Absorbable covering for wound treatment

Abstract

The present invention relates to a covering membrane (10) for treating wound surfaces, particularly for treating burn wounds, or for preventing adhesions. The covering membrane (10) comprises a carrier layer (12) containing an absorbent polymer material, and collagen particles (14) having a particle size I greater than 80 μm, disposed so as to remain at least partially embedded in the polymer material of the carrier layer (12). The present invention also relates to a method for producing the covering membrane (10).

Description

[Technical field]

[0001] The present invention relates to an absorbent covering for treating wound surfaces.

[0002] Such a covering membrane is known, for example, from EP 1 181 941 A1 and is sold under the name Suprathel® by Polymedics GmbH (Germany) and is established in medical practice as a wound contact material, for example as a skin replacement material in burns or also for the treatment of so-called décollement, i.e. dermabrasion wounds.

[0003] US Patent No. 8,951,598 discloses a coating comprising a biodegradable polymeric carrier layer of polylactic acid or polyglycolic acid doped with collagen nanoparticles. The polymeric carrier layer can comprise, for example, polylactic acid-co-glycolic acid (PLGA) containing 10-40% by weight of nanoscale collagen particles.

[0004] The coatings mentioned at the outset do indeed provide analgesic and anti-infective effects during the treatment of open wounds and at the same time, due to their good mechanical properties, allow for the almost unhindered formation of granulation tissue. However, the hemostatic effect of the coatings is rather limited, and they only show a slow adsorption and absorption capacity on bloody or exudate-wet wounds. It is clinically known that postoperative adhesions occur frequently after intraperitoneal operations. Such tissue adhesions can lead to chronic pain recurrences, infertility and even in some cases mechanical obstruction of the small intestine (= ileus). It is known that even microscopically small peritoneal tissue lesions can cause adhesions when combined with blood. In this respect, supplementary preventive measures that help promote postoperative healing and combat such adhesions are useful. Therefore, due to their slow adsorption and absorption capacity, the above-mentioned coatings are only suitable to a limited extent for intraperitoneal application for the prevention of adhesions.

[0005] It is therefore an object of the present invention to define a coating which exhibits improved hemostasis and allows for a wider range of applications. It is also an object of the present invention to define a method for producing said coating.

[0006] These problems with respect to the coating are solved according to the invention by a coating having the features set forth in claim 1. A production method according to the invention is set forth in claim 13. Preferred developments of the invention are set forth in the dependent claims and the description.

[0007] According to the invention, the coating membrane comprises collagen particles with a particle size of more than 80 μm, which are arranged at least partially embedded in the polymeric material of the carrier layer. The known swelling ability of fibrillar collagen, i.e. collagen with intact secondary or tertiary structure, can promote the binding of water to the coating membrane and increase the water binding capacity per unit area of ​​the coating membrane. In the present application, fibrillar collagen, or structurally intact collagen, means collagen in which α and β bands are detectable in the SDS-PAGE test.

[0008] In addition, the collagen particles are fixed to the polymeric material of the carrier layer, which is water-absorbent, and the polymeric material of the carrier layer itself can further promote water absorption. Therefore, when the covering film is applied to the wound surface, excess plasma and / or wound exudate can be removed more quickly and effectively from the wound surface. The swelling of the collagen particles increases the thickness of the covering film, at least locally, and therefore the distance between the covering film and the wound tissue to which the covering film is applied can be increased, at least locally and limitedly.

[0009] Furthermore, collagen particles can allow rapid contact with blood or wound exudate present on the wound surface. It is known that collagen contact with the wound promotes the binding of von Willebrand factor (vWF) to collagen, as well as the binding of platelets to the corresponding receptors on the platelet membrane and platelet adhesion. The depletion of platelet granules (degranulation) can be increased, and blood clotting of plasma (secondary hemostasis) can be induced or increased. This is in favor of an accelerated and effective hemostasis, which does not occur when using nanoscale collagen particles. Due to the particularly high bioavailability of collagen, the hemostatic properties of the covering membrane can be improved and further vascularization of the wound surface and thus wound healing can be promoted.

[0010] By designing the covering membrane to be appropriately flexible and deformable, it can be easily adapted to intraperitoneal surfaces, which are difficult to cover three-dimensionally, and to wounded surfaces of skin, such as in joint areas.

