Wound dressing for detecting infection in wound exudate

Abstract

The invention relates to a wound dressing (40) comprising a support layer (1) suitable for enzymatic detection of infections in wound exudate wherein the support layer (1) comprises a liquid-conducting carrier material (10) having a first surface (11) and a second surface (12) opposite the first surface (11), and wherein the carrier material (10) comprises at least one test region (20), the carrier material (10) has at least one test region (20) on which a test substance (21, 22) is applied, characterized in that the carrier material (10) comprises a diffusion barrier (30) which prevents lateral diffusion of the test substance (21, 22) such that the test substance (21, 22) is confined by the diffusion barrier (30) in the at least one test region (20). The invention also relates to a method for producing such a support layer.

Description

[0001] The present invention relates to a wound dressing comprising a support layer suitable for enzymatic detection of infection in wound exudate.

[0002] A wound can be considered as a disruption in the continuity of skin tissue, which may be accompanied by loss of material.

[0003] The healing of wounds is based on the ability of skin regeneration tissue (such as epithelial tissue, connective tissue and supporting tissue). Tissue regeneration is a complex process in which cell activities overlap with each other, wherein the cell activities progressively promote the healing process. The accumulation of wound exudates that may especially comprise blood, protein, cell residues, microorganisms and leukocytes may promote bacterial growth. Such bacteria can be, for example, Staphylococcus aureus (Staphylococcus aureus) and Pseudomonas aeruginosa (Pseudomonas aeruginosa), and these bacteria are present on the skin or are widely present in a moist environment. These bacteria cause infection and therefore delay the healing of wounds.

[0004] With this in mind and in order to improve wound healing through appropriate management or treatment, the status of the wound with respect to the infection grade should be tested as early as possible.

[0005] Wound fluid (also often called exudate or wound exudate) is typically liquid secreted by a wound, and its composition generally reflects the inflammation and colonization state of the wound. Wound fluid may contain, among other things, cells from the patient as well as bacteria.

[0006] For on-site testing of analytes suspected to be present in a patient's medical sample, it is important to minimize the number of steps, test components, and reagent handling. Many commercially available medical tests consist of a sampler and transport unit for transporting the freshly collected sample to a laboratory for further analysis. However, this approach has numerous disadvantages due to the demands placed on the sampler, transport medium, and transport unit itself. Furthermore, it often results in unavoidable delays in obtaining assay results from the laboratory.

[0007] In order to overcome these defects, different types of on-site tests have been developed. There are some known self-contained assay devices that carry reagents (test substances) that detect analytes by reacting with the analyte. For example, a positive result can be indicated by a visible color change. In general, this type of assay device carries the reagent on a matrix material and then adds the sample thereto for detection.

[0008] Typical examples of this type of assay devices are pregnancy tests and tests for determining protein, proteolytic enzymes and leukocytes in urine samples.

[0009] Wound dressings with integrated testing functions are also known. By using such wound dressings, the status of wound infection can be determined directly at the wound site without having to remove the dressing. Such wound dressings are known, for example, from WO 2014 / 011207A1.

[0010] However, it is often observed that the test substance applied to the carrier matrix (e.g. gauze) diffuses laterally and therefore cannot clearly define the reaction field. This problem is more prominent in test systems where several reagent substances are applied adjacent to each other and where it is observed that the reagent substances produce a color change on the analyte. Diffusion may cause the test liquids to mix with each other and therefore lead to evaluation errors.

[0011] Furthermore, it is desirable to digitally record and evaluate the test strips, for example using a smartphone. Such digital recording and evaluation of the color change caused by the test reaction requires that the test substance be applied and fixed precisely in clearly defined areas of the carrier, thereby avoiding overlap.

[0012] EP 3 435 941 B1 discloses a wound dressing having at least one test substance capable of displaying a color change, wherein the test substance is molecularly anchored to a matrix. This method requires chemical modification of the test substance, which is time-consuming and costly.

