A multilayer composite dressing with interlayer continuous antibacterial network and a method of making the same

Abstract

The present application relates to the technical field of medical devices, in particular to a multi-layer composite dressing with interlayer continuous antibacterial network and a preparation method thereof. The dressing comprises at least two layers of polymer substrate layers, the polymer substrate layers having a through pore network; a metal antibacterial layer, the metal antibacterial layer being coated on the surface of the skeleton of each polymer substrate layer to form a metalized skeleton; and a connecting structure arranged between adjacent polymer substrate layers; the connecting structure is distributed in discrete point shape between adjacent polymer substrate layers to fix and connect adjacent polymer substrate layers; the metalized skeletons of adjacent polymer substrate layers form physical contact at the interlayer interface to constitute an electrical path of the interlayer metal antibacterial layer. The dressing of the present application constructs a three-dimensional continuous electrochemical antibacterial network in the full-thickness direction, effectively solving the industry problems of internal biofilm breeding and drainage blockage in deep wound care.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a multilayer composite dressing with a continuous antibacterial network between layers and its preparation method. Background Technology

[0002] Polymer foam materials, especially polyurethane (PU) foam materials, are widely used in medical wound dressings due to their good biocompatibility, high porosity, and excellent exudate management capabilities, particularly as fillers for negative pressure wound therapy (NPWT) or for highly exudative wounds (such as burns and pressure ulcers). Imparting antibacterial properties to polymer foam dressings to prevent wound infection has been a research hotspot and a key industry challenge in this field.

[0003] Currently, the main technical approaches to imparting antibacterial properties to polymer foam dressings include the following:

[0004] One method is the mixed foaming method, which involves directly incorporating antibacterial agents (such as silver powder, silver salts, or other metal particles) into the polymer raw materials for physical mixing, followed by foaming. This method is simple to operate, but it has inherent drawbacks: most of the antibacterial agent is encapsulated inside the polymer matrix, failing to effectively contact wound exudate, resulting in a waste of expensive antibacterial materials; at the same time, increasing the amount of antibacterial agent to ensure sufficient antibacterial effect will significantly alter the pore structure, porosity, and mechanical properties of the foam, affecting the dressing's absorbency and comfort.

[0005] Secondly, the impregnation or spraying method involves loading an antibacterial coating onto the surface and internal pore walls of the formed foam through impregnation reduction or spraying. This method achieves a certain degree of distribution of antibacterial components within the three-dimensional structure of the foam. However, for thicker dressings, the coating loading rate deep within the foam is often low due to limitations in liquid penetration and mass transfer resistance. When a large amount of exudate is absorbed and remains inside the foam, bacteria can easily proliferate and form biofilms in the deeper layers due to the lack of sufficient antibacterial components, leading to the risk of "reverse infection." Furthermore, improper reduction processes or excessively thick coatings can clog small-pore foam channels, creating conditions conducive to bacterial growth.

[0006] Thirdly, multi-layer composite processes. To meet clinical needs for dressing size, gradient function, or composite function, multiple layers of foam often need to be bonded together. However, traditional adhesive bonding processes form a dense, continuous film between layers, clogging the pore network and severely reducing the vertical liquid absorption rate and water vapor permeability of the dressing; while flame bonding processes can easily damage the pre-prepared functional coating due to high temperatures, affecting the overall performance of the dressing.

[0007] Therefore, there is an urgent need to develop a new dressing structure that can achieve "bulk antibacterial" properties throughout the thickness direction, maintain the original permeability of the foam, and have long-term stability. Summary of the Invention

[0008] To address the shortcomings of the prior art, this invention provides a multilayer composite dressing with a continuous antibacterial network between layers and a method for preparing the same.

[0009] A first aspect of the present invention provides a multilayer composite dressing having an interlayer continuous antimicrobial network, comprising:

[0010] At least two polymer substrate layers, the polymer substrate layers having a through-pore network;

[0011] A metal antibacterial layer, wherein the metal antibacterial layer is coated on the skeleton surface of each of the polymer substrate layers to form a metallized skeleton; and

[0012] A connection structure disposed between adjacent polymer substrate layers;

[0013] The connection structure is distributed in a discrete point pattern between adjacent polymer substrate layers to fix and connect adjacent polymer substrate layers.

[0014] The metallized skeletons of adjacent polymer substrate layers form physical contacts at the interlayer interface, constituting the electrical pathway of the interlayer metal antibacterial layer.

[0015] In one embodiment of the present invention, the multilayer composite dressing has a pore size gradient structure in the thickness direction, wherein the pore size of the polymer substrate layer closer to the wound is larger than the pore size of the polymer substrate layer farther from the wound.

[0016] In one embodiment of the present invention, the pore size of the polymer substrate layer on the side closer to the wound is 1000 μm to 1500 μm; and the pore size of the polymer substrate layer on the side farther from the wound is 500 μm to 1000 μm.

[0017] In one embodiment of the present invention, the metal antibacterial layer is a pure silver layer, and the thickness of the pure silver layer is 500nm to 2000nm.

[0018] In one embodiment of the present invention, the metal antibacterial layer is a tantalum-silver composite coating or a tantalum-silver alloy coating, wherein the mass percentage of silver in the coating is 20wt% to 50wt%, and the thickness of the coating is 100nm to 500nm.

[0019] In one embodiment of the present invention, the connecting structure is a nonwoven hot-melt web film, and the basis weight of the hot-melt web film is 10 g / m². 2 Up to 25g / m 2 .

[0020] In one embodiment of the present invention, the melting point of the hot melt mesh is lower than the softening temperature of the polymer substrate layer.

[0021] In one embodiment of the present invention, the material of the hot melt film is selected from one or more of copolyamide, copolyester, thermoplastic polyurethane or ethylene-vinyl acetate copolymer.

[0022] A second aspect of the present invention provides a method for preparing a multilayer composite dressing having an interlayer continuous antimicrobial network as described in the first aspect of the present invention, characterized by comprising the following steps:

[0023] Provide at least two polymer substrate layers, the polymer substrate layers having a through-pore network;

[0024] A metal antibacterial layer is formed on the skeleton surface of each of the polymer substrate layers to obtain a metallized skeleton.

[0025] Connecting structures are set between adjacent metallized skeletons to form a laminate;

[0026] The laminate is subjected to hot pressing treatment, which melts the connecting structure and forms discrete point distributions between adjacent polymer substrate layers, fixing the adjacent polymer substrate layers together and making the metallized skeleton of the adjacent polymer substrate layers physically contact at the interlayer interface, thus forming the electrical pathway of the interlayer metal antibacterial layer.

