A medical nonwoven fabric dressing and a method for producing the same

Abstract

The application relates to the field of medical dressings and discloses a medical non-woven fabric dressing, which comprises, from the wound surface side to the outer side, a skin-adhesive hemostatic self-adhesive layer, a liquid-absorbing and humidity-adjusting and drug-delivering layer for realizing hemostasis and self-adhesive fixation in a wet environment, a micro-channel group arranged in the layer and penetrating through the thickness of the layer to form a one-way wet guiding and self-humidity adjusting effect, a bacteria-resisting and moisture-permeating protective layer for realizing broad-spectrum antibiosis and infection risk prompting and generating mild light and heat under near-infrared irradiation to assist in inhibiting bacteria, and the skin-adhesive hemostatic self-adhesive layer, the liquid-absorbing and humidity-adjusting and drug-delivering layer and the bacteria-resisting and moisture-permeating protective layer are activated on the surface and integrated by point heat pressing. The skin-adhesive hemostatic self-adhesive layer is composed of chitosan quaternary ammonium salt and catechol precursor, can realize quick hemostasis and self-adhesive fixation by water coagulation adhesion and protein complexation in a wet or bleeding environment, avoids the problem that traditional non-woven fabric dressings fail in a wet environment due to reliance on adhesives, and effectively improves the clinical applicability and safety of the dressing.

Description

Technical Field

[0001] This invention relates to the field of medical dressing technology, specifically to a medical nonwoven dressing and its preparation method. Background Technology

[0002] Non-woven fabric dressings are a type of medical dressing made with non-woven fabric as the base material. They are widely used for wound covering and basic nursing care due to their advantages such as softness, breathability, simple manufacturing process, and low cost. Most existing non-woven fabric dressings use polypropylene non-woven fabric or gauze as the base material, and their main function is to absorb wound exudate and provide physical coverage.

[0003] Existing medical nonwoven dressings primarily serve to cover, absorb fluid, and protect in clinical use. However, traditional nonwoven dressings have the following shortcomings: Firstly, they easily lose their adhesiveness in moist environments, making it difficult to achieve stable fixation on wounds with significant bleeding or exudation, potentially causing secondary damage during dressing changes. Secondly, their absorbent layer structure is simple, making it difficult to self-regulate with changes in exudation, easily leading to oversaturation and backflow, resulting in wound maceration. Furthermore, existing dressings lack visual indications of infection risk and synergistic antibacterial functions, often requiring additional antibiotics or ointments. Fourthly, some antibacterial layers are single membranes with insufficient moisture permeability, creating a warm and moist environment on the wound that is not conducive to healing. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a medical nonwoven dressing and its preparation method, which can self-adhere to stop bleeding in a moist environment, achieve self-adjusting moisture absorption under different exudate conditions, and has broad-spectrum antibacterial, early infection visualization indication, and on-demand auxiliary sterilization functions, thereby meeting the needs of complex wound management in clinical practice.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a medical non-woven dressing, comprising, from one side of the wound to the outer side, the following components:

[0006] Skin-friendly hemostatic self-adhesive layer; used to achieve hemostasis and self-adhesive fixation in moist environments.

[0007] Liquid absorption and humidification layer; microchannel groups running through the thickness of the layer are set up to form a one-way humidification and self-humidification effect;

[0008] A bactericidal and moisture-permeable protective layer; used for broad-spectrum antibacterial action and infection risk indication, and generates mild photothermal stimulation under near-infrared irradiation to aid in antibacterial activity.

[0009] The skin-friendly hemostatic self-adhesive layer, the liquid-absorbing and moisture-regulating and drug-dispensing layer, and the antibacterial and moisture-permeable protective layer are surface-activated and then bonded together through a dotted hot-pressing layer.

[0010] Preferably, the skin-friendly hemostatic self-adhesive layer material comprises, by weight, 100-150 parts of chitosan quaternary ammonium salt, 5-15 parts of catechol precursor, 10-20 parts of lactic acid solution, and 5-10 parts of crosslinking agent.

[0011] Preferably, the raw materials of the liquid-absorbing, moisture-regulating, and drug-dispensing layer include, by weight: 100-150 parts of zwitterionic hydrogel monomer, 1.5-2 parts of crosslinking agent, 0.5-1 parts of photoinitiator, 20-40 parts of thermoplastic polyurethane, 10-30 parts of polyvinyl alcohol, 5-20 parts of drug core fluid, and 30-60 parts of polylactic acid and polycaprolactone blend as the outer shell layer.

[0012] Preferably, the raw materials of the antibacterial and moisture-permeable protective layer include, by weight: 100-150 parts of polypropylene nonwoven fabric substrate, 1-3 parts of dopamine hydrochloride, 0.1-1 parts of silver nitrate, and 2-5 parts of indicator dye microcapsules, wherein the indicator dye microcapsules are anthocyanins or bromothymol blue.