[0013] It is therefore an object of the present invention to overcome the disadvantages inherent in the prior art and to provide a wound dressing for detecting field infections which is easy to manufacture and allows accurate detection of the colour change that occurs following a test reaction.

[0014] This problem is solved by a wound dressing comprising a support layer suitable for detecting infection in wound exudate. The support layer comprises a liquid-conducting carrier material. The carrier material has a first surface and a second surface opposite the first surface. The carrier material comprises at least one test area to which a test substance is applied, wherein the carrier material further comprises a diffusion barrier. The diffusion barrier prevents lateral diffusion of the test substance, thereby confining the test substance within the at least one test area.

[0015] The present invention eliminates the need for chemical modification of the test substance. Instead, the test substance can be applied to the carrier material in liquid form without further modification. The liquid diffuses only up to the diffusion barrier and cannot propagate beyond it in the carrier material. Therefore, in contrast to support layers known from the prior art, this support layer is compatible with a wide range of test substances without the need for further chemical modification.

[0016] The support layer according to the present invention is simple and cost-effective to produce. Furthermore, it allows for a clear distinction between different types of test substances applied to the same carrier material sample. Thus, wound dressings according to the present invention can be provided in a cost-effective manner.

[0017] According to the present invention, a support layer is understood to be any layer suitable for carrying the system for detecting infection in wound exudate. Alternatively, it may also be referred to as a "carrier layer".

[0018] Preferably, the support layer may be a sheet-like layer, wherein the first surface and the second surface have substantially parallel courses.

[0019] The liquid-conducting carrier material can also be a sheet-like layer, in which case the two surfaces have essentially parallel courses.

[0020] The term “substantially” is to be interpreted such that irregularities may occur, for example due to material manufacturing, such that the parallel course of the two surfaces, ie the first surface and the second surface, deviates from parallelism only in limited areas.

[0021] When the support layer is in its intended use, ie integrated into a wound dressing applied to a wound, the first surface typically faces away from the wound and the second surface faces the wound. According to the present invention, the surface to which the test substance is applied is considered the first surface.

[0022] The at least one test area is defined by means of the diffusion barrier. According to the present invention, a test area is understood to be an area or portion on or in the carrier material that is separated from other areas on or in the carrier material by a diffusion barrier. The at least one test area can be completely surrounded by the diffusion barrier or separated from another portion of the carrier material by the diffusion barrier in such a way that liquid cannot pass to the other side of the diffusion barrier and thus from one portion to another.

[0023] In the context of the present invention, "diffusion" is understood to mean any penetration or propagation of a substance, usually a liquid, into a carrier material. This can occur, for example, by compensating for concentration differences, in particular by capillary effects, but is not limited to these physical effects.

[0024] Wound exudate (also often referred to as exudate or wound fluid) is typically a liquid secreted by a wound, and its composition generally reflects the inflammation and colonization state of the wound. Wound fluid may contain, among other things, cells, blood, and bacteria from the patient.

[0025] A parameter (also referred to as a biological parameter, biomarker or biomarker) is a measurable indicator of a physiological state or condition. Biomarkers are typically measured and evaluated using blood, urine or soft tissue to examine normal physiological processes, pathological processes or pharmacological responses to drug interventions. Examples of biological parameters are pH or any type of blood value. In the context of the present invention, particularly preferred biological parameters to be measured in wound exudate are parameters related to the state of the wound. The measurement can be based on enzymes present in the wound exudate that are associated with the body's inflammatory response due to wound infection. Therefore, such a measurement can indicate the infection state of the wound.

[0026] The support layer comprises a carrier material or consists entirely of a carrier material. The carrier material is liquid-conducting. This means that the liquid can penetrate the carrier material and disperse in the carrier material, for example, by capillary forces.

[0027] Thus, the carrier material may comprise or consist of an absorbent material, paper, a hydrogel, a nonwoven textile, a woven textile, or a foam. The carrier material may also comprise or consist of a combination of the aforementioned materials. Particularly preferably, the carrier material comprises or consists of gauze. The support layer may be configured as a wound dressing.

