Patent Application
20200246191
The present application relates to a wound dressing, and more particularly to a wound dressing for a negative pressure wound therapy.
Negative Pressure Wound Therapy (NPWT) is an auxiliary treatment for wound healing. It is suitable for many acute and chronic wounds, including orthopedics, soft tissues, skin grafts, pressure sores, lower extremity venous ulcers, diabetic foot, surgery infection, postoperative wounds, etc. The NPWT is placed in a cleaned wound with a foam corresponding to a shape of the wound, and the foam is in full contact with the wound surface. Since there are many holes in the foam, a vacuum pump can be used to apply a negative pressure to the wound filled with the foam. The pressure causes pus and infectious substances in the wound to be discharged through the holes in the foam, and also attracts the tissue fluid into the foam to maintain the moist therapy environment of the wound, so as to promote blood microcirculation around the wound and the growth of the new tissue. Thus, the effect of accelerating wound healing is achieved.
However, the foam in NPWT, especially those using hydrophobic polyurethane foam, has high adhesion to the wound, and the new tissue easily grows into the holes in the foam, and the foam must be replaced about every two to three days. If the infection of the wound is serious, the frequency of replacing the foam may be more according to the physician's diagnosis. Every time the foam is changed, due to the adhesion of the wound and the growth of the new tissue, patients often suffer severe pain, and there is also a secondary injury to the wound, which is a serious problem in clinical application.
Therefore, how to avoid the adhesion of foam to the wound and to avoid the growth of new tissue into the holes in the foam is keenly aimed to be achieved in the clinical and industrial fields.
To solve the above problems, the present application provides a negative pressure wound dressing comprising foam and a bio-cellulose film, the bio-cellulose film having a three-dimensional reticular structure and bonded to the surface of the foam, wherein a projected area of the bio-cellulose film on the surface of the form bonded to the bio-cellulose film is greater than or equal to that of the foam.
The bio-cellulose film refers to a microorganism, for example, bacteria of at least one genus selected from the group consisting of Gluconacetobacter, Acetobacter, Rhizobium, Sarcina, Pseudomonas, Achromobacter, Alcaligenes, Enterobacter, Azotobacter and Agrobacterium, which uses the carbon source in the culture medium to form β-1,4-glucan chain in the cell, and then secrets bio-cellulose extracellularly to form the bio-cellulose film.
In one embodiment, the bio-cellulose film is formed by culturing bacteria in a culture medium having a carbon source, a nitrogen source, and, optionally, a yeast extract. The culture is, for example, a static culture. The carbon source includes, for example, glucose, mannitol, molasses, fructose, sucrose, etc. The nitrogen source is such as peptone. Further, a weight ratio of the carbon source, the nitrogen source, and the yeast extract may be 60:6:6 to 15:3:0; or 60:6:6 to 15:3:0.5; or 60:6:6 to 15:3:1; or 60:6:6 to 15:3:2; or 60:6:6 to 15:3:3; or 60:6:6 to 15:3:4; or 60:6:6 to 15:3:5.
In one embodiment, the three-dimensional reticular structure has a plurality of backbone fibers parallel to each other and a plurality of interlayered fibers interwoven with any two adjacent backbone fibers, wherein the plurality of backbone fibers and the plurality of interlayered fibers are interwoven with each other to form nano-sized pores. In another embodiment, the backbone fibers and the interlayered fibers are made of bio-celluloses, and a diameter of the backbone fiber is greater than or equal to a diameter of the interlayered fiber.
In one embodiment, the bio-cellulose has a diameter of 20 to 100 nm.
In one embodiment, the bio-cellulose film has a bio-cellulose content of 0.0013 to 0.0018 g/cm2 per unit area.
In one embodiment, the negative pressure wound dressing comprises a drug. For example, the drug for promoting wound healing, e.g., antibacterial or anti-inflammatory, and promotion of cell growth, includes but is not limited to, at least one selected from the group consisting of antibiotics, antibacterial agents, growth factors, fibrin, vasodilators, angiogenesis promoters, antioxidants, and anti-inflammatory agents. More specifically, the drug is contained in the foam, in the bio-cellulose film, or in both of the foam and the bio-cellulose film.
In one embodiment, the foam comprises at least one material selected from the group consisting of polyurethane foam, polyvinyl alcohol foam, polyether foam, polyester foam, polylactic acid foam, polyolefin foam, chitosan foam, cellulose foam, alginate foam, gelatin foam, and collagen foam.