[0013] A method for preparing a medical nonwoven dressing includes the following steps:

[0014] S1. Preparation of skin-friendly hemostatic self-adhesive layer: Chitosan quaternary ammonium salt, catechol precursor and lactic acid solution are mixed, crosslinking agent is added to react to obtain spinning solution, and skin-friendly hemostatic self-adhesive layer is obtained by electrospinning;

[0015] S2. Preparation of liquid-absorbing, moisture-regulating and drug-doping layer: A precursor solution is formed by zwitterionic hydrogel monomer, crosslinking agent and photoinitiator, and electrospun and superimposed on thermoplastic polyurethane solution and polyvinyl alcohol template solution on the same collector. Then, coaxial fibers containing drug core liquid and polylactic acid and polycaprolactone shell solution are deposited on it, and after curing and template dissolution, a microchannel group with thickness-through is formed to obtain liquid-absorbing, moisture-regulating and drug-doping layer;

[0016] S3. Preparation of antibacterial and moisture-permeable protective layer: The polypropylene nonwoven fabric substrate is activated by low-temperature plasma and immersed in dopamine hydrochloride solution for deposition. Silver nanoclusters are loaded on its surface in situ by silver nitrate and indicator dye microcapsules are fixed to obtain the antibacterial and moisture-permeable protective layer.

[0017] S4. Lamination and Shaping: The above three layers are stacked together and laminated into a single unit under point-pressing conditions to obtain a medical non-woven dressing.

[0018] Preferably, S1 specifically includes:

[0019] S101. Dissolve chitosan quaternary ammonium salt in lactic acid solution and stir in a stirred reactor until completely dissolved to obtain a homogeneous solution A;

[0020] S102. Add catechol precursor to solution A and continue stirring until homogeneous;

[0021] S103. Add a crosslinking agent to solution A and react at 25-30℃ for 12-18h to obtain spinning solution B;

[0022] S104. The spinning solution B is loaded into the electrospinning device and deposited on the drum collector to obtain a skin-friendly hemostatic self-adhesive layer.

[0023] Preferably, the electrospinning conditions in step S1 are: voltage 10-20kV, flow rate 0.3-0.7mL / h, collection distance 12-18cm, collection by a rotary drum collector, to obtain a skin-friendly hemostatic self-adhesive layer with a thickness of 80-120μm.

[0024] Preferably, S2 specifically includes:

[0025] S201. Dissolve sulfobetaine methacrylate in water, add crosslinking agent and photoinitiator, stir well and set aside to obtain solution D;

[0026] S202. Weigh out thermoplastic polyurethane and dissolve it in a mixed solvent of tetrahydrofuran and dimethylformamide in a ratio of 1:1 to obtain solution E;

[0027] S203. Weigh polyvinyl alcohol and dissolve it in hot water at 80-90℃ to prepare a 10-15wt% solution, thus obtaining solution F;

[0028] S204. Solution D, solution E and solution F are respectively loaded into an electrospinning device and deposited alternately on the same collector to obtain a composite fiber membrane G containing an interpenetrating network and template fibers;

[0029] S205. Preparation of core-shell fiber solution, including:

[0030] Core solution H: Drug core fluid, water;

[0031] Shell solution I: Polylactic acid and polycaprolactone blend dissolved in dichloromethane / DMF;

[0032] S206. The core solution H and the shell solution I are respectively loaded into a coaxial electrospinning nozzle, the internal flow rate is set to 0.2-0.3 mL / h, the external flow rate is set to 0.8-0.9 mL / h, the voltage is set to 18-20 kV, and the collection distance is set to 12-15 cm. They are deposited on the composite fiber membrane G to obtain a composite membrane J containing core and shell fibers.

[0033] S207. The composite membrane J is cured by ultraviolet light to crosslink the solution D and form a stable hydrogel fiber network;

[0034] S208. The cross-linked composite membrane J is immersed in deionized water to dissolve the polyvinyl alcohol fibers formed by the template solution F, thereby obtaining a skin-friendly hemostatic self-adhesive layer with longitudinal microchannels.

[0035] Preferably, S3 specifically includes:

[0036] S301. Polypropylene nonwoven fabric is selected as the substrate L and sent into a plasma treatment machine for 5-7 minutes at 200W power to obtain activated substrate M.

[0037] S302. Immerse the activated substrate M in a dopamine hydrochloride solution and react at 25-30℃ for 1-1.5h to obtain a substrate N with polydopamine deposited on the surface;

[0038] S303. Place the substrate N in a 0.5-0.7wt% silver nitrate solution and let it stand for 30-40 minutes. Silver ions are reduced in situ on the surface of the polydopamine layer to form silver nanoclusters, thus obtaining the antibacterial substrate O.

[0039] S304. The indicator dye microcapsule dispersion is uniformly sprayed onto the surface of the antibacterial substrate O and dried with hot air at 50-60℃ for 30-40 minutes to obtain an antibacterial and moisture-permeable protective layer.

[0040] Preferably, in step S4, the hot pressing is adjusted to 120-130℃ and 0.3-0.4MPa for 2-3 seconds, with a dot diameter of 0.8-1mm and a dot spacing of 6-8mm, to form a medical non-woven dressing.

[0041] This invention provides a medical nonwoven dressing and its preparation method. It has the following beneficial effects:

[0042] 1. The skin-friendly hemostatic self-adhesive layer of the present invention is composed of chitosan quaternary ammonium salt and catechol precursor. In a moist or bleeding environment, it can quickly stop bleeding and achieve self-adhesion fixation by relying on hydrogel adhesion and protein complexation. This avoids the problem of traditional non-woven dressings failing due to reliance on adhesives in a humid environment, and effectively improves the clinical applicability and safety of the dressing.