[0011] The collagen particles preferably have a particle size in the range of 80 μm to 500 μm, particularly preferably in the range of 100 μm to 250 μm, very particularly preferably in the range of 100 μm to 150 μm. Indeed, it has surprisingly been found that above an average particle size of about 500 μm, the hemostatic effect of the collagen in situ is reduced and the fixation of the collagen in the carrier layer is no longer sufficiently stable against the mechanical forces acting during handling and application of the covering membrane. This can lead to undesired detachment of the collagen particles from the carrier layer. With a particle size of 100 μm to 150 μm, a particularly reliable hemostasis can be achieved.

[0012] According to a preferred development of the invention, the covering membrane comprises 0.4 to 80% by weight, preferably 0.5 to 25% by weight, of collagen particles. It should be noted that the improvement in the hemostatic properties of the sheet material provided by collagen is already achieved with about 1% by weight of collagen. In this respect, the sheet material can in particular comprise 0.4 to 2% by weight of collagen particles.

[0013] According to a preferred development of the invention, at least a part of the collagen particles extends away from the carrier layer. They therefore form collagen poles on the rear or front side of the carrier layer. Due to the size of the collagen particles alone, the coating membrane has a higher hydrophilicity in the area of ​​the collagen pole than it would have in the absence of such collagen poles. Due to this structure of the coating membrane, it is possible to achieve an immediate bioavailability of the collagen particles and thus an even faster development of the hemostatic effect of the coating membrane.

[0014] Alternatively or additionally, at least a portion of the collagen particles may protrude from a front or rear surface area of ​​the carrier layer surrounding or enclosing each collagen particle, in which case each collagen particle is preferably kept disposed completely embedded in the polymeric material of the carrier layer.

[0015] According to the invention, said collagen poles of the carrier layer have a pile height of more than 10%, preferably more than 20%, of the nominal thickness of the carrier layer. This makes it easy to achieve a reliable contact of the wound by the collagen particles even with a minimal bending radius of the covering membrane. This is favorable for a liquid absorption effect and a hemostatic effect over the entire functional surface of the covering membrane. In this way, the occurrence of undesirable accumulation of blood and wound fluid on the wound and the associated risk of infection can be particularly reliably prevented.

[0016] According to the invention, the carrier layer can have a collagen pole on each side, which is made up of collagen fibers. Firstly, this eliminates the risk of applying the covering membrane inside out on the wound surface to which it is to be applied. Secondly, the collagen poles on each side of the carrier layer can differ from each other with respect to their nominal thickness, their average density of collagen fibers per unit area of ​​the covering membrane and / or their collagen particle size. This allows one and the same covering membrane to be used for different wound management requirements, thus further expanding its range of application. This further prevents undesired mutual adhesion of the covering membrane parts when they are turned over.

[0017] It is possible for one collagen pole of the covering membrane to contain collagen particles with an average particle size of, for example, 100-150 μm and the other pole of the covering membrane to contain collagen particles with an average particle size of 250-500 μm, so that the swelling behavior of the collagen particles of each occupation or pole of the carrier layer can be adapted to the respective wound area to be cared for.

[0018] The collagen particles of the coating membrane may in particular be made from native collagen of type I and / or type III, in particular from bovine collagen, which is commercially available in sufficient quantities and with high purity.

[0019] According to the invention, the carrier layer may in particular comprise copolymers based on lactide, glycolide, trimethylene carbonate, ε-caprolactone and / or 1,4-dioxane-2-one monomers or polyhydroxybutyrate (PHB) or mixtures of these polymers, which allows the coating to exert its anti-infective and pain-relieving effects while retaining its complete hydrolytic and enzymatic degradability.

[0020] According to the invention, the carrier layer may comprise 20% to 99.6% by weight of copolymer and / or polyhydroxybutyrate and 0.4% to 80% by weight of collagen particles with a particle size >80 μm, preferably 0.8% to 25% by weight of said collagen particles.

[0021] According to the invention, the carrier layer may in particular comprise a terpolymer consisting of 65-87% by weight of lactide, 5-20% by weight of trimethylene carbonate and 5-20% by weight of ε-caprolactone, in which the lactide, trimethylene carbonate and ε-caprolactone monomers may in particular be present in the range of 85 / 10 / 5 to 70 / 20 / 10% by weight.

