A dressing for difficult-to-heal wounds and a method of making the same

Abstract

This invention provides a dressing for difficult-to-heal wounds and its preparation method, to solve the problems encountered when using amniotic membrane to promote the healing of difficult-to-heal wounds, such as easy breakage, difficulty in fixing wrinkles, and low mechanical strength; a dressing for difficult-to-heal wounds and its preparation method, wherein the dressing includes at least one amniotic membrane layer, wherein the amniotic membrane layer is formed by splicing several individual amniotic membranes of the same size through an amniotic membrane assembly, wherein the amniotic membrane assembly consists of a substrate and several microneedles perpendicular to the substrate.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, particularly to the field of wound dressings, specifically to a dressing for difficult-to-heal wounds and its preparation method. Background Technology

[0002] The amnion is the innermost layer of the placenta. It is smooth, without blood vessels, nerves, or lymph nodes, and has a certain degree of elasticity. The amnion contains a large number of different types of collagen, fibronectin, laminin, and other components. These components enable the amnion to act as a "transplantable basement membrane," playing a new and suitable role as a healthy matrix to promote epithelialization. The amnion has the following characteristics: (1) immune immunity; (2) containing a large number of growth factors required for tissue growth / regeneration; (3) anti-inflammatory and analgesic effects; and (4) promoting epithelialization. These characteristics give the amnion a very significant advantage and potential in wound treatment, tissue repair, and regenerative medicine. Although the amnion can promote wound healing by accelerating epithelialization, reducing inflammatory response, inhibiting scar formation, and antibacterial effects, it has great potential in wound repair.

[0003] Paggiaro conducted a literature analysis to find scientific evidence that amniotic membrane promotes the repair of diabetic foot ulcers. Six studies included commercially available amniotic membrane products such as Grafix®, AmnioBand®, EpiFix®, and AmnioExcel®, while the control group used traditional wound care methods. Comparative analysis revealed no statistically significant difference between the amniotic membrane treatment group and the traditional dressing treatment group. However, the amniotic membrane treatment group had a 2.32 times higher healing rate and a 32-day faster healing time than the control group, indicating that amniotic membrane has a significant promoting effect on the repair of diabetic foot ulcers.

[0004] Diabetic foot ulcers are clinically challenging to treat due to their slow healing and potentially severe consequences (amputation). Amniotic membrane dressings are an ideal choice as they can accelerate wound healing and promote recovery, or slow disease progression. However, the thinness of the amniotic membrane makes it prone to rupture, wrinkling, and difficult to fix, hindering surgical manipulation and limiting its application. Therefore, it is necessary to modify amniotic membrane materials to prepare dressings suitable for difficult-to-heal wounds. Summary of the Invention

[0005] This invention provides a dressing for difficult-to-heal wounds and a method for preparing the dressing thereon, in order to solve the problems encountered when using amniotic membrane to promote the healing of difficult-to-heal wounds, such as easy breakage, difficulty in fixing wrinkles, and low mechanical strength.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A dressing for difficult-to-heal wounds and a method for preparing the same, wherein the dressing comprises at least one amniotic membrane layer, the amniotic membrane layer being formed by splicing several individual amniotic membranes of the same size together through an amniotic membrane assembly, the amniotic membrane assembly being composed of a substrate and several microneedles perpendicular to the substrate.

[0007] Furthermore, the dressing also includes an absorbent layer and a waterproof and breathable membrane. The absorbent layer and the waterproof and breathable membrane are sequentially fixedly connected above the amniotic membrane layer. The amniotic membrane layer and the absorbent layer are fixed together by an amniotic membrane assembly, or the amniotic membrane layer, the absorbent layer, and the waterproof and breathable membrane are fixed together by the amniotic membrane assembly.

[0008] Furthermore, the microneedles in the amnion assembly consist of hollow needle bodies and through holes, with the through holes penetrating the substrate.

[0009] Furthermore, the amnion assembly is provided with fixing heads and fixing holes on the left and right sides respectively, for splicing the amnion assembly.