[0028] The carrier material can comprise or consist of an absorbent material such as paper, hydrogel, nonwoven textile, woven textile, knitted fabric or foam. The carrier material can also comprise or consist of a combination of the materials mentioned.

[0029] According to the present invention, absorption refers to the ability of a material to absorb liquid. Liquid is absorbed by the material through capillary forces and is to a certain extent trapped in the material. This effect is also known as wicking.

[0030] It has been shown that the carrier material according to the invention can be based on the same materials typically used for wound dressings, for example materials containing cellulose, cellulose derivatives, or absorbent synthetic or natural fibers. This allows the support layer to be easily integrated into the wound dressing.

[0031] Preferably, the diffusion barrier has hydrophobic properties.It is essential to the present invention that the material from which the diffusion barrier is made prevents liquids from overcoming or breaking through the diffusion barrier.

[0032] According to the present invention, the wound dressing not only has a diffusion barrier on the first surface, but also extends from the first surface into the carrier material in the direction of the second surface. The diffusion barrier thus has a three-dimensional configuration and prevents lateral diffusion of fluid not only on the surface of the wound dressing but also in the interior of the wound dressing (i.e., in the carrier material).

[0033] In a preferred embodiment, the diffusion barrier comprises a hydrophobic substance, a polymeric material and / or a lipid.Preferably, the diffusion barrier may comprise one or more silicones, in particular polydimethylsiloxane.

[0034] Preferably, the diffusion barrier is printed, drawn, stamped, sprayed or coated onto the carrier material, in particular onto the first surface of the carrier material.Preferably, the diffusion barrier is screen printed onto the first surface of the carrier material.

[0035] According to a preferred embodiment, the diffusion barrier is produced by applying a printable liquid to a carrier material during the manufacturing process. The printable liquid comprises a liquid barrier composition. After the liquid barrier composition is applied to the carrier material, the liquid dries or solidifies, thereby forming the diffusion barrier. This allows the use of printers or other liquid applicators present in the production line to produce the diffusion barrier. Therefore, the support layer according to the present invention can be produced simply and inexpensively. The barrier composition may contain a solvent and dry after application to the carrier material. Alternatively, the barrier composition may contain a monomer or an uncured polymer that solidifies after application to the carrier material.

[0036] Since the barrier composition is in liquid form for manufacture, it penetrates the carrier material after application and then dries or cures. The longer the curing or drying time, the deeper the diffusion barrier can extend into the carrier material.

[0037] Preferably, the diffusion barrier extends substantially completely through the carrier material in a vertical direction from the first surface toward the second surface. Generally, the diffusion barrier only needs to extend into the material sufficiently to prevent the test substance from escaping the test area. Thus, the depth to which the diffusion barrier penetrates the substrate can depend on the amount of test substance applied.

[0038] Thus, the diffusion barrier may be tubular and act in the manner of a channel.The diffusion barrier may guide wound fluid from the second surface of the carrier material to the first surface of the carrier material.

[0039] Thus, in a preferred embodiment, the diffusion barrier can extend in a tubular shape from the first surface towards the second surface of the carrier material.

[0040] In an embodiment, the diffusion barrier extends in the vertical direction from the first surface towards the second surface at least 10%, preferably at least 50%, into the carrier material and particularly preferably substantially throughout the carrier material.

[0041] The thickness of the walls of the diffusion barrier, measured from the side to which the diffusion barrier has been applied, ie at the first surface of the carrier material, may be between 0.1 mm and 5.0 mm, preferably between 0.5 mm and 3.0 mm and more preferably between 0.6 mm and 2.0 mm.

[0042] In the case where the at least one test area is circular, the diameter of the test area can be 1 mm to 20 mm, preferably 2 mm to 10 mm, and more preferably 3 mm to 5 mm, also measured at the first surface of the carrier material. This enables a good assessment of the reaction of the test substance in the test area, for example, with the naked eye, with a photodetector, or with any other suitable sensor device.