[0022] The carrier layer of the coating membrane preferably has a nominal thickness d of 50 to 3,000 μm, preferably 80 to 500 μm or 800 to 2,500 μm.

[0023] The method for producing the above-described coating according to the invention comprises the following steps: grinding the provided, advantageously dried, native collagen to obtain collagen particles having an average particle size of more than 80 μm, preferably more than 100 μm; preparing a polymer solution consisting of an absorbent polymer and a suitable solvent; a) suspending collagen particles in a polymer solution and applying the collagen suspension thus obtained, which contains the collagen particles suspended therein, to an areal support; or b) applying a polymer solution to the planar carrier, with the proviso that this application is performed after pre-spraying the carrier with collagen particles and / or after this application, spraying the polymer solution containing collagen particles; and Removal of the solvent by drying, in particular freeze-drying.

[0024] The suspension / dispersion of collagen particles in the polymer solution must be done very carefully to avoid further damage to the collagen particles, either directly or by shear forces, especially to avoid further comminution. Very finely divided collagen (<50 μm) can be degraded very quickly in the polymer solution to gelatin, destroying the collagen particle fibers with their original helical shape. Therefore, in order to maintain the integrity and the desired function of collagen in vivo, it is necessary for process engineering to maintain a particle size of more than 80 μm. Therefore, the collagen particles must be suspended / dispersed in such a way that they maintain their size and structure. According to the invention, this is preferably achieved by dispersing or suspending the collagen particles in the polymer solution with stirring for a maximum of 2 minutes, preferably for a maximum of 1 minute.

[0025] It is also possible to suspend / disperse the collagen particles by stirring in pure solvent for up to 2 minutes, preferably 1 minute, and then carefully mixing the collagen suspension with the polymer solution.

[0026] Drying stabilizes the carrier layer of the coating film. Longitudinal segments of collagen particles located outside the carrier layer may partially stand up during drying or when the coating film is peeled off from the planar carrier. If the planar carrier is, for example, in the form of a plate with a completely flat surface, in particular a glass plate, the back side of the dried coating film is correspondingly smooth, i.e. in particular the collagen particles do not extend away from the back side of the carrier material. If the coating film has one collagen pole on each side, then, for example, a glass plate with fine recesses or a carrier with a microporous coating can also be used as the planar carrier.

[0027] When the collagen particles are sprinkled onto the carrier or onto the polymer solution / collagen suspension applied to the carrier, this can be done by gravity alone or by forced application of compressed gas / air, in this way the collagen particles can be particularly reliably fixed in the polymer solution or collagen suspension.

[0028] According to the invention, either the native collagen is dried before being ground or the ground collagen particles are advantageously dried before being suspended in the solution: in the former case, a particularly efficient grounding of the collagen can be achieved, and in the latter case, a particularly efficient suspension of the collagen particles in the solution can be achieved.

[0029] Further advantages of the present invention are evident from the detailed description and the drawings. Likewise, the features mentioned above and those described in more detail can be used according to the present invention either individually or in any combination of several. The following examples are not to be understood as a definitive enumeration, but rather as exemplary in nature for illustrating the present invention. [Brief description of the drawings]

[0030] [Figure 1] FIG. 2 is a schematic cross-sectional view of a coating membrane having a carrier layer on which collagen particles having a particle size of more than 80 μm are fixed. [Diagram 2] FIG. [Diagram 3] A top view of the coating membrane according to Figure 2, showing that the collagen particles are arranged completely embedded in the polymer material of the carrier layer and protrude from the (flat) surface area of ​​the carrier layer that surrounds each of the collagen particles. [Figure 4] FIG. 3 shows the coating membrane according to FIG. 2 after swelling in water at 37 degrees Celsius for several hours. [Diagram 5] FIG. 2 is a block diagram of a method according to the invention for producing a coating according to the invention. [Figure 6] FIG. 1 shows an SDS-PAGE study to detect unwanted degradation of collagen particles as a function of mixing time when collagen particles are mixed with a polymer solution.