[0027] In one embodiment of the present invention, the temperature of the hot pressing treatment is higher than the melting point of the connecting structure and lower than the softening temperature of the polymer substrate layer.

[0028] Based on the above, compared with the prior art, the composite dressing structure of the present invention constructs a continuous conductive and metal ion release channel in the dressing thickness direction, overcoming the technical defects of existing surface coatings that cannot solve deep infections and traditional laminated adhesive films that block vertical flow channels.

[0029] The composite dressing of this invention has excellent fluid management capabilities (vertical absorption time ≤ 5 seconds, MVTR ≥ 7000 g / m²). 2 It has a 24-hour antibacterial effect and long-lasting antibacterial properties (168h antibacterial rate ≥90%), making it particularly suitable for deep cavity wound filling and negative pressure wound therapy (NPWT) systems. The preparation process is simple and suitable for large-scale production.

[0030] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other beneficial effects of the invention can be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships shown in the drawings in the following description are based on the direction in which the components are drawn in the figure.

[0032] Figure 1 A photograph of a single-layer silver-plated polyurethane foam provided in an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of the structure of a multilayer composite dressing with a continuous antibacterial network between layers provided in an embodiment of the present invention;

[0034] Figure 3 Photograph of the multilayer silver-plated polyurethane foam composite dressing provided in an embodiment of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention 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 all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0037] Existing multilayer composite foam dressings struggle to balance deep antibacterial properties with interlayer permeability: traditional surface silver loading processes only work on the surface, causing exudate to stagnate deep within the dressing, making it easy for bacteria to grow and form a biofilm; while using adhesive or lamination processes for multilayer composites creates a dense adhesive film between layers, blocking vertical drainage channels and severely weakening drainage and breathability, and the antibacterial layers are isolated from each other, making it impossible to build a continuous antibacterial network in the thickness direction.

[0038] Therefore, the technical problem to be solved by the first aspect of the present invention is how to achieve the construction of a continuous antibacterial network and stable interlayer bonding in the entire thickness direction while maintaining the high permeability and excellent flowability of the multilayer dressing.

[0039] An embodiment of the first aspect of the present invention provides a multilayer composite dressing having an interlayer continuous antimicrobial network, comprising: at least two polymer substrate layers, a metal antimicrobial layer covering the skeleton surface of each of the polymer substrate layers, and a connecting structure disposed between adjacent polymer substrate layers;

[0040] The polymer substrate layer provides the main support structure of the dressing. The polymer material has good biocompatibility, flexibility, and processing performance. The number of polymer substrate layers can be 2, 3, 4, 5, or more, which can be selected according to clinical needs and dressing thickness requirements to meet different needs. The polymer substrate layer has a through-pore network that ensures that exudate can flow freely in the thickness direction, realizing vertical drainage function, while providing space for tissue ingrowth.

[0041] The polymer substrate layer can be made of thermoplastic polymers such as polyurethane (PU), polyethylene (PE), polypropylene (PP), polyetheretherketone (PEEK), polysulfone (PSU), polyimide (PI), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), ethylene-vinyl acetate copolymer (EVA), polyvinyl chloride (PVC), polystyrene (PS), polyamide (PA), polyester (PET, PBT), polylactic acid (PLA), polyglycolic acid (PGA), and polycaprolactone (PCL), or copolymers or blends thereof;

[0042] The polymer substrate layer can be a porous material with a through-pore network, such as a foamed material, a fiber-woven material, an electrospun membrane, a nonwoven fabric, or a hydrogel porous material. In other words, the pore network can be a three-dimensional network structure of open-cell foam, inter-fiber pores of fiber materials, or a nanofiber network of electrospun materials, as long as it can enable the through-flow of the permeate in the thickness direction.

[0043] In this invention, the structural design of coating the skeleton surface of each polymer substrate layer with a metal antibacterial layer lays the foundation for full-thickness antibacterial properties. Since each substrate layer is endowed with antibacterial function, the dressing maintains antibacterial capability at any depth. Furthermore, by coating the skeleton surface with the metal antibacterial layer rather than filling the pores, it can directly contact the exudate absorbed into the dressing, thereby achieving highly efficient antibacterial action. Simultaneously, this coating method does not block the inherent interconnected pore network of the substrate, maintaining the material's original high permeability. In addition, the coating of the metal antibacterial layer on the skeleton surface effectively forms a metallized skeleton, imparting conductivity to the originally insulating polymer skeleton, creating the necessary conditions for subsequent interlayer electrical conduction.

[0044] Metallic antibacterial materials can be metals with antibacterial properties such as silver (Ag), copper (Cu), and zinc (Zn), or alloys of them (such as silver-copper alloys, silver-zinc alloys, silver-tantalum alloys, copper-tantalum alloys, etc.) or composite coatings (such as composite structures formed by multi-layer alternating deposition or co-deposition).

[0045] Connection structures are disposed between adjacent polymer substrate layers; the connection structures are distributed in a discrete point-like manner between adjacent polymer substrate layers to fix and connect adjacent polymer substrate layers.

[0046] In this invention, the connecting structure, as a functional unit for interlayer fixation, binds multiple substrates into a whole through a discrete point-like distribution. This point-like distribution differs from traditional continuous adhesive films, occupying only a local area of ​​the interlayer interface, avoiding clogging of interlayer pores, and thus maintaining a high porosity at the interlayer interface. Since most areas are unobstructed by connecting materials, exudate can flow freely between layers, ensuring that the dressing achieves structural stability without sacrificing its conductivity, guaranteeing sufficient interlayer peel strength while maintaining excellent vertical conductivity.

[0047] The materials for the connecting structure can be hot-melt polymers (such as copolyamide PA, copolyester PES, thermoplastic polyurethane TPU, ethylene-vinyl acetate copolymer EVA, polyolefin PO, polycaprolactone PCL, etc.), thermosetting adhesives, light-curing adhesives, pressure-sensitive adhesives, etc., as long as they can form a dotted distribution and fix adjacent substrates.

[0048] It should be noted that the dotted distribution can be formed by hot pressing and melting shrinkage, by dispensing glue directly, by printing dot matrix, by spraying mask to form dot pattern, or by electrospinning to form dot deposition, etc.

[0049] The metallized skeletons of adjacent polymer substrate layers form physical contacts at the interlayer interface, constituting the electrical pathway of the interlayer metal antibacterial layer.

