processing and without drug loading, Figure 8 b in the figure is the actual picture of the bacteriostatic circle of the polyurethane dressing without processing and directly loaded with drugs, Figure 8c is the inhibition zone of the drug-loaded polyurethane dressing after laser processing in the figure, Figure 8 d is the diameter of the inhibition zone of the three dressings.

[0034] Figure 9 The 3D micro-nano laser etching technology assisted antibiotic combined polyurethane dressing is used to observe the wound healing of rats, wherein, Figure 9 a is the wound healing of rats of the polyurethane dressing without processing and without drug loading, Figure 9 b is the wound healing of rats of the polyurethane dressing without processing and directly loaded with drugs, Figure 9 c is the wound healing of rats of the polyurethane dressing loaded with drugs after laser processing. DETAILED DESCRIPTION

[0035] The application will be further described in detail below in combination with the drawings, examples and experimental examples. Of course, the protection scope of the application is not limited to the following examples. Those skilled in the art can understand that various changes and modifications can be made to the application without departing from the spirit of the application. The application generally and / or specifically describes the materials used in the experiments and the experimental methods. Although many materials and operation methods used to achieve the purpose of the application are well known in the art, the application is still described as detailed as possible. The following examples are further to illustrate the application, rather than to limit the application. Any formal but not substantial equivalent transformation made according to the concept of the application should be regarded as the scope of the technical solutions of the application.

[0036] The test methods or test methods described in the following examples are all conventional methods unless otherwise specified. The reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0038] The 3D micro-nano laser etching instrument used in the application is provided by Professor Xiong Wei's team of Wuhan Optoelectronic National Research Center of Huazhong University of Science and Technology. The device outputs ultrashort pulse laser with a wavelength covering 266-2000 nm, a frequency of 1-2000 kHz and a pulse width of 15 ps. The maximum scanning speed of the galvanometer can reach 75 m / s, and the maximum average power of the laser can reach 100 W.

[0039] Skin soft tissue trauma is often accompanied by acute and chronic infection, which seriously hinders the repair process of skin soft tissue and may cause serious systemic infection dissemination and endanger life. In order to solve this problem, the polyurethane substrate layer used in the present application has good biocompatibility and physical properties, ensuring the safety and comfort of the application. The 3D micro-nano laser etched polyurethane outer layer still maintains good moisture permeability and water resistance, protects the wound from external pollution, and allows water evaporation to avoid the generation of excessive wet environment. The 3D micro-nano laser etching technology enhances the antibiotic drug loading capacity of polyurethane film and provides effective antibacterial effect, which can prevent wound infection and accelerate the healing process. The wound dressing preparation method is simple, easy to mass produce, and has good market application prospect.

[0040] The application will be further described below in conjunction with examples.

[0041] Example 1

[0042] The continuous laser etching process includes: fixing the untreated polyurethane film on the ceramic plate substrate, and adjusting the focal length to focus the laser on the middle layer of the film. Then use ultrafast laser to scan 1-2 times at a speed of 0.05-5 m / s, a power of 500-1500 mW and a spacing of 10-80 μm to form linear, cross-shaped or chessboard patterns. Then incubate with clindamycin-FITC fluorescent drug diluted with PBS solution, and store at 4°C for two hours. Finally, use Nikon Ni-E fluorescence confocal microscope to observe the drug loading, and get three-dimensional fluorescence intensity image by FIJI software processing. The effect of laser power on the drug loading capacity of polyurethane dressing is shown in Figure 4 By adjusting the processing power parameters, the drug loading capacity is improved by 18 times compared with the unprocessed area, and on this basis, it is improved by 42 times after adjusting the line spacing, as shown in Figure 5 and 7 .

[0043] Example 2

[0044] The interval laser ablation process includes: fixing the untreated or oxygen plasma treated polyurethane film for 300 s on a ceramic plate substrate, and adjusting the focal length to focus the laser on the middle layer of the film. Then use the ultrafast laser to perform X-axis linear scanning at a speed of 0.1-0.5 m / s, a power of 800-1200 mW and a spacing of 10-20 μm, and after waiting for 0-4 minutes for the bubbles generated by ablation to disappear, move 5-10 μm along the Y axis to perform laser ablation again. Then incubate with clindamycin-FITC fluorescent drug solution diluted with PBS solution, and store at 4°C for two hours. Finally, use Nikon Ni-E fluorescence confocal microscope to observe the drug loading, and use FIJI software to process to obtain three-dimensional fluorescence intensity image. This interval scanning method can avoid the ablation phenomenon caused by heat accumulation, and realize a larger effective drug loading (see Figure 6 ). As shown in Figure 6 , the heat accumulation time is 1-3 minutes. As shown in Figure 7 , the drug loading of example 2 can be increased by 53 times by the intermittent scanning method, and the total drug loading of the dressing can be increased by 61 times by the prior plasma cleaning treatment.