[0031] Fig. 1 shows a covering membrane 10 for treating wounds, which is also particularly suitable for preventing adhesions in the abdominal cavity. The covering membrane 10 comprises a carrier layer 12 having a front and a back surface 12a, 12b. The carrier layer 12 is here structurally formed from copolymers based on lactide, trimethylene carbonate, ε-caprolactone and / or 1,4-dioxane-2-one monomers or polyhydroxybutyrate (PHB) or mixtures of these polymers. The carrier layer 12 is therefore biocompatible, degradable by hydrolysis and / or by endogenous enzymes, and completely absorbable.

[0032] The carrier layer has a nominal thickness d, which can be 50-3,000 μm, preferably 80-500 μm or 1,000-2,500 μm, depending on the mechanical service requirements imposed on the covering membrane 10. In order to improve hemostasis or to more quickly absorb blood and wound fluids, collagen particles 14 are arranged at least partially embedded in the material of this carrier layer 12. In other words, the collagen particles 14 are fixed in the material of the carrier layer 12. The collagen particles 14 may be arranged as a whole embedded in the polymeric material of the carrier layer and may extend at least partially away from the carrier layer 12 according to FIG. 1 or may protrude from the front surface, as will be further explained below in connection with FIG. 4. If the collagen particles 14 extend away from the carrier layer, they can collectively form a collagen pole 16 of the carrier layer 12. When the covering membrane 10 is ready for use, the pile-up height h of the collagen poles 16 may be greater than 10%, preferably greater than 20%, of the nominal thickness d of the carrier layer 12 .

[0033] The collagen particles 14 consist entirely of comminuted native collagen, for example type I and / or type III collagen, which may in particular be of bovine, murine or porcine origin. The collagen particles 14 have a particle size I of more than 80 μm, preferably between 100 μm and 500 μm, particularly preferably between 100 μm and 250 μm.

[0034] Due to the collagen pole 16, in the embodiment shown in FIG. 1, the covering membrane 10 has two different useful surfaces 18, 20. If the useful surface 18 of the covering membrane 10 on the polar side is applied to the wound surface (not shown), a direct contact of the wound surface by the collagen particles 14 is possible. This ensures a particularly high bioavailability of the collagen and allows its functional advantages in the treatment of the wound surface to be fully utilized at an early stage. These include, in particular, the known hemostatic properties of fibrous collagen, its swelling properties due to its significant ability to absorb blood and wound exudate, as well as its advantageous effects on the rapid vascularization of the wound surface and wound healing. Here, it has been found in practice that even a small weight percentage of collagen particles 14 is already advantageous for the aforementioned effects. In this respect, the covering membrane 10 can contain 0.5 to 80% by weight of collagen particles 14, preferably 0.8 to 25% by weight of collagen particles 14. In fact, the covering membrane 10 can be folded and the respective folded parts (not shown) can be superimposed, for example, with their opposite back faces 12b. This provides the advantage, particularly in adhesion prevention, of a particularly high fluid absorption capacity per unit area 22 of the folded covering membrane 10 in contact with the wound surface, and furthermore, this allows for easier application of the covering membrane during laparoscopy.

[0035] According to an embodiment not shown in the drawings, the covering membrane 10 can also have one collagen pole 16 of the collagen particles 14 on both sides. This in fact makes it possible, firstly, to prevent the covering membrane 10 from being applied in an inverted state by mistake and to provide one collagen-useful surface 20 on both sides. At the same time, this makes it possible to prevent troublesome adhesion of the covering membranes 10 to each other when applying the covering membrane to the wound. It should be noted that the collagen poles 16 of the front and rear sides 12a, 12b of the carrier layer 12 can differ from each other in terms of the average density of their collagen particles 14 per unit area 22 of the covering membrane 10 and / or the size of their collagen particles 14 or their pile-up height h. In this way, a covering membrane 10 with different collagen-useful surfaces 18, 20 can be provided and thus the possible range of applications of the covering membrane 10 in wound care can be expanded.

[0036] In figures 2 to 4 a further coating membrane 10 is shown ready for use. This coating membrane differs substantially from the embodiment described above in connection with figure 1 in that the collagen particles 14 are arranged so as to remain completely embedded in the polymer material of the carrier layer 12. In other words, the collagen particles 14 are in this case completely surrounded or covered by the polymer material of the carrier layer. Figure 2 shows a side view of the coating membrane, in which the nominal thickness d of the carrier layer is clearly visible.