[0043] Preferably, the carrier material can have a thickness of between 0.5 mm and 10.0 mm, more preferably between 1.0 mm and 8.0 mm, and in particular between 1.5 mm and 5.0 mm. This allows the test substance to be integrated into materials commonly used for wound dressings. The thickness or layer thickness of the carrier material is defined as the distance from the first surface to the second surface of the carrier material.

[0044] The carrier material may contain 10% to 100% viscose. Preferably, the carrier material consists of 100% viscose. However, materials made of 100% cotton or a blend of cotton and viscose can also be used as the carrier material. In the case of blended fabrics, the cotton content may preferably be between 10% and 90%.

[0045] Generally speaking, synthetic materials and natural materials or mixtures of synthetic materials and natural materials are suitable as carrier materials. However, materials that can absorb liquids are preferred.

[0046] In a preferred embodiment, the carrier material may contain 85% viscose fibers and 15% PE / PET fibers.

[0047] For determining wound parameters, in particular for detecting wound infection, the test substance may comprise a compound selected from the group consisting of Fast Blue RR, N-(methoxysuccinyl)-Ala-Ala-Pro-Val p-nitroanilide, N-succinyl-Ala-Ala-Ala-p-nitroanilide or PG-RBB, preferably TMB and particularly preferably guaiacol, and any combination thereof.

[0048] Preferably, the test substance is suitable for reacting with the target enzyme. The target enzyme can be selected from the group consisting of lysozyme, cathepsin G, elastase, catalase, lipase, and esterase, in particular myeloperoxidase (MPO), and any combination thereof. Selecting such a test substance allows the status of the wound to be determined, and therefore the infection associated with the support layer according to the present invention to be determined. When the support layer is integrated into a wound dressing, the wound status can be determined on-site, i.e., without removing the wound dressing from the wound. This allows for rapid results and, therefore, the possibility of immediately initiating appropriate therapeutic measures. This can reduce hospitalization rates and, therefore, also reduce costs for the healthcare system.

[0049] In a particularly preferred embodiment, the carrier material comprises at least 2, preferably 2 to 50, more preferably 2 to 10 test areas.

[0050] Preferably, the test area is circular. This allows for the arrangement of a large number of test areas on the carrier material. Dot-shaped application of the test substance can also be easily achieved mechanically and is therefore preferred. Preferably, the test substance is applied to the carrier material by drop casting.

[0051] In principle, the present invention is not limited to the number of test areas arranged on the support layer. Preferably, at least four test areas are applied to the carrier material. Thus, at least two test areas can be provided with one test substance, and at least two other test areas can be provided with another test substance. This increases the probability that the body fluid to be tested reaches the test areas and reacts with the test substance.

[0052] Between 5% and 90%, preferably between 10% and 85%, and more preferably between 20% and 80%, of the first surface can be covered by the at least one test area. This means that the support layer can have a single, larger test area, but also several test areas of different or equal sizes. The size of the test area is determined by the path of the diffusion barrier.

[0053] In a further embodiment, each of the test areas comprises only one type of test substance. However, it is particularly preferred that different types of test substances are applied multiple times, i.e., for example, two test areas are provided with a first type of test substance and two further test areas are provided with a second type of test substance, wherein the first type of test substance and the second type of test substance are different types of test substances, i.e., they differ from each other in composition and / or function.

[0054] For example, each of the test areas may comprise only one type of test substance, or the test areas may comprise at least two different types of test substances.

[0055] In a particularly preferred embodiment, the test areas include at least two different types of test substances. This improves the accuracy and reliability of wound infection detection, as one or the other test substance can serve as a backup in the event that one of the detection systems fails or has very low sensitivity and specificity. Furthermore, having a single test substance in several test areas increases the likelihood that exudate will come into contact with the test substance and, therefore, will result in a rapid response to wound infection.