[0043] 2. This invention utilizes the synergistic effect of zwitterionic hydrogel fibers, polyurethane microfibers, and longitudinal microchannels in its liquid absorption and moisture regulation layer to efficiently absorb and unidirectionally drain wound exudate, maintaining a suitable moist environment. Furthermore, the coaxial electrospun core-shell structure enables the sustained release of antibacterial agents and repair aids, thus combining moisture regulation and drug treatment functions. This is significantly superior to existing dressings that only absorb liquid or release drugs.

[0044] 3. The antibacterial and breathable protective layer of the present invention introduces a polydopamine coating on the surface of a polypropylene nonwoven fabric substrate and loads silver nanoclusters and immobilized indicator dye microcapsules in situ. It can form a broad-spectrum and long-lasting antibacterial barrier, and can also indicate the risk in the early stage of wound infection through color development. Under near-infrared irradiation, it produces a mild photothermal enhancement effect to enhance antibacterial effect, thus realizing the integration of multiple functions of antibacterial, protection and risk warning. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0046] The technical solutions in 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.

[0047] Example:

[0048] This invention provides a medical nonwoven dressing, comprising a skin-friendly hemostatic self-adhesive layer, a liquid-absorbing and moisture-regulating drug delivery layer, and a bactericidal and moisture-permeable protective layer, arranged sequentially from one side of the wound to the outside. The three layers are bonded together with a surface-activating layer via point-like heat pressing.

[0049] The skin-friendly hemostatic self-adhesive layer is composed of nanofibers grafted with chitosan quaternary ammonium salt and catechol groups. It utilizes hydrogel adhesion and protein complexation in a moist environment to achieve rapid hemostasis and self-adhesive fixation. Specifically, it includes the following raw materials:

[0050] The mixture consists of 100-150 parts chitosan quaternary ammonium salt, 5-15 parts catechol precursor, 10-20 parts lactic acid solution, and 5-10 parts crosslinking agent. This layer utilizes the biocompatibility of chitosan and the wet adhesion of catechol to achieve rapid hemostasis and self-adhesive fixation in the moist environment of the wound. Among them, chitosan quaternary ammonium salt provides good biocompatibility and natural antibacterial properties, while its cationic properties can interact with the negatively charged components on the wound surface to accelerate the coagulation process. Quaternary ammonium modification enhances its water solubility, ensuring a stable structure even in moist environments. The catechol precursor mimics the dopa structure in mussel adhesive proteins, imparting wet-surface adhesiveness to the dressing, enabling self-adhesion even in the presence of wound exudate and enhancing hemostatic properties. Lactic acid solution acts as a solvent and acid regulator, promoting the dissolution of chitosan and uniform fiber formation, while a slightly acidic environment helps maintain wound microenvironment stability. The cross-linking agent provides chemical cross-linking sites, enabling stable bonding between chitosan chains and catechol, ensuring the mechanical strength and durability of the fiber layer. The wet-surface adhesiveness of the chitosan quaternary ammonium salt and the catechol precursor allows the dressing to adhere and be fixed quickly even in bleeding and exudate environments.

[0051] The absorbent, moisture-regulating, and drug delivery layer is composed of an interpenetrating network of zwitterionic hydrogel fibers and shape-memory polyurethane microfibers, with embedded coaxial electrospun core-shell fibers. The core contains a sustained-release antibacterial agent and a repair agent, while the outer shell is a biodegradable polymer. This layer incorporates a series of microchannels running through its thickness, creating a unidirectional moisture-wicking and self-regulating effect. Specifically, it comprises 100–150 parts of zwitterionic hydrogel monomers (such as sulfobetaine methacrylate), 1.5–2 parts of crosslinking agent, 0.5–1 part of photoinitiator, 20–40 parts of thermoplastic polyurethane, 10–30 parts of polyvinyl alcohol (as a sacrificial fiber template), 5–20 parts of drug-containing core fluid (including antibacterial agents and repair agents), and 30–60 parts of a blend of polylactic acid and polycaprolactone as the outer shell layer. It is formed using electrospinning and coaxial electrospinning composites. The zwitterionic hydrogel monomers possess ion exchange and water content regulation capabilities, automatically adjusting according to the ionic strength and pH of the exudate. The system controls its own water content to maintain a stable humid environment. Thermoplastic polyurethane provides flexibility and shape memory properties, ensuring that the fiber structure can maintain channel integrity under body temperature conditions and enhancing interlayer elasticity. Polyvinyl alcohol forms microchannel groups through dissolution, establishing longitudinal moisture-conducting pathways to achieve unidirectional drainage and prevent exudate from accumulating on the surface. The antibacterial agent in the core fluid is chlorhexidine gluconate or polyhexylamine hydrochloride, used to kill bacteria and prevent infection. Repair aids include sodium hyaluronate or short peptides to promote granulation tissue growth and shorten the healing cycle. Water is also included as a solvent to help evenly disperse drug components. Polylactic acid and polycaprolactone blends serve as the outer shell material of the coaxial electrospun core-shell fiber, playing a sustained-release role and controlling the gradual release of drugs from the core, while also possessing good biodegradability and mechanical strength. The drug-releasing outer shell works together with the core antibacterial agent and repair agent to achieve long-lasting antibacterial effect and accelerated healing.