[0037] 3 shows the ready-to-use coating membrane 10 in a microscopic top view in the region of the collagen particles 14 and also the height profile along the measurement section indicated with S. The collagen particles 14 protrude (locally limited) together with the polymer material from a surface area 24 of the front surface 12a of the carrier layer 12 that surrounds the collagen particles 14. Here, the surface area 24 of the carrier layer 12 is flat or substantially flat.

[0038] When the coated membrane 10 shown in FIG. 3 was immersed in water and then examined by measurements, it was found that in the region of the collagen particles 14, i.e. locally limited, there was an increased swelling of the coated membrane 10 compared to the collagen-free carrier layer part of the coated membrane or to the surface area of ​​the carrier layer 12 surrounding the collagen particles 14. In this regard, FIG. 4 shows a microscopic image of the coated membrane 10 after 22 hours in a water bath at 37° C. According to this height profile image, the nominal thickness d (see FIG. 1) of the coated membrane 10 is on average about 250 μm, and the illustrated collagen particles 14 (see FIG. 1) protrude by about 350 μm from the surface area 24 (carrier layer part not containing collagen particles) of the carrier layer 12 surrounding the collagen particles 14.

[0039] Moisture coming into contact with the covering membrane 10 is diffused by the polymeric material of the carrier layer that covers the collagen particles 14 and is absorbed by the collagen particles 14. In this way, the collagen particles 14 draw moisture away from the bleeding wound, thus promoting hemostasis. The combination of collagen particles 14 with a synthetic absorbent polymer (e.g., poly-lactide-caprolactone-trimethylene carbonate) combines the favorable properties of both materials. The absorbent polymeric material of the carrier layer 12 is in direct contact with the wound (e.g., burn) and can improve wound healing by enzymatic release of lactic acid, exert analgesic and anti-infective effects.

[0040] Manufacturing method In the following example of a method 100 for producing a coating 10 according to the invention, reference is also made to the block diagram depicted in FIG.

[0041] The method 100 comprises the following method steps: In a first step 102, the provided, advantageously dried, native collagen 200 is milled to obtain collagen particles 14 having a particle size greater than 80 μm, preferably greater than 100 μm.

[0042] These collagen particles 14 can then, in an optional step 104, be suspended in an organic solvent 202, such as dimethyl sulfoxide (DMSO), to form a collagen stock suspension 204. Surprisingly, the collagen particles 14 are stable or sufficiently stable in pure DMSO that the collagen particles 14 suspended in DMSO do not degrade.

[0043] In a further step 106, a polymer solution 206 is prepared, which is comprised of an absorbent polymer 208 and a suitable solvent 210.

[0044] In step 108 , collagen particles 14 or collagen particles 14 contained in collagen stock suspension 204 are suspended / dispersed in polymer solution 206 to obtain collagen suspension 212 .

[0045] Here, care must be taken that the collagen particles 14 retain their size and functionality (i.e. structural integrity with detectability of α and β bands in SDS-PAGE tests). Surprisingly, it has been found that the collagen particles 14 are not stable in the solution 206 of, for example, a statistical terpolymer of D,L-lactide-trimethylene carbonate-caprolactone, and can degrade over time to collagen particles 14 with a particle size of <50 μm. In this respect, on the one hand, a rapid processing of the collagen suspension 212 is indicated. Furthermore, when mixing the collagen particles 14 with the polymer solution 206, a very gentle stirring, especially for a limited time, is indicated in order not to further crush or destroy the collagen particles 14 directly or by shear. For this purpose, for example, a dispersing device of the Ultra Turrax® series from IKA® Werke GmbH & CO. KG (Germany) can be used.

[0046] FIG. 6 shows the results of an SDS-PAGE test (sodium dodecyl sulfate-polyacrylamide gel electrophoresis test) of the collagen suspension 212 versus the stirring time using the Ultra Turrax® stirrer described above. In the first (left) lane, the protein marker PM (protein marker: BioRad "Precision Plus Protein Standard", nominal molecular weight 10-250 kDa; sample volume 10 μl) was applied. A typical reference band of the protein marker PM is shown. In the second lane, a solution containing native bovine collagen (sample volume 4 μl) was applied. In the seventh to tenth lanes, respectively, samples of the collagen suspension 212 (sample volume 33 μl) were applied with stirring times of 2×15 s (lane 7), 2×30 s (lane 8), 2×60 s (lane 9), and 2×5 min (lane 10).