[0050] In this invention, another key function of the dotted distribution connection structure is that it enables physical contact to be formed at the interlayer interface between the metallized skeletons of adjacent polymer substrate layers. Since the connection structure occupies only discrete points, most of the interlayer interface is unobstructed by connecting material, allowing direct contact between the upper and lower metallized skeletons. This physical contact constitutes an electrical pathway for the interlayer metal antibacterial layer, enabling electrical conduction between the upper and lower metal antibacterial layers and forming a continuous conductive network throughout the entire thickness of the dressing. The establishment of this electrical pathway allows for the formation of a three-dimensional continuous electrochemical antibacterial network within the dressing. When exudate enters the dressing, it not only directly contacts the metal antibacterial layers on the surface of each skeleton layer but also generates a micro-electric field due to the interlayer electrical conduction. The synergistic effect of metal ion release and the micro-electric field significantly enhances the antibacterial effect. Particularly for alloy coatings such as tantalum-silver, the establishment of the electrical pathway helps to regulate the silver ion release rate by utilizing the potential difference between different metals, avoiding explosive release and thus achieving long-lasting and stable antibacterial performance.

[0051] It should be noted that the physical contact can take the form of point contact, line contact, or surface contact. It can be direct contact between the ends of the skeleton or mutual compression between the side walls of the skeleton. The purpose is to achieve electrical conduction.

[0052] Therefore, this invention utilizes a metal antibacterial layer to coat the surface of the skeleton of each polymer substrate layer, enabling the dressing to possess antibacterial capabilities throughout its thickness direction. Regardless of where the exudate is absorbed, it can always contact the antibacterial interface, effectively eliminating bacterial breeding dead zones and preventing deep biofilm formation. Furthermore, the discrete point-like distribution of the connecting structure occupies only a localized area of ​​the interlayer interface, avoiding the pore blockage of traditional continuous adhesive films. This ensures that most of the interlayer interface remains open, allowing exudate to flow freely in the thickness direction, maintaining the dressing's excellent vertical conductivity and breathability. Simultaneously, the point-like connecting structure reliably fixes adjacent substrate layers, providing sufficient interlayer bonding strength to ensure structural stability of the dressing during use without sacrificing permeability. In addition, the physical contact between the metallized skeletons of adjacent substrate layers at the interlayer interface forms an electrical pathway, creating a three-dimensional conductive network throughout the dressing. The synergistic effect of metal ion release and micro-electric field further enhances the antibacterial effect, achieving long-lasting and stable antibacterial performance.

[0053] Compared to using a dense inner pore size, its core mechanism is to use the microporous structure to generate extremely high capillary force to actively absorb exudate. However, within the small pore size range, drainage blockage caused by the accumulation of exudate and tissue is more likely to occur, making it less suitable for granulation tissue growth and repair.

[0054] In a preferred embodiment of the present invention, the multilayer composite dressing has a pore size gradient structure in the thickness direction, wherein the pore size of the polymer substrate layer closer to the wound is larger than the pore size of the polymer substrate layer farther from the wound.

[0055] Specifically, the dressing consists of multiple polymer substrate layers, arranged with the side closer to the wound as the inner layer and the side farther from the wound as the outer layer. The inner substrate layer uses polymer foam with larger pore sizes, while the outer substrate layer uses polymer foam with relatively smaller pore sizes. For example, the inner layer pore size can be set to 1000-1500 μm, and the outer layer pore size to 500-1000 μm; alternatively, it can be a three-layer structure, with a large-pore inner layer, transitional pores in the middle layers, and small pores in the outer layer; or, for a four-layer structure, it can be a large-pore inner layer, transitional pores in the two middle layers, and small pores in the outer layer.

[0056] By employing a gradient pore size design, the inner layer, closer to the wound, uses a large-pore structure to provide ample space for tissue ingrowth, promoting granulation tissue growth and blood revascularization. Furthermore, the large-pore channels can accommodate high-viscosity exudate and pus, avoiding the filtration and clogging problems common in microporous structures. Additionally, under negative pressure treatment, the large pore size provides a stronger ability to extract high-viscosity exudate. The outer layer, further away from the wound, uses a relatively smaller pore size, generating stronger suction under negative pressure to rapidly draw exudate from the inner layer and temporarily store it in the outer pores. This gradient change in pore size between the inner and outer layers creates a fluid resistance gradient, allowing exudate to be rapidly and unidirectionally guided away from the wound and stored in the outer layer of the dressing, effectively preventing backflow and wound maceration.

[0057] In a preferred embodiment of the present invention, the pore size of the polymer substrate layer on the side closer to the wound is 1000 μm to 1500 μm; and the pore size of the polymer substrate layer on the side farther from the wound is 500 μm to 1000 μm.

[0058] Specifically, the dressing consists of at least two polymer substrate layers. When used, the inner substrate layer closest to the wound surface uses macroporous polymer foam with a pore size of 1000 μm to 1500 μm, such as 1000 μm, 1100 μm, 1200 μm, 1300 μm, 1400 μm, 1500 μm, etc., but is not limited to the listed values; other unlisted values ​​within this range also apply. The outer substrate layer furthest from the wound surface (for two-layer structures) or the outer / middle substrate layer (for three-layer or higher structures) uses polymer foam with a smaller pore size of 500 μm to 1000 μm, such as 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, etc., but is not limited to the listed values; other unlisted values ​​within this range also apply.

[0059] This invention targets negative pressure wound therapy environments, employing a pore size gradient design with an inner layer of 1000-1500 μm and an outer layer of 500-1000 μm. In this environment, the dressing relies on external negative pressure to drive the fluid rather than capillary force. The large pores in the inner layer not only completely eliminate the risk of "filtration blockage" in high-viscosity pus under microporous structures, but also provide stronger extraction capacity for high-viscosity exudate under therapeutic negative pressure ranging from 75 mmHg to -125 mmHg. Simultaneously, this pore size range is an optimal size for promoting granulation tissue ingrowth and providing a vascular environment—large enough to allow cell migration and tissue ingrowth without being excessively large and affecting the mechanical support performance of the skeletal structure. The small pores in the outer layer (500-1000 μm) generate sufficient suction force under negative pressure, rapidly extracting exudate from the inner layer and storing it in the outer pores. The synergistic effect of the inner and outer pore sizes ensures that the dressing has a vertical liquid absorption time of ≤5 seconds and an MVTR of ≥7000g / m² / 24h, effectively preventing wound maceration.