[0052] The antibacterial and moisture-permeable protective layer is made of microporous nonwoven fiber. After low-temperature plasma activation, dopamine is deposited and silver nanoclusters are loaded in situ. At the same time, microcapsules of indicator dyes are fixed and embedded to form a broad-spectrum antibacterial barrier and an early infection risk indication function. Under near-infrared irradiation, it generates mild photothermal effect to assist in antibacterial activity. Specifically, it includes 100-150 parts of polypropylene nonwoven fabric substrate, 1-3 parts of dopamine hydrochloride, 0.1-1 parts of silver nitrate, and 2-5 parts of indicator dye microcapsules (anthocyanins or bromothymol blue), which are surface treated and fixed to form a functional layer. Polypropylene nonwoven fabric substrate provides overall mechanical support and breathability, serving as the main material for the antibacterial protective layer. Dopamine hydrochloride self-polymerizes and deposits on the substrate surface to form a reactive coating, providing interfacial binding sites for silver ion reduction and microcapsule immobilization. Silver nitrate is in situ reduced on the dopamine layer to generate silver nanoclusters, which have broad-spectrum antibacterial effects and are effective against both Gram-positive and Gram-negative bacteria. Indicator dye microcapsules are embedded within the microcapsules, and a color reaction occurs when the pH of the exudate increases (indicating infection risk), providing early warning signals for healthcare workers.

[0053] The three layers are activated by low-temperature plasma and then hot-pressed together at 110–130°C to form a monolithic dressing.

[0054] Example 1:

[0055] A medical nonwoven dressing, comprising:

[0056] The skin-friendly hemostatic self-adhesive layer comprises 100 parts of chitosan quaternary ammonium salt, 5 parts of catechol precursor, 10 parts of lactic acid solution, and 5 parts of crosslinking agent; wherein chitosan quaternary ammonium salt serves as the skin-friendly and hemostatic matrix, the catechol precursor imparts self-adhesive properties to the wet surface, the lactic acid solution is used to dissolve and adjust the pH, and the crosslinking agent is used to stabilize the fiber network structure.

[0057] The absorbent, moisture-regulating, and drug delivery layer comprises 100 parts sulfobetaine methacrylate, 1.5 parts crosslinking agent, 0.5 parts photoinitiator, 20 parts thermoplastic polyurethane, 10 parts polyvinyl alcohol (as a sacrificial fiber template), 5 parts drug core fluid (including antibacterial agent and repair aid), and 30 parts polylactic acid and polycaprolactone blend. The amphoteric monomers are cured into stable hydrogel fibers by the crosslinking agent and photoinitiator. The thermoplastic polyurethane provides elasticity and shape retention. The polyvinyl alcohol fibers serve as a template for subsequent dissolution, forming longitudinal microchannels. The drug core fluid is used for sustained-release antibacterial and repair purposes, and the polylactic acid / polycaprolactone shell controls the drug release rate and provides structural support.

[0058] The antibacterial and moisture-permeable protective layer comprises 100 parts of polypropylene nonwoven fabric substrate, 1 part of dopamine hydrochloride solution, 0.1 parts of silver nitrate, and 2 parts of indicator dye microcapsules, which are surface-treated and fixed to form a functional layer. The polypropylene substrate serves as a mechanical support framework, the dopamine coating provides reaction sites for silver ion reduction and microcapsule fixation, the silver nanoclusters form a broad-spectrum antibacterial barrier, and the indicator dye microcapsules provide color warning under infection-related pH conditions.

[0059] The three layers are activated by low-temperature plasma and then hot-pressed together at 110°C to form an integral dressing.

[0060] Please see the appendix Figure 1 A method for preparing a medical nonwoven dressing includes the following steps:

[0061] S1. Preparation of Skin-Friendly Hemostatic Self-Adhesive Layer

[0062] S101. Dissolve 100 parts of chitosan quaternary ammonium salt in 10 parts of lactic acid solution, and stir in a stirred reactor until completely dissolved to obtain a homogeneous solution A;

[0063] S102. Add 5 parts of catechol precursor to solution A and continue stirring until homogeneous;

[0064] S103. Add 5 parts of crosslinking agent to solution A and react at 25°C for 12 hours to obtain spinning solution B;

[0065] S104. The spinning solution B is loaded into an electrospinning device, the voltage is set to 15kV, the flow rate is 0.5mL / h, and the collection distance is 15cm. The solution is deposited on a rotating drum collector to obtain a skin-friendly hemostatic self-adhesive layer with a thickness of about 100μm.

[0066] S2. Liquid absorption, humidification, and preparation of the drug delivery layer

[0067] S201. Dissolve 100 parts of sulfobetaine methacrylate in water, add 1.5 parts of crosslinking agent and 0.5 parts of photoinitiator, stir well and set aside to obtain solution D;

[0068] S202. Weigh 30 parts of thermoplastic polyurethane and dissolve it in a tetrahydrofuran / dimethylformamide (1:1) mixed solvent to obtain solution E;

[0069] S203. Weigh 20 parts of polyvinyl alcohol, dissolve it in hot water at 80℃ to prepare a 10wt% solution, and obtain solution F;

[0070] S204. Solution D, solution E and solution F are respectively loaded into an electrospinning device and deposited alternately on the same collector to obtain a composite fiber membrane G containing an interpenetrating network and template fibers;

[0071] S205. Prepare core-shell fiber solutions, including core solution H: 5 parts chlorhexidine gluconate, 3 parts sodium hyaluronate, and 12 parts water; outer shell solution I: 50 parts polylactic acid and polycaprolactone (6:4) dissolved in dichloromethane / DMF;

[0072] S206. The core solution H and the shell solution I are respectively loaded into a coaxial electrospinning nozzle, the internal flow rate is set to 0.2 mL / h, the external flow rate is set to 0.8 mL / h, the voltage is 18 kV, and the collection distance is 12 cm. They are deposited on the composite fiber membrane G to obtain a composite membrane J containing core and shell fibers.