[0056] Preferably, the test substance is capable of generating a detectable signal, particularly a visible color change upon interaction with the target enzyme. This allows for visual reading by the user of the wound dressing. For example, a person can visually detect the color change on the support layer without having to remove the wound dressing. Thus, using a suitable test substance or a suitable combination of test substances in the test area allows for easy and rapid characterization of the body fluid beneath the wound dressing.

[0057] The visible color change can also be recorded and evaluated digitally, for example using a smartphone.

[0058] In order to indicate in which area the at least one test area is located, the at least one test area may be surrounded by a visually visible marking line.

[0059] The wound dressing may be, for example, a wound patch, a bandage, a cover for a negative pressure wound therapy bandage used in negative pressure wound therapy ("npwt"), or a first aid dressing.

[0060] The wound dressing may further comprise a wound contact layer and / or a backing layer and / or an absorbent layer.According to the present invention, the support layer is in fluid communication with the wound contact layer, and the backing layer covers the first surface of the support layer.

[0061] Such a wound dressing offers the advantage that biological parameters and thus wound infection can be determined in the wound exudate without having to remove the wound dressing.Thus, there is a centralized information transfer from the second surface of the support layer to the first surface of the support layer.

[0062] The invention further relates to a method for producing a support layer of a wound dressing according to the invention.

[0063] In a first step, a carrier material is provided. The carrier material is capable of conducting liquids and has a first surface and a second surface opposite the first surface. Next, a barrier composition comprising a hydrophobic substance is applied to the first surface of the carrier material. The barrier composition is capable of forming a diffusion barrier in the carrier material, thereby forming a test area defined by the diffusion barrier. The barrier composition is cured and / or dried. A test substance is applied to the test area on the first surface, such that the test substance is confined within the test area by the diffusion barrier. Thus, the diffusion barrier prevents lateral spread of the test substance and achieves precise confinement of the test substance.

[0064] The method according to the invention makes it possible to easily produce a support layer for test substances without having to modify the test substance. The support layer according to the invention is therefore universal and can be provided with all common test substances, since the diffusion barrier prevents the test substance from flowing or spreading in the carrier material.

[0065] The diffusion barrier allows the test area to be designed into any desired shape, as the test area can be determined by the application pattern of the diffusion barrier.

[0066] Preferably, the diffusion barrier is applied to the substrate in a circular shape, such that the circular area (ie the area enclosed by the diffusion barrier) corresponds to the test area.

[0067] In an alternative embodiment, the diffusion barrier is applied in such a way that the test area represents a symbol or logo. This allows the support layer to be individually designed and labeled, for example by applying the diffusion barrier in such a way that the test area takes the shape of a company logo. Similarly, it is conceivable to design the test area as text. Furthermore, the shapes of the test areas can be combined as desired.

[0068] To form the diffusion barrier, the barrier composition can be inkjet printed, painted, sprayed, slot-coated, or, in particular, screen-printed onto the carrier material. Applying the barrier composition via a printing process allows for faster and more cost-effective production. Furthermore, known materials can be used as carrier materials, which also simplifies production and reduces costs.

[0069] The printing process also allows conventional printers in this field to be used without requiring any additional changes to the printing equipment.

[0070] For the same reasons, the test substance can also be applied to the test area by a printing process, such as inkjet printing, painting, spraying or by slot coating.Preferably, the test substance is applied to the test area by drop casting.

[0071] The invention and its further advantageous embodiments are described and explained in more detail below with reference to the examples shown in the accompanying drawings. The features extracted from the description and the drawings can be used individually or in any combination according to the invention. In the drawings:

[0072] Figure 1 shows a schematic top view of a first embodiment of a support layer having a diffusion barrier surrounded by a marking line,

[0073] Figure 2 Schematic SEM image of a first surface of a support layer with a diffusion barrier is shown,

[0074] Figure 3 Shown along the basis Figure 1 Schematic cross-sectional view of line AA of the support layer,

[0075] Figure 4 Shown according to Figure 3 Schematic SEM image of a cross-sectional view, and

[0076] Figure 5 A schematic cross-sectional view of a support layer integrated into a wound dressing is shown.