[0060] In a preferred embodiment of the present invention, the metal antibacterial layer is a pure silver layer with a thickness of 500 nm to 2000 nm. Silver is a broad-spectrum and highly effective inorganic antibacterial material. Silver ions can bind to enzymes within bacterial cells and inhibit their activity, interfering with bacterial metabolism; they can also promote the generation of reactive oxygen species within bacterial cells, causing damage to bacterial DNA, proteins, and lipids. Coating the surface of the polymer skeleton with a pure silver layer allows the silver layer to directly contact the exudate absorbed into the dressing, efficiently utilizing the antibacterial properties of silver. The thickness range of 500-2000 nm is an experimentally verified preferred range: too small a thickness (<500 nm) may lead to discontinuity or insufficient adhesion of the silver layer, affecting the antibacterial effect and service life; too large a thickness (>2000 nm) may lead to excessive internal stress in the silver layer, making it prone to cracking and peeling, while also increasing costs. Within this thickness range, through a multi-layer stacked structure and a gradient silver plating thickness design between the inner and outer layers, the dressing can maintain a continuous antibacterial rate of ≥90% after immersion in simulated wound fluid for 168 hours.

[0061] Simultaneously, vacuum deposition processes such as magnetron sputtering can be used to deposit a pure silver layer on the surface of the framework of each polymer substrate layer, forming a silver-coated metallized framework. The thickness of the pure silver layer is controlled within the range of 500nm to 2000nm, such as 500nm, 800nm, 1000nm, 1200nm, 1500nm, 1800nm, and 2000nm, but it is not limited to the listed values; other unlisted values ​​within this range are also applicable. Depending on the location of the substrate layer and the application requirements, different thicknesses of silver layers can be applied to different layers. For example, a thinner silver layer (e.g., 500-1000nm) can be applied to the inner layer near the wound, while a thicker silver layer (e.g., 1000-2000nm) can be applied to the outer layer to balance antibacterial efficiency and silver ion release rate.

[0062] In a preferred embodiment of the present invention, the multilayer composite dressing includes at least two polymer substrate layers, wherein the thickness of the metal antibacterial layer on each polymer substrate layer gradually increases in the direction away from the wound; preferably, the thickness of the metal antibacterial layer on the polymer substrate layer near the wound is 300 nm to 800 nm, and the thickness of the metal antibacterial layer on the polymer substrate layer away from the wound is 1500 nm to 2500 nm; more preferably, when the multilayer composite dressing includes at least three polymer substrate layers, the thickness of the metal antibacterial layer on the middle polymer substrate layer is 800 nm to 1500 nm.

[0063] Specifically, vacuum coating processes such as magnetron sputtering can be used to deposit metal antibacterial layers of different thicknesses on the skeleton surface of each polymer substrate layer, forming a thickness gradient distribution.

[0064] For two-layer composite dressings: the inner layer (closer to the wound) has a thinner metal antibacterial layer deposited on the polymer substrate, with a thickness controlled within the range of 300nm to 800nm, such as 300nm, 400nm, 500nm, 600nm, 700nm, and 800nm; the outer layer (away from the wound) has a thicker metal antibacterial layer deposited on the polymer substrate, with a thickness controlled within the range of 1500nm to 2500nm, such as 1500nm, 1600nm, 1700nm, 1800nm, 1900nm, 2000nm, 2100nm, 2200nm, 2300nm, 2400nm, and 2500nm. After both layers are coated, the inner and outer layers are fixed and composited using a dotted connecting structure.

[0065] For composite dressings with three or more layers: the inner layer (closest to the wound) has a thin metal antibacterial layer deposited on the polymer substrate, with a thickness controlled within the range of 300nm to 800nm; the middle layer (farthest from the wound) has a medium-thickness metal antibacterial layer deposited on the polymer substrate, with a thickness controlled within the range of 800nm ​​to 1500nm, such as 800nm, 900nm, 1000nm, 1100nm, 1200nm, 1300nm, 1400nm, 1500nm, etc.; the outer layer (farthest from the wound) has a thicker metal antibacterial layer deposited on the polymer substrate, with a thickness controlled within the range of 1500nm to 2500nm. For structures with four or more layers, a multi-layered, progressively increasing thickness distribution can be used, with each layer gradually increasing in thickness. After each layer is coated, the layers are sequentially fixed and composited using a dotted connection structure.

[0066] By employing a gradient coating design with a thin inner layer and a thick outer layer (two-layer structure), or a gradient coating design with a thin inner layer, a medium middle layer, and a thick outer layer (three-layer or higher structure), it is possible not only to create a metal ion concentration gradient along the thickness of the dressing, transforming ion release from an explosive burst to a stable and controllable process; but also to extend the overall antibacterial lifespan of the dressing, preventing antibacterial failure due to premature depletion of metal ions; and to optimize metal utilization, reducing the waste of expensive metals and lowering material costs while ensuring antibacterial efficacy.

[0067] In a preferred embodiment of the present invention, the metal antibacterial layer is a tantalum-silver composite coating or a tantalum-silver alloy coating, wherein the mass percentage of silver in the coating is 20wt% to 50wt%, and the thickness of the coating is 100nm to 500nm.

[0068] The tantalum-silver composite / alloy coating can produce the following synergistic effects: (1) Tantalum has excellent biocompatibility and chemical stability, and can form a stable oxide layer on the coating surface, improving the corrosion resistance and long-term stability of the coating; (2) There is a potential difference between tantalum and silver. When the two coexist in the same coating and form an electrical pathway, a micro-battery effect can be generated. The release rate of silver ions can be regulated by the inert anode effect of tantalum, avoiding the explosive release of silver and achieving long-term stable antibacterial performance; (3) The introduction of tantalum can reduce the amount of precious metal silver used, reduce material costs, and at the same time, it does not affect the antibacterial effect. Experimental verification shows that the tantalum-silver composite / alloy coating of this preferred embodiment can make the dressing maintain a continuous antibacterial rate of ≥99.9% after soaking in simulated wound fluid for 168 hours, showing excellent long-term antibacterial performance.

[0069] Specifically, vacuum deposition processes such as dual-target co-sputtering can be used to deposit a tantalum-silver composite coating or a tantalum-silver alloy coating on the surface of the framework of each polymer substrate layer. The mass percentage of silver in the coating is controlled within the range of 20wt% to 50wt%, such as 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, etc.; the coating thickness is controlled within the range of 100nm to 500nm, such as 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable; tantalum atoms are distributed in the interstices of the silver lattice or form a nanoscale tantalum phase in the coating, playing a pinning and stabilizing role.