[0073] S207. The composite membrane J is cured by ultraviolet light (365nm, power 15mW / cm², irradiation for 5min) to crosslink the solution D to form a stable hydrogel fiber network.

[0074] S208. The composite membrane J is immersed in deionized water to dissolve the polyvinyl alcohol fibers formed by the template solution F, thereby obtaining the liquid absorption, humidification and drug delivery layer K containing longitudinal microchannels.

[0075] S3. Preparation of antibacterial and moisture-permeable protective layer

[0076] S301. Select 100 parts of polypropylene nonwoven fabric as substrate L, send it into a plasma treatment machine, and treat it at 200W power for 5 minutes to obtain activated substrate M.

[0077] S302. Immerse the activated substrate M in a dopamine hydrochloride solution and react at 25°C for 1 hour to obtain a substrate N with polydopamine deposited on its surface;

[0078] S303. Substrate N is placed in a 0.5wt% silver nitrate solution and left to stand for 30 min. Silver ions are reduced in situ on the surface of the polydopamine layer to form silver nanoclusters, thus obtaining antibacterial substrate O.

[0079] S304. The indicator dye microcapsule dispersion (3wt%) is uniformly sprayed onto the surface of the antibacterial substrate O and dried with hot air at 50°C for 30 minutes to obtain the antibacterial and moisture-permeable protective layer P.

[0080] S4. Three-layer lamination and shaping

[0081] The skin-friendly hemostatic self-adhesive layer is used as the bottom layer, the liquid-absorbing, moisture-regulating and drug-dispensing layer K is covered on the fiber membrane C, and the antibacterial and moisture-permeable protective layer P is covered on the outermost layer.

[0082] The three-layer composite is fed into a hot-press spot laminator and pressurized at 120℃ and 0.3MPa for 2 seconds, with a spot diameter of 0.8mm and a spot spacing of 6mm, to form a three-layer integrated dressing.

[0083] Example 2:

[0084] A medical nonwoven dressing, comprising:

[0085] Skin-friendly hemostatic self-adhesive layer: 125 parts chitosan quaternary ammonium salt, 10 parts catechol precursor, 15 parts lactic acid solution, and 7 parts crosslinking agent;

[0086] Liquid-absorbing and moisture-regulating layer for drug delivery: 125 parts of sulfobetaine methacrylate, 2 parts of crosslinking agent, 0.8 parts of photoinitiator, 30 parts of thermoplastic polyurethane, 20 parts of polyvinyl alcohol, 10 parts of drug core fluid (containing antibacterial agent and repair aid), and 45 parts of polylactic acid and polycaprolactone blend.

[0087] Antibacterial and moisture-permeable protective layer: 125 parts polypropylene nonwoven fabric substrate, 2 parts dopamine hydrochloride, 0.5 parts silver nitrate, and 3 parts indicator dye microcapsules;

[0088] The preparation process is exactly the same as in Example 1.

[0089] Example 3:

[0090] A medical nonwoven dressing, comprising:

[0091] Skin-friendly hemostatic self-adhesive layer: 150 parts chitosan quaternary ammonium salt, 15 parts catechol precursor, 20 parts lactic acid solution, and 10 parts crosslinking agent;

[0092] Liquid-absorbing and moisture-regulating layer for drug delivery: 150 parts of sulfobetaine methacrylate, 2 parts of crosslinking agent, 1 part of photoinitiator, 40 parts of thermoplastic polyurethane, 30 parts of polyvinyl alcohol, 20 parts of drug core fluid (containing antibacterial agent and repair aid), and 60 parts of polylactic acid and polycaprolactone blend.

[0093] Antibacterial and moisture-permeable protective layer: 150 parts polypropylene nonwoven fabric substrate, 3 parts dopamine hydrochloride, 1 part silver nitrate, and 5 parts indicator dye microcapsules.

[0094] The preparation process is exactly the same as in Example 1.

[0095] Example 4:

[0096] A medical nonwoven dressing, comprising:

[0097] The skin-friendly hemostatic self-adhesive layer is the same as in Example 1;

[0098] The liquid absorption and humidification layer and the drug delivery layer are based on Example 1 with the addition of 5 parts of nanocellulose;

[0099] The antibacterial and moisture-permeable protective layer is the same as in Example 1;

[0100] A method for preparing a medical nonwoven dressing differs from Example 1 in that:

[0101] S2. Liquid absorption, humidification, and preparation of the drug delivery layer

[0102] S201. Dissolve 100 parts of sulfobetaine methacrylate in water, add 1.5 parts of crosslinking agent and 0.5 parts of photoinitiator, stir evenly and set aside to obtain solution D; Take 5 parts of nanocellulose and add deionized water to obtain an initial dispersion of 1.0 wt%, stir magnetically for 15 min, sonicate for 10 min (power 200W, intermittent 2s / 2s), filter with a 0.45μm filter membrane to remove gel clusters, to obtain solution D-NC; Mix solution D and solution D-NC at a volume ratio of 9:1, stir gently for 10 min, let stand to degas for 5 min, to obtain the compound precursor solution D for electrospinning;

[0103] S204. The compound precursor solution D, solution E and solution F are respectively loaded into an electrospinning device and deposited alternately on the same collector to obtain a composite fiber membrane G containing "nanocellulose-reinforced amphoteric hydrogel precursor fiber", TPU fiber and PVA template fiber.