In another embodiment, the foam has a multilayer structure, including, e.g., a contact layer, an absorption layer and a drainage layer, wherein the contact layer is in contact with the bio-cellulose film.
The present application also provides a negative pressure wound treatment device, comprising: the negative pressure wound dressing; a liquid delivery tube connected to the negative pressure wound dressing; and a negative pressure source.
In one embodiment, the negative pressure wound treatment device further comprises a sealing film, which is disposed on the negative pressure wound dressing and is used to cover a wound and a normal skin outside the wound.
In another embodiment, an opening is provided in the center of the sealing film and penetrates through two opposite surfaces of the sealing film, and one end of the liquid delivery tube extends through the opening to the foam of the negative pressure wound dressing.
In one embodiment, the negative pressure wound treatment device further comprises a liquid-collecting tank connected to the other end of the liquid delivery tube, and the liquid-collecting tank is connected to the negative pressure source through a connecting tube.
The negative pressure wound dressing of the present application is bonded to the surface of the foam through the bio-cellulose film. When performing the negative pressure wound treatment (NPWT), the bio-cellulose film exists between the foam filled in the wound and the wound surface. When changing the dressing, it can avoid the wound adhering to the material, and reduce the severe pain in the patient. Further, since the bio-cellulose film has a three-dimensional reticular structure and the three-dimensional reticular structure has nano-sized pores formed by interweaving backbone fibers and interlayered fibers, it has excellent gas permeability, and does not damage the negative pressure environment. On the other hand, the nano-sized pores of the bio-cellulose film and the pores of the foam can also carry drugs, which can release the drug on the surface of the wound while sucking out the pus and the infectious substance, so as to promote the healing of the wound.
The examples of the present application are described below by way of embodiments, and those skilled in the art can readily appreciate the advantages and functions of the present application from the disclosure herein. The present application may be embodied or applied by other different embodiments. The details of the present specification may also be based on different opinions and applications, and various modifications and changes may be made without departing from the spirit of the present application. In addition, all ranges and values herein are inclusive and combinable. Any value or point falling within the ranges recited herein, such as any integer, may be the minimum or maximum value to derive the lower range and the like.
In the preparation of the negative pressure wound dressing in the present application, the foam is placed on a bottom surface or fixed in a container with a culture medium, and the liquid level of the culture medium is slightly higher than the foam. The foam is completely immersed in the culture medium, and statically culturing bacteria of at least one genus selected from the group consisting of genus Gluconacetobacter, Acetobacter, Rhizobium, Sarcina, Pseudomonas, Achromobacter, Alcaligenes, Enterobacter, Azotobacter and Agrobacterium in the culture medium, preferably, bacteria of one single genus such as genus Gluconacetobacter or Acetobacter. The culture time is preferably 24 to 96 hours. After the culture, the bio-cellulose film is formed on the foam, and the bio-cellulose film is bonded to the surface of the foam, wherein the culture medium includes a carbon source, a nitrogen source, and a yeast extract.
The projected area of the foam on the horizontal plane needs to be less than or equal to the solution surface area of the culture medium, so that the projected area of the bio-cellulose film, which formed by the gas-liquid interface, on the surface where the foam is bonded to the bio-cellulose film is greater than or equal to the projected area of the foam.
As shown in
In one embodiment, the culture medium comprises mannitol as a carbon source, peptone as a nitrogen source, and, optionally, a yeast extract, in a ratio by weight of 60:6:6 to 15:3:0. The culture medium is controlled to be acidic, for example, with a pH of between 0.5 and 6.5, the absorbance value reflecting the microbial concentration in the culture medium (wavelength setting of 620 nm) is controlled in the range of between 0.006 to 0.01, culture temperature is between 25 to 28° C., and the culture time is 24 to 96 hours. After testing, the bio-cellulose film has a thickness of at least 0.3 to 0.6 mm, and the bio-cellulose in the bio-cellulose film has a diameter of about 20 to 100 nm. Further, the bio-cellulose film has a bio-cellulose content of from 0.0013 to 0.0018 g/cm2 per unit area.
The static culture refers to the bacteria form a bio-cellulose in a non-woven manner on the surface of the culture medium; the bio-cellulose accumulates and extends from the surface of the culture medium toward the bottom of the container; then accumulated bio-cellulose gradually touches the surface of the foam; and finally, the bio-cellulose grows into the foam, such that the bio-cellulose film is bonded with the foam.