[0070] In a preferred embodiment of the present invention, the connecting structure is a nonwoven hot-melt mesh film, and the basis weight of the hot-melt mesh film is 10 g / m². 2 Up to 25g / m 2Specifically, the connecting structure employs a non-woven hot-melt mesh film, meaning it is a non-woven mesh material with openings before lamination. The basis weight of the hot-melt mesh film is controlled at 10 g / m². 2 Up to 25g / m 2 Within a range, for example, 10g / m 2 12g / m 2 15g / m 2 18g / m 2 20g / m 2 22g / m 2 25g / m 2 This includes, but is not limited to, the listed values; other unlisted values ​​within this range also apply. During the hot-pressing process, a hot-melt mesh is laid between two adjacent metallized skeleton layers. Under heating and pressure, the hot-melt mesh melts and, under surface tension, shrinks and converges towards the skeleton nodes of the polyurethane substrate, ultimately forming discrete point-like bonding points at the skeleton nodes.

[0071] This embodiment concretizes the connection structure as a nonwoven hot-melt mesh, thus achieving a preferred material form for discrete point distribution. The nonwoven hot-melt mesh is randomly interwoven with hot-melt fibers, and has the following characteristics: (1) it is a loose mesh structure in its initial state, which facilitates gas discharge and melt flow; (2) after hot pressing and melting, due to surface tension and capillary action, the melt tends to crawl along the skeleton surface and converge at the nodes, spontaneously forming a point distribution; (3) the number and size of the final bonding points can be adjusted by controlling the basis weight. Using 10-25 g / m³... 2 The weight range is an experimentally verified optimal range to avoid excessively low weight (<10g / m³). 2 Insufficient number of bond points and inadequate interlayer peel strength, or excessive basis weight (>25g / m²) can lead to these problems. 2 Excessive melt can lead to the formation of a continuous film in some areas, which can clog the pores.

[0072] In a preferred embodiment of the present invention, the melting point of the hot melt web film is lower than the softening temperature of the polymer substrate layer. By limiting the thermal property relationship between the hot melt web film and the polymer substrate layer, a point-like interlocking structure is achieved. When the hot pressing temperature is higher than the melting point of the hot melt web film but lower than the softening temperature of the substrate layer: (1) the hot melt web film can be fully melted and transformed into a flowable viscous fluid; (2) the substrate layer remains solid, and its three-dimensional porous network structure is completely preserved without collapse or deformation; (3) the molten hot melt web film shrinks along the surface of the solid skeleton under the action of surface tension and converges at the nodes to form point-like adhesion.

[0073] In a preferred embodiment of the present invention, the material of the hot melt web film is selected from one or more of copolyamide, copolyester, thermoplastic polyurethane, or ethylene-vinyl acetate copolymer. Specifically, it can be a single material, or a blend or composite fiber of two or more materials. For example, a hot melt web film made of CoPA / TPU blended spinning or CoPES / EVA composite fiber can be used. The copolyamide (CoPA) can be nylon 6 / 66 copolymer, nylon 6 / 12 copolymer, nylon 6 / 69 copolymer, etc.; the copolyester (CoPES) can be polyethylene terephthalate-isophthalic acid copolymer, polybutylene terephthalate-polyethylene glycol copolymer, etc.; the thermoplastic polyurethane (TPU) can be polyester-type TPU, polyether-type TPU, etc.; the vinyl acetate content in the ethylene-vinyl acetate copolymer (EVA) can be adjusted within the range of 10%-40%; or other hot melt materials. Biodegradable hot-melt materials such as polyolefins (e.g., high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polycaprolactone (PCL), polylactic acid (PLA), polyhydroxyalkanoates (PHA), polybutylene succinate (PBS), and their copolymers or blends; or core-sheath structured composite fibers (e.g., CoPA sheath / PP core, EVA sheath / PET core), through which the sheath is melt-bonded and the core maintains the fiber morphology, further controlling the dotted distribution pattern.

[0074] A second aspect of the present invention provides a method for preparing a multilayer composite dressing having an interlayer continuous antimicrobial network as described in the first aspect, comprising the following steps:

[0075] Provide at least two polymer substrate layers, the polymer substrate layers having a through-pore network;

[0076] A metal antibacterial layer is formed on the skeleton surface of each of the polymer substrate layers to obtain a metallized skeleton.

[0077] Connecting structures are set between adjacent metallized skeletons to form a laminate;

[0078] The laminate is subjected to hot pressing treatment, which melts the connecting structure and forms discrete point distributions between adjacent polymer substrate layers, fixing the adjacent polymer substrate layers together and making the metallized skeleton of the adjacent polymer substrate layers physically contact at the interlayer interface, thus forming the electrical pathway of the interlayer metal antibacterial layer.

[0079] Specifically, the preparation method includes the following steps:

[0080] S1 Substrate Preparation: Provide at least two polymer substrate layers with a continuous pore network. Substrates of different pore sizes, thicknesses, and number of layers can be selected as needed. The substrate can be polyurethane foam, polyethylene foam, etc., and the required specifications can be obtained through foaming and cutting processes.

[0081] S2 Metallization: A metallic antibacterial layer is formed on the surface of the skeleton of each polymer substrate layer, resulting in a metallized skeleton. Vacuum deposition processes (such as magnetron sputtering, vacuum evaporation, ion plating, etc.), chemical plating, electroplating, etc., can be used to deposit the metallic antibacterial layer on the substrate skeleton surface. The metallic antibacterial layer can be a pure silver layer, a tantalum-silver composite / alloy layer, or other metal layers; the thickness and composition can be controlled as needed.

[0082] S3 Layered Construction: Connecting structures are set between adjacent metallized skeletons to form a laminate. The connecting structures can be in the form of hot-melt mesh, hot-melt powder, hot-melt fiber, etc., and are stacked alternately in the order of metallized skeleton-connecting structure-metallized skeleton.

[0083] S4 Hot-Pressure Composite: The laminate is hot-pressed. The hot-pressing temperature is selected within a range higher than the melting point of the connecting structure but lower than the softening temperature of the polymer substrate layer. The hot-pressing pressure and time are adjusted according to the material properties. During the hot-pressing process, the connecting structure melts and shrinks along the skeleton surface under the action of surface tension, eventually converging at the skeleton nodes to form a discrete point distribution. At the same time, due to the shrinkage of the connecting structure and the pressure, the metallized skeletons of adjacent substrate layers form direct physical contact at the interlayer interface. After cooling, the adjacent substrate layers are fixedly connected by the point-distributed connecting structure, and the physical contact of the metallized skeletons constitutes an interlayer electrical pathway.