[0010] Furthermore, the outer surface of the microneedle has several evenly distributed barbs.

[0011] Furthermore, the method for preparing the monomeric amniotic membrane is as follows: the placenta is washed with a double-antibiotic PBS solution, the amniotic membrane is bluntly peeled off, the amniotic membrane is cut and fixed to form a monomeric amniotic membrane, the cut monomeric amniotic membrane is placed in inner packaging and then subjected to irradiation and cobalt-60 inactivation treatment, and finally packaged into a finished product and stored in a refrigerator at low temperature.

[0012] Furthermore, the method for preparing the amnion assembly is as follows: S11: The amniotic membrane assembly model is designed using CAD with a taper of 10-15%, and the positive mold is obtained through precision 3D printing. S12: Obtain a female mold using medical-grade silicone molding; S13: Prepare a 10%-20% concentration hyaluronic acid solution; S14: The hyaluronic acid solution is fully filled into the female mold by pressurization and centrifugation, and the mold is formed at 25-70℃ for 3-24 hours.

[0013] Furthermore, the microneedles or amnion are loaded with drugs, including gentamicin, cephalexin, and alprostadil.

[0014] Furthermore, the method for loading the drug onto the amnion is as follows: S21: Select chitosan with a degree of deacetylation of 80% and a molecular weight of 300,000 Da, dissolve it in 1% acetic acid solution, stir evenly, and prepare a 5% w / v chitosan solution. S22: Dissolve β-cyclodextrin in distilled water to prepare a 15% w / v cyclodextrin solution; S23: Dissolve the drug in distilled water, physiological saline, or glucose solution to prepare a drug solution; S24: Add the drug solution dropwise to the cyclodextrin solution and stir thoroughly; S25: Slowly add the cyclodextrin solution containing the drug to the chitosan solution while stirring to mix thoroughly. Adjust the pH of the solution to neutral and continue stirring for 4-6 hours to obtain the coating solution. S26: Apply the coating solution evenly to a single amnion membrane, and after application, place it in a sterile environment to dry, forming a medicated film.

[0015] Furthermore, the method for loading the drug onto the amnion is as follows: S31: Dissolve sodium alginate in distilled water to prepare a 3% w / v sodium alginate solution; S32: Add pharmaceutical grade gelatin to distilled water at 30-40℃, stir thoroughly to dissolve the gelatin, and prepare a gelatin solution with a concentration of 8% w / v. S33: Prepare a drug solution by dissolving the drug in distilled water, physiological saline, or glucose solution; S34: Add the drug solution to the sodium alginate solution and stir until homogeneous; slowly add the gelatin solution to the sodium alginate solution containing the drug while stirring, and react at 40-50℃ for 30-60 minutes to ensure the solution is homogeneous. S35: The mixed solution in S34 is sprayed onto the monosodium amnion, then the amnion is immersed in a 2% w / v calcium chloride solution for 1-2 minutes, and finally dried in a sterile environment to obtain the drug film.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention cuts the amnion into individual amnions for assembly and use, which not only facilitates commercialization but also reduces the impact of breakage during processing on the use of the entire amnion. The amniotic membrane assembly used in this invention is used in a splicing manner, and both its direction and length can be adjusted. Moreover, the amniotic membrane assembly can also be assembled on both sides, providing a new way of connecting the amniotic membrane with other dressing components without the need for adhesives. When assembling amniotic membranes using amniotic membrane assemblies, this invention can maintain a small distance between adjacent amniotic membranes (which can be achieved by using double rows of microneedles on the same substrate). This has the advantage of providing a drainage channel, which can enhance the drainage effect. This invention can prepare microneedles into hollow microneedles, which can also achieve the effect of helping with drainage; The present invention enhances the fixation effect by using barbs on the microneedles, thus preventing the microneedles from coming out; This invention can enhance blood circulation by using microneedles. By fixing the microneedles around the perimeter of the dressing and penetrating the amniotic membrane, the microneedle tips can contact the skin, thereby improving microcirculation. The microneedles and amniotic membrane in this invention provide excellent drug-carrying space, making the dressing a drug dressing, which is more suitable for difficult-to-heal wounds; The method for loading the amniotic membrane with drugs in this invention is simple and easy to implement, and the drug membrane can directly contact the wound surface over a large area, which can achieve better drug delivery effect. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an amniotic membrane dressing for use in difficult-to-heal wounds according to the present invention. Figure 2 This is a schematic diagram of a multilayer amniotic membrane dressing for use in difficult-to-heal wounds according to the present invention. Figure 3 This is a schematic diagram of the structure of an amniotic membrane assembly in a dressing for difficult-to-heal wounds according to the present invention; Figure 4 This is a schematic diagram of the structure of the fixation hole in a dressing for difficult-to-heal wounds according to the present invention; Figure 5 This is a schematic diagram of the structure of a fixation head in a dressing for difficult-to-heal wounds according to the present invention; Figure 6 This is a schematic diagram of the structure of microneedles in a dressing for difficult-to-heal wounds according to the present invention; Figure 7 This is a schematic diagram of the through-hole structure in a dressing for difficult-to-heal wounds according to the present invention; Figure 8 This is a schematic diagram of the structure of barbs in a dressing for difficult-to-heal wounds according to the present invention; Figure 9 This is a photograph of the amniotic membrane in a dressing for difficult-to-heal wounds according to the present invention; Figure 10 This is a photograph of a single unfolded amniotic membrane in a dressing for difficult-to-heal wounds according to the present invention; Figure 11 This is a schematic diagram of microneedles in a dressing for difficult-to-heal wounds according to the present invention; Figure 12 This is a diagram showing the state of the microneedles after they have been inserted into the skin in a dressing for difficult-to-heal wounds according to the present invention.