[0047] With a mixing time of 2×15 seconds with Ultra Turrax® (lane 7), the collagen bands (α, β and γ regions) typical of the collagen particles 14 are clearly visible. With mixing times of 2×30 seconds and 2×60 seconds, the intensity of the bands of the γ and β regions is already gradually reduced. With a mixing time of 2×5 minutes, the bands of the γ region are barely visible, and the bands of the α and β regions are clearly less intense. Surprisingly, therefore, the reduction in the intensity of the α, β and γ regions clearly indicates collagen degradation already after 5 minutes of stirring. With longer stirring, the α and β bands of the collagen suspension 212 are also no longer visible (not shown). For the reasons mentioned above, the collagen particles 14 are dispersed / suspended in the respective polymer solution 206 for a time of preferably less than 2 minutes, very particularly preferably at most 1 minute.

[0048] The collagen suspension 212 thus obtained is applied in step 110, preferably by means of a blade 214, to an areal carrier 216. As areal carrier 216, in particular a glass sheet can be used.

[0049] In a final step 112 , the collagen suspension 212 is dried, in particular freeze-dried, to remove the solvent 210 .

[0050] Alternatively or in addition to steps 104 and 108, the collagen particles 14 can be applied or sprinkled onto the surface carrier 210 before the solution 206 or collagen stock suspension 212 is applied to the surface carrier 216, or onto the solution 206 / collagen suspension 212 in step 114 after the solution 206 / collagen suspension 212 is applied to the surface carrier 210. In the latter case, this can be performed by compressed gas or by compressed air in order to introduce the collagen particles 14 at least partially into the solution 206 or collagen suspension 212.

[0051] Example 1 In step 102, 0.5 g of dried bovine collagen 200 is ground to obtain collagen particles 14 with a particle size >80 μm. The collagen particles 14 are then dispersed in an organic solvent 202 in step 104 to obtain a collagen stock suspension 204. For this, the collagen particles 14 are placed in, for example, 49.5 g of dimethyl sulfoxide (DMSO) and gently dispersed therein for 15 seconds. In this way, a 1% collagen stock suspension 204 is obtained.

[0052] In a subsequent step 106, 150 g of a 23% solution 206 of, here illustratively, a statistical terpolymer of D,L-lactide-trimethylene carbonate-caprolactone in a solvent 208 is provided.

[0053] Subsequently, in step 108, a total of 50 g of the 1% DMSO collagen stock suspension 204 is mixed with 150 g of a 23% solution of a statistical terpolymer of D,L-lactide-trimethylene carbonate caprolactone to obtain a collagen suspension 212, which is homogenized twice by stirring for 15 seconds each.

[0054] This collagen suspension 212 is blade coated in step 110 onto a substrate 216, e.g. a glass plate, using a blade 214 with a blade gap of 250 μm, and then freeze-dried in step 112. This results in a coating 10 of nominal thickness d of about 120 μm, consisting of 98.6% lactide-trimethylene carbonate-caprolactone terpolymer and 1.4% bovine collagen particles 14.

[0055] Example 2 In step 108, a total of 1.15 g of crushed collagen particles 14 having a particle size >80 μm is added to 100 ml of a 23% polymer solution 206 of statistical terpolymer of D,L-lactide-trimethylene carbonate-caprolactone in DMSO and gently mixed to obtain a collagen suspension 212.

[0056] This collagen suspension 212 is then blade coated in step 110 onto a planar carrier 216 using a blade 214 with a blade gap of 500 μm. Finally, the solvent 210 of the collagen suspension 212 is removed by freeze-drying the collagen suspension 212. This results in a coating membrane of about 100-250 μm thickness in the form of a collagen composite membrane composed of 95% lactide-trimethylene carbonate-caprolactone statistical terpolymer and 5% collagen particles 14 with a particle size >80 μm.

[0057] Example 3 Alternatively, a total of 4.6 g of collagen particles 14 with a particle size >80 μm is suspended in the polymer solution 206 according to Example 2, and the further method steps are not otherwise changed, to obtain a coating film 10 with a thickness of about 100-250 μm, composed of 80% statistical terpolymer of D,L-lactide-trimethylene carbonate-caprolactone and 20% bovine collagen particles 14 with a particle size above 80 μm.