[0077] Figure 1 A schematic top view of a first surface 11 of a carrier material 10 of a support layer 1 is shown. The support layer 1 comprises a carrier material 10, in particular gauze. In the example shown, the carrier material 10 has four diffusion barriers 30. The barriers are made of a material containing silicone. The diffusion barriers 30 each enclose a circular test area 20. Every two test areas 20 or diffusion barriers 30 are surrounded by a visually identifiable colored marking line 23. This creates a visually separated test field. The marking line 23 serves to indicate to the user of the support layer 1 where the test area 20 is located. However, the diffusion barrier 30 may also comprise a dye, and thus the marking line 23 may be omitted. The test substances 21, 22 may also be visible to the naked eye, so that there is no need to provide the marking line 23.

[0078] In an alternative embodiment (not shown), each diffusion barrier 30 is individually surrounded by a visually identifiable colored marking line 23 .

[0079] A user is understood to be any individual who uses the wound dressing 40. For example, the user may be a patient, a nurse or a doctor.

[0080] exist Figure 1In the embodiment, by way of example, the test area 20 in the upper test field is provided with a test substance 21, and the test area 20 in the lower test field is provided with a test substance 22. The test substance 21 comprises a pH indicator, the color of which changes according to the pH value. The test substance 22 is an indicator substrate, which can be converted into a colored product by the enzyme. Particularly preferably, according to Figure 1 The test substance 22 in the embodiment of comprises guaiacol. In the presence of hydrogen peroxide, guaiacol is converted into a colored product by myeloperoxidase (MPO).

[0081] The support layer 1 integrated into the wound dressing 40 is suitable for detecting wound infections.

[0082] exist Figure 2 In the schematic representation of the SEM image shown, the diffusion barrier 30 is printed on the first surface 11 of the carrier material 10. Figure 2 Only one quarter of the diffusion barrier 30 surrounding the test area 20 is shown. In this embodiment, the carrier material 10 is a nonwoven. The diffusion barrier 30 penetrates the carrier material 10 between and along the fibers 15 by capillary forces. Due to the irregularities caused by the arrangement of the fibers 15, the diffusion barrier 30 is not clearly defined but has an irregular path. The test area 20 is surrounded by the diffusion barrier 30.

[0083] Figure 3 Shown along line AA through Figure 1 Schematic cross-sectional view of a carrier material 10. In this embodiment, a diffusion barrier 30, which circularly surrounds the test area 20, extends completely through the carrier material 10 from the first surface 11 toward the second surface 12. Thus, the diffusion barrier 30 extends through the carrier material 10 in a tubular, channel-like, or columnar manner. Consequently, the test area 20 defined by the diffusion barrier 30 also has a three-dimensionally extending structure and provides a sufficient inner cavity for the test substances 21 and 22. It can be seen that the test area 20 has a three-dimensionally extending structure along the surfaces 11 and 12 and through the carrier material 10.

[0084] The test area 20 itself consists of a carrier material 10 which has absorption properties. The test area 20 is delimited by a diffusion barrier 30 and the surfaces 11 and 12 .

[0085] The thickness d of the diffusion barrier 30 is essentially determined by the manufacturing process of the support layer 1. If the diffusion barrier 30 is applied to the first surface 11, for example, by a printing process, the thickness d varies in the direction of the second surface 12, because the initial liquid composition forming the diffusion barrier 30 diffuses into the carrier material 10 before it hardens.

[0086] The representation of the diffusion barrier 30 in the drawings is idealized and schematic. As the composition penetrates, is absorbed or diffuses into the material, the thickness d will change until the composition is sufficiently dry.