[0018] Among them, 10-amniotic membrane, 20-amniotic membrane assembly, 210-substrate, 220-microneedle, 221-needle body, 222-through hole, 223-barb, 230-fixing head, 231-connecting post, 232-protrusion, 240-fixing hole, 30-absorbent layer, 40-waterproof and breathable membrane. Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that, based on the description of the present invention, those skilled in the art can make any modifications or alterations to the present invention, but these equivalent methods also fall within the scope defined by the claims of this application.

[0020] Amniotic membrane is thin and easily broken, and may also break during processing. It also varies in shape and size, which is not conducive to commercial production. Therefore, it is advisable to make the amniotic membrane into individual units and use them by splicing. When considering splicing, microneedles can be selected. First, they can match the thickness of the amniotic membrane. Second, microneedles also bring many additional benefits, such as stimulating the skin around the wound to accelerate blood circulation. Hollow microneedles can also be selected to assist in drainage by working with the gaps between the amniotic membranes. Example 1

[0021] The dressing is primarily composed of amniotic membranes 10 spliced ​​together. The spliced ​​structure is an amniotic membrane assembly 20, specifically, the amniotic membrane assembly 20 is embedded and fixed within two adjacent amniotic membranes (either upper and lower or left and right). Adjacent amniotic membranes can overlap for fixation, with no gaps between them. Figure 1 As shown, a small distance is maintained between two adjacent amniotic membranes, usually 1-3 mm. The amniotic membrane assembly 20 is embedded and fixed in the upper and lower or left and right amniotic membranes, respectively.

[0022] In this embodiment, the amniotic membrane can be directly applied to the wound after assembly, so the assembly method of seamlessly connecting two adjacent amniotic membranes is usually adopted. Example 2

[0023] Based on Example 1, in order to make the amniotic membrane more suitable for difficult-to-heal wounds, the dressing in this example is formed. Difficult-to-heal wounds need to maintain a moist environment and also need to be able to absorb and drain exudate.

[0024] like Figure 2 As shown, the bottom layer of the dressing is an amniotic membrane layer composed of the amniotic membranes described in Example 1, assembled using the method described in the example where there are gaps between adjacent amniotic membranes. Above the amniotic membrane layer is an absorbent layer 30, made of sponge or hydrogel material, which absorbs exudate and keeps the wound environment moist. Above the absorbent layer is a waterproof and breathable membrane 40, which encapsulates the entire dressing, maintaining the connection between the wound and the outside environment.