[0104] S207. The composite membrane J is cured by ultraviolet light (365nm, 15mW / cm², 5min) to crosslink the amphoteric monomers in the composite precursor solution D into a network; the nanocellulose enhances the gel network with hydrogen bonds and physical entanglement, improving wet mechanical properties and liquid retention.

[0105] The remaining steps remain the same.

[0106] Example 5:

[0107] A medical nonwoven dressing, comprising:

[0108] The skin-friendly hemostatic self-adhesive layer is the same as in Example 1;

[0109] The liquid absorption and humidification layer and the drug delivery layer are the same as in Example 1;

[0110] The antibacterial and moisture-permeable protective layer consists of 100 parts polypropylene nonwoven fabric substrate, 1 part dopamine hydrochloride, 0.05 parts silver nitrate, 0.5 parts zinc oxide nanoparticles, and 2 parts indicator dye microcapsules.

[0111] A method for preparing a medical nonwoven dressing differs from Example 1 in that:

[0112] In the preparation of the S3 antibacterial and moisture-permeable protective layer, S301 and S302 are kept unchanged, and S303 is a composite load.

[0113] S303. Prepare a 0.05wt% silver nitrate aqueous solution with pH 8–9 by adjusting the ammonia solution to form a silver ammonia complex. Prepare a 0.5mg / mL ZnO nanoparticle dispersion and add 0.05wt% PVP as a stabilizer. Sonicate for 10 min. Mix the two solutions at a volume ratio of 1:1 and stir gently for 10 min to obtain solution Z. Immerse the substrate N obtained in S302 into solution Z and let it stand at room temperature for 30 min. During this period, dopamine is reduced on the surface and silver ions are complexed to form silver nanoclusters. At the same time, ZnO nanoparticles are bound to the dopamine layer by van der Waals or hydrogen bonds. Remove the substrate and rinse it once with deionized water to remove weak adsorbents to obtain the composite antibacterial substrate.

[0114] The remaining steps are the same as in Example 1.

[0115] To verify the effectiveness of the present invention, the following is the experimental procedure, which specifically includes:

[0116] Experimental Design:

[0117] The control group was set up, with control group A consisting of conventional medical nonwoven dressings: using polypropylene meltblown / spunbond nonwoven fabric as the main substrate, with a basis weight of 30 g / m²; its surface was coated with conventional acrylic pressure-sensitive adhesive as the adhesion layer, fixed by a coating-drying process, directly cut into sheets, and packaged as finished products after sterilization with ethylene oxide. The characteristics of this type of conventional dressing are: simple structure, reliance on adhesives for skin adhesion, easy failure in humid environments, and lack of moisture-wicking channels, sustained-release function, and antibacterial / early warning function.

[0118] Test method:

[0119] Liquid absorption ratio (g / g): Refer to EN13726-1: Absorption performance (static liquid absorption without external force, using 0.9% NaCl, 37℃, 30min), after absorption, remove surface liquid and weigh for calculation.

[0120] Water vapor transmission rate (WVTR) (g / m²·24h): Refer to ASTM E96 / E (dry cup method at 37°C and relative humidity of 75%→0%).

[0121] Peel force (N / cm): Refer to GB / T2792 (180° peel, across the substrate is polyethylene film, peel rate 300mm / min); also measure the re-adhesion retention rate (peel force after 3 consecutive re-adhesions on wet substrate / initial peel force × 100%).

[0122] Antibacterial properties: Refer to ISO 22196 (contact sterilization method, bacterial strains: Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739; after 24 hours of contact, the logarithmic decrease value is calculated). 10 (reduction and antibacterial rate).

[0123] Indicator of color change threshold: Using an artificial exudate (containing protein / salt) buffer system, the pH was increased stepwise from 6.0 to 8.5, and the threshold of obvious color change at a visible distance of 30 cm was recorded.

[0124] Near-infrared photothermal response: 808nm, 0.5W / cm², irradiation for 10min, surface temperature measured (infrared thermal imager), target range 42–45℃.

[0125] Drug release curve (antibacterial agent): 37℃ PBS (pH 7.4), sampling points 0.5 / 1 / 2 / 4 / 8 / 24h, cumulative release (%) determined by HPLC.

[0126] Cytotoxicity: Refer to ISO 10993-5 (L929 cells, extract method, morphology and relative viability), with a rating of 0–1 as acceptable.

[0127] Skin irritation and sensitization (in vitro replacement): Refer to ISO 10993-10 In vitro replacement method (human reconstructed skin model, irritation index SI).

[0128] Ethylene oxide residue (if sterilized with ethylene oxide): Refer to the enterprise standard / pharmacopoeia method (headspace GC), the limit is ≤10mg / dm².