[0058] Example 4: In a first step 102, native bovine collagen is milled to obtain collagen particles 14 with an average particle size >80 μm. After this, in step 104, 0.25 g of dried collagen particles 14 are added to 49.5 g of DMSO and gently dispersed for 15 seconds. This results in a 1% collagen stock suspension 204. In step 108, 50 g of the 1% DMSO collagen stock suspension 204 is mixed with 150 g of a 12.5% ​​solution of a statistical terpolymer of D,L-lactide-trimethylene carbonate-caprolactone and homogenized by stirring for 2×15 seconds. The collagen suspension 212 thus obtained is blade-coated onto an iso-shaped carrier 216 using a blade 214 with a blade gap of 600 μm.

[0059] In step 112, the collagen suspension 212 is freeze-dried to obtain a coating of nominal thickness d of approximately 180 μm, composed of 98.6% lactide-trimethylene carbonate-caprolactone terpolymer and 1.4% bovine collagen particles 14 with a particle size >80 μm.

Claims

1. A covering film (10) for treating a wound surface or preventing adhesions, the covering film (10) comprising: a carrier layer (12) comprising an absorbent polymer material; Collagen particles (14) having an average particle size I of 80 μm to 500 μm, which are disposed so as to remain at least partially embedded in the polymer material of the carrier layer (12); having The carrier layer (12) Copolymers based on lactide, trimethylene carbonate, glycolide, ε-caprolactone and / or 1,4-dioxane-2-one monomers or polyhydroxybutyrate (PHB) or a mixture of said polymers Including, Coating membrane (10).

2. The coating (10) of claim 1, wherein the collagen particles (14) have an average particle size I in the range of 100 μm to 250 μm.

3. The coating (10) of claim 1 or 2, wherein the coating (10) comprises 0.4 to 80% by weight of collagen particles (14).

4. 4. The coating membrane (10) of claim 1, wherein at least a portion of the collagen particles (14) protrude from a surface area of ​​the carrier layer (12) surrounding each collagen particle (14) or extend away from the carrier layer (12) to form a collagen pole (16).

5. The coating membrane (10) of claim 4, wherein, in a ready-to-use state of the coating membrane (10), the collagen poles (16) have a build-up height h that is greater than 10% of a nominal thickness d of the carrier layer (12).

6. 6. The coating membrane (10) of claim 4 or 5, wherein the carrier layer (12) has one collagen pole (16) on each side.

7. The coating (10) according to any one of claims 1 to 6, wherein the collagen particles (14) are made from native collagen of type I and / or type III.

8. 8. The coating membrane (10) of claim 1, wherein the carrier layer (12) comprises a terpolymer consisting of 65-87% by weight lactide, 5-20% by weight trimethylene carbonate, and 5-20% by weight ε-caprolactone.

9. The coating of claim 8, wherein the lactide, trimethylene carbonate and ε-caprolactone monomers are present in the terpolymer in a range of 87 / 8 / 5 to 70 / 20 / 10 weight percent.

10. The coating (10) according to any one of claims 1 to 9, wherein the carrier layer (12) has a nominal thickness d of 50 μm to 3,000 μm.

11. A method (100) for producing a coating (10) according to any one of claims 1 to 10, comprising the steps of: grinding (102) the native collagen provided (200), advantageously dried, to obtain collagen particles (14) having an average particle size between 80 μm and 500 μm; Preparing (106) a polymer solution (206) composed of an absorbent polymer (208) and a suitable solvent (210); a) suspending (108) said collagen particles (14) in said polymer solution (206) and applying (104) the collagen suspension (212) thus obtained, containing said collagen particles (14) suspended therein, to an areal carrier (216); or b) applying (104) the polymer solution (204) to a planar support (216), with the provision that the application (104) is performed after the support (216) has been previously sprayed (114) with the collagen particles (16) or after the application (104), the polymer solution (206) containing the collagen particles (14) is sprayed (114); and removing (112) said solvent (210) by drying; Including, In this case, copolymers based on lactide, trimethylene carbonate, glycolide, ε-caprolactone and / or 1,4-dioxane-2-one monomers or polyhydroxybutyrate (PHB) or mixtures of said polymers are used, method.

12. The method of claim 11, wherein the collagen particles (14) are dispersed in the polymer solution (206) by stirring for up to 2 minutes.

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