[0084] This invention utilizes the surface tension of the hot-melt bonding material in its molten state to drive its self-shrinkage behavior, transforming it from an initial continuous or network distribution into a point-like distribution, thereby achieving interlayer fixation without clogging pores. Simultaneously, by controlling the hot-pressing process parameters (temperature, pressure, and time), the bonding material is fully melted and shrinks to the nodes, while the polymer substrate remains solid, preventing substrate deformation or collapse. The preparation method provided by this invention is simple, highly controllable, and suitable for large-scale production, stably yielding multilayer composite dressings with a continuous antibacterial network, high permeability, and excellent flow conductivity.

[0085] In a preferred embodiment of the present invention, the hot-pressing temperature is higher than the melting point of the connecting structure and lower than the softening temperature of the polymer substrate layer. In this hot-pressing composite step, the hot-pressing temperature is set to be higher than the melting point (or the upper limit of the melting temperature range) of the connecting structure but lower than the softening temperature (or heat distortion temperature) of the polymer substrate layer. For example, when the connecting structure is a copolyamide hot-melt mesh with a melting point of 90-110°C and the polymer substrate layer is polyurethane with a softening temperature of 120-150°C, the hot-pressing temperature can be selected as 95-115°C. The specific temperature can be optimized according to the specific material properties of the connecting structure and the substrate to ensure that the connecting structure is fully melted while the substrate layer remains solid.

[0086] The following describes embodiments of the present invention. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0087] Example 1

[0088] This embodiment provides a method for preparing a pure silver multilayer dot-shaped sintered dressing, including the following steps:

[0089] Step 1, Substrate preparation: Select medical-grade polyurethane foam and cut it into 3 sheets with a thickness of 1cm and a pore size of 1500 / 1000 / 500μm.

[0090] Step 2, PVD Silver Plating: Place all three foam pieces in the magnetron sputtering vacuum chamber. Use pure silver (99.99%) as the target material, and maintain a vacuum level of 5.0 × 10⁻⁶. -2 Pa is used to perform double-sided and side-sided coating to obtain silver-plated foam. The thickness of the inner silver layer is controlled at approximately 340 nm, and the thickness of the outer silver layer is controlled at approximately 800 nm. At this point, the framework of each foam piece is wrapped with a nano-silver layer. Figure 1 .

[0091] Step 3, Stacking: See reference Figure 2 According to "silver-plated foam / PA hot melt mesh (15g / m 2 Stack the following in sequence: silver-plated foam, PA hot melt mesh, and silver-plated foam.

[0092] Step 4, Point-like Sintering: Hot pressing at 105℃ and 0.2MPa for 15 seconds. The hot-melt mesh melts and shrinks to the skeleton nodes, forming a physical interlock. (See reference...) Figure 3 .

[0093] The dressing prepared in Example 1 was tested as follows:

[0094] (1) Total Thickness

[0095] Reference standard: GB / T 24218.2-2009 Textiles - Test methods for nonwoven fabrics - Part 2: Determination of thickness.

[0096] Testing instrument: Digital fabric thickness gauge.

[0097] Test method: Under standard atmospheric pressure, cut a dressing sample with an area of ​​10cm × 10cm. Place the sample flat on the reference plate of the thickness gauge, lower the pressure foot under the specified pressure (usually 0.5 kPa or 2 kPa, to avoid flattening the sponge skeleton), let it stand for 10 seconds, and then read the data. Measure each sample 5 times at different locations and take the arithmetic mean. The unit is mm or cm.

[0098] (2) Gram Weight (mass per unit area)

[0099] Reference standard: GB / T 24218.1-2009 Textiles - Test methods for nonwoven fabrics - Part 1: Determination of mass per unit area.

[0100] Testing instruments: 100 cm² disc sampler, 0.0001 g electronic balance.

[0101] Test method: Using a disc sampler, uniformly cut circular samples with an area of ​​100 cm² from different parts of the dressing and weigh them on an electronic balance (accurate to 0.001 g). Calculate the mass of the dressing per square meter, in g / m².

[0102] (3) Water vapor transmission rate (MVTR)

[0103] Reference standard: YY / T 0471.2-2004 "Test methods for contact wound dressings - Part 2: Moisture permeability".

[0104] Testing instruments: constant temperature and humidity chamber, water vapor transmission rate tester (permeability cup method).

[0105] Test Method: The dressing sample is fixed to the mouth of a permeation cup containing a specific volume of pure water or desiccant, with the edges sealed to ensure that water vapor can only pass through the dressing. The permeation cup is placed in a constant temperature and humidity chamber at 37±1℃ and 20% relative humidity. The permeation cup is accurately weighed at the initial stage and after 24 hours. The permeability per square meter of dressing over 24 hours is calculated using the mass difference, expressed as g / m² / 24h.

[0106] (4) Liquid Strike-Through Time

[0107] Reference standard: GB / T 24218.8-2010 Textiles - Nonwovens - Test methods - Part 8: Determination of liquid penetration time.

[0108] Test instrument: Liquid Strike-Through Tester.

[0109] Test method: Lay the dressing sample (wound side facing up) flat on standard absorbent filter paper. Instantly inject 5 ml of simulated wound exudate (or 0.9% saline) into a standard funnel above the sample. The instrument automatically records the time required for the liquid to travel from contact with the dressing surface to complete penetration and absorption by the underlying filter paper, in seconds (s).

[0110] (5) Silver content

[0111] Testing instruments: Microwave digester, inductively coupled plasma mass spectrometer (ICP-MS) or atomic absorption spectrometer (AAS).

[0112] Test Method: Accurately weigh 0.1g of dressing sample and place it in a polytetrafluoroethylene digestion vessel. Add a mixture of nitric acid and hydrogen peroxide (or perchloric acid) and place the vessel in a microwave digester for complete digestion until clear and transparent. After removing the acid, bring the volume to a final volume with deionized water. Determine the silver concentration in the final volume solution using ICP-MS (or AAS), and finally convert it to the silver content per unit area of ​​dressing, expressed in g / m² or mg / 100cm².

[0113] (6) Initial Antibacterial Rate

[0114] Reference standards: Refer to AATCC 100-2012 "Evaluation of antimicrobial properties of textile materials" (absorption method) or GB / T20944.3-2008 (oscillation method).

[0115] Testing instruments: constant temperature incubator, biosafety cabinet.