[0087] Figure 4 It is along Figure 1 A cross-sectional view of line AA passing through the support layer 1 . Figure 4 Based on the SEM image, the actual path of the diffusion barrier 30 is shown, i.e., the diffusion barrier 30 has an irregular path from the first surface 11 to the second surface 12 of the carrier material 10. In this example, the diffusion barrier 30 extends completely along the entire thickness of the carrier material 10. The diffusion barrier 30 has penetrated the carrier material 10 between and along the fibers 15 by capillary forces. Due to the irregularities caused by the arrangement of the fibers 15, the diffusion barrier 30 is not clearly defined but has an irregular path. Test substances 21, 22 (not shown) can be applied to the test area 20.

[0088] Figure 5 There is shown a support layer 1 integrated into a wound dressing 40. The support layer 1 is adhered to a backing layer 42 by means of an adhesive (not shown).

[0089] The backing layer 42 covers the first surface 11 of the support layer 1 and seals the wound dressing 40. The backing layer 42 is suitably transparent, although it may be slightly opaque to allow the user to see the test areas 20. The support layer 1 includes test areas 20, each of which has a test substance 21 applied thereto. Optionally, a wound contact layer 41 is provided on the side of the backing layer 1 that faces the wound in use (i.e., the second surface 12). In this embodiment, the wound contact layer 41 is formed as an absorbent wound pad and is in fluid communication with the support layer 1, such that wound exudate can be absorbed from the wound and pass through the wound contact layer 41 to the support layer 1.

[0090] Support Layer Examples and Support Layer Manufacturing for Wound Dressings

[0091] In the following, the production process of a particularly preferred embodiment of a support layer of a wound dressing according to the invention is described in a non-limiting example.

[0092] In a first step, a gauze comprising 85% viscose fibers and 15% PE / PET fibers is provided. The preparation of the barrier composition is achieved by using a two-component liquid silicone resin set (Sylgard 184, supplied by DOW CORNING), which contains 12% w / w dimethyl vinyl and trimethyl silica. The two components are mixed in a ratio of 10:1. The composition cures slowly at room temperature (completely cured after 48 hours at 25°C) and cures faster at elevated temperatures (completely cured after 35 minutes at 100°C). At room temperature (25°C), the curable polydimethylsiloxane elastomer is deposited on the gauze by screen printing. The template for screen printing contains the pattern of the diffusion barrier, i.e. a circle with an inner diameter of 3 mm in this example. After application, the barrier composition is cured at 80°C for 30 minutes in order to obtain a diffusion barrier that completely surrounds the test area. The amount of barrier composition applied is 3.11 mg / cm 2 It was found that curing the composition at 80°C for at least 30 min provided sufficient curing for immediate further processing of the sample, ie application of the test substance.

[0093] In addition, a visually identifiable colored marking line was screen-printed on the same gauze surface as the barrier composition to create a visually separated test field. The marking line serves to indicate to the user of the wound dressing where the test area is located. To print the marking line, a printable dielectric ink (CFSN6057: SUNTRONIC 681DIELECTRIC: BG04, supplied by SunChemical) was used.

[0094] Then, 3 μL of the test substance was applied to each test area by drop casting.

[0095] Examples of test substances used for detecting myeloperoxidase (MPO) infection levels include 24.8 mM guaiacol, 7.35 mM H 2 O 2 , 45.6 mM PBS pH=7.2, and 200 μM 4-aminobenzoic acid hydrazide.

Claims

1. A wound dressing (40) comprising a support layer (1) suitable for enzymatic detection of infection in wound exudate, wherein the support layer (1) comprises a liquid-conducting carrier material (10), the carrier material (10) having a first surface (11) and a second surface (12) opposite the first surface (11), and wherein the carrier material (10) comprises at least one test area (20) to which a test substance (21, 22) is applied, characterized in that The carrier material (10) comprises a diffusion barrier (30) which prevents lateral diffusion of the test substance (21, 22), so that the test substance (21, 22) is confined in the at least one test area (20) by the diffusion barrier (30).