[0025] In this embodiment, the amniotic membrane assembly 20 can directly penetrate the waterproof and breathable membrane 40 and the absorbent layer 30 sequentially until it is embedded in or passes through the amniotic membrane layer for fixation. Of course, as a preferred embodiment, the amniotic membrane assembly 20 is located inside the waterproof and breathable membrane 40, meaning the waterproof and breathable membrane 40 is wrapped and fixed to the outside of other dressing components. In this case, the amniotic membrane assembly 20 connects the absorbent layer 30 and the amniotic membrane layer at the top and bottom respectively, both assembling the amniotic membrane into an amniotic membrane layer and fixing the amniotic membrane layer within the absorbent layer 30. The advantage of this preferred embodiment is that the waterproof and breathable membrane 40 is the outermost and complete layer of the dressing. Furthermore, a portion of the amniotic membrane assembly 20 can be designed as a hollow structure, which has the advantage of assisting in drainage, allowing exudate from the wound to be drained into the absorbent layer 30. Example 3

[0026] Amniotic membrane assembly 20 was used for assembly in both Embodiment 1 and Embodiment 2. This embodiment provides amniotic membrane assembly 20, such as... Figure 3 As shown, the amnion assembly 20 consists of a substrate 210 and several microneedles 220 uniformly distributed on the substrate 210. The substrate 210 is a narrow, elongated, rounded rectangular sheet, which can be made of a polymer material with a certain degree of flexibility (bendability). Figure 4 and Figure 5 As shown, each end of the amniotic membrane assembly 20 is provided with a fixing head 230 and a fixing hole 240. The amniotic membrane assemblies 20 are connected together by fixing the fixing head 230 of one amniotic membrane assembly 20 into the fixing hole 240 of another amniotic membrane assembly 20. The fixing head 230 is composed of a connecting post 231 and a protrusion 232 connected together. The connecting post 231 is fixed to the surface of the base plate 210, and the protrusion 232 is integrally formed and fixed to the upper side of the connecting post 231. The diameter of the protrusion 232 is larger than the maximum diameter of the connecting post 231, which is approximately the same size as the fixing hole 240. Thus, the protrusion 232 passes through the fixing hole 240 and is fixed in place. The advantage of using the amniotic membrane assembly 20 is that different numbers of amniotic membranes can be combined according to the size of the wound, and because the fixing head 230 can rotate within the fixing hole 240, the assembly direction can be adjusted freely.

[0027] like Figure 6 and Figure 7 As shown, the microneedle 220 is hollow and consists of a needle body 221 and a through hole 222. The needle body 221 is vertically fixed to the substrate 210, and the through hole 222 penetrates the substrate 210. The hollow microneedle 220 is suitable for the structure of assembling the amniotic membrane layer and the absorbent layer 30 in Embodiment 2, as it can both fix the structure and facilitate drainage. Of course, the microneedle 220 can also be a solid structure, such as... Figure 11 and Figure 12As shown, the solid microneedles 220 primarily serve a fixation function. In addition, they can be used around the perimeter of the amniotic membrane. The microneedles 220 can penetrate the amniotic membrane and contact the skin around the wound. The advantage of this is that it can stimulate the skin and blood vessels around the wound to promote blood circulation.

[0028] To enhance the fixation effect of microneedles 220, such as Figure 8 As shown, the outer surface of the needle body 221 is fixed with several barbs 223 that are opposite to the direction of the diameter reduction of the needle body 221. The barbs 223 are not easy to come out after the micro needle 220 is embedded. Example 4

[0029] In the above embodiments, an important component of the dressing is the amniotic membrane 10, and this embodiment relates to a method for preparing the amniotic membrane 10.