[0116] Test Method: Representative bacterial strains were selected: Staphylococcus aureus (representing Gram-positive bacteria) and Escherichia coli (representing Gram-negative bacteria). A bacterial suspension at a concentration of 1 × 10⁵ CFU / mL was quantitatively added and inoculated onto the dressing sample and a blank control sample without antibiotics. After incubation at 37°C for 24 hours, the bacteria in the sample were eluted with elution buffer. The elution buffer was serially diluted and plated onto agar plates. Colony counts (CFU) were performed after incubation, and the inhibition rate (%) was calculated by comparing with the blank control group.

[0117] (7) Antibacterial rate after 168 hours of immersion in simulated wound fluid

[0118] Test Method: First, simulated wound fluid (SWF) is prepared, usually by mixing equal volumes of 0.9% saline and fetal bovine serum (FBS, which provides a protein environment). The dressing sample is completely immersed in SWF and placed in a 37°C constant temperature shaking incubator for continuous immersion (or a peristaltic pump is used to simulate continuous flushing and elution of the exudate) for 168 hours (7 days). After the time is reached, the sample is removed, and the surface is gently rinsed with sterile saline. Then, immediately, the inoculation, culture, and antimicrobial rate calculation are performed again according to the above-mentioned standard "(6) Initial Antimicrobial Rate" (such as AATCC 100) to verify the antimicrobial durability of the dressing in a long-term high-protein, high-exudate environment.

[0119] The test results are shown in the table below:

[0120] Table 1

[0121]

[0122] Example 2

[0123] This embodiment provides a method for preparing a tantalum-silver alloy long-lasting antibacterial dressing, including the following steps:

[0124] Step 1, Substrate preparation: Select medical-grade polyurethane foam and cut it into 3 sheets with a thickness of 1cm and a pore size of 1500 / 1000 / 500μm.

[0125] Step 2, PVD alloy deposition: Tantalum-silver foam is obtained using dual-target co-sputtering with a silver target and a tantalum target. The power ratio is controlled to ensure that the silver content in the deposited layer is approximately 70 wt% and the tantalum content is 60 wt%. The total thickness of the inner coating is approximately 150 nm, and the total thickness of the outer coating is approximately 400 nm.

[0126] Step 3, Lamination: Press "Tantalum silver foam / TPU hot melt mesh (20g / m)" 2) / Tantalum silver foam" are stacked in sequence.

[0127] Step 4, point sintering: Hot pressing at 115℃ and 0.2MPa for 15 seconds, so that the TPU hot melt mesh melts and shrinks to the skeleton nodes, forming a physical interlock.

[0128] The dressing prepared in Example 2 was tested using the methods described above;

[0129] The test results are shown in the table below:

[0130] Table 2

[0131]

[0132] Example 3

[0133] This embodiment provides a method for preparing a gradient aperture guiding dressing, including the following steps:

[0134] Step 1, Substrate Preparation: Prepare two types of foam. The inner layer uses 1200μm foam with a thickness of 0.5cm; the middle and outer layers use 850μm foam, each with a thickness of 1.0cm.

[0135] Step 2, PVD Silver Plating: Foam of different specifications are placed in a magnetron sputtering vacuum chamber. Pure silver (99.99%) is used as the target material, and the vacuum level is 5.0 × 10⁻⁶. -2 Pa is used to perform double-sided and side-sided coating to obtain silver-plated foam. The thickness of the inner silver layer is controlled at approximately 340 nm, and the thickness of the outer silver layer is controlled at approximately 800 nm. At this point, the skeleton of each foam piece is wrapped with a nano-silver layer.

[0136] Step 3, Layering: Press "Silver-plated foam (inner layer) / PA hot melt mesh (15g / m)" 2 Stack the following layers in sequence: silver-plated foam (middle layer), PA hot melt mesh, and silver-plated foam (outer layer).

[0137] Step 4, point sintering: Hot pressing at 105℃ and 0.2MPa for 15 seconds. After the hot-melt mesh melts, it shrinks to the skeleton nodes, forming a physical interlock.

[0138] Results: Tests show that this gradient structure can more quickly transfer viscous simulated pus (viscosity > 20 cP) from the bottom to the upper storage area, with significantly less residual fluid at the bottom layer than homogeneous dressings, effectively reducing the risk of wound maceration.

[0139] Comparative Example 1

[0140] This comparative example provides a composite dressing with pressure-sensitive adhesive spraying;

[0141] The same silver-plated foam as in Example 1 was used;

[0142] Multi-layer composite structures are achieved using a composite process involving spraying medical-grade pressure-sensitive adhesive.

[0143] The following performance was compared with that of the dressing in Example 1;

[0144] (1) Water vapor transmission rate (g / m 2 ):

[0145] "Water vapor transmission rate (MVTR) test: Performed according to YY / T 0471.2-2004 standard. Fix the dressing sample in the mouth of a permeation cup containing a specific volume of distilled water (or a desiccant with a specific humidity), ensuring an effective test area. Place the permeation cup in a constant temperature and humidity chamber at a temperature of 37±1℃ and a relative humidity of 20% (or the temperature and humidity specified in the standard). Record the mass change of the permeation cup before and after 24 hours, and calculate the water vapor transmission rate per square meter of sample over 24 hours, in g / m² / 24h."

[0146] (2) Liquid penetration time (5ml, seconds):

[0147] "Liquid penetration time test: Refer to the standard method of GB / T 24218.8-2010. Lay the composite dressing sample flat on the standard test filter paper (wound side facing up), and place a test plate with a standard funnel on top. Quickly inject 5 ml of simulated wound exudate (or physiological saline) into the funnel, and use an electrode induction timer to record the time required from the liquid contacting the sample surface to the liquid completely penetrating the sample and entering the bottom filter paper, in seconds (s). The shorter the time, the stronger the vertical conduction ability."

[0148] (3) Interlayer peel strength (N / cm):

[0149] "Interlayer peel strength test: The test was conducted according to GB / T 2792-2014 standard (T-type peel method). The multilayer composite dressing was cut into standard strip specimens with a width of 25 mm (i.e., 2.5 cm) and a length of 150 mm. At one end of the specimen, the two adjacent layers (i.e., the two polyurethane substrate layers bonded by the hot melt mesh) were manually peeled apart by about 50 mm. The peeled ends were clamped into the upper and lower clamps of the electronic universal testing machine, and tensile peeling was performed at a constant speed of 300 mm / min. The average load (N) during the peeling process was recorded, and the interlayer peel strength was calculated by dividing it by the width of the specimen (2.5 cm), with the unit being N / cm."

[0150] The test results are shown in the table below:

[0151] Table 3

[0152]

[0153] The results showed that when an interlayer film was formed, the vertical liquid absorption rate decreased by 71%, and the liquid penetration ability was much lower than that of the dressing in Example 1.