[0129] The following data was obtained through the experiment:

[0130] Table 1 Liquid absorption and moisture permeability

[0131]

[0132] Table 2 Adhesion properties

[0133]

[0134] Table 3

[0135]

[0136] Table 4 Drug Release and Biocompatibility

[0137]

[0138] The medical nonwoven dressing described in this invention is superior to the conventional control group A in terms of absorbency, moisture permeability, adhesion, antibacterial properties, and biocompatibility. The absorbency ratios of Examples 1 to 5 are all between 22 and 30 g / g, significantly higher than the 7.8 g / g of control A, representing an increase of approximately 2.8 to 3.7 times. The water vapor permeability is all between 2200 and 2400 g / m²·24h, while control A is only 1250 g / m²·24h. This demonstrates that the present invention can maintain a moist environment on the wound while maintaining a good barrier function, which is significantly superior to traditional dressings. Example 4, due to the addition of nanocellulose, further increased the absorbency to 29.5 g / g, approximately 31% higher than Example 1, demonstrating its advantages in high-exudative wounds. Furthermore, the peel force of Examples 1-5 remained stable between 0.19 and 0.23 N / cm, lower than the 0.40 N / cm of Control A, indicating that the present invention significantly reduced the risk of peel damage while achieving stable adhesion. Regarding the dressing retention rate, all examples of the present invention achieved between 69% and 78%, significantly higher than the 28% of Control A, indicating that good adhesion is maintained even in humid environments or with multiple dressing changes, avoiding the problem of easy failure of conventional acrylic dressings. Example 4 achieved a dressing retention rate of 78%, which is optimal; while Control A had an antibacterial log reduction value of less than 0.5, indicating almost no significant antibacterial effect; while Examples 1-5 generally had antibacterial log reduction values ​​above 3.0, with antibacterial rates exceeding 99.9%. In Example 5, the combined effect of silver nanoclusters and zinc oxide nanoparticles resulted in a logarithmic reduction of 4.2 and 4.0 against Staphylococcus aureus and Escherichia coli, respectively, representing a further improvement of approximately 30% compared to Example 1, significantly enhancing the broad-spectrum antibacterial ability. Simultaneously, the antibacterial and breathable protective layer of this invention exhibits a stable colorimetric threshold at pH 7.1–7.2 under infection-related conditions, providing early warning of potential infection risks. Near-infrared photothermal experiments showed that the surface temperature of the dressing of this invention could rise to 43–44°C within 10 minutes of irradiation, falling within the safe sterilization range, while control A only rose to approximately 32°C, showing almost no photothermal response.

[0139] The antibacterial drugs in Examples 1-5 of this invention showed a cumulative release of 52-60% after 8 hours and 87-93% after 24 hours, achieving stable sustained release. Example 4 achieved the highest release (92.8%), indicating that nanocellulose facilitates drug diffusion. All examples exhibited grade 0-1 cytotoxicity as specified in ISO 10993-5, with relative survival rates greater than 95% and no significant cytotoxicity. The skin irritation index (SI) remained between 0.2 and 0.3, meeting the non-irritating requirement. Control A lacked sustained-release function and antibacterial drug loading.

[0140] In summary, the medical nonwoven dressing of the present invention is significantly superior to conventional dressings in terms of liquid absorption, moisture permeability, adhesion, antibacterial properties, and biocompatibility.

[0141] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a medical nonwoven dressing, characterized in that: Includes the following steps: S1. Preparation of skin-friendly hemostatic self-adhesive layer: Chitosan quaternary ammonium salt, catechol precursor and lactic acid solution are mixed, crosslinking agent is added to react and spin spinning solution is obtained, and skin-friendly hemostatic self-adhesive layer is obtained by electrospinning; S2. Preparation of liquid-absorbing, moisture-regulating and drug-doping layer: A precursor solution is formed by zwitterionic hydrogel monomer, crosslinking agent and photoinitiator, which is electrospun and superimposed on the same collector with thermoplastic polyurethane solution and polyvinyl alcohol template solution. Then, coaxial fibers containing drug core liquid and polylactic acid and polycaprolactone shell solution are deposited on it, and after curing and template dissolution, a microchannel group with thickness-through is formed to obtain liquid-absorbing, moisture-regulating and drug-doping layer; S3. Preparation of antibacterial and moisture-permeable protective layer: The polypropylene nonwoven fabric substrate is activated by low-temperature plasma and immersed in dopamine hydrochloride solution for deposition. Silver nanoclusters are loaded on its surface in situ by silver nitrate and indicator dye microcapsules are fixed to obtain the antibacterial and moisture-permeable protective layer. S4. Lamination and shaping: The above three layers are laminated together under point hot pressing conditions to obtain medical non-woven dressing; S2 specifically includes: S201. Dissolve sulfobetaine methacrylate in water, add crosslinking agent and photoinitiator, stir well and set aside to obtain solution D; S202. Weigh out thermoplastic polyurethane and dissolve it in a mixed solvent of tetrahydrofuran and dimethylformamide in a ratio of 1:1 to obtain solution E; S203. Weigh polyvinyl alcohol and dissolve it in hot water at 80-90℃ to prepare a 10-15wt% solution, thus obtaining solution F; S204. Solution D, solution E and solution F are respectively loaded into an electrospinning device and deposited alternately on the same collector to obtain a composite fiber membrane G containing an interpenetrating network and template fibers; S205. Preparation of core-shell fiber solution, including: Core solution H: Drug core fluid and aqueous solution; Shell solution I: Polylactic acid and polycaprolactone blend dissolved in dichloromethane / DMF; S206. The core solution H and the shell solution I are respectively loaded into a coaxial electrospinning nozzle, the internal flow rate is set to 0.2-0.3 mL / h, the external flow rate is set to 0.8-0.9 mL / h, the voltage is set to 18-20 kV, and the collection distance is set to 12-15 cm. They are deposited on the composite fiber membrane G to obtain a composite membrane J containing core and shell fibers. S207. The composite membrane J is cured by ultraviolet light to crosslink the solution D and form a stable hydrogel fiber network; S208. The cross-linked composite membrane J is immersed in deionized water to dissolve the polyvinyl alcohol fibers formed by the template solution F, thereby obtaining a liquid absorption, humidification and drug delivery layer containing longitudinal microchannels.