[0045] Example 3

[0046] The polyurethane dressing prepared in example 1 is used to illustrate, and the cross section of the dressing film is observed by SEM to obtain the average thickness of the dressing film of about 30-100 μm (see Figure 1 a). The high drug loading polyurethane film after processing is characterized by generating a rough area of about 20 μm wide (see Figure 1 b) ; and the low drug loading polyurethane film after processing is characterized by generating obvious grooves (see Figure 1 c).

[0047] Example 4

[0048] The maximum drug loading polyurethane dressing prepared in example 2 is used to illustrate, and a single column bench material tensile test system is used to test the mechanical properties of the polyurethane film before and after processing. The sample is prepared by cutter to form a dumbbell-shaped sample with a length of 40 mm, a width of 30 mm, and an inner width of 20 mm, and the tensile test is performed at a tensile rate of 15 mm / min. Five groups of parallel samples are set for each film sample (see Figure 2 ). PU-U represents the untreated polyurethane film; PU-U-AL represents the untreated polyurethane film incubated with drug; and PU-S-AL represents the processed and drug incubated polyurethane film. The mechanical properties of the polyurethane film are shown in Figure 2 , the tensile strength is 5-15 MPa, the elongation at break is 400-700%, and the Young's modulus is 5-15 MPa.

[0049] Example 5

[0050] The maximum drug-loaded polyurethane patch prepared in Example 2 was used to illustrate the water vapor permeability analysis of the polyurethane film, which was performed according to GB / T 12704.1-2009. An equal amount of desiccant CaCl2was added to a water vapor permeation cup, and the cup opening was covered with the polyurethane film. The cup was tightly sealed to ensure that water vapor could only pass through the polyurethane film. Then, the water vapor permeation cup was placed in a constant temperature and humidity chamber. The program was set to 23°C and 50% relative humidity, and the mass of CaCl2in the water vapor permeation cup was measured after 24 hours. Figure 3 The water vapor permeability of the polyurethane film before and after processing was analyzed, and PU-U represents the unprocessed polyurethane film; PU-U-AL represents the unprocessed polyurethane film incubated with the drug; and PU-S-AL represents the processed polyurethane film incubated with the drug. The water vapor permeability of the polyurethane film is shown in Figure 3 , which is 200-400 grams per square meter per 24 hours.

[0051] Example 6

[0052] The maximum drug-loaded polyurethane patch prepared in Example 2 was used to illustrate the antibacterial experiment using S. aureus. The culture medium was weighed according to the ratio of 100 ml of deionized water: 0.5 g of yeast extract: 1 g of tryptone: 0.58 g of sodium chloride, and autoclaved for later use. S. aureus was taken from the freezer in a -40°C refrigerator, thawed at room temperature, and then added to the culture solution at a ratio of 1:1000 and shaken thoroughly. The mixture was incubated in a 37°C constant temperature shaking incubator for 8-10 hours. A sterile agar plate was taken, and the bacterial suspension was evenly coated on the surface of the plate. The coated plate was placed in a constant temperature incubator, and the temperature was set to 37°C. The incubation time was 24 hours.

[0053] The polyurethane film was cut into 1 cm * 1 cm samples and soaked in medical alcohol for 15 minutes and then dried. The test samples were attached to the S. aureus plate, and then the plate was covered and placed in a 37°C constant temperature incubator for 24 hours, 48 hours, and 72 hours. The diameter of the inhibition zone was measured at each time point using a ruler (see Figure 8 ). PU-U represents the unprocessed polyurethane film; PU-U-AL represents the unprocessed polyurethane film incubated with the drug; and PU-S-AL represents the processed polyurethane film incubated with the drug. The in vitro experiment of the polyurethane patch with 3D micro-nano laser etching technology assisted antibiotic combination showed that the diameter of the S. aureus inhibition zone in the PU-S-AL group was significantly larger than that in the PU-U-AL and PU-U groups. Figure 8

[0054] Example 7

[0055] ​The polyurethane dressing with the maximum drug loading prepared in Example 2 was used to illustrate the main purpose of the animal experiment, which was to evaluate the effects of different dressings on the inflammatory response of wounds by establishing an infectious wound model. SD rats were selected as experimental subjects, and Staphylococcus aureus was used as the pathogen of traumatic wounds. The Staphylococcus aureus was cultured in LP liquid medium to the logarithmic phase, and the bacterial liquid concentration was adjusted for standby use. The animals were anesthetized, the skin was prepared, and the dorsal wound was prepared. It is appropriate to be 2 cm apart on both sides of the dorsal spine, 1x1 cm 2 pocket-shaped wound, contacting the dermis. The bacterial solution was dropped on the wound to model it.