[0154] Comparative Example 2

[0155] Using a single 3cm thick piece of foam, PVD silver plating is applied only to the outermost surface, with a thickness of approximately 350nm.

[0156] The dressing prepared in Comparative Example 2 was tested using the methods described above;

[0157] The test results are shown in the table below:

[0158] Table 4

[0159]

[0160] The results showed that after 168 hours of immersion in simulated wound fluid, the bacterial colony count in the center of the dressing (incision test) was significantly higher than in Example 1. Furthermore, this coating method resulted in no coating covering the porous foam.

[0161] In summary, compared with the prior art, the multilayer composite dressing provided by the present invention has the following beneficial effects:

[0162] First, this invention constructs a continuous, full-thickness "bulk" antibacterial network. Unlike existing technologies that only load antibacterial components onto the dressing surface or a single substrate layer, this invention uses a "metallic antibacterial layer coating the skeleton surface of each polymer substrate layer" combined with an interlayer "point-like connection" structure. This allows the metallized skeletons of adjacent substrate layers to form physical contact and electrical pathways at the interface, thereby constructing a three-dimensional continuous antibacterial network throughout the entire thickness of the dressing. Regardless of the depth to which exudate is absorbed into the dressing, it can directly contact the metallic antibacterial interface, completely eliminating "dead zones" for bacterial growth and effectively preventing the formation of deep biofilms.

[0163] Secondly, this invention achieves excellent instantaneous vertical flow conduction performance. The invention employs a discrete, point-distributed connection structure to fix adjacent substrate layers, with the connecting material existing only at the skeleton nodes. The vast majority of the interlayer interface remains open, avoiding the clogging of pores by the continuous adhesive film formed by traditional adhesive bonding processes. Experiments show that the vertical liquid penetration time of the dressing of this invention is ≤5 seconds, far faster than traditional spray adhesive processes (>45 seconds), and the water vapor transmission rate is ≥7000 g / m³. 2 The 24-hour system ensures efficient pressure transmission and fluid aspiration during negative pressure therapy.

[0164] Furthermore, the preferred embodiment of the present invention achieves a synergistic antibacterial effect of tantalum and silver. In the preferred embodiment of introducing a tantalum-silver composite / alloy coating, tantalum not only utilizes its chemical stability to support the silver layer and prevent it from peeling off, but also fully leverages the presence of electrical pathways and the potential difference between tantalum and silver to form a micro-battery effect, achieving a stable and continuous release of silver ions. This reduces the amount of precious silver used, lowers costs, and significantly extends the dressing's lifespan. In particular, during negative pressure therapy or when the dressing is deformed under pressure, the severe deformation of the flexible skeleton can easily lead to cracking and peeling of the hard Ta-Ag coating. However, the dotted sintering structure formed by the hot-melt mesh of the present invention not only reliably binds the multi-layer flexible substrate, but the adhesive dots at the skeleton nodes also act as flexible buffer hinges, effectively absorbing the stress generated by negative pressure deformation. This significantly improves the mechanical adhesion of the Ta-Ag film on the three-dimensional flexible skeleton, thereby ensuring the stable performance of long-lasting antibacterial properties.

[0165] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multilayer composite dressing with a continuous interlayer antibacterial network, characterized in that, include: At least two polymer substrate layers, the polymer substrate layers having a through-pore network; A metal antibacterial layer is coated on the skeleton surface of each polymer substrate layer to form a metallized skeleton. The metal antibacterial layer is a pure silver layer, a tantalum-silver composite coating, or a tantalum-silver alloy coating. as well as A connection structure disposed between adjacent polymer substrate layers; The connection structure is distributed in a discrete point pattern between adjacent polymer substrate layers to fix and connect adjacent polymer substrate layers. The metallized skeletons of adjacent polymer substrate layers form physical contacts at the interlayer interface, constituting the electrical pathway of the interlayer metal antibacterial layer.

2. The multilayer composite dressing with a continuous interlayer antibacterial network according to claim 1, characterized in that, The multilayer composite dressing has a pore size gradient structure in the thickness direction, wherein the pore size of the polymer substrate layer closer to the wound is larger than that of the polymer substrate layer farther from the wound.

3. The multilayer composite dressing with a continuous interlayer antibacterial network according to claim 2, characterized in that, The pore size of the polymer substrate layer on the side closer to the wound is 1000μm to 1500μm; and the pore size of the polymer substrate layer on the side farther from the wound is 500μm to 1000μm.

4. The multilayer composite dressing with a continuous interlayer antibacterial network according to claim 1, characterized in that, The thickness of the pure silver layer is 500 nm to 2000 nm.

5. The multilayer composite dressing with a continuous interlayer antibacterial network according to claim 1, characterized in that, The mass percentage of silver in the tantalum-silver composite coating or tantalum-silver alloy coating is 20wt% to 50wt%, and the thickness of the tantalum-silver composite coating or tantalum-silver alloy coating is 100nm to 500nm.

6. The multilayer composite dressing with a continuous interlayer antibacterial network according to claim 1, characterized in that, The connecting structure is a non-woven hot-melt web film with a basis weight of 10 g / m². 2 Up to 25g / m 2 .

7. The multilayer composite dressing with a continuous interlayer antibacterial network according to claim 6, characterized in that, The melting point of the hot melt web film is lower than the softening temperature of the polymer substrate layer.

8. The multilayer composite dressing with a continuous interlayer antibacterial network according to claim 7, characterized in that, The material of the hot melt film is selected from one or more of copolyamide, copolyester, thermoplastic polyurethane, or ethylene-vinyl acetate copolymer.

9. A method for preparing a multilayer composite dressing having an interlayer continuous antibacterial network as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Provide at least two polymer substrate layers, the polymer substrate layers having a through-pore network; A metal antibacterial layer is formed on the skeleton surface of each of the polymer substrate layers to obtain a metallized skeleton. Connecting structures are set between adjacent metallized skeletons to form a laminate; The laminate is subjected to hot pressing treatment, which melts the connecting structure and forms discrete point distributions between adjacent polymer substrate layers, fixing the adjacent polymer substrate layers together and making the metallized skeleton of the adjacent polymer substrate layers physically contact at the interlayer interface, thus forming the electrical pathway of the interlayer metal antibacterial layer.

10. The method according to claim 9, characterized in that, The hot-pressing temperature is higher than the melting point of the connecting structure and lower than the softening temperature of the polymer substrate layer.

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