2. The wound dressing (40) according to claim 1, characterized in that The diffusion barrier (30) comprises a hydrophobic substance, a polymeric material and / or a lipid, preferably one or more silicones, in particular polydimethylsiloxane.

3. The wound dressing (40) according to claim 1 or claim 2, characterized in that The diffusion barrier (30) is printed, drawn, embossed, sprayed or coated on the first surface (11) of the carrier material (10), the diffusion barrier (30) is preferably screen-printed on the first surface (11) of the carrier material (10).

4. The wound dressing (40) according to any one of the preceding claims, characterized in that The diffusion barrier (30) completely surrounds the at least one test area (20).

5. The wound dressing (40) according to any one of the preceding claims, characterized in that The diffusion barrier (30) extends in the vertical direction from the first surface (11) toward the second surface (12) into at least 10%, preferably at least 50%, of the carrier material (10), and particularly preferably substantially throughout the carrier material.

6. The wound dressing (40) according to any one of the preceding claims, characterized in that The thickness (d) of the wall of the diffusion barrier (30) measured at the first surface (11) is between 0.1 mm and 5.0 mm, preferably between 0.5 mm and 3.0 mm and more preferably between 0.6 mm and 2.0 mm.

7. The wound dressing (40) according to any one of the preceding claims, characterized in that The carrier material (10) comprises or consists of an absorbent material, paper, hydrogel, nonwoven textile, woven textile or foam, in particular gauze.

8. The wound dressing (40) according to any one of the preceding claims, characterized in that The support layer (1) is configured as a wound pad.

9. The wound dressing (40) according to any one of the preceding claims, characterized in that The distance from the first surface (11) to the second surface (12) of the carrier material (10) is between 0.5 mm and 10.0 mm, preferably between 1.0 mm and 8.0 mm and more preferably between 1.5 mm and 5.0 mm.

10. The wound dressing (40) according to any one of the preceding claims, characterized in that The carrier material (10) comprises at least 2, preferably 2 to 50, more preferably 2 to 10 test areas (20).

11. The wound dressing (40) according to claim 10, characterized in that Each of these test areas (20) comprises only one type of test substance (21, 22).

12. The wound dressing (40) according to claim 10, characterized in that The test areas (20) contain at least two different types of test substances (21, 22).

13. The wound dressing (40) according to any one of the preceding claims, characterized in that Between 5% and 90%, preferably between 10% and 85% and more preferably between 20% and 80% of the first surface (11) is covered by the at least one test area (20).

14. A method of manufacturing a support layer (1) for a wound dressing (40), wherein the support layer (1) is suitable for enzymatic detection of infection in wound exudate, the method comprising the following steps: - providing a liquid-conducting carrier material (10) having a first surface (11) and a second surface (12) opposite the first surface (11), - applying a barrier composition comprising a hydrophobic substance on the first surface (11), the barrier composition being capable of forming a diffusion barrier (30) in the carrier material (10), thereby forming a test area (20) defined by the diffusion barrier (30), - curing and / or drying the barrier composition, - applying a test substance (21, 22) to the test area (20) on the first surface (11) such that the test substance (21, 22) is confined within the test area (20) by the diffusion barrier (30).

15. The method according to claim 14, characterized in that The barrier composition is inkjet printed, painted, sprayed or slot-coated, in particular screen-printed, onto the carrier material (10).

16. The method according to claim 14 or claim 15, characterized in that The test substance (21, 22) is applied to the test area (20) by inkjet printing, drawing, spraying or slot coating, in particular by drop casting.

17. The wound dressing (40) according to claim 1, characterized in that The carrier material (10) contains an absorbent material, and the diffusion barrier (30) is hydrophobic, so that the hydrophobic diffusion barrier (30) prevents the test substance (21, 22) from lateral diffusion, so that the test substance (21, 22) is confined in the at least one test area (20) by the diffusion barrier (30), and the diffusion barrier (30) extends at least partially into the carrier material (10) in a vertical direction from the first surface (11) toward the second surface (12).

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