[0056] The polyurethane film was cut into a 2cm*2cm sample and soaked in medical alcohol for 15min and then dried. The test sample was attached to the rat wound and fixed, and after 24h of standing, the purulent secretion of the rat skin wound was observed Figure 9 ). PU-U represents unprocessed polyurethane film; PU-U-AL represents unprocessed but incubated drug-loaded polyurethane film; PU-S-AL represents processed and incubated drug-loaded polyurethane film. The arrow indicates the location of the purulent secretion under the dressing. As shown in Figure 9 , the PU-S-AL group had significantly less purulent secretion on the rat skin wound than the PU-U-AL and PU-U groups after 24h of standing.

[0057] Results: The present application successfully constructed a new type of polyurethane wound dressing assisted by 3D micro-nano laser etching technology to bind antibiotics, overcoming the shortcomings of the prior art. The polyurethane dressing material includes an ultra-thin transparent polyurethane processed by 3D micro-nano laser etching and an antibiotic.

[0058] In summary, the present application uses polyurethane with excellent biocompatibility and physical properties as the base material, ensuring the safety and comfort of the dressing. The outer layer of the polyurethane treated by 3D micro-nano laser etching technology maintains good moisture permeability and water resistance, protecting the wound from contamination, while allowing water vapor to evaporate and preventing the wound from becoming too wet. In addition, this technology also enhances the antibiotic drug loading capacity of the polyurethane film, effectively preventing wound infection and accelerating healing. The preparation process of the wound dressing is simple, suitable for large-scale production, and has good market application potential.

[0059] The above is only a preferred embodiment of the present application, and it should be noted that the above preferred embodiment should not be regarded as limiting the present application, and the protection scope of the present application should be limited by the scope defined in the claims. For ordinary skilled persons in the art, several improvements and refinements can be made without departing from the spirit and scope of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A medical dressing for preventing infection of a skin wound, characterized by comprising a porous sheet of a water-absorbing material and a water-soluble film. The medical dressing comprises a polyurethane film and an antibiotic loaded on the polyurethane film. The preparation method of the medical dressing comprises: Step 1: etching the polyurethane film by means of a 3D micro-nano laser etching instrument, using continuous or interval laser etching method of point scanning patterning; Step 2: after etching, incubating with antibiotics and storing at low temperature to obtain the medical dressing; In step 1, the continuous laser etching method comprises: fixing the untreated polyurethane film on a ceramic plate substrate, adjusting the focal length to focus the laser on the middle layer of the polyurethane film, then using ultrafast laser to scan 1-2 times at a speed of 0.05-5 m / s, a power of 500-1500 mW and a spacing of 10-80 μm to form the required pattern on the polyurethane film; In step 1, the interval laser etching method comprises: fixing the untreated polyurethane film on a ceramic plate substrate, adjusting the focal length to focus the laser on the middle layer of the polyurethane film, then using ultrafast laser to scan along the X-axis at a speed of 0.1-0.5 m / s, a power of 800-1200 mW and a spacing of 10-20 μm, waiting for 0-4 minutes after the bubbles generated by etching disappear, then moving 5-10 μm along the Y-axis to perform laser etching again to form the required pattern on the polyurethane film; The polyurethane film has a tensile strength of 5-15 MPa, an elongation at break of 400-700%, and a Young's modulus of 5-15 MPa; the polyurethane film has a moisture permeability of 200-400 g / (m 2 ·24h).

2. The medical dressing for skin wounds according to claim 1, wherein The polyurethane film is an ultra-thin transparent material with an average film thickness of 30-100 µm.

3. The medical dressing for skin wounds according to claim 1, wherein The drug loading of the antibiotic on the polyurethane film is 0.0625-0.625 μg / mm 2 .

4. The medical dressing for skin wounds according to claim 1, wherein The antibiotic is selected from β-lactam antibiotics, macrolide antibiotics, aminoglycoside antibiotics, tetracycline antibiotics, lincomycin antibiotics, chloramphenicol antibiotics, polypeptide antibiotics, sulfonamides and quinolone drugs.

5. The medical dressing for skin wounds according to claim 1, wherein In the interval laser etching method, the heat accumulation time is 1-3 minutes.

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