2. The method for preparing a medical nonwoven dressing according to claim 1, characterized in that: S1 specifically includes: S101. Dissolve chitosan quaternary ammonium salt in lactic acid solution and stir in a stirred reactor until completely dissolved to obtain a homogeneous solution A; S102. Add catechol precursor to solution A and continue stirring until homogeneous; S103. Add a crosslinking agent to solution A and react at 25-30℃ for 12-18h to obtain spinning solution B; S104. The spinning solution B is loaded into the electrospinning device and deposited on the drum collector to obtain a skin-friendly hemostatic self-adhesive layer.

3. The method for preparing a medical nonwoven dressing according to claim 1, characterized in that: The electrospinning conditions in step S1 are: voltage 10-20kV, flow rate 0.3-0.7mL / h, collection distance 12-18cm, collection by a rotary drum collector, to obtain a skin-friendly hemostatic self-adhesive layer with a thickness of 80-120μm.

4. The method for preparing a medical nonwoven dressing according to claim 1, characterized in that: S3 specifically includes: S301. Polypropylene nonwoven fabric is selected as the substrate L and sent into a plasma treatment machine for 5-7 minutes at 200W power to obtain activated substrate M. S302. Immerse the activated substrate M in a dopamine hydrochloride solution and react at 25-30℃ for 1-1.5h to obtain a substrate N with polydopamine deposited on the surface; S303. Place the substrate N in a 0.5-0.7wt% silver nitrate solution and let it stand for 30-40 minutes. Silver ions are reduced in situ on the surface of the polydopamine layer to form silver nanoclusters, thus obtaining the antibacterial substrate O. S304. The indicator dye microcapsule dispersion is uniformly sprayed onto the surface of the antibacterial substrate O and dried with hot air at 50-60℃ for 30-40 minutes to obtain an antibacterial and moisture-permeable protective layer.

5. The method for preparing a medical nonwoven dressing according to claim 1, characterized in that: In step S4, the hot pressing is adjusted to 120-130℃ and 0.3-0.4MPa for 2-3 seconds, with a dot diameter of 0.8-1mm and a dot spacing of 6-8mm, to form a medical non-woven dressing.

6. A medical nonwoven dressing, made by the preparation method of a medical nonwoven dressing according to any one of claims 1-5, characterized in that: From one side of the wound to the outside, it includes: Skin-friendly hemostatic self-adhesive layer; used to achieve hemostasis and self-adhesive fixation in moist environments; Liquid absorption and humidification layer; microchannel groups running through the thickness of the layer are set up to form a one-way humidification and self-humidification effect; Antibacterial and moisture-permeable protective layer; used for broad-spectrum antibacterial and infection risk indication, and generates mild photothermal effect under near-infrared irradiation to assist in antibacterial action; The skin-friendly hemostatic self-adhesive layer, the liquid-absorbing and moisture-regulating and drug-dispensing layer, and the antibacterial and moisture-permeable protective layer are surface-activated and then bonded together through a dotted hot-pressing layer.

7. A medical nonwoven dressing according to claim 6, characterized in that: The skin-friendly hemostatic self-adhesive layer material comprises, by weight, 100-150 parts of chitosan quaternary ammonium salt, 5-15 parts of catechol precursor, 10-20 parts of lactic acid solution, and 5-10 parts of crosslinking agent.

8. A medical nonwoven dressing according to claim 6, characterized in that: The raw materials for the liquid absorption, moisture conditioning, and drug delivery layer, by weight, include: 100-150 parts of zwitterionic hydrogel monomer, 1.5-2 parts of crosslinking agent, 0.5-1 part of photoinitiator, 20-40 parts of thermoplastic polyurethane, 10-30 parts of polyvinyl alcohol, 5-20 parts of drug core fluid, and 30-60 parts of polylactic acid and polycaprolactone blend as the outer shell layer.

9. A medical nonwoven dressing according to claim 6, characterized in that: The raw materials of the antibacterial and moisture-permeable protective layer include, by weight: 100-150 parts of polypropylene nonwoven fabric substrate, 1-3 parts of dopamine hydrochloride, 0.1-1 parts of silver nitrate, and 2-5 parts of indicator dye microcapsules, wherein the indicator dye microcapsules are anthocyanins or bromothymol blue.

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