[0030] In this embodiment, animal-derived amnion was used, taken from a ewe. The placenta was washed with a double-antibody PBS solution, and the amnion was bluntly peeled off. Figure 9 The amnion shown is cut and fixed to form a single amnion, such as... Figure 10 As shown. After the cut amniotic membrane is placed in the inner packaging, it is subjected to irradiation and cobalt-60 inactivation treatment, and finally packaged into a finished product and stored in a refrigerator at low temperature.

[0031] The double-antibody PBS solution refers to a PBS buffer solution containing 100 U / mL penicillin and 100 μg / mL streptomycin. Example 5

[0032] Amniotic membrane assembly 20 was used in Examples 1, 2 and 3. This example describes the preparation method of amniotic membrane assembly 20.

[0033] S11: The amniotic membrane assembly model is designed using CAD, with a taper of 10-15% and a height determined by the thickness of the dressing. The positive mold is obtained through precision 3D printing. S12: Obtain a female mold using medical-grade silicone molding; S13: Prepare a 10%-20% concentration hyaluronic acid solution; S14: The hyaluronic acid solution is fully filled into the female mold by pressurization and centrifugation, and the mold is formed at 25-70℃ for 3-24 hours.

[0034] The microneedles in the prepared amnion assembly 20 have the following shapes: Figure 11 As shown in the diagram, the state of the skin after the needle is inserted is as follows: Figure 12 As shown. Example 6

[0035] Based on the above embodiments, the functionality of the dressing can be further expanded. This is possible for two reasons: firstly, the microneedles can provide space for drug delivery and release; secondly, the amniotic membrane is extremely thin and easy to modify. The modified amniotic membrane becomes a drug carrier, and its direct contact with the wound surface is beneficial for treatment.

[0036] This embodiment provides one method: S21: Select chitosan with a degree of deacetylation of 80% and a molecular weight of 300,000 Da, dissolve it in 1% acetic acid solution, stir evenly, and prepare a 5% w / v chitosan solution. S22: Dissolve β-cyclodextrin in distilled water to prepare a 15% w / v cyclodextrin solution; S23: Prepare a drug solution from an appropriate drug; S24: Add the drug solution dropwise to the cyclodextrin solution and stir thoroughly; S25: Slowly add the cyclodextrin solution containing the drug to the chitosan solution while stirring to mix thoroughly. Adjust the pH of the solution to neutral and continue stirring for 4-6 hours to obtain the coating solution. S26: Apply the coating solution evenly to the single amniotic membrane treated in Example 4, and dry it in a sterile environment after application to form a drug film.

[0037] Among them, drugs such as gentamicin or cephalexin can be selected, which are soluble in water; or drugs such as alprostadil that improve microcirculation can be selected, which should also be soluble in physiological saline or glucose solution. Example 7

[0038] This embodiment provides another method for preparing a drug film compared to Embodiment 6: S31: Dissolve sodium alginate in distilled water to prepare a 3% w / v sodium alginate solution; S32: Add pharmaceutical grade gelatin to distilled water at 30-40℃, stir thoroughly to dissolve the gelatin, and prepare a gelatin solution with a concentration of 8% w / v. S33: Prepare the drug solution using the same method as in Example 6; S34: Add the drug solution to the sodium alginate solution and stir until homogeneous; slowly add the gelatin solution to the sodium alginate solution containing the drug while stirring, and react at 40-50℃ for 30-60 minutes to ensure the solution is homogeneous. S35: The mixed solution in S34 is sprayed onto the amnion membrane, then the amnion membrane is immersed in a 2% w / v calcium chloride solution for 1-2 minutes, and finally dried in a sterile environment to obtain the drug film.

Claims

1. A dressing for difficult-to-heal wounds and its preparation method, characterized in that, The dressing includes at least one amniotic membrane layer, which is formed by splicing together several individual amniotic membranes of the same size through an amniotic membrane assembly. The amniotic membrane assembly consists of a substrate and several microneedles perpendicular to the substrate.

2. The dressing for difficult-to-heal wounds and its preparation method according to claim 1, characterized in that, The dressing also includes an absorbent layer and a waterproof and breathable membrane. The absorbent layer and the waterproof and breathable membrane are fixedly connected in sequence on the top of the amniotic membrane layer. The amniotic membrane layer and the absorbent layer are fixed together by an amniotic membrane assembly, or the amniotic membrane layer, the absorbent layer and the waterproof and breathable membrane are fixed together by an amniotic membrane assembly.