In addition, the container for static culture is preferably a flat container, which means that a height of the container is lower relative to a length and width of the container; through a lower container height and a wider growth area, the oxygen consumption of bacteria is controlled, so as to regulate the diameter of the bio-cellulose.
In one embodiment, the bio-cellulose film is formed by statically culturing bacteria of the genus Gluconacetobacter in a culture medium having mannitol, peptone, and yeast extract for fermentation.
The bacteria of the genus Gluconacetobacter are preferably Gluconacetobacter xylinum, which is characterized in that it is easy to control the degree of the thickness of the obtained bio-cellulose.
In one embodiment, the bio-cellulose film of the negative pressure wound dressing in the present application, which has a three-dimensional reticular structure, is as shown in
Referring to
The foam in the present application is not limited, as long as it is an open cell and biocompatible foam. For example, Polyurethane foam, polyvinyl alcohol foam, polyether foam, polyester foam, polylactic acid foam, polyolefin foam, chitosan foam, cellulose foam, alginate foam, gelatin foam and collagen foam.
The foam is made of a single material or is made of a plurality of materials to form a foam having a composite structure. Further, the foam may have a multilayer structure, which refers to the layers each are continuous and the same in material, but have different physical properties such as density, porosity, permeability, compression ratio, etc. The physical properties can be obtained by adjusting various parameters during the manufacturing process. Also, the multilayer structure may refer to the layers each are different in materials, for example, a layered structure of polyurethane and polyvinyl alcohol. The layers each in the multilayer structure can provide different functions as desired, such as contact layers, absorption layers and drainage layers.
The foam of the negative pressure wound dressing in the present application can be a single layer structure, besides, in an embodiment as shown in
After the bio-cellulose film is formed on and bond to the foam, the negative pressure wound dressing in the present application is formed. Then the obtained negative pressure wound dressing is washed to be neutral. The washing method is, for example, boiling with 1% of NaOH solution at 80° C. or higher for 15 minutes, then washed with water.
The washed negative wound dressing is then subjected to sterilization treatment. The sterilization treatment includes, but not limited to, autoclaving, gamma irradiation sterilization, ethylene oxide (EO) sterilization, and the like. Preferably, the autoclaving is used, for example, at 1.2 atm and 121° C., for 20 minutes.
The negative pressure wound dressing of the present application may further comprise a drug. In one embodiment, the drug can be added after the washing procedure. Since the bio-cellulose film and the foam both have pores, the drug can be kept in the bio-cellulose film, in the foam, or in both of them. For example, the drug for promoting wound healing, such as antibacterial, anti-inflammatory, and promoting cell growth drugs can be selected. The drug includes but is not limited to, at least one selected from the group consisting of antibiotics, antibacterial agents, growth factors, fibrin, vasodilators, angiogenesis promoters, antioxidants, and anti-inflammatory agents.
The negative pressure wound dressing of the present application can be applied to the negative pressure wound therapy (NPWT). In one embodiment, the negative pressure wound dressing and the sealing film, the liquid delivery tube, the liquid-collecting tank and the negative pressure source constitute a negative pressure wound treatment device. Specifically, the negative pressure wound treatment device of the present application can be implemented as shown in the schematic diagrams of
As shown in
The shape and volume of the foam 10 must be compatible with the wound 440. Before filling the foam 10 into the wound 440, the foam 10 can be appropriately trimmed so that the bio-cellulose film 12 is completely adhered to the surface of the wound 440 and the foam 10 is approximately flush with normal skin at injured site 44 outside the wound 440.
As shown in
As shown in
Due to the barrier of the bio-cellulose film between the foam and the wound surface, wherein the bio-cellulose film has excellent anti-adhesion properties, therefore, the negative pressure wound dressing of the present application does not stick to the wound, and the new tissue does not grown into the foam, reducing the pain that the patient suffers when replacing the negative pressure wound dressing, and greatly decreasing the secondary damage to the wound. By leaving the drug in the pores of the foam and/or bio-cellulose film, the drug can be further released to the wound during the treatment, promoting the healing of the wound.
| Number | Date | Country | Kind |
|---|---|---|---|
| 108201730 | Feb 2019 | TW | national |