3. The dressing for difficult-to-heal wounds and its preparation method according to claim 2, characterized in that, The microneedles in the amnion assembly consist of hollow needle bodies and through holes, with the through holes penetrating the substrate.

4. The dressing for difficult-to-heal wounds and its preparation method according to claim 1, characterized in that, The amniotic membrane assembly is provided with fixing heads and fixing holes on its left and right sides, respectively, for splicing the amniotic membrane assembly.

5. The dressing for difficult-to-heal wounds and its preparation method according to claim 1, characterized in that, The outer surface of the microneedle has several evenly distributed barbs.

6. The dressing for difficult-to-heal wounds and its preparation method according to claim 1, characterized in that, The method for preparing the monomeric amniotic membrane is as follows: the placenta is washed with a double-antibiotic PBS solution, the amniotic membrane is bluntly peeled off, the amniotic membrane is cut and fixed to form a monomeric amniotic membrane, the cut monomeric amniotic membrane is placed in inner packaging and then subjected to irradiation and cobalt-60 inactivation treatment, and finally packaged into a finished product and stored in a refrigerator at low temperature.

7. The dressing for difficult-to-heal wounds and its preparation method according to claim 1, characterized in that, The method for preparing the amnion assembly is as follows: S11: The amniotic membrane assembly model is designed using CAD with a taper of 10-15%, and the positive mold is obtained through precision 3D printing. S12: Obtain a female mold using medical-grade silicone molding; S13: Prepare a 10%-20% concentration hyaluronic acid solution; S14: The hyaluronic acid solution is fully filled into the female mold by pressurization and centrifugation, and the mold is formed at 25-70℃ for 3-24 hours.

8. The dressing for difficult-to-heal wounds and its preparation method according to claim 1, characterized in that, The microneedles or amnion are loaded with drugs, including gentamicin, cephalexin, and alprostadil.

9. A dressing for difficult-to-heal wounds and its preparation method according to claim 8, characterized in that, The method for loading drugs onto the amnion membrane is as follows: S21: Select chitosan with a degree of deacetylation of 80% and a molecular weight of 300,000 Da, dissolve it in 1% acetic acid solution, stir evenly, and prepare a 5% w / v chitosan solution. S22: Dissolve β-cyclodextrin in distilled water to prepare a 15% w / v cyclodextrin solution; S23: Dissolve the drug in distilled water, physiological saline, or glucose solution to prepare a drug solution; S24: Add the drug solution dropwise to the cyclodextrin solution and stir thoroughly; S25: Slowly add the cyclodextrin solution containing the drug to the chitosan solution while stirring to mix thoroughly. Adjust the pH of the solution to neutral and continue stirring for 4-6 hours to obtain the coating solution. S26: Apply the coating solution evenly to a single amnion membrane, and after application, place it in a sterile environment to dry, forming a medicated film.

10. A dressing for difficult-to-heal wounds and its preparation method according to claim 8, characterized in that, The method for loading drugs onto the amnion membrane is as follows: S31: Dissolve sodium alginate in distilled water to prepare a 3% w / v sodium alginate solution; S32: Add pharmaceutical grade gelatin to distilled water at 30-40℃, stir thoroughly to dissolve the gelatin, and prepare a gelatin solution with a concentration of 8% w / v. S33: Prepare a drug solution by dissolving the drug in distilled water, physiological saline, or glucose solution; S34: Add the drug solution to the sodium alginate solution and stir until homogeneous; slowly add the gelatin solution to the sodium alginate solution containing the drug while stirring, and react at 40-50℃ for 30-60 minutes to ensure the solution is homogeneous. S35: The mixed solution in S34 is sprayed onto the monosodium amnion, then the amnion is immersed in a 2% w / v calcium chloride solution for 1-2 minutes, and finally dried in a sterile environment to obtain the drug film.

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